HK40009791B - Fused tricyclic pyridazinone compounds useful to treat orthomyxovirus infections - Google Patents

Description

Fused tricyclic pyridazinone compounds for treating orthomyxovirus infections

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Application No. 62/380,712, filed August 29, 2016, the contents of which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates to compounds that inhibit the replication of orthomyxoviruses, and are therefore useful in treating viral infections caused by orthomyxoviruses. The present invention also provides pharmaceutical compositions containing these compounds, and methods of using these compounds to treat or prevent viral infections caused by orthomyxoviruses.

Background Art

Orthomyxoviruses have a negative-sense, single-stranded RNA genome and replicate in the nucleus of infected cells because they lack the machinery to generate a cap structure to produce their own mRNA. Members of the Orthomyxoviridae family possess an RNA-dependent RNA polymerase with endonuclease activity that cleaves the capped 5' end of cellular mRNA; the RNA polymerase then uses the cleavage product as a primer for viral mRNA synthesis. This process is known as "cap-snatching." This endonuclease has been identified as a promising target for the development of antiviral drugs effective against Orthomyxoviruses. ACS Med. Chem. Letters, 2014, Vol. 5, 61-64. Inhibitors of this endonuclease have been disclosed, for example, in WO 2015/038660, U.S. Pat. No. 8,987,441, WO 2010/147068, and U.S. Patent Application Nos. US2012/022251, US2013/0197219, US2014/256937, and US2015/0072982, which report the use of these inhibitors for treating influenza infection in mammals.

The Orthomyxoviridae family includes influenza A, B, and C (all of which can infect humans), as well as several other genera of viruses that do not normally infect humans. Influenza A is the most virulent of these human pathogens and often causes large-scale severe cases during a typical flu season. An estimated 40,000 people die from influenza each year in the United States, although widespread use of vaccines has reduced the incidence of influenza; therefore, there is still a great need for antiviral therapeutics that are effective in treating influenza, especially influenza A. The present invention provides compounds that inhibit the replication of orthomyxoviruses (including influenza A, influenza B, and influenza C). Without being limited by theory, it is believed that these compounds achieve their antiviral effect by inhibiting the endonuclease function of the viral polymerase. Because this endonuclease is highly conserved among influenza A viruses (ibid.), these compounds are particularly suitable for treating influenza A.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides compounds of formula (A):

As further described herein.

In another aspect, the present invention provides compounds of formula (I):

or a pharmaceutically acceptable salt thereof, wherein:

R ¹ is H, halogen, CN, COOR*, -CONR* ₂ , or C ₁ -C ₆ alkyl, C ₁ -C ₄ haloalkyl which may be optionally substituted with one or two groups selected from -OR* and -NR* ₂ ;

R*, at each occurrence, is independently H or C ₁ -C ₆ alkyl, which may be optionally substituted with —OR or —NR ₂ ;

Z ¹ is N, and Z ² is C(R) ₂ ;

or Z ¹ is CH, and Z ² is NR, O, S, or CH ₂ ;

Z ³ is CH ₂ , Q, -CH ₂ -CH ₂ -, -Q-CH ₂ -, –CH ₂ -Q-, -CH ₂ -Q-CH ₂ - or -CH ₂ -CH ₂ -CH ₂ -;

Q is selected from –NR-, O, S, SO and SO ₂ ;

R ² is selected from H, halogen, CN, C _1-4 alkyl, OR and C _1-4 haloalkyl which may be optionally substituted with up to three groups independently selected from halogen, CN, C _1-4 alkyl, -OR, C _1-4 haloalkoxy _, -NR ₂ , and C _1-4 haloalkyl;

each R ³ is a substituent that may optionally be present on any carbon atom of the ring containing Z ² and Z ³ , and is independently selected from -OR, C _1-4 haloalkyl, C _1-4 haloalkoxy, oxo, CN, -NR ₂ , and C _1-4 alkyl that may be optionally substituted with up to three groups independently selected from halogen, CN, C _1-4 alkyl, -OR, C _1-4 haloalkoxy, -NR ₂ and C _1-4 haloalkyl;

n is 0-2;

Ar ¹ and Ar ² each independently represent phenyl or a 5-6 membered heteroaromatic ring containing 1-3 heteroatoms selected from N, O and S as ring members, and each independently substituted by up to three of the following groups: halogen, C _1-4 alkyl, C _1-4 haloalkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, C _2-4 alkyne and CN;

and Ar ¹ and Ar ² may optionally be linked together by a bridge of formula -C( ^RL ) ₂ -L- to form a tricyclic group, wherein Ar ¹ and Ar ² are each independently substituted with up to two groups independently selected from the group consisting of halogen, _C1-4 alkyl, _C1-4 haloalkyl, _C1-4 alkoxy, _C1-4 haloalkoxy, _C2-4 alkyne, and CN;

R, at each occurrence, is independently H or C ₁ -C ₄ alkyl optionally substituted with up to three groups independently selected from the group consisting of halogen, OH, oxo, C _1-4 alkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, and C _1-4 haloalkyl;

L is selected from S, S=O, SO ₂ , O, NR, C( ^RL ) ₂ and CF ₂ ; and

Each ^RL is independently H or _C1-2 alkyl;

As further described herein.

The present invention includes these compounds, pharmaceutically acceptable salts thereof, compositions and combinations comprising these compounds (including pharmaceutically acceptable salts), and methods of use thereof, as further described below.

The compounds of formula (A) are inhibitors of influenza virus endonuclease function (as shown by the data provided herein) and inhibit influenza virus replication. Therefore, these compounds are useful for treating or preventing orthomyxovirus infection in mammals susceptible to orthomyxovirus infection, and are particularly useful for treating influenza virus infection in humans. They are also useful for inhibiting the replication of orthomyxoviruses (including influenza viruses) in cells.

In another aspect, the present invention provides a pharmaceutical composition comprising a compound of formula (A) in admixture with at least one pharmaceutically acceptable carrier or excipient, optionally in admixture with two or more pharmaceutically acceptable carriers or excipients. The compound may be used as a pharmaceutically acceptable salt.

In another aspect, the present invention provides a method for treating a subject infected with influenza A, B, or C virus, comprising administering to a subject in need of such treatment an effective amount of a compound of formula (A), or any subgenus or species described herein, or a pharmaceutical composition comprising the compound. The subject can be a mammal, preferably a human, although the compounds and methods of the present invention are suitable for treating other species exposed to influenza A, B, or C virus and other orthomyxoviruses. The present invention includes compounds of formula (A) and its subgenus Formula (I) described herein, as well as all stereoisomers (including diastereomers and enantiomers), except for specific isomers specifically indicated, tautomers thereof, and isotopically enriched forms thereof (including deuterated substitutions), and pharmaceutically acceptable salts of these compounds. Compounds of the present invention also include polymorphs of compounds of formula (A) (or its subformulas) and salts thereof.

DETAILED DESCRIPTION

Unless otherwise stated, the following definitions apply:

As used herein, "halogen" or "halo" refers to fluorine, bromine, chlorine, or iodine, typically fluorine or chlorine, especially when attached to an alkyl group, and also includes bromine or iodine when attached to an aryl or heteroaryl group.

As used herein, unless otherwise specified, the term "heteroatom" refers to a nitrogen (N), oxygen (O), or sulfur (S) atom.

The term "alkyl" as used herein refers to a fully saturated branched or unbranched hydrocarbon moiety with up to 10 carbon atoms. Unless otherwise provided, an alkyl group refers to a hydrocarbon moiety with 1-6 carbon atoms. Representative examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, etc. Substituted alkyl groups are alkyl groups containing one or more, such as one, two or three (up to the number of hydrogen atoms present on the unsubstituted alkyl group) substituents of a hydrogen atom. Unless otherwise specified, suitable alkyl substituents may be selected from halogen, CN, oxo, hydroxy, C _1-4 alkoxy, substituted or unsubstituted C _3-6 cycloalkyl, substituted or unsubstituted phenyl, amino, (C _1-4 alkyl)amino, di(C _1-4 alkyl)amino, C _1-4 alkylthio, C _1-4 alkylsulfonyl, —C(═O)—C _1-4 alkyl, COOH, COO(C _1-4 alkyl), —O(C═O)—C _1-4 alkyl, —NHC(═O)C _1-4 alkyl and —NHC(═O)OC _1-4 alkyl groups, wherein the substituents of the substituted cycloalkyl or phenyl groups are up to three groups selected from the group consisting of Me, Et, —OMe, —OEt, CF ₃ , halogen, CN, OH, and NH ₂ .

As used herein, the term "alkylene" refers to a divalent alkyl group having 1-10 carbon atoms and two open valences in combination with other features. Unless otherwise provided, alkylene refers to a moiety having 1-6 carbon atoms. Representative examples of alkylene include, but are not limited to, methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, neopentylene, n-hexylene, 2,2-dimethylbutylene, and the like. Substituted alkylene is an alkylene group containing one or more, e.g., one, two, or three, substituents; unless otherwise specified, suitable substituents for alkylene are selected from the alkyl substituents listed above.

As used herein, the term "haloalkyl" refers to an alkyl group, as defined herein, substituted with one or more halogen groups. A haloalkyl group may be monohaloalkyl, dihaloalkyl, trihaloalkyl, or polyhaloalkyl, including perhaloalkyl. A monohaloalkyl group may contain one chlorine or fluorine within the alkyl group. Chlorine and fluorine are common substituents on alkyl or cycloalkyl groups; fluorine, chlorine, and bromine are commonly found on aryl or heteroaryl groups. Dihaloalkyl and polyhaloalkyl groups may contain two or more identical halogen atoms or a combination of different halo groups on the alkyl group. Typically, a polyhaloalkyl group contains up to 12, 10, 8, 6, 4, 3, or 2 halo groups. Non-limiting examples of haloalkyl groups include fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl, trichloromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, heptafluoropropyl, difluorochloromethyl, dichlorofluoromethyl, difluoroethyl, difluoropropyl, dichloroethyl, and dichloropropyl. Perhaloalkyl refers to an alkyl group in which all hydrogen atoms are replaced by halogen atoms, such as trifluoromethyl.

The term "alkoxy" as used herein refers to an alkyl-O- group, wherein alkyl is as defined above. Representative examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, 2-propoxy, butoxy, tert-butoxy, pentoxy, hexoxy, and the like. Typically, an alkoxy group has 1 to 6 carbon atoms, more typically 1 to 4 carbon atoms.

"Substituted alkoxy" is an alkoxy group containing one or more, e.g., one, two, or three, substituents on the alkyl portion of the alkoxy group. Unless otherwise specified, suitable substituents are selected from the substituents listed above for alkyl groups, except that hydroxy and amino groups are generally not present on the carbon atom directly bonded to the oxygen atom of a substituted "alkyl-O" group.

Similarly, the alkyl moieties in other groups such as "alkylaminocarbonyl," "alkoxyalkyl," "alkoxycarbonyl," "alkoxy-carbonylalkyl," "alkylsulfonyl," "alkylsulfoxyl," "alkylamino," and "haloalkyl" shall have the same meaning as described above in the definition of "alkyl." When used as such, unless otherwise specified, alkyl groups are typically 1-4 carbon alkyl groups that are not substituted with other groups other than the indicated moiety. When these alkyl groups are substituted, suitable substituents are those mentioned above for alkyl groups, unless otherwise specified.

The term "haloalkoxy" as used herein refers to a haloalkyl-O- group, wherein haloalkyl is as defined above. Representative examples of haloalkoxy include, but are not limited to, fluoromethoxy, difluoromethoxy, trifluoromethoxy, trichloromethoxy, 2-chloroethoxy, 2,2,2-trifluoroethoxy, 1,1,1,3,3,3-hexafluoro-2-propoxy, and the like. Typically, a haloalkyl group has 1 to 4 carbon atoms.

As used herein, the term "cycloalkyl" refers to a saturated or unsaturated non-aromatic monocyclic, bicyclic, tricyclic, or spirocyclic hydrocarbon radical having 3 to 12 carbon atoms: a cycloalkyl radical may be unsaturated and may be fused to another ring which may be saturated, unsaturated, or aromatic, provided that the cycloalkyl ring atom attached to the molecular formula of interest is not an aromatic ring carbon atom. Unless otherwise provided, a cycloalkyl radical refers to a cyclic hydrocarbon radical having 3 to 9 ring carbon atoms or having 3 to 7 ring carbon atoms. Preferably, a cycloalkyl radical is a saturated monocyclic ring having 3 to 7 ring atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl, unless otherwise specified.

Substituted cycloalkyl is a cycloalkyl substituted by one or two, or three or more than three substituents up to the number of hydrogen atoms on the unsubstituted group. Typically, substituted cycloalkyl has 1-4 substituents, unless otherwise stated. Unless otherwise stated, suitable substituents are independently selected from the following: halogen, hydroxy, thiol, cyano, nitro, oxo, C1-C4-alkylimino, C1-C4-alkoxyimino, hydroxyimino, C1-C4-alkyl, C2-C4-alkenyl, C2-C4-alkynyl, C1-C4-alkoxy, C1-C4-thioalkyl, C2-C4-alkenyloxy, C2-C4-alkynyloxy, C1-C4-alkylcarbonyl, carboxyl, C1-C4-alkoxycarbonyl, amino, C1-C4-alkylamino, di -C1-C4-alkylamino, C1-C4-alkylaminocarbonyl, di-C1-C4-alkylaminocarbonyl, C1-C4-alkylcarbonylamino, C1-C4-alkylcarbonyl(C1-C4-alkyl)amino, C1-C4-alkylsulfonyl, C1-C4-alkylsulfamoyl and C1-C4-alkylaminosulfonyl, wherein each of the above-mentioned hydrocarbon groups (e.g., alkyl, alkenyl, alkynyl, alkoxy) at each occurrence may be further substituted with one or more groups independently selected from the list of "alkyl" substituents herein. Preferred substituents for cycloalkyl include C1-C4-alkyl, as well as the substituents listed above for suitable substituents for alkyl.

Exemplary monocyclic hydrocarbon groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, and cyclohexenyl, etc. Exemplary bicyclic hydrocarbon groups include bornyl, indolyl, hexahydroindolyl, tetrahydronaphthyl, decahydronaphthyl, bicyclo[2.1.1]hexyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.1]heptenyl, 6,6-dimethylbicyclo[3.1.1]heptyl, 2,6,6-trimethylbicyclo[3.1.1]heptyl, bicyclo[2.2.2]octyl, etc. Exemplary tricyclic hydrocarbon groups include adamantyl, etc.

Similarly, the cycloalkyl moiety of other groups, such as "cycloalkoxy," "cycloalkoxyalkyl," "cycloalkoxycarbonyl," "cycloalkoxy-carbonylalkyl," "cycloalkylsulfonyl," and "halocycloalkyl," shall have the same meaning as described above in the definition of cycloalkyl. When used in these terms, cycloalkyl is typically a monocyclic ring of 3 to 7 carbon atoms, unsubstituted or substituted with 1 to 2 groups. When optionally substituted, the substituents are typically selected from C1-C4 alkyl and those listed above as suitable alkyl groups.

As used herein, the term "aryl" refers to an aromatic hydrocarbon radical having 6-14 carbon atoms in the ring portion. Typically, an aryl radical is a monocyclic, bicyclic, or tricyclic aromatic radical having 6-14 carbon atoms, often 6-10 carbon atoms, such as phenyl or naphthyl. Additionally, as used herein, the term "aryl" refers to an aromatic substituent, which may be a monocyclic aromatic radical or a plurality of aromatic rings fused together. Non-limiting examples include phenyl, naphthyl, and 1,2,3,4-tetrahydronaphthyl, provided that the tetrahydronaphthyl radical is attached to the formula through a carbon on the tetrahydronaphthyl aromatic ring. Unless otherwise indicated, a preferred aryl radical is phenyl.

Substituted aryl is aryl substituted with 1 to 5 (e.g., one or two or three) substituents independently selected from the group consisting of hydroxy, thiol, cyano, nitro, C ₁ -C ₄ -alkyl, C 2 -C 4 -alkenyl, C ₂ -C ₄ -alkynyl, C ₁ -C ₄ -alkoxy, C ₁ -C ₄ -thioalkyl, C ₂ -C ₄ -alkenyloxy, C ₂ -C ₄ -alkynyloxy, halogen, C ₁ -C ₄ -alkylcarbonyl, carboxyl, C ₁ -C ₄ -alkoxycarbonyl, amino, C ₁ -C ₄ -alkylamino, di- _{C 1 -C 4} -alkylamino, C ₁ -C ₄ -alkylaminocarbonyl, di-C _{1 -C 4 -alkylaminocarbonyl} , C ₁ -C ₄ -alkylcarbonylamino, C ₁ -C ₄ -alkylcarbonyl(C ₁ -C ₄ -alkyl)amino, C ₁ - _C4 -alkylsulfonyl, sulfamoyl, _C1 - _C4 -alkylsulfamoyl and _C1 - _C4 -alkylaminosulfonyl, wherein each of the above-mentioned hydrocarbon groups (e.g., alkyl, alkenyl, alkynyl, alkoxy) at each occurrence may be further substituted by one or more groups independently selected from the list of suitable substituents for alkyl groups herein. Preferred substituents for substituted aryl groups are _C1-4- alkyl and the groups listed above as suitable substituents for alkyl groups, except divalent groups such as oxo.

Similarly, each aryl portion of other groups such as "aryloxy", "aryloxyalkyl", "aryloxycarbonyl", "aryloxy-carbonylalkyl" shall have the same meaning as described in the above definition of aryl.

The term "heterocyclyl" as used herein refers to a heterocyclic group that is saturated or partially unsaturated, but not aromatic, and can be monocyclic or polycyclic (for polycyclics, particularly bicyclic, tricyclic or spirocyclic); and has 3-14, more commonly 4-10, more preferably 5 or 6 ring atoms; wherein one or more, preferably 1-4, especially 1 or 2 ring atoms are heteroatoms independently selected from O, S, and N (the remaining ring atoms are therefore carbon). Even if it is described as, for example, a C5-6 atom ring, the heterocycle contains at least one heteroatom as a ring atom, while the other ring atoms are carbon and have the number of ring atoms, i.e., 5-6 in this example. Preferably, the heterocyclic group has 1 or 2 heteroatoms as such ring atoms, and preferably the heteroatoms are not directly connected to each other. The bonded ring (i.e., the ring connected to the formula of interest) preferably has 4-12, especially 5-7 ring atoms, unless otherwise stated. The heterocyclic group may be fused to an aromatic ring, provided that the atoms of the heterocyclic group connected to the formula of interest are not aromatic. Heterocyclic group can be combined with the formula of interest by the heteroatom (usually nitrogen) or carbon atom of heterocyclic group.Heterocyclic group can include condensed or bridged rings, and spirocycles, and only one ring of polycyclic heterocyclic group needs to contain the heteroatom as ring atom.The example of heterocyclic group includes tetrahydrofuran (THF), dihydrofuran, 1,4-dioxane, morpholine, 1,4-dithiane, piperazine, piperidine, 1,3-dioxolane, imidazolidine, imidazoline, pyrroline, pyrrolidine, tetrahydropyran, dihydropyran, oxathiolane (oxathiolane), dithiolane, 1,3-dioxane, 1,3-dithiane, oxathiolane, thiomorpholine etc.

Substituted heterocyclic groups are heterocyclic groups independently substituted with 1 to 5 (eg, one, two, or three) substituents selected from the substituents listed above for cycloalkyl groups.

Similarly, each heterocyclyl portion of other groups such as "heterocyclyloxy", "heterocyclyloxyalkyl" and "heterocyclyloxycarbonyl" shall have the same meaning as described in the above definition of heterocyclyl.

The term "heteroaryl" as used herein refers to a 5-14 membered monocyclic, bicyclic or tricyclic aromatic ring system having 1-8 heteroatoms as ring atoms and the remaining ring atoms being carbon; the heteroatoms are selected from N, O and S. Typically, the heteroaryl group is a 5-10 membered ring system, especially a 5-6 membered monocyclic or 8-10 membered bicyclic group. Typical heteroaryl groups include 2- or 3-thienyl, 2- or 3-furyl, 2- or 3-pyrrolyl, 2-, 4- or 5-imidazolyl, 1-, 3-, 4- or 5-pyrazolyl, 2-, 4- or 5-thiazolyl, 3-, 4- or 5-isothiazolyl, 2-, 4- or 5-oxazolyl, 3-, 4- or 5-isoxazolyl, 3- or 5-1,2,4-triazolyl, 4- or 5-1,2,3-triazolyl, 1- or 2-tetrazolyl, 2-, 3- or 4-pyridinyl, 3- or 4-pyridazinyl, 3-, 4- or 5-pyrazinyl, 2-pyrazinyl and 2-, 4- or 5-pyrimidinyl.

The term "heteroaryl" also refers to a group in which a heteroaromatic ring is fused to one or more aryl, cycloalkyl, or heterocyclic rings. Non-limiting examples include 2-, 3-, 4-, 5-, 6-, 7-, or 8-quinolyl, 1-, 3-, 4-, 5-, 6-, 7-, or 8-isoquinolyl, 2-, 3-, 4-, 5-, 6-, or 7-indolyl, 2-, 3-, 4-, 5-, 6-, or 7-benzo[b]thienyl, 2-, 4-, 5-, 6-, or 7-benzoxazolyl, 2-, 4-, 5-, 6-, or 7-benzimidazolyl, and 2-, 4-, 5-, 6-, or 7-benzothiazolyl.

Substituted heteroaryl groups are heteroaryl groups that contain one or more substituents, typically one or two substituents, selected from the substituents listed above as suitable for aryl groups.

Similarly, each heteroaryl portion of other groups such as "heteroaryloxy", "heteroaryloxyalkyl" and "heteroaryloxycarbonyl" shall have the same meaning as described in the above definition of "heteroaryl".

Various embodiments of the present invention are described herein. It should be appreciated that the features described in each embodiment can be combined with other described features to provide other embodiments of the present invention. The embodiments listed below are representative aspects of the invention:

In one embodiment, the present invention provides a compound of formula (A):

or a pharmaceutically acceptable salt thereof, wherein:

Y is a group of the formula:

wherein the dotted line represents the bond connecting Y to the tricyclic core of formula (A);

G is H or a group selected from: –C(O)R ⁰ , –C(O)—OR ⁰ , –C( ^RG ) ₂ -OC(O)R ⁰ , –C( ^RG ) ₂ -OC(O)—OR ⁰ , –C(O)—N(R ⁰ ) ₂ , and –C( ^RG ) ₂ -OC(O)N(R ⁰ ) ₂ , wherein each R ⁰ is independently H or a group selected from: C ₁ -C ₆ alkyl, phenyl, pyridyl, C ₃ -C ₇ cycloalkyl, and a 3-6 membered heterocycle containing one or two heteroatoms selected from N, O, and S as ring atoms; and each R ⁰ that is not H may be optionally substituted by one or two groups selected from: halogen, CN, –OH, amino, C _1-4 alkyl, phenyl, C _1-4 alkoxy, C _1-4 haloalkyl, and C _1-4 haloalkoxy;

and each R ^G is independently selected from H and C _1-4 alkyl;

R ¹ is H, halogen, CN, COOR*, -CONR* ₂ , or C ₁ -C ₆ alkyl, C ₁ -C ₄ haloalkyl which may be optionally substituted by one or two groups selected from -OR* and -NR* ₂ ;

R*, at each occurrence, is independently H or C ₁ -C ₆ alkyl, which may be optionally substituted with —OR or —NR ₂ ;

Z ¹ is N, and Z ² is C(R) ₂ ;

or Z ¹ is CH, and Z ² is NR, O, S, or CH ₂ ;

Z ³ is CH ₂ , Q, -CH ₂ -CH ₂ -, -Q-CH ₂ -, –CH ₂ -Q-, -CH ₂ -Q-CH ₂ - or -CH ₂ -CH ₂ -CH ₂ -;

Q is selected from –NR-, O, S, SO and SO ₂ ;

R ² is selected from H, halogen, CN, C _1-4 alkyl, OR, C _1-4 haloalkoxy, -NR ₂ and C _1-4 haloalkyl, OR and C ₁ - _{C 4} haloalkyl;

each R ³ is a substituent which may be optionally present on any carbon atom of the ring containing Z ² and Z ³ and is independently selected from —OR, C _1-4 haloalkyl, C _1-4 haloalkoxy, oxo, CN, —NR ₂ , and C _1-4 alkyl which may be optionally substituted with up to three groups independently selected from halogen, CN, C _1-4 alkyl, —OR, C _1-4 haloalkoxy, —NR ₂ , and C _1-4 haloalkyl;

n is 0-2;

Ar ¹ and Ar ² each independently represent phenyl or a 5-6 membered heteroaromatic ring containing 1-3 heteroatoms selected from N, O and S as ring members, and each independently substituted by up to three groups selected from the group consisting of halogen, C _1-4 alkyl, C _1-4 haloalkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, C _2-4 alkyne and CN;

and Ar ¹ and Ar ² may be optionally linked together by a bridge of formula -C( ^RL ) ₂ -L- to form a tricyclic group, wherein Ar ¹ and Ar ² may each be optionally substituted with up to two groups independently selected from the group consisting of halogen, _C1-4 alkyl, _C1-4 haloalkyl, _C1-4 alkoxy, _C1-4 haloalkoxy, _C2-4 alkyne, and CN;

R, at each occurrence, is independently H or C ₁ -C ₄ alkyl optionally substituted with up to three groups selected from the group consisting of halogen, OH, oxo, C _1-4 alkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, and C _1-4 haloalkyl;

L is selected from S, S=O, SO ₂ , O, NR, C( ^RL ) ₂ and CF ₂ ; and

Each ^RL is independently H or _C1-2 alkyl.

Compounds of formula (A) wherein G is not H may act as prodrugs, which are readily converted into compounds wherein G is H in vivo.

In one embodiment of the compound of formula (A), G is H.

In another embodiment of the compounds of formula (A), G is selected from the group consisting of: –C(O)R ⁰ , –C(O)-OR ⁰ , –C( ^RG ) ₂ -OC(O)R ⁰ , –C( ^RG ) ₂ -OC(O)-OR0, –C(O)-N(R0) ₂ , and –C( ^RG ) ₂ -OC(O)N(R ⁰ ) ₂ , wherein each R ⁰ is independently H or a group selected from the group consisting of: C ₁ -C ₄ alkyl, phenyl, pyridyl, C ₃ -C ₇ cycloalkyl, and a 3-6 membered heterocycle containing one or two heteroatoms selected from N, O, and S as ring atoms; and each R that is not H may be optionally substituted with one or two of the following groups: halogen, CN, –OH, amino, C _1-4 alkyl, phenyl, C _1-4 alkoxy, C _1-4 haloalkyl, and C _1-4 haloalkoxy.

In some embodiments of the above, G is selected from —C(O)R ⁰ , —C(O)—OR ⁰ , —C( ^RG ) ₂ —OC(O)R ⁰ , and —C( ^RG ) ₂ —OC(O)—OR ⁰ , wherein each R ⁰ is independently H or C ₁ -C ₄ alkyl, and each ^RG is H or C ₁ -C ₄ alkyl. In some of these embodiments, each ^RG is H, and R ⁰ is C ₁ -C ₄ alkyl.

In some of the above embodiments, the compound of formula (A) is the following:

or a pharmaceutically acceptable salt thereof.

In some compounds of this formula, Z ² is CH ₂ , Z ³ is CH ₂ , n is 0, 1 or 2, and each R ³ is Me.

In another embodiment (Embodiment 1), the present invention provides a compound of formula (I):

or a pharmaceutically acceptable salt thereof, wherein:

R ¹ is H, halogen, CN, COOR*, -CONR* ₂ , or C ₁ -C ₆ alkyl, C ₁ -C ₄ haloalkyl which may be optionally substituted with one or two groups selected from -OR* and -NR* ₂ ;

R*, at each occurrence, is independently H or C ₁ -C ₆ alkyl, optionally substituted with -OR or -NR ₂ ;

Z ¹ is N, and Z ² is C(R) ₂ ;

or Z ¹ is CH, and Z ² is NR, O, S, or CH ₂ ;

Z ³ is CH ₂ , Q, -CH ₂ -CH ₂ -, -Q-CH ₂ -, –CH ₂ -Q-, -CH ₂ -Q-CH ₂ - or -CH ₂ -CH ₂ -CH ₂ -;

Q is selected from -NR-, O, S, SO, and SO ₂ ;

R ² is selected from H, halogen, CN, C _1-4 alkyl, -OR, C _1-4 haloalkoxy, -NR ₂ and C _1-4 haloalkyl, OR and C ₁ - _{C 4} haloalkyl;

each R ³ is a substituent which may be optionally present on any carbon atom of the ring containing Z ² and Z ³ and is independently selected from -OR, C _1-4 haloalkyl, C _1-4 haloalkoxy, oxo, CN, -NR ₂ , and C _1-4 alkyl which may be optionally substituted with up to three groups independently selected from halogen, CN, C _1-4 alkyl, -OR, C _1-4 haloalkoxy, -NR ₂ and C _1-4 haloalkyl;

n is 0-2;

Ar ¹ and Ar ² each independently represent phenyl or a 5-6 membered heteroaromatic ring containing 1-3 heteroatoms selected from N, O and S as ring members, and each independently substituted by up to three of the following groups: halogen, C _1-4 alkyl, C _1-4 haloalkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, C _2-4 alkyne and CN;

and Ar ¹ and Ar ² may be optionally linked together by a bridge of formula -C( ^RL ) ₂ -L- to form a tricyclic group, wherein Ar ¹ and Ar ² may each be optionally substituted with up to two groups independently selected from the group consisting of halogen, _C1-4 alkyl, _C1-4 haloalkyl, _C1-4 alkoxy, _C1-4 haloalkoxy, _C2-4 alkyne, and CN;

R, at each occurrence, is independently H or C ₁ -C ₄ alkyl optionally substituted with up to three groups independently selected from the group consisting of halogen, OH, oxo, C _1-4 alkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, and C _1-4 haloalkyl;

L is selected from S, S=O, SO ₂ , O, NR, C( ^RL ) ₂ and CF ₂ ; and

Each ^RL is independently H or _C1-2 alkyl.

_In preferred embodiments of any of the compounds of formula (G) or formula (I) of the above embodiments, if ^Z2 is NR, O, or S, then ^Z3 is _CH2 , _CH2CH2 , _{or CH2CH2CH2 .}

The following numbered embodiments describe and illustrate certain aspects of the invention.

2. The compound of embodiment 1, or any embodiment of formula (A), or a pharmaceutically acceptable salt thereof, wherein Z ¹ is CH.

3. A compound according to embodiment 1 or embodiment 2, or any embodiment of formula (A), or a pharmaceutically acceptable salt thereof, wherein Z ¹ is N.

4. The compound of any one of embodiments 1-3, or any embodiment of formula (A), or a pharmaceutically acceptable salt thereof, wherein Z ² is CH ₂ or —CH ₂ —CH ₂ —.

5. The compound according to any one of the above embodiments, or a pharmaceutically acceptable salt thereof, wherein Z ³ is CH ₂ , —CH ₂ —CH ₂ —, —CH ₂ —CH ₂ —CH ₂ —, —CH ₂ —O—, or O.

6. The compound according to any one of the above embodiments, or a pharmaceutically acceptable salt thereof, wherein R ¹ is H.

7. A compound according to any one of the above embodiments, or a pharmaceutically acceptable salt thereof, wherein R ² is H.

8. A compound according to any of the above embodiments, or a pharmaceutically acceptable salt thereof, wherein Ar ¹ and Ar ² are both phenyl and are each independently substituted with up to two groups selected from the group consisting of halogen, C _1-4 alkyl, C _1-4 haloalkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, C _2-4 alkyne, and CN.

9. A compound according to any of the above embodiments, which is of the formula:

wherein Y represents a group selected from the following:

wherein each R ^y is independently selected from H, halogen, C _1-4 alkyl, C _1-4 haloalkyl, C _1-4 alkoxy, C _1-4 haloalkoxy, C _2-4 alkyne and CN,

or a pharmaceutically acceptable salt thereof.

10. The compound according to embodiment 9 or a pharmaceutically acceptable salt thereof, which is of the formula:

wherein Z ¹ is N or CH; and

Z ³ is CH ₂ or –CH ₂ -CH ₂ -.

11. A compound of embodiment 1 or any embodiment of formula (A) selected from Examples 1-149, or a pharmaceutically acceptable salt thereof. Each of the compounds of the Examples is a specific embodiment of the present invention, and thus the present invention provides a compound selected from the following:

1 12-Benzhydryl-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

2 12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

3 12-(bis(4-chlorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

4 12-(bis(3-chlorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

5 12-(bis(4-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

6 13-Benzhydryl-4-hydroxy-8,9,10,11-tetrahydro-7H,13H-pyridazino[1',6':4,5][1,2,4]triazino[1,2-a][1,2]diazepine-3,5-dione;

7 13-(Bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,10,11-tetrahydro-7H,13H-pyridazino[1',6':4,5][1,2,4]triazino[1,2-a][1,2]diazepine-3,5-dione;

8(R)-12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

9(S)-12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

10(9aR,10S)-10-benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

11(9aR,10R)-10-benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

12(9aS,10R)-10-benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

13(9aS,10S)-10-benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

14(9aR,10S)-10-((R)-(3-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

15(9aR,10R)-10-(bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

16(9aR,10S)-10-(bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

17(9aR,10R)-10-((S)-(3-chlorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

18(10aS,11R)-11-benzhydryl-4-hydroxy-7,8,10a,11-tetrahydro-10H-pyridazino[1',6':4,5]pyrazino[2,1-c][1,4]oxazine-3,5-dione;

19A 12-Benzhydryl-7-hydroxy-3,4,12,12a-tetrahydro-2H-pyridazino[1',6':4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione;

19B 12-Benzhydryl-7-hydroxy-3,4,12,12a-tetrahydro-2H-pyridazino[1',6':4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione;

20 11-(Bis(3-fluorophenyl)methyl)-4-hydroxy-8,9-dihydro-7H,11H-pyrazolo[1,2-a]pyridazino[1,6-d][1,2,4]triazine-3,5-dione;

21 12-(1,1-diphenylethyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

22 12-(bis(2-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

23A 12-Benzhydryl-4-hydroxy-10-methyl-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

23B 12-Benzhydryl-4-hydroxy-10-methyl-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

24 12-Benzhydryl-4-hydroxy-7-methyl-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

25A 12-Benzhydryl-4-hydroxy-7,10-dimethyl-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

25B 12-Benzhydryl-4-hydroxy-7,10-dimethyl-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

26A 12-(6,11-dihydrodibenzo[b,e]thia-11-yl(thiepin-11-yl))-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

26B 12-(6,11-dihydrodibenzo[b,e]thia-11-yl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

27A 12-(6,11-dihydrodibenzo[b,e]oxepin-11-yl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

27B 12-(6,11-dihydrodibenzo[b,e]oxepin-11-yl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

28A 12-(7,8-difluoro-6,11-dihydrodibenzo[b,e]thia-11-yl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

28B 12-(7,8-difluoro-6,11-dihydrodibenzo[b,e]thia-11-yl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

29(S)-12-Benzhydryl-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

30(S)-12-(bis(4-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

31(R)-12-(bis(4-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione;

32(9aR,10S)-10-((R)-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

33(9aR,10S)-10-((R)-(3,4-difluorophenyl)(2-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

34(9aR,10S)-10-((S)-(3,4-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

35(9aR,10S)-10-((R)-(2-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

36(9aR,10S)-10-((S)-(3,5-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

37(9aR,10S)-10-((S)-(4-fluoro-2-methylphenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

38(9aR,10S)-10-((S)-(3,4-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

39(9aR,10S)-10-((R)-(2-fluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

40(9aR,10S)-10-((R)-(3,5-difluorophenyl)(2-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

41(9aR,10S)-10-((R)-(4-fluoro-2-methylphenyl)(2-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

42(9aR,10S)-10-((R)-(2-fluorophenyl)(2-methoxyphenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

43(9aR,10S)-10-((R)-(2-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

44(9aR,10S)-10-(bis(2-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

45(9aR,10S)-10-((R)-(3,5-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

46(9aR,10S)-10-((R)-(2,6-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

47(9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

48(9aR,10S)-10-((R)-(2,6-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

49(9aR,10S)-10-((R)-(2,6-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

50(9aR,10S)-10-((S)-(3-fluorophenyl)(3,4,5-trifluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

51(9aR,10S)-10-((S)-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

52(9aR,10S)-10-((R)-(3,4-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

53(9aR,10S)-10-((S)-(3,4-difluorophenyl)(2-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

54(9aR,10S)-10-((S)-(3,5-difluorophenyl)(2-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

55(9aR,10S)-10-((S)-(2-fluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

56(9aR,10S)-10-((S)-(4-fluoro-2-methylphenyl)(2-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

57(9aR,10S)-10-((S)-(2-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

58(9aR,10S)-10-((S)-(4-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

59(9aR,10S)-10-((S)-(3-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

60(9aR,10S)-10-((S)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

61(9aR,10S)-10-((S)-(2,6-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

62(9aR,10S)-10-((S)-(2,6-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

63(9aR,10S)-10-((S)-(2,6-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

64(9aR,10S)-10-((R)-(3-fluorophenyl)(3,4,5-trifluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

65(9aR,10S)-10-((R)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

66(9aR,10S)-10-((R)-(4-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

67(9aR,10R)-10-((S)-(4-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

68(9aR,10S)-10-((R)-(4-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

69(9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

70(9aR,10S)-10-((S)-(3,4-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

71(9aR,10S)-10-((S)-(4-fluoro-2-methylphenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

72(9aR,10S)-10-((R)-(2,3-difluorophenyl)(2,4-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

73(9aR,10R)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

74(9aR,10S)-10-((R)-(2,3-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

75(9aR,10S)-10-((S)-(3,5-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

76(9aR,10S)-10-((S)-(3,4-difluorophenyl)(3,5-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

77(9aR,10S)-10-((R)-(3,4-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

78(9aR,10S)-10-(bis(3,4-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

79(9aR,10S)-10-(bis(2,4-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

80(9aR,10S)-10-((R)-(2,5-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

81(9aR,10S)-10-((R)-(2,5-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

82(9aR,10S)-10-((R)-(2,5-difluorophenyl)(3,4-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

83(9aR,10S)-10-((S)-(3,5-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

84(9aR,10S)-10-((R)-(2,5-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

85(9aR,10S)-10-((R)-(2,4-difluorophenyl)(3,4-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

86(9aR,10S)-10-((S)-(4-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

87(9aR,10S)-10-((R)-(2,4-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

88(9aR,10S)-10-((R)-(2,4-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

89(9aR,10S)-10-((R)-(2,4-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

90(9aR,10S)-10-((R)-(2,3-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

91(9aR,10S)-10-((S)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

92(9aR,10S)-10-((R)-(4-fluoro-2-methylphenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

93(9aR,10S)-10-((R)-(3,4-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

94(9aR,10S)-10-((R)-(3,4-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-2-(hydroxymethyl)-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

95(9aR,10S)-10-((S)-(2,3-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

96(9aR,10S)-10-((R)-(3,4-difluorophenyl)(3,5-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

97(9aR,10S)-10-((R)-(3,5-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

98(9aR,10S)-10-((S)-(2,5-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

99(9aR,10S)-10-((S)-(2,5-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

100(9aR,10S)-10-((S)-(2,5-difluorophenyl)(3,4-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

101(9aR,10S)-10-((R)-(3,5-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

102(9aR,10S)-10-((S)-(2,4-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

103(9aR,10S)-10-((S)-(2,4-difluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

104(9aR,10S)-10-((S)-(2,4-difluorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

105(9aR,10S)-10-((S)-(2,4-difluorophenyl)(3,4-difluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

106 10-(Bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

107 4-((R)-(3-Fluorophenyl)((9aR,10S)-4-hydroxy-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-10-yl)methyl)benzonitrile;

108(9aR,10S)-10-((S)-(4-chlorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

109(9aR,10S)-10-((R)-(3-chlorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

110(9aR,10S)-10-((S)-(2-bromophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

111(9aR,10S)-10-((R)-(2-bromophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

112(9aR,10S)-10-((S)-(3-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

113(9aR,10S)-10-((S)-(3-chlorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

114(9aR,10S)-10-((R)-(3-chlorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

115(9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7,7-dimethyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

116(9aR,10R)-10-((S)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7,7-dimethyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

117(7S,9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

118(7S,9aR,10S)-10-((S)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

119(7R,9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

120(7R,9aR,10R)-10-((S)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

121(8S,9aR,10S)-10-(bis(3-fluorophenyl)methyl)-4-hydroxy-8-methoxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

122(8R,9aR,10S)-10-(bis(3-fluorophenyl)methyl)-4-hydroxy-8-methoxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

123(10aR,11S)-11-benzhydryl-4-hydroxy-7,8,10a,11-tetrahydro-10H-pyridazino[1',6':4,5]pyrazino[2,1-c][1,4]oxazine-3,5-dione;

124A 11-Benzhydryl-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

124B 11-Benzhydryl-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

125A 11-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

125B 11-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

126 11-Benzhydryl-4-hydroxy-7,8,10a,11-tetrahydro-10H-pyridazino[1',6':4,5]pyrazino[2,1-c][1,4]oxazine-3,5-dione;

127 11-Benzhydryl-4-hydroxy-7-methyl-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione;

128(9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl 3-methylbutyrate;

129(9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl 3-methylbutyrate;

130(9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl acetate;

131(9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl isobutyrate;

132 (9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl isopropyl carbonate;

133 1-((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)ethyl ethyl carbonate;

134(S)((12-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,7,8,9,10-hexahydro-12H-diapyridazino[1,2-a:1',6'-d][1,2,4]triazin-4-yl)oxy)methyl ethyl carbonate;

135 (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl (2-methoxyethyl) carbonate;

136 1-(((9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)ethyl ethyl carbonate;

137 (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl methyl carbonate;

138 (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl ethyl carbonate;

139(((9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl methyl carbonate;

140 (((9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl ethyl carbonate;

141(((9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl isopropyl carbonate;

142 (((9aR,10S)-10-((R)-(4-fluorophenyl)(phenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl methyl carbonate;

143 (((9aR,10S)-10-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl pivalate;

144(S)((12-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,7,8,9,10-hexahydro-12H-diapyridazino[1,2-a:1′,6′-d][1,2,4]triazin-4-yl)oxy)methyl methyl carbonate;

145 (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl L-valine ester;

146(9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yldimethylcarbamate;

147 (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methylethyl(methyl)carbamate;

148 Methyl 2-(((((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)(ethoxy)phosphoryl)oxy)acetate;

and

149 methyl 2-((((((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methoxy)carbonyl)oxy)-2-methylpropanoate;

and pharmaceutically acceptable salts of these compounds.

12. A pharmaceutical composition comprising a compound according to any of the above embodiments or a pharmaceutically acceptable salt thereof, and one or more pharmaceutically acceptable carriers.

13. A combination comprising a therapeutically effective amount of a compound according to any one of embodiments 1 to 11 or any embodiment of formula (A) or a pharmaceutically acceptable salt thereof, and one or more therapeutically active adjuvants.

14. A method for treating influenza, comprising administering to a subject in need thereof a therapeutically effective amount of a compound according to any one of Embodiments 1 to 11 or any embodiment of Formula (A), or a pharmaceutically acceptable salt thereof.

15. A compound according to any one of embodiments 1-11 or any embodiment of formula (A), or a pharmaceutically acceptable salt thereof, for use as a medicament.

16. A compound according to any one of embodiments 1-11 or any embodiment of formula (A), or a pharmaceutically acceptable salt thereof, for use in treating influenza.

17. Use of a compound according to any one of embodiments 1-11 or any embodiment of formula (A), or a pharmaceutically acceptable salt thereof, for preparing a medicament for treating influenza.

In some embodiments, the compound of formula (A) is a compound of one of the following formulae:

wherein G is H, or G is selected from —C(O)R ⁰ , —C(O)—OR ⁰ , —C( ^RG ) ₂ —OC(O)R ⁰ , and —C( ^RG ) ₂ —OC(O)—OR ⁰ , wherein each R ⁰ is independently H or C ₁ -C ₄ alkyl, and each ^RG is H or C ₁ -C ₄ alkyl. In some of these embodiments, each ^RG is H, and R ⁰ is C ₁ -C ₄ alkyl;

n is 0, 1, or 2;

each R ³ represents Me, OH, Ome or halogen; and Y represents:

wherein each R ^y is independently selected from F, Cl, Me, OMe, CF ₃ , OCF ₃ and CN; and each q is independently 0, 1 or 2.

In some embodiments, the compound of formula (I) is a compound of one of the following formulae:

Where n is 0, 1 or 2;

each R ³ represents Me, OH, Ome or halogen; and Y represents:

wherein each R ^y is independently selected from H, F, Cl, Me, OMe, CF ₃ , OCF ₃ and CN.

As used herein, the terms "optical isomer" or "stereoisomer" refer to any of the various stereoisomeric configurations in which a given compound of the present invention may exist, and include geometric isomers. It is understood that substituents may be attached at carbon atom chiral centers. The term "chiral" refers to molecules that are non-superimposable on their mirror-image partners, while the term "achiral" refers to molecules that are superimposable on their mirror-image partners. Thus, the present invention includes enantiomers, diastereomers, or racemates of a compound. "Enantiomers" are a pair of stereoisomers that are non-superimposable mirror images of each other. A 1:1 mixture of a pair of enantiomers is a "racemic" mixture. This term is used to refer to a suitable racemic mixture. "Diastereomers" are stereoisomers that have at least two asymmetric atoms, but that are not mirror images of each other. Absolute stereochemistry is designated according to the Cahn-Ingold-Prelog "R-S" system. When a compound is a pure enantiomer, the stereochemistry at each chiral carbon atom can be designated by R or S. Dissociated compounds whose absolute conformation is unknown can be designated as (+) or (-) according to the direction (dextrorotatory or levorotatory) in which they rotate plane-polarized light at the sodium D-line wavelength. Certain compounds described herein contain one or more asymmetric centers or axes and may thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that can be defined in terms of absolute stereochemistry as (R)- or (S)-.

Depending on the choice of starting materials and synthetic procedures, the compound may exist as one of the possible isomers or as a mixture thereof, for example as a pure optical isomer, or as a mixture of isomers, such as a racemate and a diastereomeric mixture, depending on the number of asymmetric carbon atoms. The present invention is intended to include all such possible isomers, including racemic mixtures, diastereomeric mixtures, and optically pure forms. Optically active (R)- and (S)-isomers can be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques. If the compound contains a double bond, its substituents may be in the E or Z configuration, unless otherwise indicated. If the compound contains a disubstituted cycloalkyl group, the cycloalkyl substituent may have a cis or trans configuration. All tautomeric forms are also intended to be included.

In many cases, the compounds of the present invention are capable of forming acid and/or base salts due to the presence of amino and/or carboxyl groups or similar groups. As used herein, the terms "salts" or "salts" refer to acid addition salts and base addition salts of the compounds of the present invention. "Salts" specifically include "pharmaceutically acceptable salts." The term "pharmaceutically acceptable salts" refers to salts that retain the biological effects and properties of the compounds of the present invention and generally do not have biological or other disadvantages.

Pharmaceutically acceptable acid addition salts can be formed with inorganic and organic acids, for example, acetate, aspartate, benzoate, benzenesulfonate, bromide/hydrobromide, bicarbonate/carbonate, bisulfate/sulfate, camphorsulfonate, chloride/hydrochloride, chlorotheophyllinate, citrate, edisylate, fumarate, glucoheptonate, gluconate, glucuronate, hippurate, hydroiodide/iodide, isethionate, lactate, lactobionate, laurylsulfate, malate, maleate, malonate, mandelate, methanesulfonate, methylsulfate, naphthoate, naphthylate, nicotinate, nitrate, octadecanoate, oleate, oxalate, palmitate, pamoate, phosphate/hydrogenphosphate/dihydrogenphosphate, polygalacturonate, propionate, stearate, succinate, sulfosalicylate, tartrate, tosylate, and trifluoroacetate. Lists of other suitable salts can be found, for example, in Remington's Pharmaceutical Sciences, 20th edition, Mack Publishing Company, (1985); and in Handbook of Pharmaceutical Salts: Properties, Selection, and Use, Stahl and Wermuth, eds. (Wiley-VCH, Weinheim, Germany, 2002).

Inorganic acids from which salts can be obtained include, for example, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like.

Organic acids from which salts can be obtained include, for example, acetic acid, propionic acid, glycolic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, toluenesulfonic acid, sulfosalicylic acid, and the like.

Pharmaceutically acceptable base addition salts can be formed with inorganic or organic bases and may have inorganic or organic counterions.

Inorganic counterions for these base salts include, for example, ammonium salts and metals from columns I to XII of the periodic table. In certain embodiments, the counterion is selected from sodium, potassium, ammonium, alkylammonium having 1-4 C1-C4 alkyl groups, calcium, magnesium, iron, silver, zinc, and copper; particularly suitable salts include ammonium, potassium, sodium, calcium, and magnesium salts.

Organic bases from which salts can be obtained include, for example, primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, basic ion exchange resins, and the like. Suitable organic amines include isopropylamine, benzathine, cholinate, diethanolamine, diethylamine, lysine, meglumine, piperazine, and tromethamine.

Pharmaceutically acceptable salts of the present invention can be synthesized by traditional chemical methods by alkaline or acidic moieties. Usually, this type of salt can be prepared by reacting the free acid form of these compounds with the appropriate alkali (such as sodium hydroxide, Ca, Mg or K, carbonate, bicarbonate etc.) of stoichiometric amount, or by reacting the free base form of these compounds with the appropriate acid of stoichiometric amount. This type of reaction is usually carried out in water or an organic solvent or a mixture of the two. Usually, where feasible, it is desirable to use a non-aqueous medium, such as ether, ethyl acetate, tetrahydrofuran, toluene, chloroform, methylene dichloride, methanol, ethanol, isopropyl alcohol or acetonitrile.

Any formula provided herein is also intended to represent the unlabeled form (i.e., a compound in which all atoms exist in natural isotopic abundances rather than isotopically enriched states) and isotopically enriched or labeled forms of the compound. An isotopically enriched or labeled compound has the structure described by the formula provided herein, except that at least one atom of the compound is replaced by an atom having an atomic mass or mass number different from that of the naturally occurring atomic mass or atomic mass distribution. Examples of isotopes that can be incorporated into the enriched or labeled compounds of the present invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, fluorine, and chlorine, such as ² H, ³ H, ¹¹ C, ¹³ C, ¹⁴ C, ¹⁵ N, ¹⁸ F, ³¹ P, ³² P, ³⁵ S, ³⁶ Cl, and ¹²⁵ I, respectively. The present invention includes various isotopically labeled compounds as described herein, for example, compounds in which radioactive isotopes (such as ³ H and ¹⁴ C) or non-radioactive isotopes (such as ² H and ¹³ C) are present at levels significantly above the natural abundance of these isotopes. These isotopically labeled compounds are useful in metabolic studies (e.g., using ¹⁴ C), reaction kinetic studies (using, for example, ² H or ³ H), detection or imaging techniques (e.g., drug or substrate tissue distribution assays including positron emission tomography (PET) or single photon emission computed tomography (SPECT)), or in radiotherapy of patients. In particular, ¹⁸ F-labeled compounds may be particularly desirable for use in PET or SPECT studies. Isotopically labeled compounds of formula (I) can generally be prepared by conventional techniques known to those skilled in the art or by methods analogous to those described in the following examples and preparations, employing an appropriate isotopically labeled reagent in place of the unlabeled reagent used.

In addition, substitution with heavier isotopes, particularly deuterium (i.e., ^2H or D), can provide certain therapeutic advantages due to greater metabolic stability, such as increased in vivo half-life or reduced dosage requirements or improved therapeutic profiles. The concentration of such heavier isotopes, particularly deuterium, can be defined by an isotopic enrichment factor. As used herein, the term "isotopic enrichment factor" refers to the ratio between the isotopic abundance and the natural abundance of a particular isotope. Where a substituent in a compound of the invention is represented as deuterium, such compound has an isotopic enrichment factor for each designated deuterium atom of at least 3500 (52.5% deuterium incorporated for each designated deuterium atom), at least 4000 (60% deuterium incorporated), at least 4500 (67.5% deuterium incorporated), at least 5000 (75% deuterium incorporated), at least 5500 (82.5% deuterium incorporated), at least 6000 (90% deuterium incorporated), at least 6333.3 (95% deuterium incorporated), at least 6466.7 (97% deuterium incorporated), at least 6600 (99% deuterium incorporated), or at least 6633.3 (99.5% deuterium incorporated).

Pharmaceutically acceptable solvates according to the present invention include those wherein the solvent of crystallization may be isotopically substituted (eg, D ₂ O, d ₆ -acetone, d ₆ -DMSO), as well as solvates with non-enriched solvents.

Compounds of the present invention (i.e., compounds of formula (I)) containing groups capable of acting as hydrogen bond donors and/or acceptors can form co-crystals with suitable co-crystal formers. These co-crystals can be prepared from compounds of formula (I) by known co-crystal formation methods. Such methods include grinding, heating, co-subliming, co-melting the compound of formula (I) and the co-crystal former under crystallization conditions, or contacting the compound of formula (I) with the co-crystal former in solution and isolating the co-crystals thus formed. Suitable co-crystal formers include those described in WO 2004/078163. Therefore, the present invention also provides co-crystals comprising compounds of formula (I).

As used herein, the term "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, surfactants, antioxidants, preservatives (e.g., antibacterial agents, antifungal agents), isotonic agents, absorption delaying agents, salts, preservatives, pharmaceutical stabilizers, binders, excipients, disintegrants, lubricants, sweeteners, flavorings, dyes, the like, and combinations thereof, which would be known to one of ordinary skill in the art for use in pharmaceutical compositions for administration to human subjects (see, e.g., Remington: The Science and Practice of Pharmacy, 22nd ed.). Unless any conventional carrier is incompatible with the active ingredient, such carrier is contemplated for use in therapeutic or pharmaceutical compositions.

The term "a therapeutically effective amount of a compound of the present invention" refers to an amount of a compound of the present invention that is capable of eliciting a biological or pharmacological response in a subject, for example, an amount sufficient to reduce one or more symptoms, alleviate symptoms, slow or delay disease progression, or prevent disease. In one non-limiting embodiment, the term "therapeutically effective amount" refers to an amount of a compound of the present invention that, when administered to a subject, is effective in reducing one or more symptoms associated with influenza virus infection, or shortening the duration of the symptomatic phase of influenza virus infection, or slowing the progression of influenza virus infection, or reducing or stopping the worsening of a condition caused by influenza virus infection.

In another non-limiting embodiment, the term "therapeutically effective amount" refers to an amount of a compound of the invention that, when administered to a cell or tissue or non-cellular biological material or medium, is sufficient to cause a statistically significant decrease in the replication or proliferation rate of an Orthomyxovirus strain.

As used herein, the term "subject" refers to an animal. Typically, the subject is a human.

As used herein, the terms "inhibit," "inhibition," or "inhibited" refer to the reduction or suppression of a given condition, symptom, disorder, or disease, or a significant decrease in the baseline activity of a biological activity or process.

As used herein, the terms "treating," "treatment," or "therapy" of any disease or disorder refer to, in one embodiment, ameliorating the disease or condition (i.e., slowing or preventing or reducing the progression of the disease or at least one clinical symptom thereof). In other embodiments, "treating," "treatment," or "therapy" refers to alleviating or improving at least one physical parameter, including those parameters not identified by the patient. In yet other embodiments, "treating," "treatment," or "therapy" refers to modulating the disease or condition physically (e.g., stabilization of an overt symptom) or physiologically (e.g., stabilization of a physical parameter), or both. In yet other embodiments, "treating," "treatment," or "therapy" refers to preventing or delaying the onset or progression of a disease or condition.

As used herein, a subject is "in need of" a treatment if the subject would benefit biologically, medically, or in quality of life from such treatment.

As used herein, the terms “a,” “an,” “the” and similar referents used in the context of the invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated or clearly contradicted by context.

All methods described herein can be performed in any suitable order unless otherwise indicated or clearly contradicted by the context. Any and all embodiments/examples, or exemplary language (e.g., "for example/such as") referred to herein are intended solely to better illustrate the present invention, rather than to limit the scope of the present invention.

Any asymmetric atom (e.g., carbon, etc.) of one or more compounds of the present invention may be present in a racemic or enantiomerically enriched form, such as (R)-, (S)-, or (R,S)-configuration. In some embodiments, each asymmetric atom has at least 50% enantiomeric excess, at least 60% enantiomeric excess, at least 70% enantiomeric excess, at least 80% enantiomeric excess, at least 90% enantiomeric excess, at least 95% enantiomeric excess, or at least 99% enantiomeric excess of either (R) or (S)-configuration; i.e., for optically active compounds, it is generally preferred to use one enantiomer to the substantial exclusion of the other, and thus an enantiomeric purity of at least 95% is generally preferred. Substituents at atoms at unsaturated double bonds may (if possible) exist in cis-(Z)- or trans-(E)-form.

Accordingly, as used herein, the compounds of the present invention may be in the form of one of the possible isomers, rotamers, atropisomers, tautomers, or mixtures thereof, for example, substantially pure geometric (cis or trans) isomers, diastereomers, optical isomers (enantiomers), racemates, or mixtures thereof. As used herein, "substantially pure" or "substantially free of other isomers" means that the product contains less than 5% by weight, preferably less than 2% by weight, of other isomers relative to the amount of the preferred isomer.

The resulting isomeric mixtures can typically be separated on the basis of the physicochemical differences of the constituents into the pure or substantially pure geometric or optical isomers, diastereomers, racemates, for example, by chromatography and/or fractional crystallization.

The racemate of the final product or intermediate can usually be split into optical antipodes by known methods, for example, by separating its diastereomeric salts, obtaining with optically active acids or bases and releasing optically active acidic or basic compounds. Specifically, the compound of the present invention can therefore be split into its optical antipodes using a basic moiety, for example, by fractional crystallization of a salt formed from an optically active acid, such as tartaric acid, dibenzoyltartaric acid, diacetyltartaric acid, di-O,O'-p-benzoyltartaric acid, mandelic acid, malic acid or camphor-10-sulfonic acid. The racemic product can also be split by chiral chromatography, for example, using high pressure liquid chromatography (HPLC) of a chiral stationary phase.

In addition, the compounds of the present invention, including their salts, can also be obtained in the form of their hydrates, or include other solvents for their crystallization. The compounds of the present invention can inherently or by design form solvates with pharmaceutically acceptable solvents (including water); therefore, the present invention is intended to include solvated and non-solvated forms. The term "solvate" refers to a molecular complex of a compound of the present invention (including its pharmaceutically acceptable salt) with one or more solvent molecules. Such solvent molecules are commonly used in the pharmaceutical field and are known to be harmless to the recipient, for example, water, ethanol, etc. The term "hydrate" refers to a complex in which the solvent molecule is water.

In another aspect, the present invention provides a pharmaceutical composition comprising a compound of the present invention or a pharmaceutically acceptable salt thereof, and at least one pharmaceutically acceptable carrier. In some embodiments, the pharmaceutical composition contains at least two pharmaceutically acceptable excipients or carriers. Pharmaceutically acceptable carriers and other excipients are known to those skilled in the art and can be selected from, for example, carriers and excipients for the formulation of therapeutic agents approved (registered) for administration by similar routes of administration. Pharmaceutical compositions for specific routes of administration can be formulated, such as oral administration, parenteral administration, and rectal administration. In addition, the pharmaceutical composition of the present invention can be made into solid form (including but not limited to capsules, tablets, pills, granules, powders or suppositories), or liquid form (including but not limited to solutions, suspensions or emulsions). The pharmaceutical composition can be subjected to conventional pharmaceutical operations (e.g., sterilization) and/or it can contain conventional inert diluents, lubricants or buffers, and adjuvants, such as preservatives, stabilizers, wetting agents, emulsifiers and buffers.

In one embodiment, the compounds of the present invention are formulated for oral administration. Typically, these pharmaceutical compositions are tablets or gelatin capsules comprising the active ingredient (at least one compound of formula (I)) and one or more excipients selected from the following:

a) diluents, such as lactose, dextrose, sucrose, mannitol, sorbitol, cellulose and/or glycerol;

b) Lubricants, such as silicon dioxide, talc, stearic acid, its magnesium or calcium salts, and/or polyethylene glycol; for tablets also

c) binders, such as magnesium aluminum silicate, starch paste, gelatin, tragacanth, methylcellulose, sodium carboxymethylcellulose and/or polyvinylpyrrolidone; if necessary

d) disintegrants, for example starch, agar, alginic acid or its sodium salt, or effervescent mixtures; and/or

e) Adsorbents, colorants, flavorings and sweeteners.

Tablets may be film coated or enteric coated according to methods known in the art.

Suitable compositions for oral administration include an effective amount of a compound of the invention in the form of tablets, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Compositions for oral use are prepared according to any method known in the art for the manufacture of pharmaceutical compositions and may contain one or more agents selected from the group consisting of sweeteners, flavorings, colorants, and preservatives to provide pharmaceutically elegant and palatable formulations. Tablets may contain a mixture of the active ingredient and pharmaceutically acceptable nontoxic excipients suitable for tablet preparation. These excipients include, for example, inert diluents such as calcium carbonate, sodium carbonate, lactose, calcium phosphate, or sodium phosphate; granulating and disintegrants such as corn starch or alginic acid; binders such as starch, gelatin, or gum arabic; and lubricants such as magnesium stearate, stearic acid, or talc. Tablets may be uncoated or coated by known techniques to delay disintegration and absorption in the gastrointestinal tract, thereby providing a sustained effect over a longer period of time. For example, a time delay material such as glyceryl monostearate or glyceryl distearate may be employed. Formulations for oral use may be prepared as hard gelatin capsules in which the active ingredient is mixed with an inert solid diluent (such as calcium carbonate, calcium phosphate or kaolin), or as soft gelatin capsules in which the active ingredient is mixed with water or an oily medium (such as peanut oil, liquid paraffin or olive oil).

Some injectable compositions are isotonic aqueous solutions or suspensions, and suppositories are advantageously prepared from fat emulsions or suspensions. The compositions may be sterilized and/or contain adjuvants such as preservatives, stabilizers, wetting agents or emulsifiers, solution promoters, salts for regulating osmotic pressure, and/or buffers. In addition, they may contain other therapeutically valuable substances. The compositions are prepared according to conventional mixing, granulation, or coating methods and contain approximately 0.1-75%, or approximately 1-50%, of the active ingredient.

Suitable compositions for transdermal administration comprise an effective amount of a compound of the invention and a suitable carrier. Suitable carriers for transdermal delivery include absorbable pharmacologically acceptable solvents to aid penetration of the host's skin. For example, transdermal devices are in the form of a bandage comprising a backing member, a reservoir containing the compound and, optionally, a carrier, an optional rate-controlling barrier for long-term delivery of the compound to the host's skin at a controlled and predetermined rate, and means for securing the device to the skin.

Suitable compositions for topical application (e.g., to the skin and eyes) include aqueous solutions, suspensions, ointments, creams, gels, or sprayable formulations, e.g., delivered by aerosols, etc. These topical delivery systems may involve inhalation or intranasal administration, which may, for example, be suitable for treating influenza and may further comprise solubilizers, stabilizers, isotonicity enhancers, buffers, and preservatives. They may be delivered conventionally in the form of dry powders (either alone or as a mixture (e.g., a dry mixture with lactose), or mixed component particles (e.g., with phospholipids)) by aerosol sprays from pressurized containers, pumps, sprayers, atomizers, or nebulizers, or dry powder inhalers, with or without a suitable propellant.

The present invention also provides anhydrous pharmaceutical compositions and dosage forms comprising the compounds of the present invention as active ingredients, since water may facilitate disintegration of some compounds.

The anhydrous pharmaceutical compositions and dosage forms of the present invention can be prepared using anhydrous or low-water content components and low-moisture or low-humidity conditions. Anhydrous pharmaceutical compositions can be prepared and stored so that they maintain anhydrous properties. Therefore, the anhydrous compositions are packaged with materials known to prevent contact with water and are contained in suitable formulation kits. Examples of suitable packaging include, but are not limited to, hermetically sealed foils, plastics, unit dose containers (e.g., vials), blister packs, and strip packs.

The present invention also provides pharmaceutical compositions and dosage forms comprising one or more agents capable of reducing the rate of decomposition of the compounds of the present invention as active ingredients. These agents are referred to herein as "stabilizers" and include, but are not limited to, antioxidants (e.g., ascorbic acid), pH buffers or buffer salts, and the like.

The compounds of formula (I) in free or salt form exhibit considerable pharmacological properties, such as inhibition or prevention of orthomyxovirus replication (as shown in the test data provided below), and are therefore indicated for use in treatment or as research compounds, for example as tool compounds to study the replication of orthomyxoviruses, especially influenza A, B or C viruses. Thus, the compounds of the present invention are useful for treating orthomyxovirus, especially influenza A, B or C virus infections, particularly in human subjects. In some embodiments, the subject to be treated is a human who is exposed to or is at risk of exposure to influenza virus infection. For example, subjects with pre-existing conditions (e.g., asthma or COPD) that would be greatly exacerbated by influenza virus infection can be treated with the methods or compounds of the present invention before they develop symptoms of influenza infection, especially if they are at risk of exposure to influenza due to close contact with someone who has or may have influenza (e.g., a family member). In other embodiments, the subjects treated with the methods and compositions of the present invention are subjects diagnosed with symptoms consistent with influenza infection. In other embodiments, the subject can be a human who has been tested using a known diagnostic test, such as a rapid influenza diagnostic test (RIDT) or a reverse transcriptase polymerase chain reaction (RT-PCR) method for detecting the presence of influenza virus, and found to be infected with influenza, regardless of the presence of typical influenza symptoms.

As another embodiment, the present invention provides a compound of formula (I) or any embodiment within the scope of formula (I) as described herein for use in therapy. In particular, the compound is suitable for treating a subject having or at particularly high risk of developing an orthomyxovirus infection, particularly influenza A, B, or C.

In another embodiment, the present invention provides a method for treating a disease caused by an orthomyxovirus, comprising administering to a subject in need of such treatment a therapeutically effective amount of a compound of formula (I) or any embodiment within the scope of formula (I) as described herein. In some embodiments, the compound of formula (I) is administered orally. In another embodiment, the disease is selected from influenza A, B, and C. The method generally comprises administering to a subject in need of such treatment an effective amount of a compound as described herein, or a pharmaceutical composition comprising an effective amount of the compound. The compound may be administered by any suitable method, such as as described herein, and the administration may be repeated at intervals, which may be selected by the treating physician. In some embodiments, the compound or pharmaceutical composition is administered orally.

Therefore, as another embodiment, the present invention provides the use of a compound of formula (I) or any embodiment of the compound described herein for the preparation of a medicament. In one embodiment, the medicament is for the treatment of an orthomyxovirus infection, in particular influenza A, B or C.

The compounds of the present invention may be administered simultaneously with, before, or after one or more therapeutic adjuvants. The compounds of the present invention may be administered alone by the same or different routes of administration, or together with adjuvants in the same pharmaceutical composition. Suitable adjuvants for the compounds of the present invention include those with antiviral activity against influenza virus, such as neuraminidase inhibitors, including oseltamivir, peramivir, zanamivir and laninamivir, laninamivir octanoate, and adamantanes such as amantadine and rimantadine. Other adjuvants for these methods also include M2 protein inhibitors, polymerase inhibitors, PB2 inhibitors, favipiravir, influenza enzymes, ADS-8902, beraprost, ribavirin, CAS Reg. No. 1422050-75-6, VX-787, Flu Mist quadrivalent vaccine, quadrivalent vaccine, and

In one embodiment, the present invention provides a product comprising a compound of formula (I) and at least one other therapeutic adjunct as a combined preparation for simultaneous, separate, or sequential use in therapy. In one embodiment, the treatment is for a viral infection caused by an orthomyxovirus, particularly influenza A, B, or C. Products provided as combined preparations include compositions comprising a compound of formula (I) and at least one other therapeutic adjunct in the same pharmaceutical composition; or a compound of formula (I) and at least one other therapeutic adjunct in separate forms, such as in kit form, for use in treating a subject according to the methods described herein.

In one embodiment, the invention provides a pharmaceutical composition comprising a compound of formula (I) and other therapeutic adjuvants. Suitable adjuvants include those with antiviral activity against influenza virus, such as neuraminidase inhibitors, including oseltamivir, peramivir, zanamivir and laninamivir, and adamantanes such as amantadine and rimantadine. Optionally, the pharmaceutical composition may include a pharmaceutically acceptable carrier as described above.

In one embodiment, the invention provides a test kit comprising two or more independent pharmaceutical compositions, at least one of which contains a compound of formula (I). Another pharmaceutical composition may contain one of a suitable adjuvant. In one embodiment, the test kit comprises an apparatus for independently accommodating the composition, such as a container, a sub-bottle, or a sub-foil package. An example of such a test kit is a blister pack, which is typically used for packaging tablets, capsules, etc.

The kits of the invention can be used to administer different dosage forms, e.g., oral or parenteral, for administering the separate compositions at different dosage intervals, or for titrating the separate compositions independently of one another. To aid compliance, the kits of the invention typically include instructions for administration.

In the combination therapy of the present invention, the compound of the present invention and the therapeutic adjuvant may be prepared and/or formulated by the same or different manufacturers. In addition, the methods and therapeutic adjuvants of the present invention may be incorporated into the combination therapy at the following stages: (i) before the combination product is disclosed to the physician (e.g., when the kit comprises the compound of the present invention and the other therapeutic agent); (ii) by the physician spontaneously (or under the physician's guidance) shortly before administration; (iii) by the patient himself, for example, during the sequential administration of the compound of the present invention and the therapeutic adjuvant.

Thus, the present invention provides the use of a compound of formula (I) for treating a viral infection caused by an orthomyxovirus, particularly influenza, wherein the influenza virus can be influenza A, B, or C, wherein the medicament is prepared for administration with a therapeutic adjuvant. Typically, in methods using the compounds of the present invention, influenza serotype identification is not performed prior to treatment. The present invention also provides the use of a therapeutic adjuvant for treating a disease or condition, wherein the medicament is administered with a compound of formula (I).

The present invention also provides the use of a compound of formula (I) in a method for treating a viral infection caused by an orthomyxovirus, in particular influenza A, B, or C, wherein the compound of formula (I) is prepared for administration with a therapeutic adjuvant. The present invention also provides the use of another therapeutic adjuvant in a method for treating a viral infection caused by an orthomyxovirus, in particular influenza, such as influenza A, B, or C, wherein the therapeutic adjuvant is prepared for administration with the compound of formula (I). The present invention also provides the use of a compound of formula (I) in a method for treating a viral infection caused by an orthomyxovirus, in particular influenza A, B, or C, wherein the compound of formula (I) is administered with a therapeutic adjuvant. The present invention also provides the use of a therapeutic adjuvant in a method for treating a viral infection caused by an orthomyxovirus, in particular influenza, such as influenza A, B, or C, wherein the therapeutic adjuvant is administered with the compound of formula (I).

The present invention provides the use of a compound of formula (I) for treating a viral infection caused by an orthomyxovirus, in particular an influenza virus, such as influenza A, B, or C, wherein the patient has been previously treated (e.g., within 24 hours) with another therapeutic agent. The present invention also provides the use of another therapeutic agent for treating a viral infection caused by an orthomyxovirus, in particular an influenza virus, such as influenza A, B, or C, wherein the patient has been previously treated (e.g., within 24 hours) with a compound of formula (I).

In one embodiment, the adjunctive therapeutic agent is selected from antiviral drugs believed to be useful in treating infections caused by influenza virus, such as neuraminidase inhibitors, including oseltamivir, peramivir, zanamivir, and laninamivir, and adamantanes, such as amantadine and rimantadine.

The pharmaceutical compositions or combinations of the present invention can be in unit dosage form containing about 1-1000 mg, or about 1-500 mg, or about 1-250 mg, or about 1-150 mg, or about 0.5-100 mg, or about 1-50 mg of the active ingredient for a human subject of about 50-70 kg. The therapeutically effective amount of the compound, pharmaceutical composition, or combination thereof is determined by the subject species, weight, age, and individual condition, the disorder or disease to be treated, or its severity. A physician, clinician, or veterinarian of ordinary skill can readily determine the effective amount of each active ingredient to prevent, treat, or inhibit the progression of a disorder or disease.

The properties of the above dosages are preferably demonstrated in vitro and in vivo using mammals (e.g., mice, rats, dogs, monkeys) or isolated organs, tissues, and preparations thereof. The compounds of the present invention can be administered in vitro as solutions (e.g., aqueous solutions) and in vivo in enteral or parenteral forms, advantageously intravenously, for example, as suspensions or in aqueous solutions. In vitro dosage ranges can be from about ^10-3 molar to ^10-9 molar concentrations. In vivo therapeutically effective amounts can range from about 0.1-500 mg/kg or about 0.1-50 mg/kg, depending on the route of administration.

The present invention also comprises a process for the preparation of the compounds of formula (I) as described herein, as well as any variant of this process, wherein the remaining steps are carried out using an intermediate product obtainable at any stage as starting material, or wherein the starting material is formed in situ under the reaction conditions, or wherein the reaction components are used in the form of their salts or optically pure substances.

The compounds of the present invention and the intermediates can also be converted into each other according to methods generally known to those skilled in the art.

Methods for synthesizing compounds of Formula (I) are described in Schemes A-C and illustrated in the Examples herein. Scheme A describes a method for preparing compounds wherein Z1 is N, Z2 is C(R)2, and Z3 is -CR2-CR2. Compounds with other Z3 linking groups should also be synthesized. It begins with a 5-hydroxypyridazin-4-one-3-carboxylic acid compound in which both the 5-hydroxy group and the ring NH are protected by suitable, easily removable protecting groups. The carboxylic acid is condensed with a cyclic hydrazine linker to provide two outer rings. After deprotection of the ring nitrogen, the central ring is formed by condensation with an aldehyde.

Plan A

Schemes B and C describe methods for preparing compounds of formula (I) wherein Z ¹ is CR, Z ² is CR ₂ , and Z ³ is CR ₂ .

Plan B

Plan C

Using these synthetic schemes and the examples provided, one skilled in the art can prepare compounds of formula (I).

Example

The following examples are intended to illustrate the present invention and should not be construed as limiting the present invention. Temperatures are given in degrees Celsius. If not otherwise mentioned, all evaporations are carried out under reduced pressure, generally between about 15 mmHg and 100 mmHg (about 20-133 mbar). The structures of the final products, intermediates, and starting materials are determined using standard analytical methods, such as microanalysis and spectral characteristics, such as MS, IR, and NMR. The abbreviations used are those conventional in this area.

All starting materials, building blocks, reagents, acids, bases, dehydrating agents, solvents, and catalysts used to synthesize the compounds of the present invention are commercially available or can be prepared by organic synthesis methods known to those of ordinary skill in the art (Houben-Weyl, 4th ed. 1952, "Methods of Organic Synthesis," Thieme, Vol. 21). Furthermore, the compounds of the present invention can be prepared by organic synthesis methods known to those of ordinary skill in the art, using the following examples as a reference.

abbreviation

ATP adenosine 5'-triphosphate

Bn benzyl

BOC tert-butylcarboxyl

br width

BSA bovine serum albumin

d Doublet

dd Double Peaks of Double Peaks

DCM dichloromethane

DEAD Diethyl azodicarboxylate

DBAD Di-tert-butyl azodicarboxylate

DIBAL-H Diisobutylaluminum Hydride

DIEA Diethylisopropylamine

DME 1,4-dimethoxyethane

DMF N,N-dimethylformamide

DMSO dimethyl sulfoxide

DTT dithiothreitol

EDTA Ethylenediaminetetraacetic acid

ESI electrospray ionization

EtOAc

FCC flash column chromatography

h hour

HBTU 1-[Bis(dimethylamino)methylene]-1H-benzotriazolium hexafluorophosphate (1-)3-oxide

HOBt 1-Hydroxy-7-azabenzotriazole

HPLC high-performance liquid chromatography

IR infrared spectroscopy

LCMS liquid chromatography and mass spectrometry

MEOH methanol

MS

MW microwave

m multiplet

Min minutes

mL milliliters

m/z mass-to-charge ratio

NBS N-bromosuccinimide

NCS N-chlorosuccinimide

NMP N-Methyl-pyrrolidone

NMR Nuclear Magnetic Resonance

ppm parts per million

PyBOP Benzotriazol-1-yloxytripyrrolidinophosphate hexafluorophosphate

rac racemic

rt room temperature

s singlet peak

SEM (2-(trimethylsilyl)ethoxy)methyl

t Triplet

TBDMS tert-butyldimethylsilyl

TBDPS tert-Butyldiphenylsilyl

TFA trifluoroacetic acid

THF Tetrahydrofuran

Tris·HCl

Example 1: 12-Benzhydryl-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

Intermediate 1.1: 1-Benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid

At room temperature, NaOH (0.792 g, 19.79 mmol) was added to a suspension of ethyl 5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylate (1.5 g, 4.83 mmol) in methanol. The mixture was stirred at room temperature for 2 hours. Benzyl bromide (2.067 ml, 17.38 mmol) was added and the mixture was stirred for 2 hours. The reaction was concentrated by rotary evaporation, followed by the addition of EtOAc and water. The mixture was then acidified to pH 3 with 1 M HCl. HCl was added to precipitate a solid. The mixture was filtered. The white solid was washed with a small amount of EtOAc and water. The white solid was collected on the filter and dried under vacuum to give 1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (1.1 g, 3.27 mmol, 67.7% yield), which was used without further purification. MS: m/z = 337.3 (M+1).

Intermediate 1.2: tert-Butyl 2-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)tetrahydropyridazine-1-(2H)-carboxylate

To a solution of 1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (850 mg, 2.53 mmol) in DCM (volume: 12.600 mL) at room temperature was added Huenig's Base (1.170 mL, 6.70 mmol) and HATU (1249 mg, 3.29 mmol). The mixture was stirred at room temperature for 30 minutes, then tert-butyl tetrahydropyridazine-1(2H)-carboxylate (518 mg, 2.78 mmol) was added. The mixture was stirred at room temperature for 16 hours, diluted with DCM (10 mL), and washed with water (10 mL) and then brine (10 mL). The organic layer was dried _{over Na₂SO₄} , filtered, and concentrated by rotary evaporation. The residue was purified using ISCO (40 g silica gel column, 40-100% EtOAc in heptane) to give tert-butyl 2-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)tetrahydropyridazine-1(2H)-carboxylate (1.22 g, 2.418 mmol, 96% yield) as a white foam. MS: m/z = 505.4 (M+1).

Intermediate 1.3: tert-Butyl 2-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)tetrahydropyridazine-1(2H)-carboxylate

A solution of tert-butyl 2-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)tetrahydropyridazine-1(2H)-carboxylate (220 mg, 0.436 mmol) in MeOH (volume: 21.800 mL) was purged with nitrogen. A reagent spoonful of palladium on carbon (10%) (46.4 mg, 0.044 mmol) was added and connected to a hydrogen balloon. The flask was evacuated and refilled with hydrogen (3 times), then stirred vigorously under a hydrogen balloon at room temperature. After 30 minutes, the reaction was purged with nitrogen and filtered through a Celite plug, which was washed with MeOH. The filtrate was concentrated in vacuo and used without further purification. MS: m/z = 325.3 (M+1).

Example 1: 12-Benzhydryl-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

To a vial containing crude tert-butyl 2-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)tetrahydropyridazine-1(2H)-carboxylate (141 mg, 0.436 mmol) and a stir bar was added 2,2-diphenylacetaldehyde (77 mg, 0.392 mmol). TFA (volume: 2 ml) was added, and the mixture was stirred at room temperature for 30 minutes. The reaction was concentrated in vacuo. The residue was purified by reverse-phase HPLC (MeCN/water with 0.1% TFA). Product-containing fractions were combined, frozen, and lyophilized to afford 12-benzhydryl-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione (19 mg, 0.036 mmol, 8.27% yield) as a yellow solid. ¹ H NMR (400MHz, DMSO-d6) δ7.55–7.46(m,2H),7.34(s,1H),7.30(dd,J＝8.1,1.6Hz,4H),7.25–7.10(m,4H),6.33(d,J＝10.5Hz,1H),4.62(d,J＝1 0.5Hz,1H),4.36–4.25(m,1H),3.29–3.21(m,1H),2.86(td,J＝11.1,2.6Hz,1H),2.46–2.38(m,1H),1.70–1.39(m,4H).MS:m/z＝403.4(M+1).

Example 2. 12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

This compound was prepared by the same method as in Preparation Example 1. 1H NMR (400 MHz, DMSO-d6) δ 7.50–7.45 (m, 1H), 7.39 (s, 1H), 7.39–7.33 (m, 2H), 7.32–7.13 (m, 3H), 7.12–6.94 (m, 2H), 6.41 (d, J = 10.8 Hz, 1H), 4.82 (d, J = 10.7 Hz, 1H), 4.36–4.2 6(m,1H),3.28–3.18(m,1H),2.88(td,J＝11.0,2.5Hz,1H),2.39(td,J＝12.5,3.1Hz,1H ),1.73–1.64(m,1H),1.51(dddd,J＝30.2,15.0,6.1,3.3Hz,3H).MS:m/z＝439.3(M+1).

Example 3. 12-(bis(4-chlorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

This compound was prepared by the same method as in Preparation Example 1. 1H NMR (400 MHz, DMSO-d6) δ 7.54 (d, J = 8.5 Hz, 2H), 7.43–7.31 (m, 5H), 7.30–7.23 (m, 2H), 6.36 (d, J = 10.7 Hz, 1H), 4.78 (d, J = 10.7 Hz, 1H), 4.36–4.24 (m, 1H), 3.27–3.19 (m, 1H), 2.87 (td, J = 11.1, 2.7 Hz, 1H), 2.40 (td, J = 12.5, 2.9 Hz, 1H), 1.72–1.62 (m, 1H), 1.62–1.38 (m, 3H). MS m/z 471.2 (M+1).

Example 4. 12-(Bis(3-chlorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

This compound was prepared by the same method as in Preparation Example 1. 1H NMR (400 MHz, DMSO-d6) δ 7.64 (t, J = 1.8 Hz, 1H), 7.52 (dt, J = 7.8, 1.3 Hz, 1H), 7.47 (q, J = 1.4 Hz, 1H), 7.40 (d, J = 3.1 Hz, 1H), 7.37 (m, 5H), 6.44 (d, J = 10.7 Hz, 1H), 4.83 (d, J = 10.7 Hz, 1H), 4.37-4.25 (m, 1H), 3.29-3.16 (m, 1H), 2.88 (td, J = 11.2, 2.6 Hz, 1H), 2.44-2.29 (m, 1H), 1.73-1.62 (m, 1H), 1.61-1.37 (m, 3H). MS: m/z = 471.2 (M+1).

Example 5. 12-(bis(4-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

This compound was prepared in the same manner as in Preparation Example 1. 1H NMR (400MHz, solvent (Solvent)) δppm7.52 (s, 1H) 7.43-7.49 (m, 2H) 7.21-7.28 (m, 2H) 7.04-7.13 (m, 2H) 6.88-6.95 (m, 2H) 6.12 (d, J = 10.32Hz, 1H) 4.65 (d, J ＝10.37Hz,1H)4.38-4.52(m,1H)3.23(dt,J＝10.99,3.26Hz,1H)2.88-2.99 (m,1H)2.68(td,J＝12.18,4.16Hz,1H)1.72-1.83(m,2H)1.56-1.70(m,2H). MS: m/z = 439.3 (M+1).

Example 6. 13-Benzhydryl-4-hydroxy-8,9,10,11-tetrahydropyridazino[1',6':4,5][1,2,4]triazino[1,2-a][1,2]diazepine-3,5(7H,13H)-dione

This compound was prepared by the same method as in Preparation Example 1. 1H NMR (400 MHz, DMSO-d6) δ 7.62–7.54 (m, 2H), 7.37 (s, 1H), 7.33 (dd, J = 8.3, 7.0 Hz, 2H), 7.30–7.09 (m, 6H), 6.39 (d, J = 10.8 Hz, 1H), 4.44 (d, J = 10.8 Hz, 1H), 4.00 (ddd, J = 13.4, 8.8, 4.9 Hz, 1H), 3.31 (dt, J = 10.9, 5.0 Hz, 1H), 2.70 (dq, J = 12.6, 3.7 Hz, 2H), 1.63–1.41 (m, 4H), 1.32–1.18 (m, 1H), 1.14–1.00 (m, 1H). MS: m/z=417.4 (M+1).

Example 7. 13-(Bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,10,11-tetrahydropyridazino[1',6':4,5][1,2,4]triazino[1,2-a][1,2]diazepine-3,5(7H,13H)-dione

This compound was prepared by the same method as in Preparation Example 1. 1H NMR (400 MHz, DMSO-d6) δ 7.63–7.54 (m, 1H), 7.46–7.33 (m, 3H), 7.29–7.20 (m, 2H), 7.15 (dt, J = 7.8, 1.2 Hz, 1H), 7.11–7.03 (m, 1H), 7.03–6.94 (m, 1H), 6.46 (d, J = 10.9 Hz, 1H), 4.67 (d, J = 10. 9Hz, 1H), 4.02 (ddd, J＝13.3, 8.8, 4.8Hz, 1H), 3.29 (dt, J＝10.9, 5.0Hz, 1H), 2.71 (dddd, J＝18. 7,10.9,7.1,2.9Hz,2H),1.66–1.41(m,4H),1.26(q,J＝9.4,8.9Hz,1H),1.15–1.00(m,1H).MS m/z453.3(M+1).

Example 8. (R)-12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

Intermediate 8.1. (R)-12-(Bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,7,8,9,10-hexahydro-12H-dipyridazinol[1,2-a:1',6'-d][1,2,4]triazin-4-yl(S)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoate and (S)-12-(Bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,7,8,9,10-hexahydro-12H-dipyridazinol[1,2-a:1',6'-d][1,2,4]triazin-4-yl(S)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoate

Under N₂, 12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-diazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione (127 mg, 0.290 mmol) was dissolved in dry THF (volume: 4 mL) with stirring, followed by the addition of TEA (0.081 mL, 0.579 mmol). (R)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoyl chloride (73.2 mg, 0.290 mmol) was added dropwise. The reaction was stirred at room temperature for 90 minutes, then partitioned between EtOAc (10 mL) and water (10 mL). The phases were separated, and the organic layer was washed with brine, dried over _Na₂SO₄ , and concentrated. The residue was purified using an ISCO column (24 _g silica gel column, 0-100% EtOAc in heptane). The diastereomers were then separated by chiral HPLC (IC column, heptane/EtOH=80/20) to obtain:

(R)-12-(Bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,7,8,9,10-hexahydro-12H-diapyridazino[1,2-a:1',6'-d][1,2,4]triazin-4-yl (S)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoate (63 mg, 0.096 mmol, 33% yield, 99% ee). ¹ H NMR (400MHz, chloroform-d) δ7.90(d,J＝7.5Hz,2H),7.62(s,1H),7.54–7.29(m,4H),7.19(q,J＝7.8Hz,1H),7.07–6.81(m,6H),5.57(d,J＝1 0.2Hz,1H),4.68–4.43(m,2H),3.83(s,3H),3.08(d,J＝10.5Hz,1H),3.03–2.87(m,1H),2.66(t,J＝11.5Hz,1H),1.93–1.46(m,4H). MS: m/z=655.3(M+1).

(S)-12-(Bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,7,8,9,10-hexahydro-12H-diapyridazino[1,2-a:1',6'-d][1,2,4]triazin-4-yl(S)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoate (57 mg, 0.087 mmol, 30% yield, 99% ee). NMR (400 MHz, chloroform-d) δ7.94 (s, 2H), 7.64 (s, 1H), 7.50–7.41 (m, 3H), 7.35 (q, J = 7.5 Hz, 1H), 7.19 (q, J = 7.6 Hz, 1H), 7.02 (dd, J = 14.8, 8.4 Hz, 3H), 6.96–6.88 (m, 2H), 6.85 (d, J = 7.6 Hz, 1H). z,1H),5.57(d,J＝9.9Hz,1H),4.62(s,1H),4.49(s,1H),3.84(s,3H),3.09(d,J＝10.8Hz ,1H),2.93(s,1H),2.66(td,J＝12.5,3.3Hz,1H),1.82(s,2H),1.58(s,1H),1.27(s,1H). MS: m/z=655.3(M+1).

Example 8. (R)-12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-dipyridazino[1,2-a:1',6'-d][1,2,4]triazine-3,5(12H)-dione

To a solution of (R)-12-(bis(3-fluorophenyl)methyl)-3,5-dioxo-3,5,7,8,9,10-hexahydro-12H-diapyridazino[1,2-a:1',6'-d][1,2,4]triazin-4-yl(S)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoate (50 mg, 0.076 mmol) in MeOH (volume: 382 μl, ratio: 1.000) and H ₂ O (volume: 382 μl, ratio: 1.000) was added LiOH.H ₂ O (32.1 mg, 0.764 mmol). The mixture was stirred at room temperature for 1 hour, then diluted with EtOAc, washed with 1N HCl and brine, dried over Na ₂ SO ₄ , filtered, and concentrated. The crude product was purified by reverse phase HPLC (MeCN/water with 0.1% TFA). Fractions containing product were combined, frozen and lyophilized to afford (R)-12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-3H-diapyridazino[1,2-a:1′,6′-d][1,2,4]triazine-3,5(12H)-dione (3.7 mg, 0.006 mmol, 8.33% yield). 1H NMR (400MHz, DMSO-d6) δ7.45(d,J＝10.1Hz,1H),7.39–7.30(m,3H),7.20(ddd,J＝24.4,19.0,9.8Hz,3H),7.09–6.92(m,2H),6.39(d,J＝10.8Hz ,1H),4.80(d,J＝10.7Hz,1H),4.29(d,J＝11.9Hz,1H),3.20(d,J＝9.7Hz,1H),2.86(t,J＝11.1Hz,1H),2.43–2.27(m,1H),1.72–1.33(m,4H).MS m/z 439.1(M+1).

Example 9. (S)-12-(bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10-tetrahydro-12H-diazino[1,2-a:1',6'-d][1,2,4]triazine-3,5-dione

This compound was prepared using the same method as in Example 8. 1H NMR (400 MHz, DMSO-d6) δ 7.45 (d, J = 11.7 Hz, 1H), 7.39–7.29 (m, 3H), 7.29–7.11 (m, 3H), 7.08–6.92 (m, 2H), 6.39 (d, J = 10.7 Hz, 1H), 4.80 (d, J = 10.8 Hz, 1H), 4.29 (d, J = 11.2 Hz, 1H), 3.20 (d, J = 10.1 Hz, 1H), 2.86 (t, J = 11.1 Hz, 1H), 2.42–2.28 (m, 1H), 1.70–1.35 (m, 4H). MS: m/z = 439.1 (M+1).

Example 10. (9aR,10S)-10-Benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Intermediate 10.1. (R)-2,2-Diphenyl-1-((R)-1-tritylpyrrolidin-2-yl)ethan-1-ol and (S)-2,2-Diphenyl-1-((R)-1-tritylpyrrolidin-2-yl)ethan-1-ol

At room temperature, a solution of diphenylmethane (2.155 ml, 12.89 mmol) in THF (volume: 58.6 ml) was added with n-butyllithium (2.5 M in hexane) (4.69 ml, 11.71 mmol). After 10 minutes, a solution of (R)-1-tritylpyrrolidine-2-carbaldehyde (2 g, 5.86 mmol: see J. Am. Chem. Soc., 2008, 130, 7562-7563) in THF (6 mL) was added to the mixture. After 15 minutes, the reaction mixture was quenched with saturated aqueous NH₄Cl and extracted twice with EtOAc. The combined organic extracts were washed with brine, dried _{over Na₂SO₄} , filtered, and concentrated in vacuo. The residue was purified by ISCO (220 g silica gel column, 0-40% EtOAc in heptane) to afford (R)-2,2-diphenyl-1-((R)-1-tritylpyrrolidin-2-yl)ethan-1-ol (1.64 g, 3.22 mmol, 54.9% yield) as a sticky white solid (Peak 1) (1H NMR (400 MHz, chloroform-d) δ7.50–7.43 (m, 6H), 7.41–7.36 (m, 2H), 7.36–7.09 (m, 17H), 5.90 (s, 1H), 3.96–3.79 (m, 2H), 3.62 (t, J = 6.8 Hz, 1H), 3.18 (ddd, J = 12.9, 9.3, 6.9 Hz, 1H), 3.04 (ddd, J = 13.3, 8.9, 4.9 Hz, 1H ), 1.45–1.35 (m, 1H), 0.76 (ddd, J = 12.1, 8.9, 2.8 Hz, 1H), 0.65 (ddd, J = 13.0, 5.9, 2.6 Hz, 1H), 0.59–0.46 (m, 1H)) and white solid (S)-2,2-diphenyl-1-((R)-1-tritylpyrrolidin-2-yl)ethan-1-ol (0.62 g, 1.216 mmol, 20.77% yield) (peak 2) (1H NMR (400 MHz, chloroform-d) δ7.41 (dt, J = 6.2, 1.6 Hz, 6H), 7.30–7.01 (m, 17H), 6.67–6.61 (m, 2H), 4.81 (dd, J = 10.9, 2.4 Hz, 1H), 3.64 (d, J = 10.9 Hz, 1H), 3.32 (ddd, J = 8.9, 6.8, 2.4 Hz, 1H), 3.16 (ddd, J = 1 2.1,10.4,6.3Hz,1H),2.96(ddd,J＝11.6,7.8,2.5Hz,1H),2.65(s,1H),1.82(dddd,J＝12.4,10. 0,8.0,6.6Hz,1H),1.23(ddp,J＝14.9,8.8,3.2Hz,1H),1.17–1.03(m,1H),-0.01–-0.15(m,1H)).

Intermediate 10.2. (R)-2,2-Diphenyl-1-((R)-pyrrolidin-2-yl)ethanol

To a solution of (R)-2,2-diphenyl-1-((R)-1-tritylpyrrolidin-2-yl)ethan-1-ol (348 mg, 0.683 mmol) in MeOH (volume: 6828 μl) at room temperature was added HCl (3.0 M in water) (683 μl, 2.048 mmol). The white suspension eventually cleared, after which a precipitate formed. After 1 hour, the mixture was concentrated by rotary evaporation to a yellow oil. Toluene was added, and the mixture was concentrated by rotary evaporation again to an oily white solid. This product was used without further purification. MS: m/z = 268.2 (M+1).

Intermediate 10.3. 1-Benzyl-5-(benzyloxy)-3-((R)-2-((R)-1-hydroxy-2,2-diphenylethyl)pyrrolidine-1-carbonyl)pyridazin-4(1H)-one

To a solution of 1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (253 mg, 0.751 mmol) in DCM (4 mL) was added Hunig's base (477 μl, 2.73 mmol) and HATU (338 mg, 0.888 mmol) at room temperature. The mixture was stirred at room temperature for 15 minutes, followed by the addition of a solution of crude (R)-2,2-diphenyl-1-((R)-pyrrolidin-2-yl)ethanol (208 mg, 0.683 mmol) and Hunig's base (0.4 mL) in DCM ( ₄ mL). The mixture was stirred at room temperature for 1 hour, diluted with DCM, and washed with water and brine. The organic layer was dried over _Na₂SO₄ , filtered, and concentrated by rotary evaporation. The residue was purified using ISCO (40 g silica gel column, 5-100% EtOAc (containing 10% MeOH) in heptane) to obtain 1-benzyl-5-(benzyloxy)-3-((R)-2-((R)-1-hydroxy-2,2-diphenylethyl)pyrrolidine-1-carbonyl)pyridazin-4(1H)-one (315 mg, 0.538 mmol, 79% yield) as an oil. MS: m/z = 586.4 (M+1).

Intermediate 10.4. (R)-1-((R)-1-(1-Benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2,2-diphenylethyl methanesulfonate

To a solution of 1-benzyl-5-(benzyloxy)-3-((R)-2-((R)-1-hydroxy-2,2-diphenylethyl)pyrrolidine-1-carbonyl)pyridazin-4(1H)-one (315 mg, 0.538 mmol) in pyridine (volume: 5378 μl) was added MsCl (168 μl, 2.151 mmol) at 0°C. The ice bath was removed and the mixture was stirred at room temperature for 1 hour. An additional 100 μl of methanesulfonyl chloride was added. The mixture was stirred for 30 more minutes. The reaction mixture was diluted with DCM, washed with water, then washed twice with 0.5N aqueous hydrochloric acid, and again with water. The organic layer was dried over _Na₂SO₄ , _filtered , and concentrated in vacuo. The residue was purified using ISCO (80 g silica gel column, 5-100% EtOAc (containing 10% MeOH) in heptane) to obtain (R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2,2-diphenylethyl methanesulfonate (120 mg, 0.181 mmol, 33.6% yield) as a yellow solid. MS: m/z = 664.3 (M+1).

Intermediate 10.5. (R)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2,2-diphenylethyl methanesulfonate

A solution of (R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2,2-diphenylethyl methanesulfonate (102 mg, 0.154 mmol) in MeOH (5 mL) was purged with nitrogen. A reagent spoonful of palladium on carbon (10%) (32.7 mg, 0.031 mmol) was added and connected to a hydrogen balloon. The flask was evacuated and refilled with hydrogen (3 times), then stirred vigorously under a hydrogen balloon at room temperature. After 30 minutes, the reaction was purged with nitrogen and filtered through a Celite plug, which was washed with MeOH. The filtrate was concentrated in vacuo, azeotroped with toluene, and used without further purification. MS: m/z = 484.3 (M+1).

Example 10. (9aR,10S)-10-Benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Potassium carbonate (52.7 mg, 0.381 mmol) was added to a solution of crude (R)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2,2-diphenylethyl methanesulfonate (61.4 mg, 0.127 mmol) in DMF (volume: 2 mL) at room temperature. After overnight at room temperature, the reaction mixture was filtered through a 1 μm filter and directly purified in two batches on reverse phase preparative HPLC (MeCN/H2O with 0.1% TFA eluent) to afford (9aR,10S)-10-diphenylmethyl-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione (18 mg, 0.036 mmol, 28.0% yield) as a gray solid. 1H NMR (400MHz, DMSO-d6) δ7.63–7.57(m,2H),7.38(t,J＝7.6Hz,2H),7.29–7.23(m,1H) ,7.22(s,1H),7.04(td,J＝4.9,2.3Hz,3H),6.95(dd,J＝7.6,2.0Hz,2H),5.68(dd,J＝ 9.6,3.6Hz,1H),4.55(d,J＝9.5Hz,1H),4.48(ddd,J＝10.1,5.9,4.0Hz,1H),3.76–3. 58(m,2H),1.91(tdd,J＝9.5,5.0,3.0Hz,1H),1.82–1.63(m,2H),1.51–1.40(m,1H). MS m/z=388.3(M+1).

Example 11. (9aR,10R)-10-diphenylmethyl-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

This compound was prepared using the same method as in Example 10. 1H NMR (400 MHz, DMSO-d6) δ 7.45 (s, 1H), 7.37–7.32 (m, 2H), 7.32–7.17 (m, 8H), 5.45 (dd, J = 10.4, 6.1 Hz, 1H), 5.08 (d, J = 6.1 Hz, 1H), 4.04 (td, J = 10.5, 5.7 Hz, 1H), 3.55–3.42 (m, 2H), 1.89 (dt, J = 12.6, 7.4 Hz, 1H), 1.74–1.59 (m, 1H), 1.55–1.38 (m, 2H). MS m/z = 388.3 (M+1).

Example 12. (9aS,10R)-10-Benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

This compound was prepared by the same method as in Example 10. 1H NMR (400 MHz, DMSO-d6) δ 7.66–7.55 (m, 2H), 7.38 (t, J = 7.6 Hz, 2H), 7.29–7.23 (m, 1H), 7.21 (s, 1H), 7.08–7.01 (m, 3H), 6.96 (dd, J = 7.6, 2.0 Hz, 2H), 5.68 (dd, J = 9.6, 3.6 Hz, 1H), 4.55 (d ,J＝9.6Hz,1H),4.48(ddd,J＝10.3,6.1,4.0Hz,1H),3.78–3.68(m,1H),3.62(td,J＝11.7,11 .0,7.2Hz,1H),1.91(tdd,J＝9.1,5.7,1.7Hz,1H),1.82–1.64(m,2H),1.53–1.37(m,1H).MS m/z 388.3(M+1).

Example 13. (9aR,10R)-10-Benzhydryl-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

This compound was prepared in the same manner as in Preparation Example 10. 1H NMR (400MHz, DMSO-d6) δ7.45 (s, 1H), 7.37–7.32 (m, 2H), 7.29 (dd, J = 5.8, 3.5Hz ,6H),7.21(dtd,J＝7.1,4.5,2.1Hz,2H),5.45(dd,J＝10.4,6.1Hz,1H),5.08(d,J ＝6.0Hz,1H),4.04(td,J＝10.4,5.6Hz,1H),3.61–3.52(m,1H),3.46(ddd,J＝12. 2,10.0,7.7Hz,1H),1.96–1.84(m,1H),1.75–1.58(m,1H),1.56–1.37(m,2H).MS m/z 388.3(M+1).

Example 14. (9aR,10S)-10-((R)-(3-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Intermediate 14.1. tert-Butyl (R,E)-2-(3-fluorophenylvinyl)pyrrolidine-1-carboxylate

To a solution of diethyl 3-fluorobenzylphosphonate (2.60 g, 10.54 mmol) in THF (volume: 30 mL) was added a solution of LHMDS (1.0 M in THF) (10.44 mL, 10.44 mmol) dropwise at 0°C. The reaction mixture was stirred at 0°C for 20 minutes, followed by a solution of (R)-tert-butyl 2-formylpyrrolidine-1-carboxylate (2 g, 10.04 mmol) in THF (10 mL). The reaction mixture was slowly warmed to room temperature over 1 hour and then stirred at room temperature for an additional 1 hour. The reaction mixture was quenched with water and extracted with EtOAc (twice). The combined organic extracts were washed with brine, dried over Na ₂ SO ₄ , filtered, and concentrated in vacuo. The residue was purified by ISCO (80 g silica gel column, 0-40% EtOAc in heptane) to give (R,E)-tert-butyl 2-(3-fluorostyryl)pyrrolidine-1-carboxylate (2.15 g, 7.23 mmol, 72.0% yield) as a white solid. MS m/z 292.0 (M+1).

Intermediate 14.2. (R)-tert-Butyl 2-((2S,3S)-3-(3-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate and (R)-tert-Butyl 2-((2R,3R)-3-(3-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate

To a solution of (R,E)-tert-butyl 2-(3-fluorostyryl)pyrrolidine-1-carboxylate (640 mg, 2.197 mmol) in DCM (volume: 20 mL) was added mCPBA (1327 mg, 7.69 mmol) at room temperature. The reaction mixture was stirred at room temperature overnight. The reaction mixture was quenched with water and extracted with DCM. The combined organic extracts were washed with saturated sodium thiosulfate, sodium bicarbonate, and brine. The organics were dried over _Na2SO4 , _filtered , and concentrated in vacuo. The residue was purified using ISCO (40 g silica column, 0-40% EtOAc in heptane) to give a mixture of tert-butyl (R)-2-((2S,3S)-3-(3-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate and tert-butyl (R)-2-((2R,3R)-3-(3-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate (0.35 g, 1.025 mmol, 46.7% yield). MS m/z 308.3 (M+1).

Intermediate 14.3. (R)-tert-Butyl 2-((1R,2R)-2-(3-Fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylate and tert-Butyl 2-((1S,2S)-2-(3-Fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylate

A mixture of tert-butyl (R)-2-((2S,3S)-3-(3-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate and tert-butyl (R)-2-((2R,3R)-3-(3-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate (220 mg, 0.716 mmol) and copper(I) bromide-dimethyl sulfide complex (169 mg, 0.823 mmol) in THF (volume: 4 mL) was cooled to between -20 and -30°C in an acetone bath with periodic addition of dry ice. A solution of phenylmagnesium chloride (2.0 M in THF) (2.86 mL, 5.73 mmol) was added dropwise. After 40 minutes at this temperature, the reaction mixture was slowly warmed to 0°C over 30 minutes and maintained at 0°C for an additional 60 minutes. The reaction mixture was quenched with saturated aqueous _NH4Cl and extracted twice with EtOAc. The combined organic extracts were dried _{over Na2SO4} , filtered, and concentrated in vacuo. The residue was purified by ISCO (12 g silica gel column, 0-40% EtOAc in heptane) to give tert-butyl (R)-2-((1R,2R)-2-(3-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylate (40 mg, 0.104 mmol, 14.50% yield, ¹ H NMR (400 MHz, CDCl ₃ ) δ ppm 7.39 (d, J=7.73 Hz, 2H), 7.27-7.36 (m, 2H), 7.14-7.26 (m, 4H), 6.91 (td, J=8.84, 2.62 Hz, 1H), 4.09-4.25 (m, 1H), 4.01 (d, J=2.89 Hz, 1H), 3.73-3.87 (m, 1H), 3.50 (br d, J = 4.84 Hz, 1H), 3.19-3.34 (m, 1H), 1.80-1.99 (m, 2H), 1.68-1.80 (m, 2H), 1.37-1.49 (m, 9H)) and tert-butyl (R)-2-((1S,2S)-2-(3-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylate (85 mg, 0.221 mmol, 30.8% yield, 1H NMR (400 MHz, CDCl3) δ ppm 7.31 (dt, J = 14.71, 7.44 Hz, 4H), 7.06-7.25 (m, 4H), 6.77-6.96 (m, 1H), 4.96 (br d,J＝10.03Hz,1H),3.84(d,J＝10.32Hz,1H),3.74(br s,1H),3.55(br s,1H),3.20(dt,J＝10.66,7.46Hz,1H),2.00-2.20(m,1H),1.72-1.93(m,3H),1.57-1.68(m,1H),1.49(s,9H)). MS m/z 386.3(M+1).

Intermediate 14.4. tert-Butyl (R)-2-((1R,2R)-2-(3-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate

To a solution of tert-butyl (R)-2-((1R,2R)-2-(3-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylate (85 mg, 0.221 mmol) in DCM (volume: 2 mL) at 0°C was added TEA (0.154 mL, 1.103 mmol) and MsCl (0.052 mL, 0.662 mmol). After 10 minutes at this temperature, the reaction mixture was removed from the ice bath and stirred at room temperature for 1 hour. Additional MsCl (0.052 mL, 0.662 mmol) was added. After an additional 2 hours at room temperature, the reaction was diluted with DCM and washed with water and brine. The _DCM layer was dried over _Na2SO4 , filtered, and concentrated in vacuo. The residue was purified by ISCO (12 g silica column, 0-50% EtOAc in heptane) to afford tert-butyl (R)-2-((1R,2R)-2-(3-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate (10.2 mg, 0.022 mmol, 9.98% yield). MS m/z 464.2 (M+1).

Intermediate 14.5. (1R,2R)-2-(3-Fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate

To tert-butyl (R)-2-((1R,2R)-2-(3-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate (10.2 mg, 0.022 mmol) was added HCl (1 mL, 4.0 mmol, 4.0 M in dioxane). After 1 hour at room temperature, the mixture was concentrated in vacuo and carried on to the next step. MS m/z 364.3 (M+1). Intermediate 14.6. (1R,2R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(3-fluorophenyl)-2-phenylethyl methanesulfonate

To a solution of 1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (8.14 mg, 0.024 mmol) in DCM (volume: 1 mL) was added Hunig's base (0.019 mL, 0.110 mmol) and HATU (10.88 mg, 0.029 mmol) at room temperature. After 15 minutes, the mixture was added to a solution of crude (1R,2R)-2-(3-fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate (8 mg, 0.022 mmol) and Hunig's base (0.05 mL) in DCM (0.5 mL). The mixture was stirred at room temperature for 1 hour, diluted with DCM, and washed with water and brine. The organic layer was dried over _Na₂SO₄ , filtered, and concentrated _by rotary evaporation. The residue was purified using ISCO (4 g silica column, 0-100% EtOAc (containing 10% MeOH) in heptane) to afford (1R,2R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(3-fluorophenyl)-2-phenylethyl methanesulfonate (14.2 mg, 0.021 mmol, 95% yield). MS m/z 682.1 (M+1).

Intermediate 14.7. (1R,2R)-2-(3-Fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate

A solution of (1R,2R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(3-fluorophenyl)-2-phenylethyl methanesulfonate (14.5 mg, 0.021 mmol) in MeOH (5 mL) was purged with nitrogen. A reagent spoon of palladium on carbon (10%) (4.53 mg, 4.25 μmol) was added and connected to a hydrogen balloon. The flask was evacuated, refilled with hydrogen (3 times), and then stirred vigorously under a hydrogen balloon at room temperature. After 1 hour, the reaction mixture was filtered through celite and washed with MeOH. Filtered and evaporated. The product was carried on to the next step without purification. MS m/z 502.3 (M+1).

Example 14. (9aR,10S)-10-((R)-(3-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

To a solution of (1R,2R)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate (10.6 mg, 0.021 mmol) in DMF (volume: 1 mL) was added potassium carbonate (8.76 mg, 0.063 mmol) at room temperature. The mixture was stirred at room temperature for 4 hours, filtered through a 1 μm filter, and directly purified by reverse phase HPLC (MeCN/H2O containing 0.1% TFA as eluent) in two batches. The product-containing fractions were combined and lyophilized to afford (9aR,10S)-10-((R)-(3-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione as an off-white solid (3.9 mg, 7.36 μmol, 34.8% yield). 1H NMR(400MHz,DMSO-d6)δ7.50(d,J＝10.5Hz,1H),7.46–7.35(m,2H),7.18(s,1H) ,7.11–6.99(m,4H),6.97–6.90(m,2H),5.70(dd,J＝9.6,3.5Hz,1H),4.60(d,J＝ 9.6Hz,1H),4.45(dt,J＝10.1,5.5Hz,1H),3.78–3.66(m,1H),3.66–3.53(m,1H) ,1.91(dt,J＝12.6,6.7Hz,1H),1.85–1.60(m,2H),1.40(qd,J＝11.5,6.9Hz,1H). MS m/z 406.2 (M+1).

Example 15. (9aR,10R)-10-(bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

This compound was prepared using the same method as in Example 14. 1H NMR (400 MHz, MeOD) δ ppm 7.64 (s, 1H), 7.26-7.40 (m, 2H), 7.08-7.22 (m, 3H), 6.94-7.07 (m, 3H), 5.40 (dd, J = 10.78, 6.09 Hz, 1H), 5.15 (d, J = 6.06 Hz, 1H), 4.09 (td, J = 10.51, 5.87 Hz, 1H), 3.67-3.77 (m, 1H), 3.53-3.65 (m, 1H), 1.99-2.09 (m, 1H), 1.58-1.85 (m, 3H). MS m/z 424.3 (M+1).

Example 16. (9aR,10S)-10-(bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

This compound was prepared using the same method as in Example 14. 1H NMR (400 MHz, MeOD) δ ppm: 7.29-7.52 (m, 4H), 7.01-7.12 (m, 2H), 6.70-6.86 (m, 3H), 5.76 (dd, J = 9.59, 3.62 Hz, 1H), 4.61 (d, J = 9.63 Hz, 1H), 4.51 (dt, J = 10.20, 5.12 Hz, 1H), 3.82-3.93 (m, 1H), 3.67 (td, J = 11.16, 7.56 Hz, 1H), 2.01-2.10 (m, 1H), 1.78-1.97 (m, 2H), 1.54-1.67 (m, 1H). MS m/z: 424.3 (M+1).

Example 17. (9aR,10R)-10-((S)-(3-chlorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

This compound was prepared by the same method as in Example 14. ¹ H NMR (400 MHz, DMSO-d6) δ 7.69 (t, J = 1.9 Hz, 1H), 7.66-7.60 (m, 1H), 7.42 (t, J = 7.9 Hz, 1H), 7.36-7.29 (m, 1H), 7.22 (s, 1H), 7.12-7.00 (m, 3H), 6.94 (dd, J = 7.6, 1.9 Hz, 2H), 5.73 (dd, J = 9.5, 3.6 Hz, 1H), 4. 63(d,J＝9.5Hz,1H),4.47(ddd,J＝10.2,5.4,3.4Hz,1H),3.78–3.68(m,1H),3.62(td,J＝11.7,11.0,7 .2Hz,1H),2.01–1.89(m,1H),1.87–1.78(m,1H),1.75–1.65(m,1H),1.44(qd,J＝11.6,6.8Hz,1H).MS m/z 422.3(M+1).

Example 18. (10aS)-11-Benzhydryl-4-hydroxy-7,8,10a,11-tetrahydro-10H-pyridazino[1′,6′:4,5]pyrazino[2,1-c][1,4]oxazine-3,5-dione

This compound was prepared in the same manner as in Example 14, except starting with tert-butyl (R)-3-formylmorpholine-4-carboxylate. 1H NMR (500MHz, DMSO-d6) δ7.58(d,J＝7.5Hz,2H),7.39(t,J＝7.6Hz,2H),7.29(t,J＝7.3Hz,1H),7.21(d,J＝6.6Hz,2H),7.17(s,1H),7.14(q,J＝6. 1Hz, 3H), 5.51 (d, J = 11.2Hz, 1H), 4.58 (d, J = 11.1Hz, 1H), 4.36 (d, J = 11.4Hz, 1H), 3.98 (d, J = 8.5Hz, 1H), 3.75–3.67 (m, 4H), 3.04–2.95 (m, 1H). MS m/z404.3(M+1).

Examples 19A and 19B

Intermediate 19.1. 3-((tert-Butyldimethylsilyl)oxy)-1,1-diphenylpropan-2-ol

At room temperature, under a nitrogen atmosphere, a solution of diphenylmethane (8.69 g, 51.6 mmol) in THF (258 mL) was added with n-butyllithium (2.5 M in hexane, 19.6 ml, 49.0 mmol). The red solution was stirred at room temperature for 3 minutes, then 2-((tert-butyldimethylsilyl)oxy)acetaldehyde (5.00 g, 25.8 mmol) was quickly added via syringe. The mixture was stirred for an additional 5 minutes, then quenched with saturated aqueous NH₄Cl and diluted with water. The mixture was extracted twice with EtOAc, and the combined organic extracts were washed with brine, dried _over anhydrous _Na₂SO₄ , filtered, and concentrated in vacuo. Silica gel column chromatography (0-20% EtOAc in heptane) provided 3-((tert-butyldimethylsilyl)oxy)-1,1-diphenylpropan-2-ol (4.7 g, colorless oil) in 53% yield. 1HNMR (400 MHz, chloroform-d) δ7.42–7.37 (m, 2H), 7.34–7.17 (m, 8H), 4.42 (ddd, J = 9.3, 6.2, 3.5 Hz, 1H), 4.04 (d, J = 9.0 Hz, 1H), 3.58 (dd, J = 10.1, 3.4 Hz, 1H), 3.44 (dd, J = 10.1, 6.2 Hz, 1H), 2.51 (s, 1H), 0.90 (s, 9H), 0.03–0.01 (m, 6H).

Intermediate 19.2. 3-((tert-Butyldimethylsilyl)oxy)-1,1-diphenylpropan-2-yl methanesulfonate

To a solution of 3-((tert-butyldimethylsilyl)oxy)-1,1-diphenylpropan-2-ol (4.70 g, 13.7 mmol) and triethylamine (3.8 mL, 27.4 mmol) in DCM (137 mL) at 0°C was added methanesulfonyl chloride (1.4 mL, 17.8 mmol) dropwise. The solution was stirred for 30 minutes, then diluted with DCM and washed with water. The organic layer was dried over NaSO, filtered, and concentrated in vacuo to afford crude 3-((tert-butyldimethylsilyl)oxy)-1,1-diphenylpropan-2-yl methanesulfonate as a colorless oil. This was used without further purification. MS m/z 421.4 (M+1).

Intermediate 19.3. 3-Hydroxy-1,1-diphenylpropan-2-yl methanesulfonate

To a solution of crude 3-((tert-butyldimethylsilyl)oxy)-1,1-diphenylpropan-2-yl methanesulfonate (5.8 g, 13.7 mmol) in methanol (137 mL) was added hydrogen chloride (4.0 M in dioxane, 5.2 mL, 20.6 mmol) at room temperature. The mixture was stirred for 1 hour and then concentrated in vacuo. Column chromatography on silica gel (25-80% EtOAc in heptane) provided 3-hydroxy-1,1-diphenylpropan-2-yl methanesulfonate (3.81 g, colorless oil) in 91% yield. 1HNMR (400 MHz, chloroform-d) δ7.45–7.38 (m, 2H), 7.37–7.29 (m, 6H), 7.29–7.20 (m, 2H), 5.46 (ddd, J = 10.2, 5.4, 2.6 Hz, 1H), 4.33 (d, J = 10.2 Hz, 1H), 3.87 (dd, J = 12.9, 2.6 Hz, 1H), 3.68 (dd, J = 12.9, 5.5 Hz, 1H), 2.37 (s, 3H).

Intermediate 19.4. 2-((Methylsulfonyl)oxy)-3,3-diphenylpropyl 5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylate

To a solution of 5-(benzyloxy)-4-oxo-1-((2-trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylic acid (700 mg, 1.86 mmol) in DCM (6 mL) was added Hunig's base (812 μl, 4.65 mmol) and HATU (848 mg, 2.23 mmol) at 0°C. The mixture was stirred for 15 minutes, followed by the addition of a solution of 3-hydroxy-1,1-diphenylpropan-2-yl methanesulfonate (854 mg, 2.79 mmol) in DCM (3 mL). The mixture was stirred at room temperature overnight, diluted with DCM, and washed with water. The organic layer was dried over _Na₂SO₄ , _filtered , and concentrated in vacuo. Silica gel column chromatography (5-80% EtOAc in heptane) provided 2-((methylsulfonyl)oxy)-3,3-diphenylpropyl 5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylate (878 mg, white foam) in 71% yield. MS m/z 665.2 (M+1).

Intermediate 19.5. 2-((Methylsulfonyl)oxy)-3,3-diphenylpropyl 5-hydroxy-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylate

A solution of 2-((methylsulfonyl)oxy)-3,3-diphenylpropyl 5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylate (1.0 g, 1.5 mmol) in methanol (40 mL) was purged with nitrogen. 10% palladium on carbon (160 mg, 0.15 mmol) was added, the flask was evacuated, and refilled with hydrogen using a balloon (3 times). The mixture was stirred vigorously under a hydrogen atmosphere for 30 minutes. The flask was then purged with nitrogen, and the mixture was filtered through a plug of celite, and the filter cake was washed with methanol. The filtrate was concentrated in vacuo to provide crude 2-((methylsulfonyl)oxy)-3,3-diphenylpropyl 5-hydroxy-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylate, which was used without further purification. MS m/z 575.4 (M+1).

Intermediate 19.6. 2-((Methylsulfonyl)oxy)-3,3-diphenylpropyl 5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

To a solution of crude 2-((methylsulfonyl)oxy)-3,3-diphenylpropyl 5-hydroxy-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylate (864 mg, 1.50 mmol) in DCM (5 mL) was added trifluoroacetic acid (20 mL) at room temperature. The mixture was stirred for 5 hours and then concentrated in vacuo to afford crude 2-((methylsulfonyl)oxy)-3,3-diphenylpropyl 5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carboxylate, which was used without further purification. MS m/z 445.3 (M+1).

Intermediate 19.7. 8-Benzhydryl-4-(benzyloxy)-7,8-dihydropyridazino[6,1-c][1,4]oxazine-3,5-dione

To a solution of crude 2-((methylsulfonyl)oxy)-3,3-diphenylpropyl 5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carboxylate (840 mg, 1.50 mmol) in DMF was added cesium carbonate (5.39 g, 16.5 mmol) at room temperature. The mixture was then stirred at 45°C for 3 hours. Benzyl bromide (1 mL) was then added, and the mixture was stirred at 45°C for an additional hour. The mixture was then cooled to room temperature and filtered to remove the solid. The filtrate was concentrated in vacuo, and the residue was purified in batches by reverse-phase preparative HPLC (MeCN/H2O with 0.1% TFA as eluent) to afford 8-benzhydryl-4-(benzyloxy)-7,8-dihydropyridazino[6,1-c][1,4]oxazine-3,5-dione (91 mg, white solid) in an 11% yield after lyophilization. 1H NMR (400MHz, DMSO-d6) δ7.61–7.07(m,16H),5.63(ddd,J＝11.7,2.4,1.3Hz,1H),5.46(d,J＝11.3Hz,1H),5 .33(d,J＝11.3Hz,1H), 4.92(dd,J＝12.1,2.6Hz,1H), 4.40(d,J＝11.5Hz,1H), 4.23(dd,J＝12.2,1.3Hz,1H). MS m/z439.2(M+1).

Intermediate 19.8. Isopropyl 4-(benzyloxy)-2-(3-hydroxy-1,1-diphenylpropan-2-yl)-5-oxo-2,5-dihydropyridazine-3-carboxylate

To a suspension of 8-benzhydryl-4-(benzyloxy)-7,8-dihydropyridazino[6,1-c][1,4]oxazine-3,5-dione (34 mg, 0.062 mmol) in 2-propanol (6 mL) was added titanium isopropoxide (0.11 mL, 0.37 mmol). The mixture was heated at 75°C for 3 hours and then cooled to room temperature. The mixture was diluted with EtOAc and brine. The layers were separated, and the aqueous layer was extracted twice with EtOAc. The combined organic extracts were dried over Na2SO4, filtered, and concentrated in vacuo to yield a white residue. The residue was triturated with DCM, and the DCM layer was removed by suction and concentrated in vacuo to yield a mixture of starting material and crude 4-(benzyloxy)-2-(3-hydroxy-1,1-diphenylpropan-2-yl)-5-oxo-2,5-dihydropyridazine-3-carboxylic acid isopropyl ester, which was used without further purification. MS m/z 499.3 (M+1).

Intermediate 19.9. Isopropyl 4-(benzyloxy)-5-oxo-2-(3-oxo-1,1-diphenylpropan-2-yl)-2,5-dihydropyridazine-3-carboxylate

To a solution of crude isopropyl 4-(benzyloxy)-2-(3-hydroxy-1,1-diphenylpropan-2-yl)-5-oxo-2,5-dihydropyridazine-3-carboxylate in DCM (1 ml) was added Dess-Martin periodinane (37 mg, 0.087 mmol) at room temperature. The mixture was stirred for 1 hour, then diluted with DCM and washed with saturated aqueous sodium thiosulfate and then brine. The organic layer was dried over NaSO, filtered, and concentrated in vacuo to afford crude isopropyl 4-(benzyloxy)-5-oxo-2-(3-oxo-1,1-diphenylpropan-2-yl)-2,5-dihydropyridazine-3-carboxylate, which was used without further purification. MS m/z 497.2 (M+1).

Intermediate 19. 12-Benzhydryl-7-(benzyloxy)-3,4,12,12a-tetrahydro-2H-pyridazino[1',6':4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione

Methanol (2.4 mL, 60 mmol), 3-amino-1-propanol (1.8 mL, 24 mmol), and acetic acid (1.15 mL, 20.1 mmol) were carefully added to toluene (9 mL) at room temperature (exothermic). The mixture was shaken, and 5 mL of the mixture was removed and added to crude 4-(benzyloxy)-5-oxo-2-(3-oxo-1,1-diphenylpropan-2-yl)-2,5-dihydropyridazine-3-carboxylic acid isopropyl ester (0.1 g, 0.2 mmol) in a vial. The vial was capped and the mixture was heated at 85°C for 5 _hours . The reaction was cooled to room temperature and diluted with EtOAc and water. The layers were separated, and the aqueous layer was extracted with EtOAc. The combined organic extracts were dried over _Na₂SO₄ , filtered, and concentrated in vacuo. The residue was taken up in DMSO and purified by reverse phase preparative HPLC (MeCN/water with 0.1% TFA eluent) to afford two diastereomers of 12-benzhydryl-7-(benzyloxy)-3,4,12,12a-tetrahydro-2H-pyridazino[1',6':4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione as a white solid.

Diastereomer 1: LCMS Rt 0.91/1.50 min, m/z 494.2 (M+1). 1H NMR (400 MHz, DMSO-d6) δ 7.63–7.57 (m, 2H), 7.53–7.48 (m, 2H), 7.44–7.26 (m, 7H), 7.16 (dd, J = 6.7, 3.0 Hz, 2H), 7.09 (dd, J = 5.0, 1.9 Hz, 3H), 5.45 (dd, J = 11.4, 1.3 Hz, 1H), 5.35 (d, J = 11.2 Hz, 1H), 5.20 (d, J = 11.1 Hz ,1H),4.77(d,J＝1.4Hz,1H),4.55–4.45(m,1H),4.37(d,J＝11.3Hz,1H),4.01(dd,J＝11.5,4.7Hz,1H),3.8 5–3.75(m,1H),3.00(td,J＝12.8,3.0Hz,1H),1.66(ddd,J＝17.0,8.4,4.7Hz,1H),1.44(d,J＝13.6Hz,1H).

Diastereomer 2: LCMS Rt 0.92/1.50 min, m/z 494.2 (M+1). 1H NMR (400 MHz, DMSO-d6) δ 7.70 (s, 1H), 7.51–7.44 (m, 4H), 7.40–7.28 (m, 5H), 7.27–7.20 (m, 1H), 7.16–7.03 (m, 5H), 5.61 (dd, J = 7.2, 3.3 Hz, 1H), 5.07 (d, J = 3.3 Hz, 1H), 4.96 (d, J = 1.9 Hz, 2H), 4. 88(d,J＝7.1Hz,1H),4.26(ddd,J＝13.4,5.1,2.9Hz,1H),3.94(dd,J＝11.1,4.5Hz,1H),3.45–3.3 9(m,1H),3.13(ddd,J＝13.2,11.7,4.0Hz,1H),1.93–1.79(m,1H),1.66(dt,J＝13.8,3.4Hz,1H).

Examples 19A and 19B. 12-Benzhydryl-7-hydroxy-3,4,12,12a-tetrahydro-2H-pyridazino[1′,6′:4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione

Trifluoroacetic acid (5 ml) was added to crude 12-benzhydryl-7-(benzyloxy)-3,4,12,12a-tetrahydro-2H-pyridazino[1',6':4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione (a mixture of two diastereomers) at room temperature, and the mixture was stirred for 20 minutes. The reaction was then concentrated in vacuo, and the residue was collected in DMSO. Purification by reverse-phase preparative HPLC (MeCN/H2O with 0.1% TFA eluent) and lyophilization afforded the trifluoroacetic acid salts of both diastereomers of 12-benzhydryl-7-hydroxy-3,4,12,12a-tetrahydro-2H-pyridazino[1',6':4,5]pyrazino[2,1-b][1,3]oxazine-6,8-dione (a white solid) after lyophilization.

Example 19A. LCMS Rt 0.80/1.50 min, m/z 404.2 (M+1). 1H NMR (400MHz, DMSO-d6) δ7.62–7.57(m,2H),7.42–7.25(m,7H),7.13(dd,J＝4.9,2.7Hz,2H),5.50(dd,J＝11.2,1.2Hz,1H),4.87(d,J＝1.3Hz,1H),4.48(d d,J＝11.9,7.0Hz,2H),4.04(dd,J＝11.4,4.9Hz,1H),3.91–3.79(m,1H),3.1 2(td,J＝12.8,3.1Hz,1H),1.64(dt,J＝12.8,6.6Hz,1H),1.54–1.45(m,1H).

Example 19B. LCMS Rt 0.82/1.50 min, m/z 404.2 (M+1). 1H NMR (400 MHz, DMSO-d6) δ 7.53 (s, 1H), 7.50–7.44 (m, 2H), 7.38–7.02 (m, 8H), 5.64 (dd, J=7.0, 3.5 Hz, 1H), 5.11 (d, J=3.4 Hz, 1H), 4.90 (d, J=7.0 Hz, 1H), 4.28 (qd, J=7.1, 6.0, 3.7 Hz,1H),3.98(dd,J＝11.2,4.7Hz,1H),3.43(td,J＝11.8,2.4Hz,1H),3.19(td,J＝12.9,3 .8Hz, 1H), 1.93 (dddd, J＝12.5, 9.0, 7.1, 5.2Hz, 1H), 1.68 (dddd, J＝14.1, 4.0, 2.1Hz, 1H).

Note: Examples 19A and 19B, as well as other example numbers including A or B, were isolated and tested as separate isomers, and biological activity is reported for each isolated isomer. However, because the absolute stereochemistry of the two isomers has not been determined, the structures shown in these examples do not depict stereochemistry. Therefore, structures A and B appear identical, but each represents a diastereomer.

Table 1a. Compounds of the above examples

Table 1b. Other examples prepared using the method of Example 1.

Table 1C: Additional compounds prepared using the methods of Examples 8-9.

General Synthesis of Chiral N-Boc Amino Alcohols

Step G-1: tert-Butyl (R,E)-2-(2-fluorophenylvinyl)pyrrolidine-1-carboxylate

A solution of lithium bis(trimethylsilyl)amide (1.0 M in THF, 36.5 mL, 36.5 mmol) was added dropwise to a solution of diethyl 2-fluorobenzylphosphonate (9.08 g, 36.9 mmol) in THF (80 mL) at 0°C. The mixture was stirred at 0°C for 20 minutes, followed by the dropwise addition of a solution of (R)-tert-butyl 2-formylpyrrolidine-1-carboxylate (7 g, 35.1 mmol) in THF (30 mL). The reaction mixture was stirred in an ice bath for 1 hour, then slowly warmed to room temperature over 1 hour and stirred at room temperature for _an additional 1 hour. The reaction was quenched with water and extracted twice with EtOAc. The combined organic extracts were washed with brine, dried over _Na₂SO₄ , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl (R,E)-2-(2-fluorophenylvinyl)pyrrolidine-1-carboxylate (6.5 g, white solid) in 64% yield. MS m/z 236.3 (M-tBu+1).

Step G-2: (R)-2-((2S,3S)-3-(2-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylic acid tert-butyl ester and (R)-2-((2R,3R)-3-(2-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylic acid tert-butyl ester

To a solution of (R,E)-2-(2-fluorophenylvinyl)pyrrolidine-1-carboxylic acid tert-butyl ester (1.85 g, _6.35 mmol) in DCM (60 mL) was added mCPBA (7.83 g, 31.7 mmol). The reaction mixture was stirred at room temperature for 2 hours. The reaction was quenched with water and extracted with DCM (twice). The combined organic extracts were washed sequentially with saturated _{Na2S2O3 aqueous} solution, saturated _NaHCO3 aqueous solution, and brine. The organic layer was then dried _{over Na2SO4} , filtered, and concentrated. Silica gel column chromatography (EtOAc / heptane) provided an inseparable mixture of (R) -2- ((2S, 3S) -3- (2-fluorophenyl) oxiran-2-yl) pyrrolidine-1-carboxylic acid tert-butyl ester and (R) -2- ((2R, 3R) -3- (2-fluorophenyl) oxiran-2-yl) pyrrolidine-1-carboxylic acid tert-butyl ester in 41% yield (1.6 g, colorless oil). The mixture was used in the next step without further purification.

Step G-3: (R)-2-((1R,2R)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylic acid tert-butyl ester and (R)-2-((1S,2S)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylic acid tert-butyl ester

To a mixture of (R)-tert-butyl 2-((2S,3S)-3-(2-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate and (R)-tert-butyl 2-((2R,3R)-3-(2-fluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate (0.74 g, 2.41 mmol) in THF (30 mL) at room temperature, add copper(I) bromide-dimethyl sulfide complex (0.495 g, 2.408 mmol). Cool the mixture to between -20°C and -30°C in an acetone bath, adding dry ice periodically. Add bromophenylmagnesium solution (1.0 M in THF, 9.63 mL, 9.63 mmol) dropwise. Stir for 15 minutes and then warm to 0°C. Add 2 equivalents of bromophenylmagnesium and stir for an additional 20 minutes. Add 2 equivalents of bromophenylmagnesium and stir for an additional 20 minutes. The reaction was quenched with saturated aqueous _NH4Cl and extracted twice with EtOAc. The combined organic extracts were dried over _Na2SO4 , filtered _, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided 38% yield of (R)-2-((1R,2R)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylic acid tert-butyl ester (353 mg, colorless oil, eluted first) and 32% yield of (R)-2-((1S,2S)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylic acid tert-butyl ester (300 mg, white foam, eluted later). MS m/z 286.2 (MH+-Boc).

Example 32. (9aR,10S)-10-((R)-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: (R)-tert-Butyl 2-((1R,2R)-2-(2-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate

To a solution of (R)-tert-butyl 2-((1R,2R)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylate (470 mg, 0.914 mmol) in pyridine (9 mL) was added methanesulfonyl chloride (1.069 mL, 13.72 mmol) at 0°C. The ice bath was removed after 5 minutes, and the reaction was stirred at room temperature for 2 hours. The reaction mixture was then partitioned between DCM and water. The DCM layer was separated and washed with saturated aqueous NaHCO ₃ solution and then brine, dried over Na ₂ SO ₄ , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl (R)-2-((1R,2R)-2-(2-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate (350 mg, white foam) in 83% yield. MS m/z 408.4 (MH ⁺ -tBu).

Step 2: (1R,2R)-2-(2-fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride

HCl (4.0 M in dioxane, 5 ml, 20 mmol) was added to tert-butyl (R)-2-((1R,2R)-2-(2-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate (350 mg, 0.755 mmol). Stir at room temperature for 1 hour. The reaction was then concentrated to afford (1R,2R)-2-(2-fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride, which was used in the next step without further purification. MS m/z 364.5 (MH ⁺ ).

Step 3: (1R,2R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(2-fluorophenyl)-2-phenylethyl methanesulfonate

Hunig's base (0.519 mL, 2.97 mmol) and HATU (367 mg, 0.966 mmol) were added to a solution of 1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (275 mg, 0.817 mmol) in DCM (6 mL) at room temperature. The mixture was stirred at room temperature for 15 minutes, followed by addition of a solution of crude (1R,2R)-2-(2-fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride (270 mg, 0.743 mmol) in DCM (4 mL) and 2 equivalents of Hunig's base. The mixture was stirred at room temperature for 1 hour. The reaction was then diluted with DCM and washed with water and brine. The organic layer was dried over _Na₂SO₄ , _filtered , and concentrated. Silica gel column chromatography (EtOAc/EtOH/heptane) provided (1R,2R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(2-fluorophenyl)-2-phenylethyl methanesulfonate (470 mg) in 93% yield. MS m/z 682.5 (MH ⁺ ).

Step 4: (1R,2R)-2-(2-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate

A solution of (1R,2R)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(2-fluorophenyl)-2-phenylethyl methanesulfonate (470 mg, 0.689 mmol) in methanol (12 mL) was purged with nitrogen. 10% palladium on carbon (220 mg, 0.207 mmol) was added, and a hydrogen balloon was attached. The flask was evacuated, refilled with hydrogen (3 times), and then stirred vigorously under a hydrogen balloon at room temperature for 6 hours. The reaction mixture was filtered through celite, and the filter cake was washed with methanol. The filtrate was concentrated to give crude (1R,2R)-2-(2-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate, which was used in the next step without further purification. MS m/z 502.4 (MH ⁺ ).

Step 5: (9aR,10S)-10-((R)-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Potassium carbonate (342 mg, 2.476 mmol) was added to a solution of (1R,2R)-2-(2-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate (345 mg, 0.619 mmol) in DMF (10 mL). The mixture was stirred at room temperature overnight. The reaction mixture was filtered through a 1 μm filter and purified by reverse phase HPLC. The product fractions were combined, frozen, and lyophilized to give (9aR,10S)-10-((R)-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione formate salt (125 mg, 0.275 mmol, white solid) in 44% yield over two steps. ¹ H NMR (400 MHz, CD ₃ OD) δ ppm 7.91(td,J＝7.36,2.01Hz,1H)7.26-7.42(m,3H)7.02-7.17(m,4H)6.96(dd ,J＝6.38,2.96Hz,2H)5.79(dd,J＝9.56,3.59Hz,1H)4.69(d,J＝9.63Hz,1H)4 .52(dt,J＝9.96,5.12Hz,1H)3.84-3.99(m,1H)3.57-3.73(m,1H)2.01-2.12 (m,1H)1.91-2.00(m,1H)1.78-1.91(m,1H)1.55(qd,J＝11.56,6.80Hz,1H). MS m/z 406.4 (MH ⁺ ).

Table 1d. Additional compounds prepared using the method of Example 32.

Example 51. (9aR,10S)-10-((S)-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: (R)-tert-Butyl 2-((1S,2S)-2-(2-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate

To a solution of (R)-2-((1S,2S)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carboxylic acid tert-butyl ester (300 mg, 0.778 mmol) in pyridine (9 mL) was added methanesulfonyl chloride (0.910 mL, 11.67 mmol) at 0 ° C. The ice bath was removed after 5 minutes and the reaction was stirred at room temperature for 2 hours. The reaction mixture was partitioned between DCM and water. The DCM layer was separated and washed with 1N aqueous hydrochloric acid solution, saturated NaHCO ₃ aqueous solution and brine. The organic layer was dried over Na ₂ SO ₄ , filtered and concentrated. Silica gel column chromatography (EtOAc/heptane) provided (R)-2-((1S,2S)-2-(2-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylic acid tert-butyl ester (325 mg, white foam) in a yield of 90%. MS m/z 408.3 (MH ⁺ -tBu).

Step 2: (1R,7aR)-1-((S)-(2-f-fluorophenyl)(phenyl)methyl)tetrahydro-1H,3H-pyrrolo[1,2-c]oxazol-3-one

A solution of (R)-tert-butyl 2-((1S,2S)-2-(2-fluorophenyl)-1-((methylsulfonyl)oxy)-2-phenylethyl)pyrrolidine-1-carboxylate (325 mg, 0.701 mmol) in pyridine (4 mL) was heated at 120° C. in a microwave reactor for 2 hours. Silica gel column chromatography (EtOAc/heptane) provided (1R,7aR)-1-((S)-(2-fluorophenyl)(phenyl)methyl)tetrahydro-1H,3H-pyrrolo[1,2-c]oxazol-3-one (150 mg) in 69% yield. MS m/z 312.4 (MH ⁺ ).

Step 3: (1R,2S)-2-(2-fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethan-1-ol hydrochloride

To a solution of (1R,7aR)-1-((S)-(2-fluorophenyl)(phenyl)methyl)tetrahydro-1H,3H-pyrrolo[1,2-c]oxazol-3-one (150 mg, 0.482 mmol) in dioxane (2 mL) was added 6N aqueous HCl, and the mixture was heated in a sealed vial at 90°C for 2 days until the reaction was complete. The reaction was then concentrated to provide crude (1R,2S)-2-(2-fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethan-1-ol hydrochloride, which was used in the next step without further purification. MS m/z 286.4 (MH ⁺ ).

Step 4: 1-Benzyl-5-(benzyloxy)-3-((R)-2-((1R,2S)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carbonyl)pyridazin-4(1H)-one

Hunig base (0.331 mL, 1.892 mmol) and HATU (234 mg, 0.615 mmol) were added to a solution of 1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (175 mg, 0.520 mmol) in DCM (2 mL) at room temperature. The mixture was stirred at room temperature for 15 minutes, followed by addition of a solution of crude (1R,2S)-2-(2-fluorophenyl)-2-phenyl-1-((R)-pyrrolidin-2-yl)ethan-1-ol hydrochloride (135 mg, 0.473 mmol) in DCM (2 mL) and Hunig base (0.331 ml, 1.892 mmol). The mixture was stirred at room temperature for 30 minutes. The mixture was then diluted with DCM and washed with water and brine. The organic layer was dried over _Na₂SO₄ , _filtered , and concentrated. Silica gel column chromatography (EtOAc/EtOH/heptane) provided 1-benzyl-5-(benzyloxy)-3-((R)-2-((1R,2S)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carbonyl)pyridazin-4(1H)-one (270 mg, foamy solid) in 95% yield. MS m/z 604.7 (MH ⁺ ).

Step 5: (1R,2S)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(2-fluorophenyl)-2-phenylethyl methanesulfonate

To a solution of 1-benzyl-5-(benzyloxy)-3-((R)-2-((1R,2S)-2-(2-fluorophenyl)-1-hydroxy-2-phenylethyl)pyrrolidine-1-carbonyl)pyridazin-4(1H)-one (270 mg, 0.447 mmol) in 2,6-lutidine (6 mL, 51.5 mmol) was added methanesulfonyl chloride (0.697 mL, 8.95 mmol) in an ice bath. The ice bath was removed after 5 minutes, and the reaction mixture was stirred at room temperature for 3 hours. LC-MS showed a major [M+H]+ of 682.5/1.07 minutes, corresponding to the desired product. The reaction mixture was then partitioned between DCM and water. The DCM layer was separated and washed sequentially with 1N aqueous hydrochloric acid, saturated aqueous _NaHCO₃ , and brine. The DCM layer was then dried _{over Na₂SO₄} , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided (1R,2S)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(2-fluorophenyl)-2-phenylethyl methanesulfonate (245 mg, brown solid) in 80% yield. MS m/z 682.6 (MH ⁺ ).

Step 6: (1R,2S)-2-(2-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate

To a solution of (1R,2S)-1-((R)-1-(1-benzyl-5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(2-fluorophenyl)-2-phenylethyl methanesulfonate (245 mg, 0.359 mmol) in methanol (6 mL) was added HCl (4.0 M in dioxane, 0.180 ml, 0.719 mmol), and the solution was purged with nitrogen. 10% palladium on carbon (115 mg, 0.108 mmol) was added, and a hydrogen balloon was attached. The flask was evacuated, refilled with hydrogen (3 times), and then stirred vigorously under a hydrogen balloon at room temperature for 2 hours. More palladium on carbon (115 mg, 0.108 mmol) was added, and the mixture was stirred at room temperature for an additional 2 hours. The reaction mixture was filtered through celite, and the filter cake was washed with methanol. The filtrate was concentrated to give crude (1R,2S)-2-(2-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate, which was used in the next step without further purification. MS m/z 502.3 (MH ⁺ ).

Step 7: (9aR,10S)-10-((S)-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

To a solution of crude (1R,2S-2-(2-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-phenylethyl methanesulfonate (180 mg, 0.341 mmol) in DMF (5 mL) was added potassium carbonate (188 mg, 1.364 mmol), and the mixture was stirred at room temperature overnight. The reaction was filtered through a 1 micron filter and purified by reverse phase HPLC. The product fractions were combined, frozen, and lyophilized to give the formate salt of (9aR,10S)-10-((S-(2-fluorophenyl)(phenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione (69 mg, 0.151 mmol, white solid) in 44% yield over two steps. ¹ H NMR (400MHz, CD ₃ OD) δppm 7.55(d,J＝7.63Hz,2H)7.42(t,J＝7.65Hz,2H)7.37(s,1H)7.27-7.34(m,1H)7.03-7.13(m, 2H)6.88-6.95(m,1H)6.83(dd,J＝10.37,8.31Hz,1H)5.82(dd,J＝9.88,3.57Hz,1H)4.92(br d,J＝9.98Hz,1H)4.49-4.62(m,1H)3.82-4.00(m,1H)3.57-3.73(m,1H)1.98-2.10(m,1H)1.77-1.94(m,2H)1.56-1.70(m,1H). MS m/z 406.4 (MH ⁺ ).

Table 1e Other compounds prepared using the method of Example 51.

General Synthesis of Chiral N-CBZ Amino Alcohols

Step G-1: tert-Butyl (R,E)-2-(2,3-difluorophenyl)pyrrolidine-1-carboxylate

A solution of lithium bis(trimethylsilyl)amide (1.0 M in THF, 26.3 mL, 26.3 mmol) was added dropwise to a solution of diethyl 2,3-difluorobenzylphosphonate (7.13 g, 25.1 mmol) in THF (84 mL) at 0°C. The mixture was stirred at 0°C for 1 hour, followed by the dropwise addition of (R)-tert-butyl 2-formylpyrrolidine-1-carboxylate (5.0 g, 25.1 mmol). The reaction mixture was stirred in an ice bath for 1 hour, then slowly warmed to room temperature over 1 hour and stirred at room temperature for an additional 2 hours. The reaction was quenched with water and extracted twice with EtOAc. The combined organic extracts were washed with brine, dried over _Na₂SO₄ , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl (R,E)-2-(2,3 _- difluorophenylvinyl)pyrrolidine-1-carboxylate (6.87 g, white solid) in 88% yield. MS m/z 254.3 (M-tBu+H).

Step G-2: (R,E)-2-(2,3-difluorophenylvinyl)pyrrolidine hydrochloride

A solution of HCl (4.0 M in dioxane, 19.6 ml, 78 mmol) was added to tert-butyl (R,E)-2-(2,3-difluorophenylvinyl)pyrrolidine-1-carboxylate (6.07 g, 19.6 mmol) at room temperature and stirred for 1 hour. The reaction mixture was then concentrated to provide crude (R,E)-2-(2,3-difluorophenylvinyl)pyrrolidine hydrochloride, which was used in the next step without further purification. MS m/z 210.2 (MH ⁺ ).

Step G-3: (R,E)-benzyl 2-(2,3-difluorophenylvinyl)pyrrolidine-1-carboxylate

Benzyl chloroformate (3.1 ml, 21.6 mmol) was added dropwise to a solution of triethylamine (6.84 ml, 49.1 mmol) and (R,E)-2-(2,3-difluorostyryl)pyrrolidine hydrochloride (4.11 g, 19.6 mmol) in DCM (98 ml) at 0°C. The mixture was warmed to room temperature and stirred overnight. The reaction was then diluted with additional DCM, washed successively with water and then brine, dried _{over Na₂SO₄} , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided benzyl (R,E)-2-(2,3-difluorostyryl)pyrrolidine-1-carboxylate (6.67 g, colorless oil) in 99% yield over two steps. MS m/z 344.3 ( ^MH⁺ ).

Step G-4: (R)-2-((2S,3S)-3-(2,3-difluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylic acid benzyl ester and (R)-2-((2R,3R)-3-(2,3-difluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylic acid benzyl ester

To a solution of (R,E)-2-(2,3-difluorophenylvinyl)pyrrolidine-1-carboxylate (5.9 g, 17.2 mmol) in DCM (286 mL) was added _{mCPBA (21.2 g, 86 mmol). The reaction mixture was stirred at room temperature overnight. The reaction was quenched with water and extracted with DCM (twice). The combined organic extracts were washed sequentially with saturated aqueous Na2S2O3 , saturated} aqueous _NaHCO3 , and brine. The organic layer was then dried _{over Na2SO4} , filtered, and concentrated. Silica gel column chromatography (EtOAc / heptane) provided an inseparable mixture of (R)-2-((2S,3S)-3-(2,3-difluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylic acid benzyl ester and (R)-2-((2R,3R)-3-(2,3-difluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylic acid benzyl ester in 84% yield (5.16 g, colorless oil). The mixture was used in the next step without further purification.

Step G-5: (R)-2-((1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylic acid benzyl ester and (R)-2-((1S,2S)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylic acid benzyl ester

Copper(I) bromide-dimethyl sulfide complex (286 mg, 1.39 mmol) was added to a mixture of benzyl (R)-2-((2S,3S)-3-(2,3-difluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate and benzyl (R)-2-((2R,3R)-3-(2,3-difluorophenyl)oxiran-2-yl)pyrrolidine-1-carboxylate (500 mg, 1.39 mmol) in THF (8 mL) at room temperature. The mixture was cooled to between -20°C and -30°C in an acetone bath, with dry ice added periodically. A solution of (4-fluorophenyl)magnesium bromide (1.0 M in THF, 8.35 mL, 8.35 mmol) was added dropwise. The mixture was stirred for 10 minutes and then warmed to 0°C. Two equivalents of (4-fluorophenyl)magnesium bromide were added, and the mixture was stirred for an additional 30 minutes. The reaction was quenched with saturated aqueous _NH4Cl and extracted twice with EtOAc. The combined organic extracts were dried over _Na2SO4 , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided (R)-2-((1R, 2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylic acid benzyl ester ( ₈₈ mg, colorless oil, eluted first) in 14% yield and (R)-2-((1S, 2S)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylic acid benzyl ester (350 mg, eluted last) in 55% yield. MS m/z 456.4 (MH ⁺ ).

Example 65. (9aR,10S)-10-((R)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: (R)-benzyl 2-((1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate

To a solution of (R)-2-((1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylic acid benzyl ester (88 mg, 0.19 mmol) in pyridine (2.5 mL) was added methanesulfonyl chloride (0.23 mL, 2.9 mmol) at 0°C. The ice bath was removed after 5 minutes, and the reaction was stirred at room temperature for 2 hours. The reaction mixture was partitioned between DCM and water. The DCM layer was separated and washed sequentially with 1N aqueous hydrochloric acid solution, saturated aqueous NaHCO ₃ solution, and brine. The organic layer was dried over Na ₂ SO ₄ , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided (R)-2-((1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylic acid benzyl ester (85 mg) in 82% yield. MS m/z 534.5 (MH ⁺ ).

Step 2: (1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride

A solution of benzyl (R)-2-((1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate (85 mg, 0.16 mmol) in methanol (4 mL) and HCl (4.0 M in dioxane, 0.080 ml, 0.32 mmol) was purged with nitrogen. 10% palladium on carbon (68 mg, 0.064 mmol) was added, and a hydrogen balloon was attached. The flask was evacuated, refilled with hydrogen (3 times), and then stirred vigorously under a hydrogen balloon at room temperature. After 2 hours, the reaction mixture was filtered through celite, and the filter cake was washed with methanol. The filtrate was concentrated to provide crude (1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride, which was used in the next step without further purification. MS m/z 400.4 (MH ⁺ ).

Example 65. (9aR,10S)-10-((R)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared from (1R,2R)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride by the method of Steps 3-5 of Example 32. ¹ H NMR (400 MHz, CD ₃ OD) δ ppm 7.79-7.65 (m, 1H), 7.42 (s, 1H), 7.37-7.21 (m, 2H), 7.02 (dd, J=8.6, 5.3 Hz, 2H), 6.85 (t, J=8.7 Hz, 2H), 5.79 (dd, J=9.6, 3.7 Hz, 1H), 4.74 (d, J=9.6 Hz, 1H), 4.62 (s, 1H), 4. .53(dt,J＝10.2,4.8Hz,1H),3.90(dd,J＝12.7,8.8Hz,1H),3.65(td,J＝11.1,7.0Hz, 1H), 2.04 (ddt, J＝38.5, 18.2, 6.4Hz, 2H), 1.94 (s, 1H), 1.51 (qd, J＝11.7, 6.7Hz, 1H). MS m/z442.4(MH ⁺ ).

Table 1f Other compounds prepared using the method of Example 65.

Example 91. (9aR,10S)-10-((S)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: (R)-benzyl 2-((1S,2S)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate

To a solution of (R)-benzyl 2-((1S,2S)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylate (350 mg, 0.77 mmol) in pyridine (2.5 mL) was added methanesulfonyl chloride (0.90 mL, 11.5 mmol) at 0°C. The ice bath was removed after 5 minutes, and the reaction was stirred at room temperature for 2 hours. The reaction mixture was partitioned between DCM and water. The DCM layer was separated and washed sequentially with 1N aqueous hydrochloric acid solution, saturated aqueous NaHCO ₃ solution, and brine. The organic layer was dried over Na ₂ SO ₄ , filtered, and concentrated. Silica gel column chromatography (EtOAc/heptane) provided benzyl (R)-2-((1S,2S)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate (370 mg) in a 90% yield. MS m/z 534.5 (MH ⁺ ).

Step 2: (1R,7aR)-1-((S)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)tetrahydro-1H,3H-pyrrolo[1,2-c]oxazol-3-one

A solution of (R)-benzyl 2-((1S,2S)-2-(2,3-difluorophenyl)-2-(4-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate (370 mg, 0.693 mmol) in pyridine (2 mL) was heated at 150° C. in a microwave reactor for 3 hours. Silica gel column chromatography (EtOAc/heptane) provided (1R,7aR)-1-((S)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)tetrahydro-1H,3H-pyrrolo[1,2-c]oxazol-3-one (200 mg) in 83% yield. MS m/z 348.4 (MH ⁺ ).

Example 91. (9aR,10S)-10-((S)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared from (1R,7aR)-1-((S)-(2,3-difluorophenyl)(4-fluorophenyl)methyl)tetrahydro-1H,3H-pyrrolo[1,2-c]oxazol-3-one using the method of Steps 3-7 of Example 51. ¹ H NMR (400 MHz, CD3OD) δ ppm 7.61 (dd, J=8.6, 5.2 Hz, 2H), 7.42 (s, 1H), 7.16 (t, J=8.7 Hz, 2H), 7.01 (dtd, J=9.9, 7.9, 1.7 Hz, 1H), 6.96-6.80 (m, 2H), 5.85 (dd, J=10.0, 3.6 Hz, 1H), 4.95-4.90 (m ,1H),4.54(dt,J＝10.6,4.9Hz,1H),3.89(dd,J＝12.5,8.7Hz,1H),3.72–3.60(m,1 H), 2.04 (qd, J＝7.3, 3.2Hz, 1H), 1.98–1.78 (m, 2H), 1.57 (qd, J＝11.5, 6.6Hz, 1H). MS m/z 442.4 (MH ⁺ ).

Table 1g. Additional compounds prepared using the method of Example 91.

Example 106. 10-(Bis(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared from tert-butyl 2-formylpyrrolidine-1-carboxylate using the method of Example 32. LCMS (m/z): 424.3 (MH+), ^1H NMR (400 MHz, DMSO-d6) δ 7.59–7.52 (m, 1H), 7.51–7.37 (m, 2H), 7.27 (s, 1H), 7.12 (td, J=8.2, 6.1 Hz, 2H), 6.96–6.87 (m, 1H), 6.86–6.76 (m, 2H), 5.75 (dd, J=10.0, 3.6 Hz ,1H),4.72(d,J＝10.0Hz,1H),4.48(dd,J＝10.3,5.3Hz,1H),3.79–3.68(m,1H),3.6 6–3.54(m,1H),1.96–1.86(m,1H),1.85–1.61(m,2H),1.36(td,J=11.3,6.5Hz,1H).

Example 107. 4-((R)-(3-Fluorophenyl)((9aR,10S)-4-hydroxy-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-10-yl)methyl)benzonitrile

Step 1: (R)-tert-Butyl 2-((1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylate

To a microwave vial equipped with a stir bar, add tert-butyl (R)-2-((1R,2R)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylate (190 mg, 0.362 mmol, prepared using the general method for AA-1), Zn powder (23.67 mg, 0.362 mmol), zinc cyanide (85 mg, 0.724 mmol), racemic-2-(di-tert-butylphosphino)-1,1'-binaphthyl (28.8 mg, 0.072 mmol), and bis(2,2,2-trifluoroacetyl)palladium (10.88 mg, 0.036 mmol) at room temperature. Seal the cap and purge with _N₂ for 5 minutes. Add DMA (4 mL volume) via syringe and purge with _N₂ for another 5 minutes. Place the microwave vial in a heating block and heat at 95°C for 1 hour. Dilute the reaction mixture with DCM and filter through celite. The celite was washed with DCM, and the filtrate was concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl (R)-2-((1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylate (110 mg) in a 74% yield. MS m/z 411.2 (MH ⁺ ).

Step 2: (R)-tert-Butyl 2-((1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate

Methanesulfonyl chloride (0.251 mL, 3.22 mmol) was added to a solution of (R)-2-((1R, 2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carboxylic acid tert-butyl ester (110 mg, 0.268 mmol) in pyridine (4 mL) at 0 ° C. The ice bath was removed after 5 minutes and the reaction was stirred at room temperature for 2 hours. The reaction mixture was then partitioned between DCM and water. The DCM layer was washed with saturated NaHCO ₃ aqueous solution and then with brine, dried over Na ₂ SO ₄ , filtered and concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl (R)-2-((1R, 2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate (105 mg) in a yield of 80%. MS m/z 489.3 (MH ⁺ ).

Step 3: (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride

HCl (4.0 M in dioxane, 2 ml, 8 mmol) was added to tert-butyl (R)-2-((1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((methylsulfonyl)oxy)ethyl)pyrrolidine-1-carboxylate (105 mg, 0.215 mmol). Stir at room temperature for 1 hour. The reaction was then concentrated to afford (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride, which was used in the next step without further purification. MS m/z 389.3 (MH ⁺ ).

Step 4: (1R,2R)-1-((R)-1-(5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(4-cyanophenyl)-2-(3-fluorophenyl)ethyl methanesulfonate

Hunig's base (0.142 mL, 0.812 mmol) and HATU (100 mg, 0.264 mmol) were added to a solution of 5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylic acid (84 mg, 0.223 mmol, see US 2015/0072982 A1) in DCM (1 mL) at room temperature. The mixture was stirred at room temperature for 15 minutes, followed by a solution of crude (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-pyrrolidin-2-yl)ethyl methanesulfonate hydrochloride (83 mg, 0.203 mmol) in DCM (1 mL) and 2 equivalents of Hunig's base. The mixture was stirred at room temperature for 1 hour. The reaction was then diluted with DCM and washed with water and brine. The organic layer was dried over _Na₂SO₄ , _filtered , and concentrated. Silica gel column chromatography (EtOAc/EtOH/heptane) provided (1R,2R)-1-((R)-1-(5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(4-cyanophenyl)-2-(3-fluorophenyl)ethyl methanesulfonate (130 mg) in 86% yield. MS m/z 747.4 (MH ⁺ ).

Step 5: (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate

A solution of (1R,2R)-1-((R)-1-(5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(4-cyanophenyl)-2-(3-fluorophenyl)ethyl methanesulfonate (70 mg, 0.094 mmol) in methanol (5 mL) was purged with nitrogen. 10% palladium on carbon (29.9 mg, 0.028 mmol) was added and a hydrogen balloon was attached. The flask was evacuated, refilled with hydrogen (3 times), and then stirred vigorously under a hydrogen balloon at room temperature for 1 hour. The reaction mixture was filtered through celite and the filter cake was washed with methanol. The filtrate was concentrated to give crude (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate, which was used in the next step without further purification. MS m/z 657.4 (MH ⁺ ).

Step 6: (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate

TFA (1.2 ml, 15.58 mmol) was added to crude (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate (61 mg, 0.088 mmol). The reaction mixture was stirred at room temperature for 2 h. The solvent was concentrated, and the residue was azeotroped with toluene to provide crude (1R,2R)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate, which was used in the next step without further purification. MS m/z 527.3 (MH ⁺ ).

Step 7: 4-((R)-(3-Fluorophenyl)((9aR,10S)-4-hydroxy-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-10-yl)methyl)benzonitrile

Potassium carbonate (46.3 mg, 0.335 mmol) was added to a solution of crude (1R,2S)-2-(4-cyanophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate (49 mg, 0.084 mmol) in DMF (2 mL), and the mixture was stirred at room temperature overnight. The reaction was filtered through a 1 micron filter and purified by reverse phase HPLC. The product fractions were combined, frozen and lyophilized to give 4-((R)-(3-fluorophenyl)((9aR,10S)-4-hydroxy-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-10-yl)methyl)benzonitrile (15.2 mg, 0.027 mmol, white solid) as a TFA salt in 32.7% yield over three steps. ¹ H NMR (400MHz, CD ₃ OD)δppm7.36-7.53(m,5H)7.22(d,J＝8.27Hz,2H)7.00-7.14(m,1H)5.83(dd,J＝9.93,3.62Hz,1H)4.72(d,J＝9.93Hz,1H)4 .46-4.59(m,1H)3.78-3.94(m,1H)3.68(td,J＝11.09,7.51Hz,1H)1.99-2.11(m,1H)1.73-1.96(m,2H)1.49-1.65(m,1H). MS m/z 431.2 (MH ⁺ ).

Example 108. (9aR,10S)-10-((S)-(4-chlorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: 5-(Benzyloxy)-3-((R)-2-((1R,2R)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carbonyl)-1-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-4(1H)-one

Hunig's base (0.360 mL, 2.064 mmol) and HATU (255 mg, 0.671 mmol) were added to a solution of 5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylic acid (214 mg, 0.568 mmol, see US 2015/0072982 A1) in DCM (3 mL) at room temperature. The mixture was stirred at room temperature for 15 minutes, followed by a solution of crude (1R,2R)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-((R)-pyrrolidin-2-yl)ethanol (165 mg, 0.516 mmol, prepared according to the method of Example 51, Steps 1-3) in DCM (3 mL) and 2 equivalents of Hunig's base. The mixture was stirred at room temperature for 1 hour. The reaction was then diluted with DCM and washed with water and brine. The organic layer was dried _{over Na2SO4} , filtered, and concentrated. Silica gel column chromatography (EtOAc/EtOH/heptane) provided 5-(benzyloxy)-3-((R)-2-((1R,2R)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carbonyl)-1-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-4(1H)-one (280 mg) in 80% yield. MS m/z 678.6 (MH ⁺ ).

Step 2: (1R,2S)-1-((R)-1-(5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(4-chlorophenyl)-2-(3-fluorophenyl)ethyl methanesulfonate

To a solution of 5-(benzyloxy)-3-((R)-2-((1R,2R)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-hydroxyethyl)pyrrolidine-1-carbonyl)-1-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-4(1H)-one (280 mg, 0.413 mmol) in 2,6-lutidine (4 mL) was added methanesulfonyl chloride (0.643 mL, 8.26 mmol) at 0°C. The ice bath was removed after 5 minutes, and the reaction was stirred at room temperature for 3 hours. The reaction mixture was then partitioned between DCM and water. The DCM layer was separated, washed with 1N HCl, saturated aqueous _NaHCO₃ , brine, dried over _Na₂SO₄ , _filtered , and concentrated. Silica gel column chromatography (EtOAc/EtOH/heptane) provided (1R,2S)-1-((R)-1-(5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(4-chlorophenyl)-2-(3-fluorophenyl)ethyl methanesulfonate (280 mg) in a 90% yield. MS m/z 756.6 (MH ⁺ ).

Step 3: (1R,2S)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate

To (1R,2S)-1-((R)-1-(5-(benzyloxy)-4-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(4-chlorophenyl)-2-(3-fluorophenyl)ethyl methanesulfonate (240 mg, 0.286 mmol) was added TFA (4 mL, 51.9 mmol). The reaction mixture was stirred at room temperature for 1 hour and then heated in a microwave reactor at 80°C for 20 minutes. The solvent was concentrated and the residue was azeotroped with toluene to provide crude (1R,2S)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate, which was used in the next step without further purification. MS m/z 536.2 (MH ⁺ ).

Step 4: (9aR,10S)-10-((S)-(4-chlorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Potassium carbonate (181 mg, 1.306 mmol) was added to a solution of crude (1R,2S)-2-(4-chlorophenyl)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)ethyl methanesulfonate (175 mg, 0.327 mmol) in DMF (6 mL), and the mixture was stirred at room temperature overnight. The reaction was filtered through a 1-micron filter and purified by reverse phase HPLC. The product fractions were combined, frozen and lyophilized to give the formate salt of (9aR,10S)-10-((S-(4-chlorophenyl)(3-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione (33.5 mg, 0.068 mmol, white solid) in 29% yield. ¹ H NMR (400 MHz, CD ₃ OD) δ ppm 7.57(d,J＝8.46Hz,2H)7.35-7.48(m,3H)7.02-7.13(m,1H)6.78-6.86(m,1H)6 .68-6.77(m,2H)5.74(dd,J＝9.59,3.52Hz,1H)4.60(d,J＝9.59Hz,1H)4.50(br dd,J＝10.47,5.18Hz,1H)3.82-3.94(m,1H)3.67(td,J＝11.00,7.58Hz,1H)2.01-2.13(m,1H)1.75-1.97(m,2H)1.51-1.64(m,1H). MS m/z 440.3 (MH ⁺ ).

Table 1h. Additional compounds prepared using the method of Example 108.

Example 111. (9aR,10S)-10-((R)-(2-bromophenyl)(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Prepared using the methods of Example 107 (steps 2-4) and Example 108 (steps 3-4). LCMS(m/z):484.1(MH+),1H NMR(500MHz,CD3OD)δppm 8.07(d,J＝7.7Hz,1H),7.64(d,J＝8.1Hz,1H),7.57(s,1H),7.41(s,1H),7.27(d,J＝7.7Hz,1H),7.03(s,2H),6.83(t,J＝8.3Hz,2 H), 5.78 (d, J = 9.4Hz, 1H), 4.90 (d, J = 9.6Hz, 1H), 4.52 (s, 1H), 3.94 (s, 1H), 3.67 (s, 1H), 2.07 (s, 1H), 1.89 (s, 2H), 1.38 (s, 1H).

Example 112. (9aR,10S)-10-((S)-(3-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: (1R,2R)-2-(3-fluorophenyl)-1-((R)-1-(4-oxo-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(o-tolyl)ethyl methanesulfonate

Hunig's base (0.102 mL, 0.583 mmol) and HATU (72 mg, 0.189 mmol) were added to a solution of 4-oxo-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylic acid (66.8 mg, 0.160 mmol, see US 2015/0072982 A1) in DCM (1 mL) at room temperature. The mixture was stirred at room temperature for 15 minutes, followed by the addition of a solution of crude (1R,2S)-2-(3-fluorophenyl)-1-((R)-pyrrolidin-2-yl)-2-(o-tolyl)ethyl methanesulfonate (55 mg, 0.146 mmol, prepared according to the method of Steps 1-2 of Example 32) in DCM (1 mL) and 2 equivalents of Hunig's base. The mixture was stirred at room temperature for 1 hour. The reaction was then diluted with DCM and washed with water and brine. The organic layer was dried over Na ₂ SO ₄ , filtered and concentrated. Silica gel column chromatography (EtOAc/EtOH/heptane) provided (1R, 2R)-2-(3-fluorophenyl)-1-((R)-1-(4-oxo-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(o-tolyl)ethyl methanesulfonate (48 mg) in a yield of 42%. MS m/z 776.5 (MH ⁺ ).

Step 2: (1R,2S)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(o-tolyl)ethyl methanesulfonate

TFA (1.2 mL, 15.6 mmol) was added to (1R,2R)-2-(3-fluorophenyl)-1-((R)-1-(4-oxo-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(o-tolyl)ethyl methanesulfonate (48 mg, 0.062 mmol). The reaction mixture was stirred at room temperature for 1.5 h. The solvent was concentrated, and the residue was azeotroped with toluene to provide crude (1R,2S)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(o-tolyl)ethyl methanesulfonate, which was used in the next step without further purification. MS m/z 516.3 (MH ⁺ ).

Step 3: (9aR,10S)-10-((S)-(3-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Potassium carbonate (30 mg, 0.217 mmol) was added to a solution of crude (1R,2S)-2-(3-fluorophenyl)-1-((R)-1-(5-hydroxy-4-oxo-1,4-dihydropyridazine-3-carbonyl)pyrrolidin-2-yl)-2-(o-tolyl)ethyl methanesulfonate (32 mg, 0.062 mmol) in DMF (1 mL), and the mixture was stirred at room temperature overnight. The reaction was filtered through a 1-μm filter and purified by reverse phase HPLC. The product fractions were combined, frozen, and lyophilized to give (9aR,10S)-10-((S-(3-fluorophenyl)(o-tolyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione as a TFA salt (3 mg, 0.005 mmol, white solid) in 21% yield over two steps. 1H NMR (400 MHz, MeOD) δ ppm 1.49-1.68(m,1H)1.76-2.11(m,4H)2.14-2.39(m,3H)3.66(td,J＝11.36,7.12Hz,1 H)3.80-3.96(m,1H)4.46-4.64(m,1H)5.74-6.02(m,1H)6.84-7.09(m,4H)7.16(br s,1H)7.25-7.55(m,4H), MS m/z420.3(MH+).

Table 1i. Additional compounds prepared using the method of Example 112.

Example 115. (9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7,7-dimethyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: (R)-tert-Butyl 5-(hydroxymethyl)-2,2-dimethylpyrrolidine-1-carboxylate

Borane tetrahydrofuran complex (1 M in THF) (15.41 ml, 15.41 mmol) was added dropwise to a 0°C solution of (R)-1-(tert-butoxycarbonyl)-5,5-dimethylpyrrolidine-2-carboxylic acid (2.2 g, 9.04 mmol) in THF under a nitrogen atmosphere. The mixture was stirred at room temperature for 3 hours. The solution was cooled, 2.5 ml of water was added, followed by sodium carbonate (1.960 g, 18.50 mmol), and the mixture was stirred vigorously at room temperature for 30 minutes. The mixture was extracted with ethyl acetate, washed with brine, dried _{over Na₂SO₄} , and concentrated to afford tert-butyl (R)-5-(hydroxymethyl)-2,2-dimethylpyrrolidine-1-carboxylate (2.1 g, >99% yield) as a colorless oil, which was used in the next step without further purification. LCMS [MH+] 230.1/0.91 min.

Step 2: (R)-tert-Butyl 5-formyl-2,2-dimethylpyrrolidine-1-carboxylate

DMSO (1.431 ml, 20.15 mmol) was added dropwise to a solution of oxalyl chloride (0.942 ml, 10.99 mmol) in DCM (volume: 41.6 ml, ratio: 10) at -78°C, and the solution was stirred for 15 minutes. A solution of (R)-tert-butyl 5-(hydroxymethyl)-2,2-dimethylpyrrolidine-1-carboxylate in DCM (volume: 4.16 ml, ratio: 1.000) was then added, and the solution was stirred at -78°C for 1 hour. DIPEA (6.40 ml, 36.6 mmol) was then added, and the solution was allowed to warm to room temperature. The mixture was then washed sequentially with 1M HCl, water, and brine, dried _{over Na₂SO₄} , and concentrated to afford (R)-tert-butyl 5-formyl-2,2-dimethylpyrrolidine-1-carboxylate (1.9 g, 91% yield) as a yellow oil, which was used in the next step without further purification. LCMS [MH+] 228.2/0.82 min.

Example 115: (9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7,7-dimethyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared by the method of Example 32 from (R)-tert-butyl 5-formyl-2,2-dimethylpyrrolidine-1-carboxylate. LCMS(m/z):452.3(MH+),1H NMR(500MHz,CD3OD)δppm 7.45(q,J＝7.8Hz,1H),7.41–7.34(m,3H),7.06(t,J＝8.1Hz,1H),7.04–6.98(m,2H),6.82(t,J＝8.5Hz,2H),5.70(d,J＝10.1Hz,1H), 4.67–4.58(m,1H),4.42(d,J＝9.9Hz,1H),1.89–1.79(m,2H),1.75(d,J＝12.3Hz,1H),1.69(s,3H),1.63(s,3H),1.60–1.50(m,1H).

Example 116. (9aR,10R)-10-((S)-(3-Fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7,7-dimethyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared from (R)-5-formyl-2,2-dimethylpyrrolidine-1-carboxylic acid tert-butyl ester using the method of Example 32. LCMS (m/z): 452.3 (MH+), ¹ H NMR (500 MHz, CD ₃ OD) δ ppm 7.66(s,1H),7.41–7.35(m,2H),7.29(d,J＝6.8Hz,1H),7.08(t,J＝8.5Hz,3H),6.99(d,J＝10.7Hz,1H),6.95(s,1H),5.32(dd,J＝11.3,3.9Hz, 1H), 5.09 (d, J = 3.8Hz, 1H), 4.13 (d, J = 6.5Hz, 1H), 1.93 (q, J = 9.9, 8.9Hz, 1H), 1.86 (d, J = 6.4Hz, 2H), 1.82 (s, 1H), 1.63 (s, 3H), 1.56 (s, 3H).

Example 117. (7S,9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

(2R,5S)-2-Formyl-5-methylpyrrolidine-1-carboxylic acid tert-butyl ester:

Prepared from tert-butyl (2R,5S)-2-(hydroxymethyl)-5-methylpyrrolidine-1-carboxylate using the method of Example 115, Step 2. LCMS [M+Na]+ 236.2/0.70 min.

Example 117: (7S,9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared by the method of Example 32 from tert-butyl (2R,5S)-2-formyl-5-methylpyrrolidine-1-carboxylate. LCMS(m/z):438.5(MH+),1H NMR(500MHz,CD ₃ OD)δppm 7.47–7.37(m,4H),7.07–7.02(m,1H),7.00(dd,J＝8.7,5.3Hz,2H),6.81(t,J＝8.7Hz,2H),5.70(dd,J＝9.5,3.9Hz,1H),4.69–4.63(m ,1H),4.56(d,J＝9.5Hz,1H),4.41(q,J＝6.4Hz,1H),2.26–2.18(m,1H),1.95–1.88(m,1H),1.63–1.55(m,2H),1.48(d,J＝6.3Hz,3H).

Example 118. (7S,9aR,10R)-10-((S)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Prepared from tert-butyl (2R,5S)-2-formyl-5-methylpyrrolidine-1-carboxylate using the method of Example 32. LCMS (m/z): 438.4 (MH+), 1H NMR (500 MHz, CD ₃ OD) δ ppm 7.61 (s, 1H), 7.37 (dd, J = 8.0, 5.5 Hz, 2H), 7.31 (d, J = 6.8 Hz, 1H), 7.10 (d, J = 7.8 Hz, 1H), 7.07 (t, J = 8.6 Hz, 2H), 7.04-6.94 (m, 2H), 5.37 (dd, J = 9.8, 5.8 Hz, 1H), 5.05 (d, J = 5.7 Hz, 1H), 4.29 (m, 2H). (h,J＝6.5Hz,1H),4.10(td,J＝10.1,5.6Hz,1H),2.27(dd,J＝13.1,7.2Hz,1H),1.78–1.71(m,1 H), 1.68 (dd, J＝11.2, 8.0Hz, 1H), 1.51 (ddd, J＝19.7, 11.8, 7.8Hz, 1H), 1.39 (d, J＝6.3Hz, 3H).

Example 119. (7R,9aR,10S)-10-((R)-(3-fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Prepared from tert-butyl (2R,5R)-2-formyl)-5-methylpyrrolidine-1-carboxylate using the method of Example 32 (for synthesis, see US 20120195857, using tert-butyl (2R,5R)-2-(hydroxymethyl)-5-methylpyrrolidine-1-carboxylate). LCMS (m/z): 438.4 (MH+), 1H NMR (500 MHz, CD ₃ OD) δ ppm 7.46(q,J＝7.7Hz,1H),7.40(d,J＝8.7Hz,2H),7.38(s,1H),7.08(s,1H),7.05–6. 95(m,2H),6.84(t,J＝8.5Hz,2H),5.74(dd,J＝10.2,3.1Hz,1H),4.51(dd,J＝7.4,4 .6Hz,1H),4.47–4.36(m,2H),2.01(dd,J＝13.3,6.4Hz,1H),1.86–1.75(m,1H),1 .68(dd,J＝12.5,6.3Hz,1H), 1.57(dd,J＝12.6,6.3Hz,1H), 1.46(d,J＝6.5Hz,3H).

Example 120. (7R,9aR,10R)-10-((S)-(3-Fluorophenyl)(4-fluorophenyl)methyl)-4-hydroxy-7-methyl-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Prepared from tert-butyl (2R,5R)-2-formyl-5-methylpyrrolidine-1-carboxylate using the method of Example 32 (for synthesis, see US 20120195857, using tert-butyl (2R,5R)-2-(hydroxymethyl)-5-methylpyrrolidine-1-carboxylate). LCMS (m/z): 438.4 (MH+), 1H NMR (500 MHz, CD ₃ OD) δ ppm 7.70(s,1H),7.37(dd,J＝8.7,5.3Hz,2H),7.30(td,J＝8.0,6.2Hz,1H),7.12(d,J＝7.8Hz,1H),7. 08(t,J＝8.7Hz,2H),7.03(d,J＝10.6Hz,1H),6.96(td,J＝8.4,2.3Hz,1H),5.36(dd,J＝11.4,4.6H z,1H),5.15(d,J＝4.5Hz,1H),4.37–4.26(m,1H),4.08(d,J＝5.4Hz,1H),2.07–1.96(m,1H),1.91 (dd,J＝11.6,6.2Hz,1H),1.87–1.80(m,1H),1.73(dd,J＝12.3,6.0Hz,1H),1.38(d,J＝6.5Hz,3H).

Example 121. (8S,9aR,10S)-10-(Bis(3-fluorophenyl)methyl)-4-hydroxy-8-methoxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione

Prepared from tert-butyl (2R,4S)-2-formyl-4-methoxypyrrolidine-1-carboxylate using the method of Example 32 (for synthesis, see WO2014046441A1, using tert-butyl (2R,4S)-2-(hydroxymethyl)-4-methoxypyrrolidine-1-carboxylate). LCMS (m/z): 454.3 (MH+), ¹ H NMR (500 MHz, CD ₃ OD) δ ppm 7.49–7.43(m,1H),7.43–7.34(m,3H),7.12–7.04(m,2H),6.82(td,J＝8.5,2.2Hz,1H ),6.80–6.73(m,2H),5.78(dd,J＝9.8,3.6Hz,1H),4.71(dt,J＝11.9,4.6Hz,1H),4.6 2(d,J＝9.8Hz,1H),4.06(t,J＝3.8Hz,1H),3.90(d,J＝13.5Hz,1H),3.83(dd,J＝13.5, 3.9Hz, 1H), 3.30 (s, 3H), 2.08 (dd, J = 13.3, 5.3Hz, 1H), 1.62 (td, J = 12.9, 4.0Hz, 1H).

Example 122. (8R,9aR,10S)-10-(Bis(3-fluorophenyl)methyl)-4-hydroxy-8-methoxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared from tert-butyl (2R,4R)-2-formyl-4-methoxypyrrolidine-1-carboxylate using the method of Example 32 (for synthesis, see WO2014046441A1, using tert-butyl (2R,4R)-2-(hydroxymethyl)-4-methoxypyrrolidine-1-carboxylate). LCMS(m/z):454.3(MH+),1H NMR(500MHz,CD3OD)δppm 7.53(s,1H),7.48–7.35(m,3H),7.06(t,J＝7.1Hz,2H),6.79(dd,J＝15.8,8.3Hz,2H),6.72(d,J＝10.1Hz,1H),5.67(s,1H),4.91(d ,J＝8.0Hz,1H),4.60(s,1H),4.13(d,J＝5.3Hz,1H),3.87(s,1H),3.85–3.79(m,1H),3.37(s,3H),2.42–2.31(m,1H),1.80(s,1H).

Example 123. (10aR,11S)-11-Benzhydryl-4-hydroxy-7,8,10a,11-tetrahydro-10H-pyridazino[1',6':4,5]pyrazino[2,1-c][1,4]oxazine-3,5-dione

Prepared by the method of Example 32 from tert-butyl (S)-3-formylmorpholine-4-carboxylate. LCMS(m/z):404.2(MH+),1H NMR (500MHz, DMSO-d6) δ7.61–7.55(m,2H),7.39(t,J＝7.7Hz,2H),7.29(t,J＝7.5Hz,1H),7.21(dd,J＝7.8,1.8Hz,2H),7.17(s,1H),7.17–7.10( m,3H),5.50(d,J＝11.1Hz,1H),4.58(d,J＝11.1Hz,1H),4.37(s,1H),3.98(d,J＝9.0Hz,1H),3.75–3.66(m,3H),3.48(s,1H),3.02–2.95(m,1H).

Examples 124A and 124B

Step 1: tert-Butyl 2-(1-hydroxy-2,2-diphenylethyl)piperidine-1-carboxylate

At room temperature, BuLi (2.5M in hexane) (6.47 mL, 16.18 mmol) was added dropwise to a solution of diphenylmethane (2.86 g, 16.99 mmol) in THF (volume: 35 mL). The resulting solution turned red and was stirred for another 10 minutes. At -78 ° C, the solution was titrated into a solution of tert-butyl 2-formylpiperidine-1-carboxylate (3.45 g, 16.18 mmol) in THF (volume: 21 mL) via syringe. The reaction was stirred for 15 minutes, and then the reaction was confirmed to be complete by LCMS. The reaction was quenched by adding saturated aqueous ammonium chloride. The aqueous layer was extracted with diethyl ether (3x), and the combined organic layers were washed with brine, dried over MgSO ₄ , filtered and concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl 2-(1-hydroxy-2,2-diphenylethyl)piperidine-1-carboxylate (2.80 g) in 45% yield. MS m/z 382.4 (MH ⁺ ).

Step 2: tert-Butyl 2-(2,2-diphenylacetyl)piperidine-1-carboxylate

At 5-10 ° C, Dess-Martin periodinane (DMP) (6.23 g, 14.68 mmol) was added to a solution of tert-butyl 2-(1-hydroxy-2,2-diphenylethyl)piperidine-1-carboxylate (2.80 g, 7.34 mmol) in DCM (volume: 73.4 mL). The reaction mixture was stirred at room temperature for 4 hours. After the reaction was completed, the reaction was quenched with aqueous sodium sulfite solution (20 mL) and stirred for 1 hour. The reactant was then extracted with dichloromethane (2×20 mL). The combined organic layers were washed with water (20 mL) and concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl 2-(2,2-diphenylacetyl)piperidine-1-carboxylate (1.76 g) in 63% yield. MS m/z 380.4 (MH ⁺ ).

Step 3: 2,2-Diphenyl-1-(piperidin-2-yl)ethanone

A solution of hydrochloric acid (4.0 M in dioxane) (23.19 ml, 93 mmol) was added to tert-butyl 2-(2,2-diphenylacetyl)piperidine-1-carboxylate (1.76 g, 4.64 mmol) and stirred at room temperature for 1.5 hours. The mixture was then concentrated and placed under high vacuum overnight to provide the hydrochloride salt of 2,2-diphenyl-1-(piperidin-2-yl)ethanone (1.37 g, white powder) in a 94% yield. MS m/z 280.3 (MH ⁺ ).

Step 4: 3-(2-(2,2-diphenylacetyl)piperidine-1-carbonyl)-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-4(1H)-one

DIPEA (4.27 mL, 24.52 mmol) and HATU (2.424 g, 6.37 mmol) were added to a solution of 4-oxo-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-trimethylsilyl)ethoxy)methyl)-1,4-dihydropyridazine-3-carboxylic acid (2.247 g, 5.39 mmol, see US 2015/0072982 A1) in DCM (volume: 50 mL) at room temperature. The mixture was stirred at room temperature for 15 minutes, then a solution of crude 2,2-diphenyl-1-(piperidin-2-yl)ethanone hydrochloride (1.37 g, 4.90 mmol) and DIPEA (2 mL) in DCM (volume: 25) was added. The mixture was stirred at room temperature overnight, then diluted with DCM and washed with water and brine. The organic layer was dried over _Na₂SO₄ , _filtered , and concentrated. Silica gel column chromatography (EtOAc/heptane/MeOH) provided 3-(2-(2,2-diphenylacetyl)piperidine-1-carbonyl)-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-4(1H)-one (1.85 g) in a 56% yield. MS m/z 678.5 (MH ⁺ ).

Step 5: 3-(2-(2,2-diphenylacetyl)piperidine-1-carbonyl)-5-hydroxypyridazin-4(1H)-one

A solution of 3-(2-(2,2-diphenylacetyl)piperidine-1-carbonyl)-5-((2-(trimethylsilyl)ethoxy)methoxy)-1-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-4(1H)-one (83.4 mg, 0.123 mmol) in TFA (1.5 ml, 19.47 mmol) was stirred at room temperature for 2 days. The reaction was concentrated, and the residue was azeotroped with benzene (3x) to provide crude 3-(2-(2,2-diphenylacetyl)piperidine-1-carbonyl)-5-hydroxypyridazin-4(1H)-one (51 mg), which was used in the next step without further purification. MS m/z 418.3 (MH ⁺ ).

Step 6: 11-(diphenylmethylene)-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione and 11-diphenylmethyl-4-hydroxy-7,8,9,10-tetrahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

To a solution of 3-(2-(2,2-diphenylacetyl)piperidine-1-carbonyl)-5-hydroxypyridazin-4(1H)-one (867 mg, 2.077 mmol) in 1,4-dioxane (volume: 29.7 ml) was added concentrated sulfuric acid (221 μl, 4.15 mmol). The mixture was heated to 115°C in a microwave reactor for 90 minutes. The reaction mixture was filtered, and the filtrate was purified by reverse-phase HPLC. The product fractions were combined, frozen and lyophilized to give 11-(diphenylmethylene)-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione (peak 1, MS m/z 400.3 (MH ⁺ )) and 11-diphenylmethyl-4-hydroxy-7,8,9,10-tetrahydropyrido[1′,2′:4,5]pyrazino[1,2-b]pyridazine-3,5-dione (peak 2, MS m/z 400.3 (MH ⁺ )).

Step 7A: 11-Benzhydryl-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

To a solution of 11-(diphenylmethylene)-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione (22.8 mg, 0.044 mmol) in methanol (volume: 1 mL) was added palladium hydroxide on carbon (20%) (31.2 mg, 0.044 mmol) and ammonium formate (28.0 mg, 0.444 mmol). The vial was sealed and the reaction was heated to 70°C for 2 hours. The reaction mixture was filtered through celite, and the filtrate was concentrated. The residue was dissolved in DMF and purified by reverse phase HPLC. The product fractions were combined, frozen and lyophilized to give 11-diphenylmethyl-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione as a TFA salt (4.1 mg, white solid) in 17% yield. ¹ H NMR (500 MHz, methanol-d ₄ ) δ 7.65–7.55 (m, 2H), 7.51 (s, 1H), 7.40 (t, J=7.8 Hz, 2H), 7.33–7.26 (m, 1H), 7.05 (s, 6H), 5.58 (dd, J=8.0, 3.1 Hz, 1H), 4.79 (d, J=8.0 Hz, 1H), 4.40 (d, J=13.8 Hz, 1H) ,4.18(d,J＝9.6Hz,1H),3.15–3.06(m,1H),1.89(d,J＝13.6Hz,1H),1.83–1.75(m,1 H), 1.70–1.61 (m, 2H), 1.51 (qd, J＝12.9, 3.9Hz, 1H), 1.37 (tt, J＝12.2, 3.6Hz, 1H). MS m/z 402.2 (MH ⁺ ).

Step 7B: 11-Benzhydryl-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

To a solution of 11-benzhydryl-4-hydroxy-7,8,9,10-tetrahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione (8.3 mg, 0.016 mmol) in MeOH (1 mL) was added palladium hydroxide on carbon (20%) (11.35 mg, 0.016 mmol) and ammonium formate (10.19 mg, 0.162 mmol). The vial was sealed and the reaction was heated to 70°C for 2 hours. The reaction mixture was filtered through celite, and the filtrate was concentrated. The residue was dissolved in DMF and purified by reverse phase HPLC. Product fractions were combined, frozen and lyophilized to give 11-benzhydryl-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione as a TFA salt in 17% yield (1.5 mg). ¹ H NMR (500MHz, methanol-d ₄ )δ7.53–7.49(m,2H),7.41(t,J＝7.7Hz,2H),7.35(s,1H),7.34–7.30(m,1H),7.15(tt,J＝5.5,2.6Hz,5H),5.37–5.27(m,1H) ,4.62(s,1H),4.48(d,J＝11.1Hz,1H),3.69(d,J＝11.4Hz,1H),2.81–2.67(m,1H),1.92(d,J＝18.0Hz,2H),1.70–1.49(m,4H). MS m/z 402.1 (MH ⁺ ).

Example 125A. 11-(Bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared from bis(3-fluorophenyl)methane using the method of Example 124A. LCMS (m/z): 438.0 (MH+), 1H NMR (500 MHz, methanol-d4) δ 7.51–7.44 (m, 1H), 7.42 (s, 1H), 7.38 (d, J = 7.7 Hz, 2H), 7.22–7.15 (m, 1H), 7.11 (d, J = 7.9 Hz, 1H), 7.05 (d, J = 10.2 Hz, 1H), 6.99 (d, J = 7.9 Hz, 1H), 6. 95–6.89(m,1H),5.39(d,J＝11.3Hz,1H),4.67(s,1H),4.62(d,J＝11.2Hz,1H),3.67( d, J＝10.2Hz, 1H), 2.75 (d, J＝12.2Hz, 1H), 1.94 (s, 1H), 1.67 (q, J＝11.7, 10.0Hz, 4H).

Example 125B. 11-(Bis(3-fluorophenyl)methyl)-4-hydroxy-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared from bis(3-fluorophenyl)methane using the method of Example 124B. LCMS (m/z): 438.0 (MH+), 1H NMR (500 MHz, Methanol-d4) δ 8.22 (d, J = 20.2 Hz, 1H), 7.58 (s, 1H), 7.48–7.40 (m, 2H), 7.38–7.33 (m, 2H), 7.32–7.23 (m, 3H), 5.63 (d, J = 7.7 Hz, 1H), 4.91 (d, J = 8.2 Hz, 1H), 4.42 (d, J = 14.3 Hz, 1H), 4.13 (t, J = 6.4 Hz, 2H), 3.15–3.06 (m, 1H), 7.38–7.33 (m, 1H), 1.76–1.60 (m, 4H).

Example 126. 11-Benzhydryl-4-hydroxy-7,8,10a,11-tetrahydro-10H-pyridazino[1',6':4,5]pyrazino[2,1-c][1,4]oxazine-3,5-dione

Prepared from tert-butyl 3-formylmorpholine-4-carboxylate using the method of Example 124A. LCMS (m/z): 404.2 (MH+), 1H NMR (500 MHz, methanol-d4) δ 7.58 (d, J = 7.4 Hz, 2H), 7.43 (t, J = 7.7 Hz, 2H), 7.37 (s, 1H), 7.31 (t, J = 7.4 Hz, 1H), 7.06-7.01 (m, 3H), 6.99 (dd, J = 6.8, 3.0 Hz, 2H), 5.61 (dd, J = 8.9, 3.4 Hz, 1H), 4. 81(d,J＝8.9Hz,1H),4.47(dt,J＝11.2,3.9Hz,1H),4.24(dd,J＝13.9,3.0Hz,1H),4.04(dd,J =11.9, 4.7Hz, 1H), 3.63 (td, J = 11.9, 3.6Hz, 2H), 3.25 (d, J = 11.5Hz, 1H), 3.23–3.17 (m, 1H).

Example 127. 11-Benzhydryl-4-hydroxy-7-methyl-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Step 1: tert-Butyl 2-(1-hydroxy-2,2-diphenylethyl)-6-methylpiperidine-1-carboxylate

To a solution of tert-butyl 2-methylpiperidine-1-carboxylate (1 mL, 4.70 mmol) and TMEDA (0.745 mL, 4.94 mmol) in anhydrous _Et₂O (10 mL) cooled to -78°C was added dropwise isopropyllithium (0.7 M in pentane) (8.06 mL, 5.64 mmol). The reaction mixture was stirred for 15 minutes, gradually warmed to -20°C, stirred at this temperature for 60 minutes, and then cooled again to -72°C. 2,2-Diphenylacetaldehyde (1.251 mL, 7.05 mmol) was added to the reaction mixture, which was then stirred for 30 minutes before being quenched by the addition of saturated aqueous ammonium chloride (40 mL). The mixture was warmed to room temperature and diluted with diethyl ether (100 mL) and water (50 mL). The aqueous phase was extracted with diethyl ether (2 x 25 mL). _The combined organic phases were dried over _Na₂SO₄ and concentrated. Silica gel column chromatography (EtOAc/heptane) provided tert-butyl 2-(1-hydroxy-2,2-diphenylethyl)-6-methylpiperidine-1-carboxylate (711 mg) in 38% yield.MS m/z 396.4 (MH ⁺ ).

Example 127. 11-Benzhydryl-4-hydroxy-7-methyl-7,8,9,10,10a,11-hexahydropyrido[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione

Prepared by the procedure of Example 124A, Steps 2-7A from tert-butyl 2-(1-hydroxy-2,2-diphenylethyl)-6-methylpiperidine-1-carboxylate. LCMS(m/z):416.4(MH+),1H NMR (500MHz, methanol-d4) δ7.57–7.53(m,2H),7.42(t,J＝7.6Hz,2H),7.33(d,J＝ 8.4Hz,2H),7.19–7.15(m,2H),7.13(dd,J＝5.2,2.1Hz,4H),5.35–5.25(m,1 H),4.35(d,J＝11.5Hz,1H),3.84(d,J＝10.1Hz,1H),1.88–1.81(m,1H),1.79 –1.69(m,2H),1.65–1.58(m,2H),1.50–1.32(m,1H),1.06(d,J＝7.0Hz,3H).

Example 128. (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-5,7,8,9,9a,10-hexahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl 3-methylbutanoate

To a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione (60 mg, 0.128 mmol) in DCM (3 mL) was added Huni's base (0.054 mL, 0.307 mmol) followed by 3-methylbutyryl chloride (0.019 mL, 0.160 mmol). The reaction mixture was stirred at room temperature for 1 hour, diluted with DCM, and washed with aqueous _NaHCO₃ . The organic layer was dried over _Na₂SO₄ , filtered, and concentrated. The residue was dissolved in DMSO and purified by reverse _phase HPLC. The product fractions were combined, frozen and lyophilized to give the formate salt of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-5,7,8,9,9a,10-hexahydro-3H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl 3-methylbutanoate in 76% yield (55.5 mg, 0.099 mmol, white solid).

¹ H NMR (400MHz, CD ₃ OD) δppm 7.44-7.66 (m, 3H) 7.16 (t, J = 8.68Hz, 2H) 6.88-7.01 (m, 2H) 6.77-6.90 (m, 2H) 5.71 (br dd,J＝9.85,2.91Hz,1H)4.43-4.58(m,2H)3.70-3.81(m,1H)3.64(td,J＝11.14,7.02Hz,1H)2.54(d,J＝6.94Hz,2H)2.21(dquin,J ＝13.39,6.65,6.65,6.65,6.65Hz,1H)1.94-2.05(m,1H)1.85-1.93(m,1H)1.71-1.84(m,1H)1.48-1.63(m,1H)0.98-1.18(m,6H). MS m/z 508.3 (MH ⁺ ).

Table 1j. Additional compounds prepared using the method of Example 128.

Example 133. 1-(((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)ethyl ethyl carbonate

K ₂ CO ₃ (93 mg, 0.670 mmol), KI (111 mg, 0.670 mmol) and 1-chloroethyl ethyl carbonate (90 μl, 0.670 mmol) were added to a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione (90 mg, 0.167 mmol) in DMF (volume: 3.3 mL) at room temperature and stirred at 60°C for 4 hours, at which time the reaction was complete. The reaction mixture was then filtered through a sinter funnel and purified by SFC (CO ₂ /MeOH) to give 1-(((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)ethyl ethyl carbonate (17 mg) in 19% yield. ¹ H NMR (400 MHz, DMSO-d ₆ )δ7.75(d,J＝2.9Hz,1H),7.68(dd,J＝8.6,5.4Hz,2H),7.28–7.13(m,2H),6.90(ddt,J＝27.1,8 .7, 4.6Hz, 3H), 6.68 (dq, J＝15.4, 5.2Hz, 1H), 5.71 (ddd, J＝9.4, 8.0, 3.3Hz, 1H), 4.56 (dd, J＝9. 5,2.5Hz,1H),4.46(t,J＝7.8Hz,1H),4.09(dqd,J＝14.3,7.1,2.6Hz,2H),3.67–3.52(m,2H),1 .91–1.58(m,3H),1.46(d,J＝5.2Hz,3H),1.37(t,J＝10.1Hz,2H),1.18(dt,J＝11.7,7.1Hz,3H). MS m/z 540.6(M+1).

Table 1k. Additional compounds prepared using the method of Example 133.

Example 137. (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl methyl carbonate

Potassium carbonate (48.6 mg, 0.351 mmol) and methyl iodide (50.6 mg, 0.234 mmol) were added to a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5-dione (55 mg, 0.117 mmol) in DMF (volume: 586 μL) at 0° C. The mixture was stirred at 0° C. for 1 hour and then at room temperature for another 1 hour. The reaction mixture was filtered to remove solids and purified by SFC (CO ₂ /MeOH) to give (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl methyl carbonate (41 mg, white solid) in ⁶⁸ % yield. NMR(500MHz,DMSO-d6)δ7.71–7.62(m,2H),7.52(s,1H),7.27–7.14(m,2H),6.98– 6.85(m,4H),5.76(d,J＝6.5Hz,1H),5.64(dd,J＝9.7,3.4Hz,1H),5.57(d,J＝6.5Hz ,1H),4.53(d,J＝9.7Hz,1H),4.44(ddd,J＝10.0,6.4,3.4Hz,1H),3.75(s,3H),3.6 8–3.54(m,2H),1.93–1.75(m,2H),1.68(p,J=9.5,8.8Hz,1H),1.45–1.33(m,1H). MS m/z 512.3 (M+1).

Table 11. Additional compounds prepared using the method of Example 137.

Example 145. (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl L-valine ester

Step 1. (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl(tert-butoxycarbonyl)-L-valine ester

To a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine _- 3,5-dione (50 mg, 0.093 mmol) in DMF (1.8 mL) was added _K2CO3 (51.4 mg, 0.372 mmol) and KI (15.44 mg, 0.093 mmol). The mixture was cooled to 0°C and iodomethyl(tert-butoxycarbonyl)-L-valine ester (133 mg, 0.372 mmol) was added. The reaction was stirred at room temperature for 2 hours and then diluted with EtOAc. The organic layer was washed with water, dried _{over Na2SO4} , filtered, and concentrated. Silica gel column chromatography (DCM/MeOH) provided (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl(tert-butoxycarbonyl)-L-valine ester (38 mg) in a 63% yield. MS m/z 653.7 (MH ⁺ ).

Step 2. (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl L-valine ester

To a solution of (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl(tert-butoxycarbonyl)-L-valine ester (38 mg, 0.058 mmol) in DCM (volume: 582 μl) was added HCl (1.0 M in Et ₂ O, 2.9 mL, 2.9 mmol) dropwise at 0°C. The mixture was stirred at 0°C for 5 hours and then maintained at 0°C overnight. The reaction was concentrated and the residue was triturated with Et ₂ O. The solid was filtered off and dried under high vacuum to provide (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methyl L-valine ester hydrochloride (15 mg) in ⁴⁶ % yield. NMR(400MHz, DMSO-d6)δ7.66(dd,J＝8.6,5.4Hz,2H),7.50(s,1H),7.20(t,J＝8.7Hz,2H),6.99–6.82(m ,4H),5.77(d,J＝6.3Hz,1H),5.69(d,J＝6.2Hz,1H),5.64(dd,J＝9.8,3.4Hz,1H),4.52(d,J＝9.7Hz,1H), 4.39(t,J＝9.6Hz,1H),3.66–3.50(m,2H),3.14(d,J＝5.1Hz,1H),1.92–1.72(m,1H),1.60(d,J＝33.1Hz, 1H), 1.35 (dd, J = 19.1, 8.7Hz, 1H), 1.21 (d, J = 4.2Hz, 2H), 0.86 (d, J = 6.8Hz, 3H), 0.80 (t, J = 7.3Hz, 3H). MS m/z553.4(M+1).

Example 146. (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl dimethylcarbamate

To a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione (25 mg, 0.047 mmol) in 1.5 _mL of dry _CH₂Cl₂ was added trimethylamine (0.1 mL), 2 drops of N,N-dimethylcarbamoyl chloride, and a catalytic amount of DMAP at 0°C. The mixture was stirred at room temperature overnight. An additional 0.1 mL of _Et₃N and 3 drops of N,N-dimethylcarbamoyl chloride (x3) were added and stirred until complete. The reaction was quenched with 5% aqueous NaHCO₃ and washed with brine. The organic layer was dried over sodium sulfate and concentrated. SFC purification (CO ₂ /MeOH) afforded (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-5,7,8,9,9a,10-hexahydro-3H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yldimethylcarbamate in 50% yield (12 mg). ¹ H NMR (400MHz, chloroform-d) δ7.50(d,J＝18.0Hz,1H),7.34(s,2H),7.12(t,J＝8.4Hz,2H),6.97–6.71(m,4H),5.32(s,1H),4.36(d,J＝ 58.5Hz,2H),3.89–3.77(m,1H),3.59(dq,J＝11.8,7.2Hz,1H),3.08(d,J＝73.7Hz,6H),1.89(d,J＝50.3Hz,3H),1.48(s,1H). MS m/z 495.1 (MH ⁺ ).

Example 147. (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-5,7,8,9,9a,10-hexahydro-3H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methylethyl(methyl)carbamate

To a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione (50 mg, 0.093 mmol) in DMF (volume: 0.5 mL) was added _K2CO3 (77 _mg , 0.558 mmol), KI (61.8 mg, 0.372 mmol), and chloromethylethyl(methyl)carbamate (56.4 mg, 0.372 mmol). The mixture was stirred at room temperature for 4 hours. The reaction was diluted with 2.5 ml of DMSO and the solid was removed by filtration. SFC purification (CO ₂ /MeOH) and silica gel column chromatography (DCM/MeOH) afforded (((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-5,7,8,9,9a,10-hexahydro-3H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methylethyl(methyl)carbamate (9 mg) in 17% yield. 1H NMR (400MHz, chloroform-d) δ7.39 (d, J＝25.3Hz, 3H), 7.11 (t, J＝7.1Hz, 2H), 6.95–6.71 (m,4H),5.92(s,1H),5.80(d,J＝3.9Hz,1H),5.28(d,J＝10.2Hz,1H),4.38(s,1H ),4.25(d,J＝9.7Hz,1H),3.78(s,1H),3.63(s,1H),3.33(s,2H),2.91(d,J＝14. 0Hz, 3H), 1.96 (s, 1H), 1.80 (d, J = 29.9Hz, 2H), 1.49 (s, 1H), 1.27–1.06 (m, 3H). MS m/z 539.2 (MH ⁺ ).

Example 148. Methyl 2-(((((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)(ethoxy)phosphoryl)oxy)acetate

To a solution of ethyl dichlorophosphate (45 mg, 0.279 mmol) in dichloromethane (1 mL) was added dropwise triethylamine (0.078 ml, 0.558 mmol) and a solution of methyl 2-hydroxyacetate (35 mg, 0.279 mmol) in dichloromethane (2 mL) at -78°C. After stirring the reaction mixture at room temperature for 2 hours, a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione (50 mg, 0.093 mmol) and triethylamine (3 equivalents) in DCM (1 mL) was added. The mixture was stirred at room temperature for 3 hours, filtered, and concentrated. SFC purification (CO ₂ /MeOH) afforded methyl 2-(((((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-3,5,8,9,9a,10-hexahydro-7H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)(ethoxy)phosphoryl)oxy)acetate (27 mg) in 46% yield. ¹ H NMR (400 MHz, chloroform-d) δ7.45 (d, J = 5.2 Hz, 1H), 7.39–7.31 (m, 2H), 7.12 (t, J = 8.5 Hz, 2H), 6.87 (q, J = 7.2 Hz, 2H), 6.80 (t, J = 8.4 Hz, 2H), 5.33 (dt, J = 10.0, 3.1 Hz, 1H), 5.01–4.90 (m,2H),4.60–4.40(m,3H),4.27(dd,J＝10.1,2.3Hz,1H),3.80(d,J＝7.1Hz,4H),3.62( dq,J＝12.0,6.9Hz,1H),1.99(d,J＝13.6Hz,1H),1.92–1.78(m,2H),1.56–1.34(m,4H). MS m/z 604.2 (MH ⁺ ).

Example 149. Methyl 2-((((((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-5,7,8,9,9a,10-hexahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methoxy)carbonyl)oxy)-2-methylpropanoate

To a solution of (9aR,10S)-10-(bis(4-fluorophenyl)methyl)-4-hydroxy-8,9,9a,10-tetrahydro-3H-pyrrolo[1',2':4,5]pyrazino[1,2-b]pyridazine-3,5(7H)-dione (50 mg, 0.093 mmol) in DMF (volume: 0.5 mL) was added _K2CO3 (77 _mg , 0.558 mmol), KI (61.8 mg, 0.372 mmol) and methyl 2-(((chloromethoxy)carbonyl)oxy)-2-methylpropanoate (78 mg, 0.372 mmol) at room temperature. The mixture was stirred at room temperature for 4 hours. The reaction was diluted with 2.5 ml of DMSO and the solid was removed by filtration. SFC purification (CO ₂ /MeOH) and silica gel column chromatography (heptane/EtOAc) afforded methyl 2-((((((9aR,10S)-10-(bis(4-fluorophenyl)methyl)-3,5-dioxo-5,7,8,9,9a,10-hexahydro-3H-pyrrolo[1′,2′:4,5]pyrazino[1,2-b]pyridazin-4-yl)oxy)methoxy)carbonyl)oxy)-2-methylpropanoate (12 mg) in 20% yield. ¹ H NMR (400 MHz, chloroform-d) δ 7.42 (s, 1H), 7.37 (dd, J = 8.3, 5.2 Hz, 2H), 7.12 (t, J = 8.4 Hz, 2H), 6.91–6.77 (m, 4H), 6.01–5.80 (m, 2H), 5.30 (dd, J = 10.1, 3.2 Hz, 1H), 4.40 (d, J = 4.0 Hz, 1H), 4.24(d,J＝10.0Hz,1H),3.76(s,4H),3.61(dq,J＝11.6,7.0Hz,1H),2.02–1.92(m,1H),1. 85(dd,J＝12.5,6.2Hz,1H),1.81–1.72(m,1H),1.67(d,J＝5.8Hz,6H),1.53–1.45(m,1H). MS m/z 598.3 (MH ⁺ ).

Biological experiments and data

The activity of the compounds of the present invention can be evaluated using the following in vitro and in vivo methods. Using the assays described herein, the compounds of the present invention demonstrated the inhibitory potency shown in Tables 2 and 3.

Influenza virus neuraminidase assay (NA assay)

For influenza NA experiments, MDCK cells were plated in 384-well format on phenol red-free DMEM (Gibco) plates (supplemented with 2 mM L-glutamine, 1% sodium pyruvate (Cellgro, Manassas, VA), and 0.1% BSA) at a cell density of 1.8 × 10 ⁴ cells/well. Compounds were added 2 hours before infection. Infection was performed at an MOI of 0.005, and plates were incubated at 37°C, 5% CO ₂ for 48 hours. After incubation, neuraminidase activity was assessed using a NA assay kit (ThermoFisher, Carlsbad, CA). To determine cytotoxicity, TNF-α (Promega, Madison, WI) was added to treated cells according to the manufacturer's instructions.

Influenza virus minigenome experiment (RNP experiment)

For influenza A virus minigenome reporter experiments, 293T cells were transfected with expression vectors encoding the PB2, PB1, PA, and NP proteins, along with an influenza A luciferase reporter plasmid. Cells were harvested in Dulbecco's Modified Eagle's Medium (DMEM, phenol red-free, supplemented with 10% heat-inactivated FBS (fetal bovine serum), 1% sodium pyruvate, and 1% L-glutamine; Cellgro, Manassas, VA). Five plasmids were co-transfected using Fugene 6 transfection reagent (Promega, Madison, WI) in Gibco, Carlsbad, CA, at a 1:3 ratio of DNA (μg):Fugene 6 (μl). Transfections were performed in a 384-well format at a cell density of 1.8 × ^10⁴ cells/well. Compounds were added 2 hours after transfection, and the plates were incubated at 37°C, 5% _CO₂ for 48 hours. After incubation, cells were lysed and luciferase production was quantified by the addition of Britelite (Perkin-Elmer, Waltham, MA). To determine cytotoxicity, luciferase (Promega, Madison, WI) was added to treated cells according to the manufacturer's instructions.

Table 2. Activity of selected compounds against multiple influenza strains in NA assay.

Table 3. Activity of selected compounds against various influenza strains as determined by RNP assay

Claims (25)

1. A compound of formula (A): (A) Or its pharmaceutically acceptable salt, wherein: Y is a group of the following formula: The dashed lines represent the bonds connecting the group to formula (A); G is H or selected from the following groups: –C(O) R0 , –C(O) -OR0 , –C( RG ) 2 -OC(O) R0 , –C( RG ) 2- OC(O) -OR0 , –P(=O)( OR0 ) 2 , –( CRG ) 2 -OP(=O)( OR0 ) 2 , –C(O)-N( R0 ) 2 and –C( RG ) 2 -OC(O)N( R0 ) 2 . Each R 0 is independently H or selected from the following groups: C <sub>1 -C 6  alkyl and C <sub>3 -C 7 cycloalkyl; and each R 0  that is not H may optionally be substituted by one or two groups selected from the following groups: halogen, CN, -OH, amino, C 1-4  alkyl, COOR, C 1-4  alkoxy, C 1-4  haloalkyl and C 1-4 haloalkoxy; Each RG is independently selected from H and C1-4 alkyl groups; R1 is H, halogen, CN, COOR*, -CONR* 2 , or a C1 - C6 alkyl group that may optionally be substituted with one or two groups selected from halogen, –OR* and –NR* 2 ; Each time R* appears, it is independently an H or C1 - C6 alkyl group, which may optionally be substituted with –OR or –NR 2 ; Z1 is N, and Z2 is C(R) 2 ; Or Z1 is CH, and Z2 is O, S, or CH2 ; Z 3 is CH 2 , Q, -CH 2 -CH 2 -, -Q-CH 2 -, –CH 2 -Q-, -CH 2 -Q-CH 2 - or -CH 2 -CH 2 -CH 2 -; Q is selected from O, S, SO, and SO₂ ; R2 is selected from H, halogen, CN, and C1 -C4 alkyl, OR, and C1 -C4 alkyl groups independently selected from halogen, CN, C1-4 alkyl, -OR, C1-4 haloalkoxy, -NR2 , and C1-4 haloalkyl . Each R 3 is a substituent that may optionally be present on any carbon atom of a ring containing Z 2 and Z 3 , and is independently selected from halogen, –OR, C 1-4 haloalkyl, C 1-4 haloalkoxy, oxo, CN, -NR 2 , and C 1-4 alkyl that may optionally be substituted by up to three groups independently selected from halogen, CN, C 1-4 alkyl, -OR, C 1-4 haloalkoxy, -NR 2 , and C 1-4 haloalkyl; n is 0-2; Ar 1 and Ar 2 each independently represent phenyl, and Ar 1 and Ar 2 are each independently substituted by a maximum of three of the following groups: halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 2-4 alkyne and CN; Ar 1 and Ar 2 may optionally be linked together by a bridge of the formula –C(R L ) 2 -L- to form a tricyclic group, wherein each of Ar 1 and Ar 2 may optionally be substituted by up to two independent groups selected from the following: halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 2-4 alkyne and CN; Each time R appears, it is independently H or optionally substituted by up to three C1 - C4 alkyl groups independently selected from the following groups: halogen, OH, oxo, C1-4 alkyl, C1-4 alkoxy, C1-4 haloalkoxy, and C1-4 haloalkyl; L is selected from S, S=O, SO₂ , and O; and Each RL is independently an H or C1-2 alkyl group. 2. The compound of claim 1, wherein G is H, or a pharmaceutically acceptable salt thereof. 3. The compound of claim 1, wherein G is selected from the group consisting of –C(O) RO , –C(O)-ORRO, –C( RG ) 2 - OC(O)RO, –C( RG ) 2 - OC(O) -ORRO , –C(O)-N( RO ) 2 and –C( RG ) 2 -OC(O)N( RO ) 2 , wherein each RO is independently H or optionally substituted with a C1 - C4 alkyl group selected from one or two of the following groups: halogen, CN, -OH, amino, C1-4 alkyl, C1-4 alkoxy, C1-4 haloalkyl and C1-4 haloalkoxy, or a pharmaceutically acceptable salt thereof. 4. The compound of claim 3, wherein G is selected from –C(O) RO , –C(O) -ORO , –C( RG ) 2 -OC(O) RO and –C( RG ) 2 -OC(O) -ORO , wherein each RO is independently H or a group selected from C1 - C4 alkyl, and each RG is H or C1 - C4 alkyl; Or its pharmaceutically acceptable salt. 5. The compound according to any one of claims 1-4, wherein G is selected from –C(O)RO, –C(O) -ORO , –CH2 -OC(O) RO and –CH2 -OC(O) -ORO , wherein each RO is a C1 - C4 alkyl group; or a pharmaceutically acceptable salt thereof. 6. The compound according to any one of claims 1-4, wherein it is of the following formula: ; Or its pharmaceutically acceptable salt. 7. The compound of claim 6, wherein Z2 is CH2 , Z3 is CH2 , n is 0, 1 or 2, and each R3 is Me; or a pharmaceutically acceptable salt thereof. 8. The compound of claim 1, wherein it is of formula (I): (I) Or its pharmaceutically acceptable salt, wherein: R1 is a C1 - C6 alkyl or C1 - C4 haloalkyl that is H, halogen, CN, COOR*, -CONR* 2 or optionally substituted with one or two groups selected from –OR* and –NR* 2 ; Each time R* appears, it is independently H or a C1 - C6 alkyl group that may optionally be substituted with –OR or –NR 2 ; Z1 is N, and Z2 is C(R) 2 ; Or Z1 is CH, and Z2 is O, S, or CH2 ; Z 3 is CH 2 , Q, -CH 2 -CH 2 -, -Q-CH 2 -, –CH 2 -Q-, -CH 2 -Q-CH 2 - or -CH 2 -CH 2 -CH 2 -; Q is selected from O, S, SO, and SO₂ ; R2 is selected from H, halogen, CN, and C1 -C4 alkyl, OR, and C1 -C4 alkyl groups independently selected from halogen, CN, C1-4 alkyl, -OR, C1-4 haloalkoxy, -NR2 , and C1-4 haloalkyl . Each R 3 is a substituent that may optionally be present on any carbon atom of a ring containing Z 2 and Z 3 , and is independently selected from –OR, C 1-4 haloalkyl, C 1-4 haloalkoxy, oxo, CN, -NR 2 and C 1-4 alkyl that may optionally be substituted by up to three groups independently selected from halogen, CN, C 1-4 alkyl, -OR, C 1-4 haloalkoxy, -NR 2 and C 1-4 haloalkyl; n is 0-2; Ar 1 and Ar 2 each independently represent phenyl and are each independently substituted by a maximum of three of the following groups: halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 2-4 alkyne, and CN; Ar 1 and Ar 2 may optionally be linked together by a bridge of the formula –C(R L ) 2 -L- to form a tricyclic group, wherein each of Ar 1 and Ar 2 may optionally be substituted by up to two independent groups selected from the following: halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 2-4 alkyne and CN; Each time R appears, it is independently H or optionally substituted by up to three C1 - C4 alkyl groups independently selected from the following groups: halogen, OH, oxo, C1-4 alkyl, C1-4 alkoxy, C1-4 haloalkoxy, and C1-4 haloalkyl; L is selected from S, S=O, SO₂ , and O; and Each RL is independently an H or C1-2 alkyl group. 9. The compound or a pharmaceutically acceptable salt thereof as described in any one of claims 1-4 or 8, wherein Z1 is CH. 10. The compound of claim 1 or claim 8, or a pharmaceutically acceptable salt thereof, wherein Z1 is N. 11. The compound or a pharmaceutically acceptable salt thereof as described in any one of claims 1-4 or 8, wherein Z2 is CH2 . 12. The compound or a pharmaceutically acceptable salt thereof as described in any one of claims 1-4 or 8, wherein Z3 is CH2 , –CH2 - CH2- , -CH2 - CH2 - CH2- , -CH2 -O-, or O. 13. The compound of claim 12 or a pharmaceutically acceptable salt thereof, wherein Z3 is CH2 . 14. The compound or a pharmaceutically acceptable salt thereof as described in any one of claims 1-4 or 8, wherein R1 is H. 15. The compound or a pharmaceutically acceptable salt thereof as claimed in any one of claims 1-4 or 8, wherein R2 is H. 16. The compound or a pharmaceutically acceptable salt thereof as claimed in any one of claims 1-4 or 8, wherein Ar1 and Ar2 are both phenyl groups and are each independently substituted by up to two groups selected from: halogen, C1-4 alkyl, C1-4 haloalkyl, C1-4 alkoxy, C1-4 haloalkoxy, C2-4 alkyne, and CN. 17. The compound according to any one of claims 1, 2 or 8, wherein it is of the following formula: or Where Y represents a group selected from the following: ... ,and Each Ry is independently selected from halogens, C 1-4  alkyl groups, C 1-4  haloalkyl groups, C 1-4  alkoxy groups, C 1-4  haloalkoxy groups, C 2-4  alkynes, and CN; and Each q is independently 0, 1, or 2; Or its pharmaceutically acceptable salt. 18. The compound of claim 17 or a pharmaceutically acceptable salt thereof, having the formula: or Where Z1 is N or CH; Z 3 is CH 2 or –CH 2 -CH 2- , and Where G stands for H. 19. The compound or a pharmaceutically acceptable salt thereof as claimed in any one of claims 1-4 or 8, wherein Ar1 and Ar2 are both phenyl groups, and Ar1 and Ar2 may be optionally substituted independently by one or two groups selected independently from the group consisting of F, Cl and C1 - C4 alkyl groups. 20. The compound of claim 1, wherein the compound is selected from the group consisting of: 、 ... And its pharmaceutically acceptable salts. 21. A pharmaceutical composition comprising the compound of any one of claims 1-4, 8 or 20, or a pharmaceutically acceptable salt thereof, and one or more pharmaceutically acceptable carriers. 22. A combination comprising a therapeutically effective amount of the compound of any one of claims 1-4, 8 or 20 or a pharmaceutically acceptable salt thereof, and one or more therapeutically active adjuvants. 23. The compound or a pharmaceutically acceptable salt thereof as described in any one of claims 1-4, 8 or 20, used as a medicine. 24. The compound or a pharmaceutically acceptable salt thereof as described in any one of claims 1-4, 8 or 20, for the treatment of influenza. 25. Use of the compound or a pharmaceutically acceptable salt thereof as described in any one of claims 1-4, 8 or 20 in the preparation of a medicament for treating influenza.