WO2010030811A2

WO2010030811A2 - CARBACEPHEM β-LACTAM ANTIBIOTICS

Info

Publication number: WO2010030811A2
Application number: PCT/US2009/056555
Authority: WO
Inventors: Allan Scott Wagman; Heinz Ernst Moser
Original assignee: Achaogen Inc
Current assignee: Achaogen Inc
Priority date: 2008-09-10
Filing date: 2009-09-10
Publication date: 2010-03-18
Anticipated expiration: 2011-03-10
Also published as: WO2010030811A3

Abstract

Carbacephem -lactam antibiotics having structure (I) are disclosed, including stereoisomers, pharmaceutically acceptable salts, esters and prodrugs thereof, wherein Ar1, Ar2, R1 and R2 are as defined herein. The compounds are useful for the treatment of bacterial infections, in particular those caused by methicillin-resistant Staphylococcus spp.

Description

CARBACEPHEM β-LACTAM ANTIBIOTICS

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S. C. §119(e) of U.S. Provisional Patent Application No. 61/095,820, filed September 10, 2008, and U.S. Provisional Patent Application No. 61/171,675, filed April 22, 2009, which applications are incorporated herein by reference in their entireties.

BACKGROUND

Field

The present invention relates to novel carbacephem β-lactam antibiotics, and the use of such compounds to treat bacterial infections, in particular, infections caused by bacterial species resistant to conventional β-lactams.

Description of the Related Art Over the past three decades a variety of antibiotics have become available for clinical use. One class of antibiotics that has seen remarkable growth is the β-lactams, over 70 of which have entered clinical use since 1965. Unfortunately, the widespread use of these antibiotics has resulted in an alarming increase in the number of resistant strains, especially among clinically important bacteria such as the genera Salmonella, Enter obacteriaceae, Pseudomonas and Staphylococcus.

Bacterial resistance to cephalosporins occurs primarily through three mechanisms: (a) destruction of the antibiotic by β-lactamases; (b) decreased penetration due to changes in bacterial outer membrane composition; and (c) alteration of penicillin-binding proteins (PBPs) resulting in interference with β-lactam binding. The latter pathway is especially important, as the binding of β-lactams to PBPs is essential for inhibiting peptidoglycan biosynthesis (peptidoglycan is a required bacterial cell-wall component). Certain Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus ("MRSA") and various genus Enterococcus bacteria are highly resistant to β-lactam antibiotics. The resistance of MRSA is due to the presence of a PBP called PBP2a, which binds very poorly to β-lactam antibiotics. The options for treating infections caused by MRSA are limited and there is a need for new antibiotics with activity against these strains.

In recent years, a novel family of β-lactam antibiotics, the carbacephems (1), has been sporadically touted as having promise against MRSAs and other resistant species. In compound (1), Ri and R₂ are generally described as aromatic and heteroaromatic entities, and R₃ has generally been reported as an optionally substituted alkyl group.

R₃

-O

(1)

However, one problem with the carbacephem compounds developed thus far is that researchers investigating the family have been unable to achieve an acceptable balance between MRSA potency and serum protein binding. That is, MRSA activity was demonstrated relatively early on to correlate with lipophilicity; the more lipophilic the carbacephem, the greater its potency. Unfortunately, the greater the lipophilicity of the compound, the greater is its tendency toward high protein binding. Protein binding reduces the concentration of free drug circulating in blood. Lower circulating free drug concentrations typically result in less efficacious beta-lactams. Lack of oral bioavailability is another issue facing MRSA active beta-lactams. Historically, cephalosporins were both poorly absorbed by oral dosing and suffered from hydrolytic degradation, due to chemical instability, in the acidic environment of the stomach. Carbacephems offer an advantage for treating community-acquired MRSA which is most conveniently treated by oral antibiotics. Since carbacephems, due to their molecular structure, are intrinsically more stable to the gastric environment, this class of beta-lactam has a much greater potential for development as an oral agent. Despite the above, carbacephems remain an intriguing approach to dealing with MRSA and other resistant bacterial species. What is needed, however, is a novel class of carbacephems that achieves the requisite balance of MRSA potency, protein binding and oral availability. The present invention addresses this need and provides further related advantages.

BRIEF SUMMARY

In brief, the present invention is directed to novel carbacephem β-lactam antibiotics, including stereoisomers, pharmaceutically acceptable salts, esters and prodrugs thereof, and the use of such compounds to treat bacterial infections, in particular, infections caused by bacterial species resistant to conventional β-lactams, such as MRSA.

In one embodiment, a compound is provided having the following structure (I):

(I) or a stereoisomer, pharmaceutically acceptable : salt, ester, or prodrug thereof, wherein:

R¹ is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted heteroaryl, optionally substituted heteroarylalkyl and -C(=O)R^la, wherein: R^la is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted heteroaryl and optionally substituted heteroarylalkyl;

R² is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted heteroaryl and optionally substituted heteroarylalkyl;

X is selected from -O-, -S-, -C(=O)-, -SCH₂S-, -SCH₂-, -CH₂S-, - SCH=CH-, -CH=CHS-, -OCH₂-, -CH₂O-, optionally substituted alkylene, optionally substituted alkenyl ene and optionally substituted cycloalkyl; Ar¹ is

wherein:

R³ is selected from chloro, bromo, fluoro, iodo, cyano, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, - SO₂R^3a, -SOR^3a, -SR^3a, -C(=O)R^3a, -C(=O)NR^3aR^3b, -NR^3aR^3b and -OR^3a, wherein: R^3a is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl; and

R^3b is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl and an amino acid, or R^3a and R^3b, together with the N atom to which they are attached, form an optionally substituted heterocyclyl or an optionally substituted heteroaryl;

R⁴ is selected from hydrogen, chloro, bromo, fluoro, iodo, cyano, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, - SO₂R^4a, -SOR^4a, -SR^4a, -C(=O)R^4a, -C(=O)NR^4aR^4b, -NR^4aR^4b and -OR^4a, wherein:

R^4a is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl; and

R^4b is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl and an amino acid, or R^4a and R^4b, together with the N atom to which they are attached, form an optionally substituted heterocyclyl or an optionally substituted heteroaryl; and Ar² is optionally substituted aryl or optionally substituted heteroaryl, and wherein, when R⁴ is -NH₂, R³ is not chloro, and wherein, when R⁴ is -NH₂, R³ is -CH₂ and X is S, Ar² is not

In another embodiment, a pharmaceutical composition is provided comprising a compound having structure (I), or a stereoisomer, pharmaceutically acceptable salt, ester or prodrug thereof, and a pharmaceutically acceptable carrier, diluent or excipient.

In another embodiment, a method of using a compound having structure (I) in therapy is provided. In particular, the present invention provides a method of treating a bacterial infection is provided comprising administering a pharmaceutically effective amount of a compound having structure (I), or a stereoisomer, pharmaceutically acceptable salt, ester or prodrug thereof, to a mammal in need thereof. In certain embodiments, the bacterial infection may be caused by a β-lactam antibiotic- resistant bacterium, such as a methicillin-resistant genus Staphylococcus bacterium.

These and other aspects of the invention will be evident upon reference to the following detailed description.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, one skilled in the art will understand that the invention may be practiced without these details.

Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense, that is as "including, but not limited to". Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in the specification and appended claims, unless specified to the contrary, the following terms have the meaning indicated:

"Amino" refers to the -NH₂ radical.

"Cyano" refers to the -CN radical.

"Hydroxy" or "hydroxyl" refers to the -OH radical.

"Imino" refers to the =NH substituent. "Nitro" refers to the -NO₂ radical.

"Oxo" refers to the =O substituent.

"Thioxo" refers to the =S substituent.

"Alkyl" refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, containing no unsaturation, having from one to twelve carbon atoms (C]-Ci₂ alkyl), preferably one to eight carbon atoms

(Ci-C₈ alkyl) or one to six carbon atoms (Ci-C₆ alkyl), and which is attached to the rest of the molecule by a single bond, e.g., methyl, ethyl, n-propyl, 1 -methylethyl

(zso-propyl), «-butyl, n-pentyl, 1,1-dimethylethyl (t-butyl), 3-methylhexyl,

2-methylhexyl, and the like. Unless stated otherwise specifically in the specification, an alkyl group may be optionally substituted.

"Alkenyl" refers to a straight or branched hydrocarbon chain radical group consisting solely of carbon and hydrogen atoms, containing at least one double bond, having from two to twelve carbon atoms, preferably two to eight carbon atoms and which is attached to the rest of the molecule by a single bond, e.g., ethenyl, prop-1-enyl, but-1-enyl, pent-1-enyl, penta-l,4-dienyl, and the like. Unless stated otherwise specifically in the specification, an alkenyl group may be optionally substituted.

"Alkynyl" refers to a straight or branched hydrocarbon chain radical group comprising solely of carbon and hydrogen atoms, containing at least one triple bond, optionally containing at least one double bond, having from two to twelve carbon atoms, preferably two to eight carbon atoms and which is attached to the rest of the molecule by a single bond, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, and the like. Unless stated otherwise specifically in the specification, an alkynyl group may be optionally substituted.

"Alkylene" or "alkylene chain" refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing no unsaturation and having from one to twelve carbon atoms, e.g., methylene, ethylene, propylene, /z-butylene, and the like. The alkylene chain is attached to the rest of the molecule through a single bond and to the radical group through a single bond. The points of attachment of the alkylene chain to the rest of the molecule and to the radical group can be through one carbon or any two carbons within the chain. Unless stated otherwise specifically in the specification, an alkylene chain may be optionally substituted.

"Alkenylene" or "alkenylene chain" refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing at least one double bond and having from two to twelve carbon atoms, e.g., ethenylene, propenylene, π-butenylene, and the like. The alkenylene chain is attached to the rest of the molecule through a single bond and to the radical group through a double bond or a single bond. The points of attachment of the alkenylene chain to the rest of the molecule and to the radical group can be through one carbon or any two carbons within the chain. Unless stated otherwise specifically in the specification, an alkenylene chain may be optionally substituted.

"Alkynylene" or "alkynylene chain" refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing at least one triple bond and having from two to twelve carbon atoms, e.g., propynyl ene, π-butynylene, and the like. The alkynylene chain is attached to the rest of the molecule through a single bond and to the radical group through a double bond or a single bond. The points of attachment of the alkynylene chain to the rest of the molecule and to the radical group can be through one carbon or any two carbons within the chain. Unless stated otherwise specifically in the specification, an alkynylene chain may be optionally substituted. "Alkoxy" refers to a radical of the formula -OR_a where R_a is an alkyl radical as defined above containing one to twelve carbon atoms. Unless stated otherwise specifically in the specification, an alkoxy group may be optionally substituted. "Alkoxyalkyl" refers to a radical of the formula -R_b-O-R₃ where R_b is an alkylene chain as defined above and R₃ is an alkyl radical as defined above. The oxygen atom may be bonded to any carbon in the alkylene chain and in the alkyl radical. Unless stated otherwise specifically in the specification, an alkoxyalkyl group may be optionally substituted. "Aryl" refers to a hydrocarbon ring system radical comprising hydrogen,

6 to 18 carbon atoms and at least one aromatic ring. For purposes of this invention, the aryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may included fused or bridged ring systems. Aryl radicals include, but are not limited to, aryl radicals derived from aceanthrylene, acenaphthylene, acephenanthrylene, anthracene, azulene, benzene, chrysene, fluoranthene, fluorene, αs-indacene, s-indacene, indane, indene, naphthalene, phenalene, phenanthrene, pleiadene, pyrene, and triphenylene. Unless stated otherwise specifically in the specification, the term "aryl" or the prefix "ar-" (such as in "aralkyl") is meant to include aryl radicals that are optionally substituted. "Aralkyl" refers to a radical of the formula -R_b-R_c where R_b is an alkylene chain as defined above and R_c is one or more aryl radicals as defined above, for example, benzyl, diphenylmethyl and the like. Unless stated otherwise specifically in the specification, an aralkyl group may be optionally substituted.

"Aralkenyl" refers to a radical of the formula -R_d-R_c where Ra is an alkenylene chain as defined above and R_c is one or more aryl radicals as defined above. Unless stated otherwise specifically in the specification, an aralkenyl group may be optionally substituted.

"Aralkynyl" refers to a radical of the formula -R_eR_c where R_e is an alkynylene chain as defined above and R_c is one or more aryl radicals as defined above. Unless stated otherwise specifically in the specification, an aralkynyl group may be optionally substituted. "Aryloxy" refers to a radical of the formula -ORj₃ where R^ is an aryl group as defined above. Unless stated otherwise specifically in the specification, an aryloxy group may be optionally substituted.

"Aralkyloxy" refers to a radical of the formula -OR]₃ where R]₅ is an aralkyl group as defined above. Unless stated otherwise specifically in the specification, an aralkyloxy group may be optionally substituted.

"Cycloalkyl" or "carbocyclic ring" refers to a stable non-aromatic monocyclic or polycyclic hydrocarbon radical consisting solely of carbon and hydrogen atoms, which may include fused or bridged ring systems, having from three to fifteen carbon atoms, preferably having from three to ten carbon atoms, and which is saturated or unsaturated and attached to the rest of the molecule by a single bond. Monocyclic radicals include, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptly, and cyclooctyl. Polycyclic radicals include, for example, adamantyl, norbornyl, decalinyl, 7,7-dimethyl-bicyclo[2.2.1]heptanyl, and the like. Unless otherwise stated specifically in the specification, a cycloalkyl group may be optionally substituted.

"Cycloalkylalkyl" refers to a radical of the formula -R_bR_g where R_b is an alkylene chain as defined above and R_g is a cycloalkyl radical as defined above. Unless stated otherwise specifically in the specification, a cycloalkylalkyl group may be optionally substituted.

"Cycloalkylalkenyl" refers to a radical of the formula -R_dR_g where R_d is an alkenylene chain as defined above and R_g is a cycloalkyl radical as defined above.

Unless stated otherwise specifically in the specification, a cycloalkylalkenyl group may be optionally substituted. "Cycloalkylalkynyl" refers to a radical of the formula -R_eR_g where R_e is an alkynylene radical as defined above and R_g is a cycloalkyl radical as defined above.

Unless stated otherwise specifically in the specification, a cycloalkylalkynyl group may be optionally substituted.

"Fused" refers to any ring structure described herein which is fused to an existing ring structure in the compounds of the invention. When the fused ring is a heterocyclyl ring or a heteroaryl ring, any carbon atom on the existing ring structure which becomes part of the fused heterocyclyl ring or the fused heteroaryl ring may be replaced with a nitrogen atom.

"Halo" refers to bromo, chloro, fluoro or iodo.

"Haloalkyl" refers to an alkyl radical, as defined above, that is substituted by one or more halo radicals, as defined above, e.g., trifiuoromethyl, difluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl, l-fluoromethyl-2-fluoroethyl, 3-bromo-2-fluoropropyl, 1 -bromomethyl-2-bromoethyl, and the like. Unless stated otherwise specifically in the specification, a haloalkyl group may be optionally substituted. "Haloalkenyl" refers to an alkenyl radical, as defined above, that is substituted by one or more halo radicals, as defined above. Unless stated otherwise specifically in the specification, a haloalkenyl group may be optionally substituted.

"Haloalkynyl" refers to an alkynyl radical, as defined above, that is substituted by one or more halo radicals, as defined above. Unless stated otherwise specifically in the specification, a haloalkynyl group may be optionally substituted.

"Heterocyclyl" or "heterocyclic ring" refers to a stable 3- to 18-membered non-aromatic ring radical which consists of two to twelve carbon atoms and from one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. Unless stated otherwise specifically in the specification, the heterocyclyl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heterocyclyl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized; and the heterocyclyl radical may be partially or fully saturated. Examples of such heterocyclyl radicals include, but are not limited to, dioxolanyl, thienyl[l,3]dithianyl, decahydroisoquinolyl, imidazolinyl, imidazolidinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, oxazolidinyl, piperidinyl, piperazinyl, 4-piperidonyl, pyrrolidinyl, pyrazolidinyl, quinuclidinyl, thiazolidinyl, tetrahydrofuryl, trithianyl, tetrahydropyranyl, thiomorpholinyl, thiamorpholinyl, 1 -oxo-thiomorpholinyl, and 1,1-dioxo-thiomorpholinyl. Unless stated otherwise specifically in the specification, Unless stated otherwise specifically in the specification, a heterocyclyl group may be optionally substituted.

"iV-heterocyclyl" refers to a heterocyclyl radical as defined above containing at least one nitrogen and where the point of attachment of the heterocyclyl radical to the rest of the molecule is through a nitrogen atom in the heterocyclyl radical.

Unless stated otherwise specifically in the specification, a N-heterocyclyl group may be optionally substituted.

"Heterocyclylalkyl" refers to a radical of the formula -R_bR_h where R_b is an alkylene chain as defined above and R)₁ is a heterocyclyl radical as defined above, and if the heterocyclyl is a nitrogen-containing heterocyclyl, the heterocyclyl may be attached to the alkyl radical at the nitrogen atom. Unless stated otherwise specifically in the specification, a heterocyclylalkyl group may be optionally substituted.

"Heterocyclylalkenyl" refers to a radical of the formula -RaR_h where Ra is an alkenylene chain as defined above and R_h is a heterocyclyl radical as defined above, and if the heterocyclyl is a nitrogen-containing heterocyclyl, the heterocyclyl may be attached to the alkenylene chain at the nitrogen atom. Unless stated otherwise specifically in the specification, a heterocyclylalkenyl group may be optionally substituted.

"Heterocyclylalkynyl" refers to a radical of the formula -R_eR_h where R_e is an alkynylene chain as defined above and Rj₁ is a heterocyclyl radical as defined above, and if the heterocyclyl is a nitrogen-containing heterocyclyl, the heterocyclyl may be attached to the alkynyl radical at the nitrogen atom. Unless stated otherwise specifically in the specification, a heterocyclylalkynyl group may be optionally substituted. "Heteroaryl" refers to a 5- to 14-membered ring system radical comprising hydrogen atoms, one to thirteen carbon atoms, one to six heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur, and at least one aromatic ring. For purposes of this invention, the heteroaryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heteroaryl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized. Examples include, but are not limited to, azepinyl, acridinyl, benzimidazolyl, benzthiazolyl, benzindolyl, benzodioxolyl, benzofuranyl, benzooxazolyl, benzothiazolyl, benzothiadiazolyl, benzo[δ][l,4]dioxepinyl, 1 ,4-benzodioxanyl, benzonaphthofuranyl, benzoxazolyl, benzodioxolyl, benzodioxinyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, benzothienyl (benzothiophenyl), benzotriazolyl, benzo[4,6]imidazo[l,2-a]pyridinyl, carbazolyl, cinnolinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, furanonyl, isothiazolyl, imidazolyl, indazolyl, indolyl, indazolyl, isoindolyl, indolinyl, isoindolinyl, isoquinolyl, indolizinyl, isoxazolyl, naphthyridinyl, oxadiazolyl, 2-oxoazepinyl, oxazolyl, oxiranyl, 1- oxidopyridinyl, 1 -oxidopyrimidinyl, 1 -oxidopyrazinyl, 1-oxidopyridazinyl, 1 -phenyl- lH-pyrrolyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, quinazolinyl, quinoxalinyl, quinolinyl, quinuclidinyl, isoquinolinyl, tetrahydroquinolinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, and thiophenyl (i.e. thienyl). Unless stated otherwise specifically in the specification, a heteroaryl group may be optionally substituted.

"7V-heteroaryl" refers to a heteroaryl radical as defined above containing at least one nitrogen and where the point of attachment of the heteroaryl radical to the rest of the molecule is through a nitrogen atom in the heteroaryl radical. Unless stated otherwise specifically in the specification, an 7V-heteroaryl group may be optionally substituted.

"Ηeteroarylalkyl" refers to a radical of the formula -R_bRi where R_b is an alkylene chain as defined above and R, is a heteroaryl radical as defined above. Unless stated otherwise specifically in the specification, a heteroarylalkyl group may be optionally substituted.

"Ηeteroarylalkenyl" refers to a radical of the formula -RaRi where Ra is an alkenylene chain as defined above and R₁ is a heteroaryl radical as defined above. Unless stated otherwise specifically in the specification, a heteroarylalkenyl group may be optionally substituted. "Ηeteroarylalkynyl" refers to a radical of the formula -R_eR, where R_e is an alkynylene chain as defined above and R, is a heteroaryl radical as defined above. Unless stated otherwise specifically in the specification, a heteroarylalkynyl group may be optionally substituted.

"Hydroxyalkyl" refers to an alkyl radical, as defined above, substituted by one or more hydroxy groups. The term "substituted" used herein means any of the above groups (i.e., alkyl, alkenyl, alkynyl, alkylene, alkenylene, alkynylene, alkoxy, alkoxyalkyl, aryl, aralkyl, aralkenyl, aralkynyl, aryloxy, aralkyloxy, cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl, cycloalkylalkynyl, haloalkyl, haloalkenyl, haloalkynyl, heterocyclyl, jV-heterocyclyl, heterocyclylalkyl, heterocyclylalkenyl, heterocyclylalkynyl, heteroaryl, 7V-heteroaryl, heteroarylalkyl, heteroarylalkenyl and/or heteroarylalkynyl) wherein at least one hydrogen atom is replaced by a bond to a non-hydrogen atoms such as, but not limited to: a halogen atom such as F, Cl, Br, and I; an oxygen atom in groups such as hydroxyl groups, alkoxy groups, aryloxy groups, and ester groups; a sulfur atom in groups such as thiol groups, alkyl and aryl sulfide groups, sulfone groups, sulfonyl groups, and sulfoxide groups; a nitrogen atom in groups such as amines, amides, alkylamines, dialkylamines, arylamines, alkylarylamines, diary lamines, N-oxides, imides, and enamines; a silicon atom in groups such as trialkylsilyl groups, dialkylarylsilyl groups, alkyldiarylsilyl groups, and triarylsilyl groups; and other heteroatoms in various other groups. "Substituted" also means any of the above groups in which one or more bonds are replaced by a higher-order bond (e.g., a double- or triple-bond) to a heteroatom such as oxygen in oxo, carbonyl, carboxyl, and ester groups; and nitrogen in groups such as imines, oximes, hydrazones, and nitriles. "Substituted" further means any of the above groups in which one or more bonds are replaced by a bond to an amino, cyano, hydroxyl, imino, nitro, oxo, thioxo, halo, hydroxyalkyl, alkyl, alkenyl, alkynyl, alkylene, alkenylene, alkynylene, alkoxy, alkoxyalkyl, aryl, aralkyl, aralkenyl, aralkynyl, aryloxy, aralkyloxy, cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl, cycloalkylalkynyl, haloalkyl, haloalkenyl, haloalkynyl, heterocyclyl, iV-heterocyclyl, heterocyclylalkyl, heterocyclylalkenyl, heterocyclylalkynyl, heteroaryl, 7V-heteroaryl, heteroarylalkyl, heteroarylalkenyl and/or heteroarylalkynyl group. In addition, the foregoing substituents may also be optionally substituted with one or more of the above substituents. "Prodrug" is meant to indicate a compound that may be converted under physiological conditions or by solvolysis to a biologically active compound of the invention. Thus, the term "prodrug" refers to a metabolic precursor of a compound of the invention that is pharmaceutically acceptable. A prodrug may be inactive when administered to a subject in need thereof, but is converted in vivo to an active compound of the invention. Prodrugs are typically rapidly transformed in vivo to yield the parent compound of the invention, for example, by hydrolysis in blood. The prodrug compound often offers advantages of solubility, tissue compatibility or delayed release in a mammalian organism (see, e.g., Bundgard, H., Design of Prodrugs (1985), pp. 7-9, 21-24 (Elsevier, Amsterdam)). A discussion of prodrugs is provided in Higuchi, T., et al., A.C.S. Symposium Series, Vol. 14, and in Bioreversible Carriers in Drug Design, Ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987.

The term "prodrug" is also meant to include any covalently bonded carriers, which release the active compound of the invention in vivo when such prodrug is administered to a mammalian subject. Prodrugs of a compound of the invention may be prepared by modifying functional groups present in the compound of the invention in such a way that the modifications are cleaved, either in routine manipulation or in vivo, to the parent compound of the invention. Prodrugs include compounds of the invention wherein a hydroxy, amino or mercapto group is bonded to any group that, when the prodrug of the compound of the invention is administered to a mammalian subject, cleaves to form a free hydroxy, free amino or free mercapto group, respectively. Examples of prodrugs include, but are not limited to, acetate, formate and benzoate derivatives of alcohol or amide derivatives of amine functional groups in the compounds of the invention and the like. More specifically, example of prodrugs include (in addition to the prodrugs of structures (II) and (III) described below), but are not limited to, compounds of structure (I) wherein R¹ is alkyl (such as, for example, methyl) and R¹ is bonded to an ester group (such as, for example, -OC(=O)CH₃ or - OC(=O)C(CH₃)₂). The invention disclosed herein is also meant to encompass all pharmaceutically acceptable compounds of a structure disclosed herein being isotopically-labelled by having one or more atoms replaced by an atom having a different atomic mass or mass number. Examples of isotopes that can be incorporated into the disclosed compounds include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, fluorine, chlorine, and iodine, such as ²H, ³H, ¹¹C, ¹³C, ¹⁴C, ¹³N, ¹⁵N, ¹⁵O, ¹⁷O, ¹⁸O, ³¹P, ³²P, ³⁵S, ¹⁸F, ³⁶Cl, ¹²³I, and ¹²⁵I, respectively. These radiolabeled compounds could be useful to help determine or measure the effectiveness of the compounds, by characterizing, for example, the site or mode of action on the sodium channels, or binding affinity to pharmacologically important site of action on the sodium channels. Certain isotopically-labelled compounds of a structure disclosed herein, for example, those incorporating a radioactive isotope, are useful in drug and/or substrate tissue distribution studies. The radioactive isotopes tritium, i.e. ³H, and carbon-14, i.e. ¹⁴C, are particularly useful for this purpose in view of their ease of incorporation and ready means of detection.

Substitution with heavier isotopes such as deuterium, i.e. ²H, may afford certain therapeutic advantages resulting from greater metabolic stability, for example, increased in vivo half-life or reduced dosage requirements, and hence may be preferred in some circumstances.

Substitution with positron emitting isotopes, such as ^{1 1}C, ¹⁸F, ¹⁵O and ¹³N, can be useful in Positron Emission Topography (PET) studies for examining substrate receptor occupancy. Isotopically-labeled compounds of a structure disclosed herein can generally be prepared by conventional techniques known to those skilled in the art or by processes analogous to those as set out below using an appropriate isotopically-labeled reagent in place of the non-labeled reagent previously employed.

The invention disclosed herein is also meant to encompass the in vivo metabolic products of the disclosed compounds. Such products may result from, for example, the oxidation, reduction, hydrolysis, amidation, esterifϊcation, and the like of the administered compound, primarily due to enzymatic processes. Accordingly, the invention includes compounds produced by a process comprising contacting a compound of this invention with a mammal for a period of time sufficient to yield a metabolic product thereof. Such products are typically are identified by administering a radiolabeled compound of the invention in a detectable dose to an animal, such as rat, mouse, guinea pig, monkey, or to human, allowing sufficient time for metabolism to occur, and isolating its conversion products from the urine, blood or other biological samples.

"Stable compound" and "stable structure" are meant to indicate a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.

"Mammal" includes humans and both domestic animals such as laboratory animals and household pets (e.g., cats, dogs, swine, cattle, sheep, goats, horses, rabbits), and non-domestic animals such as wildlife and the like. "Optional" or "optionally" means that the subsequently described event of circumstances may or may not occur, and that the description includes instances where said event or circumstance occurs and instances in which it does not. For example, "optionally substituted aryl" means that the aryl radical may or may not be substituted and that the description includes both substituted aryl radicals and aryl radicals having no substitution.

"Pharmaceutically acceptable carrier, diluent or excipient" includes without limitation any adjuvant, carrier, excipient, glidant, sweetening agent, diluent, preservative, dye/colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, isotonic agent, solvent, or emulsifier which has been approved by the United States Food and Drug Administration as being acceptable for use in humans or domestic animals.

"Pharmaceutically acceptable salt" includes both acid and base addition salts.

"Pharmaceutically acceptable acid addition salt" refers to those salts which retain the biological effectiveness and properties of the free bases, which are not biologically or otherwise undesirable, and which are formed with inorganic acids such as, but are not limited to, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as, but not limited to, acetic acid, 2,2-dichloroacetic acid, adipic acid, alginic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, benzoic acid, 4-acetamidobenzoic acid, camphoric acid, camphor- 10-sulfonic acid, capric acid, caproic acid, caprylic acid, carbonic acid, cinnamic acid, citric acid, cyclamic acid, dodecylsulfuric acid, ethane- 1,2-disulfonic acid, ethanesulfonic acid, 2-hydroxyethanesulfonic acid, formic acid, fumaric acid, galactaric acid, gentisic acid, glucoheptonic acid, gluconic acid, glucuronic acid, glutamic acid, glutaric acid, 2-oxo-glutaric acid, glycerophosphoric acid, glycolic acid, hippuric acid, isobutyric acid, lactic acid, lactobionic acid, lauric acid, maleic acid, malic acid, malonic acid, mandelic acid, methanesulfonic acid, mucic acid, naphthalene- 1,5- disulfonic acid, naphthalene-2-sulfonic acid, 1 -hydroxy-2-naphthoic acid, nicotinic acid, oleic acid, orotic acid, oxalic acid, palmitic acid, pamoic acid, propionic acid, pyroglutamic acid, pyruvic acid, salicylic acid, 4-aminosalicylic acid, sebacic acid, stearic acid, succinic acid, tartaric acid, thiocyanic acid, />toluenesulfonic acid, trifluoroacetic acid, undecylenic acid, and the like.

"Pharmaceutically acceptable base addition salt" refers to those salts which retain the biological effectiveness and properties of the free acids, which are not biologically or otherwise undesirable. These salts are prepared from addition of an inorganic base or an organic base to the free acid. Salts derived from inorganic bases include, but are not limited to, the sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum salts and the like. Preferred inorganic salts are the ammonium, sodium, potassium, calcium, and magnesium salts. Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as ammonia, isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, diethanolamine, ethanolamine, deanol, 2-dimethylaminoethanol, 2-diethylaminoethanol, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, benethamine, benzathine, ethyl enedi amine, glucosamine, methylglucamine, theobromine, tri ethanolamine, tromethamine, purines, piperazine, piperidine, iV-ethylpiperidine, polyamine resins and the like. Particularly preferred organic bases are isopropylamine, diethylamine, ethanolamine, trimethylamine, dicyclohexylamine, choline and caffeine. Often crystallizations produce a solvate of the compound of the invention. As used herein, the term "solvate" refers to an aggregate that comprises one or more molecules of a compound of the invention with one or more molecules of solvent. The solvent may be water, in which case the solvate may be a hydrate. Alternatively, the solvent may be an organic solvent. Thus, the compounds of the present invention may exist as a hydrate, including a monohydrate, dihydrate, hemihydrate, sesquihydrate, trihydrate, tetrahydrate and the like, as well as the corresponding solvated forms. The compound of the invention may be true solvates, while in other cases, the compound of the invention may merely retain adventitious water or be a mixture of water plus some adventitious solvent.

A "pharmaceutical composition" refers to a formulation of a compound of the invention and a medium generally accepted in the art for the delivery of the biologically active compound to mammals, e.g., humans. Such a medium includes all pharmaceutically acceptable carriers, diluents or excipients therefore.

"Effective amount" or "therapeutically effective amount" refers to that amount of a compound of the invention which, when administered to a mammal, preferably a human, is sufficient to effect treatment, as defined below, of a bacterial infection in the mammal, preferably a human. The amount of a compound of the invention which constitutes a "therapeutically effective amount" will vary depending on the compound, the condition and its severity, the manner of administration, and the age of the mammal to be treated, but can be determined routinely by one of ordinary skill in the art having regard to his own knowledge and to this disclosure.

"Treating" or "treatment" as used herein covers the treatment of the disease or condition of interest in a mammal, preferably a human, having the disease or condition of interest, and includes:

(i) preventing the disease or condition from occurring in a mammal, in particular, when such mammal is predisposed to the condition but has not yet been diagnosed as having it;

(ii) inhibiting the disease or condition, i.e., arresting its development;

(iii) relieving the disease or condition, i.e., causing regression of the disease or condition; or (iv) relieving the symptoms resulting from the disease or condition, i.e., relieving pain without addressing the underlying disease or condition. As used herein, the terms "disease" and "condition" may be used interchangeably or may be different in that the particular malady or condition may not have a known causative agent (so that etiology has not yet been worked out) and it is therefore not yet recognized as a disease but only as an undesirable condition or syndrome, wherein a more or less specific set of symptoms have been identified by clinicians.

The compounds of the invention, or their pharmaceutically acceptable salts may contain one or more asymmetric centers and may thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that may be defined, in terms of absolute stereochemistry, as (R)- or (S)- or, as (D)- or (L)- for amino acids. The present invention is meant to include all such possible isomers, as well as their racemic and optically pure forms. Optically active (+) and (-), (R)- and (S)-, or (D)- and (L)- isomers may be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques, for example, chromatography and fractional crystallization. Conventional techniques for the preparation/isolation of individual enantiomers include chiral synthesis from a suitable optically pure precursor or resolution of the racemate (or the racemate of a salt or derivative) using, for example, chiral high pressure liquid chromatography (HPLC). When the compounds described herein contain olefinic double bonds or other centers of geometric asymmetry, and unless specified otherwise, it is intended that the compounds include both E and Z geometric isomers. Likewise, all tautomeric forms are also intended to be included.

A "stereoisomer" refers to a compound made up of the same atoms bonded by the same bonds but having different three-dimensional structures, which are not interchangeable. The present invention contemplates various stereoisomers and mixtures thereof and includes "enantiomers", which refers to two stereoisomers whose molecules are nonsuperimposeable mirror images of one another.

A "tautomer" refers to a proton shift from one atom of a molecule to another atom of the same molecule. The present invention includes tautomers of any said compounds.

"MIC", which stands for minimum inhibitory concentration, refers to that concentration, in μg/mL, of a compound of this invention that inhibits the growth and/or proliferation of a strain of bacteria by at least 80% compared to an untreated control.

"MRSA" refers to methicillin-resistant Staphylococcus aureus.

"Bacterial infection" refers to the establishment of a sufficient population of a pathogenic bacteria in a patient to have a deleterious effect on the health and well-being of the patient and/or to give rise to discernable symptoms associated with the particular bacteria.

"β-lactam resistant bacterium" or "β-lactam antibiotic resistant bacterium" refers to bacterium against which a known β-lactam antibiotic, such as methicillin and ampicillin, has a minimum inhibitory concentration (MIC) greater than 8 μg/mL.

As noted above, in one embodiment of the present invention, compounds having antibacterial activity are provided, the compounds having the following structure

(I):

(I) or a stereoisomer, pharmaceutically acceptable ; salt, ester, or prodrug thereof, wherein: R¹ is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted heteroaryl, optionally substituted heteroarylalkyl and -C(=O)R^la, wherein: R^la is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted heteroaryl and optionally substituted heteroarylalkyl;

X is selected from -O-, -S-, -C(=O)-, -SCH₂S-, -SCH₂-, -CH₂S-, - SCH=CH-, -CH=CHS-, -OCH₂-, -CH₂O-, optionally substituted alkylene, optionally substituted alkenylene and optionally substituted cycloalkyl; Ar¹ is

wherein:

R^3b is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl and an amino acid, or R^3a and R^3b, together with the N atom to which they are attached, form an optionally substituted heterocyclyl or an optionally substituted heteroaryl ;

In fiαrther embodiments, R is hydrogen.

In other further embodiments, R¹ is alkyl and is selected from methyl, ethyl, n-propyl, wo-propyl, n-butyl, tert-butyl, zso-butyl and see-butyl.

In other further embodiments, R¹ is substituted alkyl and is optionally substituted haloalkyl. For example, in certain embodiments, R¹ is selected from - CH₂CH₂Cl, -CH₂CH₂F, -CH₂CHF₂, -CH₂CF₃, -CHFCH₂F, -CHFCHF₂, -CHFCF₃, - CH₂F, -CHF₂, -CF₃ and -CH₂CH₂CH₂F. In other further embodiments, R¹ is substituted alkyl and is optionally substituted alkoxyalkyl or optionally substituted hydroxyalkyl. For example, in certain embodiments, R¹ is -CH₂CH₂OH, -CH₂CH₂OMe or -CH₂CH₂OCF₃.

In other further embodiments, R¹ is substituted alkyl and is - CH₂CH₂SMe, -CH₂CH₂SO₂Me, -CH₂CH₂NMe₃, -CH₂CH₂NMe₂ or -CH₂CN. In other further embodiments, R¹ is alkenyl and is -CH₂CH=CH₂.

In other further embodiments, R¹ is substituted alkenyl and is optionally substituted haloalkenyl. For example, in certain embodiments, R¹ is -CH₂CH=CCl₂ or - CH₂CH=CF₂.

In other further embodiments, R¹ is cycloalkyl and is selected from cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, and cyclohexenyl.

In other further embodiments, R² is hydrogen.

In other further embodiments, R² is alkyl and is selected from methyl, ethyl, π-propyl, /so-propyl, n-butyl, tert-butyl, rso-butyl and sec-butyl.

In other further embodiments, R² is substituted alkyl and is selected from haloalkyl, -(CH₂)_nOR^2a, -(CH₂)_nN(R^2a)₂, -(CH₂)_nN(R^2a)₃, -(CH₂)_nSOR^2d, -(CH₂)_nSO₂R^2d and -(CH₂)_nCN; n is 1 or 2; and each R^2a is independently optionally substituted alkyl. For example, in certain embodiments, R² is selected from -CH₂F, -CH₂CN, -CH₂CH₂F, -CH₂CHF₂, -CH₂CF₃, -CH₂CH₂OCH₃, -CH₂CH₂OCF₃, -CH₂CH₂SO₂CH₃, -CH₂CH₂CN, -CH₂CH₂N(CH₃)₃ and -CH₂CH₂N(CH₃)₂. In other further embodiments, R² is cycloalkyl and is selected from cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

In other further embodiments, R² is aryl and is phenyl.

In other further embodiments, R² is substituted aryl and is substituted phenyl.

In other further embodiments, R² is heteroaryl and is a 6-membered ring comprising at least one N atom.

In other further embodiments, the compound is a pharmaceutically acceptable salt of structure (I) having the following structure (II):

(H) wherein M is an alkali metal atom.

In other further embodiments, the compound is a prodrug of structure (I) having the following structure (III):

(III) wherein R² and Y, taken together, are selected from:

(III) wherein R² and Y, taken together, are selected from:

wherein Y¹ is -CH₂-, -O-, -S-, -SO₂-, -NH-, -NCH₃-, -NCH₂CH₃-, - NCH₂CH₂CH₃- or -NCH₂CF₃-.

In other further embodiments, X is -SCH₂- or -CH₂S-. In other further embodiments, X is -SCH₂S-. In other further embodiment, X is -SCH=CH- or -CH=CHS-. In other further embodiments, X is -O-. In other further embodiments, X is -C(=O)-.

In other further embodiments, X is -OCH₂- or -CH₂O- In other further embodiments, X is alkylene. For example, X may be - CH₂- or -CH₂CH₂-.

In other further embodiments, X is substituted alkylene. For example, X may be selected from -CHF-, -CF₂-, -CHCH₃- and -C(CH₃)₂-.

In other further embodiments, X is alkenylene. For example, X may be - CH=CH-. In other further embodiments, X is cycloalkyl. For example, X may be cyclopropyl.

In other further embodiments, X is -S-.

In other further embodiments, Ar¹ is selected from:

In other further embodiments, Ar¹ is selected from:

In other further embodiments, R³ is -NHR^3aR^3b, R^3a is hydrogen and R^3b is an amino acid. For example, in certain embodiments, R^3b is glycine, alanine or valine. In other further embodiments, R³ is -OR^3a and R^3a is optionally substituted alkyl. For example, in certain embodiments, R^3a is -CH₃ or -CF₃.

In other further embodiments, R³ is substituted alkyl and is optionally substituted haloalkyl. For example, in certain embodiments, R³ is -CF₃. In other further embodiments, R⁴ is -NHR^4aR^4b, R^4a is hydrogen and R^4b is an amino acid. For example, in certain embodiments, R^4b is glycine, alanine or valine.

In other further embodiments, R⁴ is -OR^4a and R^4a is optionally substituted alkyl. For example, in certain embodiments, R^4a is -CH₃ or -CF₃. In other further embodiments, R⁴ is substituted alkyl and is optionally substituted haloalkyl. For example, in certain embodiments, R⁴ is -CF₃.

In other further embodiments, Ar² is:

wherein: each Z is independently selected from -CR⁵-, -S-, -O-, -N-, -NR⁶- such that the resulting ring is aromatic,

R⁵ is selected from hydrogen, chloro, bromo, fluoro, iodo, cyano, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, -SO₂R^5a, -SR^5a, -C(=O)R^5a, - C(=O)NR^5aR^5b, -NR^5aR^5b and -OR^5a, wherein:

R^5a is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl; and

R⁵ is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl, or R^5a and R^5b, together with the N atom to which they are attached, form an optionally substituted heterocyclyl or an optionally substituted heteroaryl; and

R⁶ is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl. For example, in certain embodiments, Ar² is selected from:

In certain of the foregoing certain embodiments, R⁵ is selected from hydrogen, chloro, fluoro, cyano, -CH₃, -CF₃, -SO₂CH₃, -SCH₃, -OCH₃, -OCF₃, -NH₂, - NHCH₃, -N(CH₃)₂, -NHCH₂CH₃, -N(CH₂CH₃)₂, -NHCH(CH₃)₂,

-N NH , -f-N N — -f-N N- -f-N

In other further embodiments, Ar² is:

R⁵ is selected from hydrogen, chloro, bromo, fluoro, iodo, cyano, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, -SO₂R^5a, -SR^5a, -C(=O)R^5a, -

C(=O)NR^5aR^5b, -NR^5aR^5b and -OR^5a, wherein:

R^5b is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl, or R^5a and R^5b, together with the N atom to which they are attached, form an optionally substituted heterocyclyl or an optionally substituted heteroaryl; and

R⁶ is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl.

For example, in certain embodiments, Ar² is selected from:

-i-N NH i-N N — i-N i-N

It is understood that any embodiment of the compounds of a structure disclosed herein, as set forth above, and any specific substituent set forth herein for an

Ar¹, Ar², X, R¹ and R² group in the compounds of a structure disclosed herein, as set forth above, may be independently combined with other embodiments and/or substituents of compounds of a structure disclosed herein to form embodiments of the inventions not specifically set forth above. In addition, in the event that a list of substituents is listed for any particular substituent group in a particular embodiment and/or claim, it is understood that each individual substituent may be deleted from the particular embodiment and/or claim and that the remaining list of substituents will be considered to be within the scope of the invention.

For example, in one embodiment of compounds of structure (I), R¹ and R² are hydrogen, and the compounds have the following structure:

In another embodiment of compounds of structure (I), R¹ is alkyl (such as, for example, methyl) and R² is hydrogen, and the compounds have the following structure:

In another embodiment of compounds of structure (I), Ar² is a heteroaryl having 6 ring atoms selected from:

It is further understood that in the present description, combinations of substituents and/or variables of the depicted formulae are permissible only if such combinations result in stable compounds. For the purposes of administration, the compounds of the present invention may be administered as a raw chemical or may be formulated as pharmaceutical compositions. Pharmaceutical compositions of the present invention comprise a compound of a structure disclosed herein and a pharmaceutically acceptable carrier, diluent or excipient. The compound of a structure disclosed herein is present in the composition in an amount which is effective to treat a particular disease or condition of interest - that is, in an amount sufficient to treat a bacterial infection, and preferably with acceptable toxicity to the patient. The antibacterial activity of compounds of a structure disclosed herein can be determined by one skilled in the art, for example, as described below. Appropriate concentrations and dosages can be readily determined by one skilled in the art.

The compounds of the present invention possess antibacterial activity against a wide spectrum of Gram-positive and Gram-negative bacteria, as well as enterobacteria and anaerobes. Representative susceptible organisms generally include those Gram-positive and Gram-negative, aerobic and anaerobic organisms whose growth can be inhibited by the compounds of the invention such as Staphylococcus, Lactobacillus, Streptococcus, Sarcina, Escherichia, Enterobacter, Klebsiella, Pseudomonas, Acinetobacter, Proteus, Campylobacter, Citrobacter, Nisseria, Baccillus, Bacteroides, Peptococcus, Clostridium, Salmonella, Shigella, Serratia, Haemophilus, Brucella and other organisms. In particular, the compounds of the present invention possess antibacterial activity against bacterial species resistant to conventional β- lactams, such as MRSA.

Administration of the compounds of the invention, or their pharmaceutically acceptable salts, in pure form or in an appropriate pharmaceutical composition, can be carried out via any of the accepted modes of administration of agents for serving similar utilities. The pharmaceutical compositions of the invention can be prepared by combining a compound of the invention with an appropriate pharmaceutically acceptable carrier, diluent or excipient, and may be formulated into preparations in solid, semi-solid, liquid or gaseous forms, such as tablets, capsules, powders, granules, ointments, solutions, suppositories, injections, inhalants, gels, microspheres, and aerosols. Typical routes of administering such pharmaceutical compositions include, without limitation, oral, topical, transdermal, inhalation, parenteral, sublingual, buccal, rectal, vaginal, and intranasal. The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques. Pharmaceutical compositions of the invention are formulated so as to allow the active ingredients contained therein to be bioavailable upon administration of the composition to a patient. Compositions that will be administered to a subject or patient take the form of one or more dosage units, where for example, a tablet may be a single dosage unit, and a container of a compound of the invention in aerosol form may hold a plurality of dosage units. Actual methods of preparing such dosage forms are known, or will be apparent, to those skilled in this art; for example, see Remington: The Science and Practice of Pharmacy, 20th Edition (Philadelphia College of Pharmacy and Science, 2000). The composition to be administered will, in any event, contain a therapeutically effective amount of a compound of the invention, or a pharmaceutically acceptable salt thereof, for treatment of a disease or condition of interest in accordance with the teachings of this invention.

A pharmaceutical composition of the invention may be in the form of a solid or liquid. In one aspect, the carrier(s) are particulate, so that the compositions are, for example, in tablet or powder form. The carrier(s) may be liquid, with the compositions being, for example, an oral syrup, injectable liquid or an aerosol, which is useful in, for example, inhalatory administration.

When intended for oral administration, the pharmaceutical composition is preferably in either solid or liquid form, where semi-solid, semi-liquid, suspension and gel forms are included within the forms considered herein as either solid or liquid. As a solid composition for oral administration, the pharmaceutical composition may be formulated into a powder, granule, compressed tablet, pill, capsule, chewing gum, wafer or the like form. Such a solid composition will typically contain one or more inert diluents or edible carriers. In addition, one or more of the following may be present: binders such as carboxymethylcellulose, ethyl cellulose, macrocrystalline cellulose, gum tragacanth or gelatin; excipients such as starch, lactose or dextrins, disintegrating agents such as alginic acid, sodium alginate, Primogel, corn starch and the like; lubricants such as magnesium stearate or Sterotex; glidants such as colloidal silicon dioxide; sweetening agents such as sucrose or saccharin; a flavoring agent such as peppermint, methyl salicylate or orange flavoring; and a coloring agent. When the pharmaceutical composition is in the form of a capsule, for example, a gelatin capsule, it may contain, in addition to materials of the above type, a liquid carrier such as polyethylene glycol or oil.

The pharmaceutical composition may be in the form of a liquid, for example, an elixir, syrup, solution, emulsion or suspension. The liquid may be for oral administration or for delivery by injection, as two examples. When intended for oral administration, preferred composition contain, in addition to the present compounds, one or more of a sweetening agent, preservatives, dye/colorant and flavor enhancer. In a composition intended to be administered by injection, one or more of a surfactant, preservative, wetting agent, dispersing agent, suspending agent, buffer, stabilizer and isotonic agent may be included. The liquid pharmaceutical compositions of the invention, whether they be solutions, suspensions or other like form, may include one or more of the following adjuvants: sterile diluents such as water for injection, saline solution, preferably physiological saline, Ringer's solution, isotonic sodium chloride, fixed oils such as synthetic mono or diglycerides which may serve as the solvent or suspending medium, polyethylene glycols, glycerin, propylene glycol or other solvents; antibacterial agents such as benzyl alcohol or methyl paraben; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose. The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic. Physiological saline is a preferred adjuvant. An injectable pharmaceutical composition is preferably sterile.

A liquid pharmaceutical composition of the invention intended for either parenteral or oral administration should contain an amount of a compound of the invention such that a suitable dosage will be obtained. The pharmaceutical composition of the invention may be intended for topical administration, in which case the carrier may suitably comprise a solution, emulsion, ointment or gel base. The base, for example, may comprise one or more of the following: petrolatum, lanolin, polyethylene glycols, bee wax, mineral oil, diluents such as water and alcohol, and emulsifiers and stabilizers. Thickening agents may be present in a pharmaceutical composition for topical administration. If intended for transdermal administration, the composition may include a transdermal patch or iontophoresis device.

The pharmaceutical composition of the invention may be intended for rectal administration, in the form, for example, of a suppository, which will melt in the rectum and release the drug. The composition for rectal administration may contain an oleaginous base as a suitable nonirritating excipient. Such bases include, without limitation, lanolin, cocoa butter and polyethylene glycol.

The pharmaceutical composition of the invention may include various materials, which modify the physical form of a solid or liquid dosage unit. For example, the composition may include materials that form a coating shell around the active ingredients. The materials that form the coating shell are typically inert, and may be selected from, for example, sugar, shellac, and other enteric coating agents. Alternatively, the active ingredients may be encased in a gelatin capsule.

The pharmaceutical composition of the invention in solid or liquid form may include an agent that binds to the compound of the invention and thereby assists in the delivery of the compound. Suitable agents that may act in this capacity include a monoclonal or polyclonal antibody, a protein or a liposome.

The pharmaceutical composition of the invention may consist of dosage units that can be administered as an aerosol. The term aerosol is used to denote a variety of systems ranging from those of colloidal nature to systems consisting of pressurized packages. Delivery may be by a liquefied or compressed gas or by a suitable pump system that dispenses the active ingredients. Aerosols of compounds of the invention may be delivered in single phase, bi-phasic, or tri-phasic systems in order to deliver the active ingredient(s). Delivery of the aerosol includes the necessary container, activators, valves, subcontainers, and the like, which together may form a kit. One skilled in the art, without undue experimentation may determine preferred aerosols.

The pharmaceutical compositions of the invention may be prepared by methodology well known in the pharmaceutical art. For example, a pharmaceutical composition intended to be administered by injection can be prepared by combining a compound of the invention with sterile, distilled water so as to form a solution. A surfactant may be added to facilitate the formation of a homogeneous solution or suspension. Surfactants are compounds that non-covalently interact with the compound of the invention so as to facilitate dissolution or homogeneous suspension of the compound in the aqueous delivery system. The compounds of the invention, or their pharmaceutically acceptable salts, are administered in a therapeutically effective amount, which will vary depending upon a variety of factors including the activity of the specific compound employed; the metabolic stability and length of action of the compound; the age, body weight, general health, sex, and diet of the patient; the mode and time of administration; the rate of excretion; the drug combination; the severity of the particular disorder or condition; and the subject undergoing therapy.

Compounds of the invention, or pharmaceutically acceptable derivatives thereof, may also be administered simultaneously with, prior to, or after administration of one or more other therapeutic agents. Such combination therapy includes administration of a single pharmaceutical dosage formulation which contains a compound of the invention and one or more additional active agents, as well as administration of the compound of the invention and each active agent in its own separate pharmaceutical dosage formulation. For example, a compound of the invention and the other active agent can be administered to the patient together in a single oral dosage composition such as a tablet or capsule, or each agent administered in separate oral dosage formulations. Where separate dosage formulations are used, the compounds of the invention and one or more additional active agents can be administered at essentially the same time, i.e., concurrently, or at separately staggered times, i.e., sequentially; combination therapy is understood to include all these regimens.

The following Examples illustrate various methods to make compounds of this invention, i.e., compounds having a structure disclosed herein, such as a compound of structure (I):

(D where Ar¹, Ar², X, R¹ and R² are described above. It is understood that one skilled in the art would be able to make these compounds by similar methods or by methods known to one skilled in the art. See, e.g., U.S. Patent No. 5,077,287; Appelbaum, P.C., et al., Current Opinion in Microbiology, 2005, 8: 510-517; Bassetti, M., et al., Current Opinion in Investigational Drugs, 2003, 4(8): 944-952; Cooper, R.D.G, et al., Exp. Opin. Invest. Drugs, 1994, 3(8): 831-848; Elston, D.M., J. Am. Acad. Dermatol, 2007, 56(1): 1-16; Furuya, et al., Nature, 2006, 4: 36-45; Glinka, T.W., Current Opinion in Investigational Drugs, 2002, 3(2): 206-217; Glinka, T. W., et al., J. Antibiotics, 2000, 53(10): 1045-1052; Glinka, T.W., et al., Bioorganic & Medicinal Chemistry, 2003, 11 : 591-600; Guzzo, P.R., et al., J. Org. Chem., 1994, 59(17): 4862-4867; Hecker, S.J., et al., J. Antibiotics, 2000, 53(11): 1272-1281 ; Hecker, S.J., et al., Antimicrobial Agents and Chemotherapy, 2003, 47(6): 2043-2046; Jackson, B.G., et al., Tetrahedron Letters, 1990, 31(44): 6317-6320; Jackson, B.G., Tetrahedron Letters, 2000, 56: 5667-5677; Lotz, B.T., et al., J. Org. Chem., 1993, 58(3): 618-625; Lowy, et al., J. Clinical Investigation, 2003, 111(9): 1265-1273; Misner, J.W., et al., Tetrahedron Letters, 2003, 44: 5991-5993; Mochida, K., et al., J. Antibiotics, 1989, 42(2): 283-292; and Rice, L.B., Am. J. Medicine, 2006, 119(6A): Sl 1 -S 19. It is also understood that one skilled in the art would be able to make in a similar manner as described below other compounds of a structure disclosed herein not specifically illustrated below by using the appropriate starting components and modifying the parameters of the synthesis as needed. In general, starting components may be obtained from sources such as Sigma Aldrich, Lancaster Synthesis, Inc., Maybridge, Matrix Scientific, TCI, and Fluorochem USA, etc. or synthesized according to sources known to those skilled in the art {see, e.g., Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 5th edition (Wiley, December 2000)) or prepared as described herein.

It will be appreciated by those skilled in the art that in the process described herein the functional groups of intermediate compounds may need to be protected by suitable protecting groups. Such functional groups include hydroxy, amino, mercapto and carboxylic acid. Suitable protecting groups for hydroxy include trialkylsilyl or diarylalkylsilyl (for example, ^-butyldimethylsilyl, ϊ-butyldiphenylsilyl or trimethylsilyl), tetrahydropyranyl, benzyl, and the like. Suitable protecting groups for amino, amidino and guanidino include ?-butoxycarbonyl, benzyloxycarbonyl, and the like. Suitable protecting groups for mercapto include -C(O)-R" (where R" is alkyl, aryl or arylalkyl), ^-methoxybenzyl, trityl and the like. Suitable protecting groups for carboxylic acid include alkyl, aryl or arylalkyl esters. Protecting groups may be added or removed in accordance with standard techniques, which are known to one skilled in the art and as described herein. The use of protecting groups is described in detail in Green, T. W. and P.G.M. Wutz, Protective Groups in Organic Synthesis (1999), 3rd Ed., Wiley. As one of skill in the art would appreciate, the protecting group may also be a polymer resin such as a Wang resin, Rink resin or a 2-chlorotrityl-chloride resin. Furthermore, all compounds of the invention which exist in free base or acid form can be converted to their pharmaceutically acceptable salts by treatment with the appropriate inorganic or organic base or acid by methods known to one skilled in the art. Salts of the compounds of the invention can be converted to their free base or acid form by standard techniques. The following Examples are provided for purposes of illustration, not limitation.

EXAMPLES

Example 1

Generation of the chiral carbacephem core

(6i?,75)-7-protected amino-3-chloro (or triflate)-8-oxo-l -azabicyclo[4.2.0]oct-2-ene-2- carboxylate esters

Scheme A

The final compound in the Evans scheme can be converted to several important carbacephem intermediates with selective protecting group manipulations. The 3-pos inflate can be displaced by nucleopliles to give sulfur linked groups, see, e.g.,

Ternansky, R.J., et al., J. Med. Chem., 1993, 36: 1971-1976 and Hatanaka, M. et al.,

Tetrahedron Letters, 1983, 24(44): 4837-4838. The triflate can also be converted to an alkene by Stille reaction to give double bond linked groups at the 3-position. The Boc can be removed for coupling to an acid at the 7-position. See, e.g., Evans, D.A., et al., Tetrahedron Letters, 1985: 3783-3787 and Evans, D.A., et al., Tetrahedron Letters,

1985: 3787-3790.

Scheme B

The Bodurow method gives the needed intermediate for the schemes below for 3 -position S-linked analogues. The Bz protected ester can be converted to the free acid by hydrogenation or saponification. See, e.g., Bodurow, CC, et al., Tetrahedron Letters, 1989: 2321-2324.

Example 2

Stille coupling from the 7-position triflate and transformation to the bromomethyl ketone

See, e.g., Hornback, WJ. , American Chemical Society National Meeting, Abstract 153, Washington, 1990.

Example 3 Carbonylation from the 7-position triflate

G.K. Cook, WJ. Hornback, CL, Jordan, J.H, McDonald III and J₅E. Munroe, J. Org. Chem., 1989, 54: 5828-5830.

Example 4 Conversion of 7-position triflate to carboxylic acid, vinyl, aldehyde and methylene- linked heterocycles

Scheme A

Scheme B

5ee, e.g., Blaszczak, L.C., et al., J. Med. Chem., 1990, 33(6): 1656-62.

Example 5 Coupling at 7-position

(77?)-7-[(Z)-2-(2-amino-5-methylthiazol-4-yl)-2-(triphenylmethoxyimino]acetamido]-3- chloro-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-earboxylate triethyl amine salt

To a solution of bis-(2-benzothiazolyl)-disulfide (0.013 mol) in dichloromethane (100 mL) was added triphenylphosphine (0.013 mol). The mixture was stirred for 15 minutes after which (Z)-2-(2-amino-5-methylthiazol4-yl)-2- (triphenylmethoxyimino)acetic acid (0.010 mol) was added. The mixture was stirred for 1 hr and was cooled to 0⁰C. In a separate flask, (7i?)-7-amino-3-chloro-8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid trifluoroacetic acid salt (0.008 mol) was suspended in dichloromethane (50 mL) and triethylamine (4.0 g, 0.04 mol) was added. The suspension was stirred for 0.5 hrs at rt and then was transferred to the flask containing the activated ester of 7-[(Z)-2-(2-amino-thiazolyl-4)-2-trityloxyimino] carboxylic acid. The resulting clear solution was allowed to warm to rt and was stirred for 48 hrs. The reaction mixture was washed twice with 100 mL portions of water, and the organic layer was separated, dried over anhydrous MgSO₄, filtered and concentrated to approximately 50 mL. The oily residue was treated with diethyl ether (250 mL), and the solid was filtered and dried giving crude product. HPLC analysis indicated that it contained approximately 0.004 mol of the desired compound as the triethylamine salt.

(7i?)-7-[(Z)-2-(2-amino-5-methylthiazol-4-yl)-2-(triphenylmethoxyimino]acetamido]-3- chloro-8-oxo-l -aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate diphenylmethyl ester

The crude (7/?)-7-[(Z)-2-(2-amino-5-methylthiazol-4-yl)-2-triphenyl methoxyimino]-acetamido]-3-chloro-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid triethylamine salt (0.004 mol) was dissolved in dichloromethane (200 mL) and was washed twice with 50% NaPO₄ H₂O and then with water. The organic layer was dried over anhydrous MgSO₄, filtered and treated with diphenyldiazomethane solution in dichloromethane (40 mL of 0.5 mol/L solution, 0.02 mol), followed by stirring at rt for 1 hr. The reaction mixture was concentrated to dryness and the residue was dissolved in ethyl acetate (20 mL). The ethyl acetate solution was then chromatographed on silica gel (200 g). Nonpolar byproducts were eluted with ethyl acetate:hexane (1 :6), and the product with ethyl:acetate:hexane (1 :1). After evaporation, the title ester was obtained. HPLC indicated that it contained approximately 0.004 mol of the desired product.

(7i?)-7-[(Z)-2-(2-amino-5-methylthiazol-4-yl)-2-(triphenylmethoxyimino]acetamido]-3- [5-amino-l ,3,4-thiadiazol-2-ylthio]-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate diphenylmethyl ester

To a solution of 5-amino-l, 3, 4-thiadiazole-2 -thiol (0.0045 mol) in dimethylformamide (25 mL) was added potassium carbonate (1.0 g, 0.0076 mol). The mixture was stirred for 1 hr at rt after which (7i?)-7[(Z)-2-(2-amino-5-methylthiazol-4- yl)-2-(triphenylmethoxyimino]acetamido]-3-chloro-8-oxo-l-aza-bicyclo[4:2.0]oct-2- ene-2-carboxylate diphenylmethyl ester (0.0039 mol) was added. Stirring was continued for 18 hrs. The mixture was partitioned between ethyl acetate (50 mL) and water (50 mL). The organic layer was separated, washed with water (30 mL), dried over anhydrous MgSO₄ and the solvent was removed with a rotary evaporator. The resultant thick oil was treated with diethyl ether (50 mL) and the solid which formed was filtered and dried to give ca. 0.0028 mol of crude product.

(7i?)-7-[(Z) 2-(2-amino-5-methylthiazol-4-yl)-2-(hydroxyimino]acetamido]-3-[5-amino- 1 ,3,4-thiadiazol-2-ylthio]-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid A solution of trifluoroacetic acid (10 mL), triethylsilane (5 mL) and dichloromethane (10 mL) was cooled to 0 ⁰C and (7i?)-7-[(Z)-2-(2-amino-5- methylthiazol-4-yl)-2-(triphenylmethoxyimino]acetamido]-3-[5-amino-l,3,4-thiadiazol- 2-ylthio]-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate diphenylmethyl ester from the previous step (ca. 0.0028 mol) was added in portions. The reaction mixture was stirred for 3 hrs at 0⁰C, allowed to warm up to rt and evaporated to dryness. The residue was treated with diethyl ether (50 mL) and the solid that formed was filtered and dried to give crude product. The crude product was purified with Diaion HP-20 resin initially with water elution until the pH was neutral, after which the product was eluted with acetonitrile:water 80:20. The solvent was evaporated to give the ca. 0.0013 mol of the title compound.

(7i?)-7-[(Z)-2-(2-amino-5-methylthiazol-4-yl)-2-(triphenylmethoxyimino]acetamido]-3- mercapto-8-oxo-l -aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate diphenylmethyl ester

A solution of (7i?)-7-[(Z)-2-(2-amino-5-methylthiazol-4-yl)-2-(triphenyl methoxyimino]-acetamido]-3-chloro-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene2-carboxylate diphenylmethyl ester (0.0036 mol) in dimethylformamide (40 mL) was cooled to -20 °C and a solution of ammonium sulfide in water (20%,5.7 mL) was added drop-wise. The mixture was stirred at -20⁰C for 4 hrs and then was poured into pH 3 phosphate buffer (100 mL). The resulting solid was filtered, washed with water and dried to afford the crude title compound (ca. 0.0036 mol).

(7i?)-7-((Z)-2-(2-amino-5-methylthiazol-4-yl)-2-(triphenylmethoxyimino]acetamido]-3-

(3-(N-tert-butoxycarbonylaminoethylthiomethyl)pyrid-4-ylthio]8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate diphenylmethyl ester

To a solution of (7i?)-7-[(2)-2-(2-amino-5-methylthiazol-4-yl)-2- (triphenyl methoxyimino]-acetamido]-3-mercapto-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene- 2-carboxylate diphenylmethyl ester (0.0036 mol) in dimethylformamide (30 mL) was added 3-(N-ter?-butoxycarbonylaminoethylthiomethyl)-4-chloropyridine (1.3 g, 0.0043 mol) at rt. After stirring overnight, the reaction mixture was treated with water (200 mL), and the solid that formed was filtered and dried to afford the crude title compound (ca. 0.0027 mol).

(7i?)-7-[(Z)-2-(2-amino-5-methylthiazol-4-yl)-2-(hydroxyimino]acetamido]-3-[3- (aminoethylthiomethyl)pyrid-4-ylthio]-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2- carboxylate, trifluoroacetic acid salt

A solution of trifluoroacetic acid (10 mL), triethylsilane (5 mL) and dichloromethane (10 mL) was cooled to 0⁰C and (7/?)-7-[(Z)-2-(2-amino-5- methylthiazol-4-yl)-2-(triphenylmethoxyimino]acetamido]-3-[3-(N- tertbutoxycarbonylaminoethylthiomemyl)-pyrid-4-ylthio]-8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate diphenyl methyl ester (ca. 0.0027 mol) was added in portions. The reaction mixture was stirred at 0⁰C for 6 hrs, was allowed to warm to room temp, and was evaporated to dryness. The residue was treated with diethyl ether (50 mL), and the solid that formed was filtered and dried to give crude product. The crude product was purified with Diaion HP -20 resin with water elution until the pH was neutral, and thereafter with acetonitrile:water 80:20, to give the product (ca. 0.0002 mol).

Example 6 Ceftobiprole style methylene linker at 7-position

PhoCHN,

The procedures used to produce ceftobiprole can be applied to carbacephem compounds. See, e.g., Canadian Patent No. 2408941, European Patent

Nos. 1 289 998 and 1 435 357, Japanese Patent No. 2003535059, U.S. Patent Application No. 2002/019381, U.S. Patent No. 6,504,025 and International PCT

Application Publication No. WO 01/90111.

Example 7

Preparation of alkylene linked groups at 7-position

Scheme A

See, e.g., U.S. Patent No. 4,855,418 and Farina, V., et al, Tetrahedron Letters, 1988, 29(47): 6043-6.

Scheme B

5ee, e.g., Chinese Patent No. 1763046; Xiao, T.Z., et al., Chinese J. Pharmaceuticals,

2004, 35(7): 388-390; Kim, G.T., et al., J. Antibiotics, 2004, 57(7): 468-472; International PCT Application Publication No. WO 2005/100330; International PCT Application Publication No. WO 2005/100367; and Hanaki, H., et al., J. Antibiotics,

2005, 58(1): 69-73.

Example 8

Methods A, B, C, D and E

Method A: To a solution of (6i?,75)-tert-butyl-7-(tert- butoxycarbonylamino)-8-oxo-3-(trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2- ene-2-carboxylate (see Example 9) (502 mg, 1.04 mmol) in dichloromethane (DCM)

(10 niL) was added triethylsilane (TES) (116 mg, 10 mmol). The mixture was cooled down to O⁰C and 2,2,2-trifluoroacetic acid (TFA) (10 mL) was added. Then, the mixture was allowed to warm to it and stirred for 4 hrs, concentrated under reduced pressure and washed with petroleum ether to obtain white solid (580 mg crude solid). The resulting product was used without further purification.

Method B: (6i?,7,S)-7-amino-8-oxo-3-(trifluoromethylsulfonyloxy)-l -aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (1.5 g, 4.3 mmol) was suspended in tetrahydrofuran (THF) (15 mL) and triethylamine (2.1 g, 21 mmol) was added. The suspension was stirred for 0.5 hr at rt, and (Z)-5'-benzo[<i]thiazol-2-yl-2-(5-amino- 1,2,4- thiadiazol-3-yl)-2-(methoxyimino)ethanethioate 1 (see Example 10) (1.4 g, 4.3 mmol) was added with stirring at O⁰C. The mixture was allowed to warm to rt and stirred for 48 hrs and concentrated under reduced pressure. The residue was dissolved in ethyl acetate (EA), washed with dilute HCl aqueous (pH = 4), washed with brine, dried with NaSO₄, filtered and then the solvent was removed in vacuo to give 2.6 g of slight yellow solid. The resulting product was used without further purification. Method C: (6Λ,75,Z)-7-(2-(5-amino-l,2,4-thiadiazol-3-yl)-2-

(methoxyimino)acetamido)-8-oxo-3-(trifluoromethylsulfonyloxy)-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (2.6 g crude solid) was dissolved in THF and (diazomethylene)dibenzene (4.9 g, 25 mmol) was added dropwise. The reaction mixture was stirred for 2 hrs at rt. Then, the solvent was concentrated in vacuo and petroleum ether (PE) was added to obtain precipitation. The resulting product was used without further purification.

Method D: A solution of l,3,4-thiadiazole-2-thiol 2 (47 mg 0.39 mmol) in dry THF was cooled down in ice and treated with NaH (14 mg, 0.36 mmol). After 10 min, the suspension was added by syringe to the solution of (6i?,75,Z)-benzhydryl-7-(2- (5-amino-l ,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetamido)-8-oxo-3-

(trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate (226 mg, 0.33 mmol) in dry tetrahydrofuran (THF) at -3O⁰C. The temperature was allowed to reach O⁰C over 2 hrs. The mixture was washed with cold HCl (aq), brine, dried with Na₂SO₄, filtered and concentrated. The residue was purified by gel column chromatography (EA:PE, 2:1) to give white solid (114 mg, 53%).

Method E: A solution of triethylsilane (TES) (0.5 mL), 2,2,2- trifluoroacetic acid (TFA) (1 mL) and dichloromethane (DCM) (1 mL) was cooled down to O⁰C and (6i?,75',Z)-benzhydryl-3-(l,3,4-thiadiazol-2-ylthio)-7-(2-(5-amino- l,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetamido)-8-oxo-l-aza-bicyclo[4.2.0]oct-2- ene-2-carboxylate (114 mg, 0.17 mmol) was added in portions. The reaction mixture was stirred for 3 hrs at O⁰C and then evaporated to dryness, washed with diethyl ether to obtain (6i?,75',Z)-3-(l,3,4-thiadiazol-2-ylthio)-7-(2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (methoxyimino)acetamido)-8-oxo-l -aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (82 mg crude solid), purified by Prep-HPLC to give 26 mg white solid, yield: 31% .

Method F

Similar to Method B, (6i?,75)-7-amino-8-oxo-3- (trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (1.5 g, 4.3 mmol) was suspended in tetrahydrofuran (THF) (15 mL) and tri ethyl amine (2.1 g, 21 mmol) was added. The suspension was stirred for 0.5 hr at rt, and (Z)-S- benzo[<i]thiazol-2-yl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2-(trityloxyimino)ethanethioate (see Example 10) (2.5 g, 4.3 mmol) was added with stirring at O⁰C. The mixture was allowed to warm to rt and stirred for 48 hrs and concentrated under reduced pressure. The residue was dissolved in ethyl acetate (EA), washed with dilute aqueous HCl (pH = 4), washed with brine, dried with NaS(X filtered and then the solvent was removed in vacuo to give 3.6 g as a slight yellow solid. The resulting product was used without further purification. To a solution of (6i?,75',Z)-7-(2-(5-amino-l,2,4-thiadiazol-3-yl)-2-

(trityloxyimino)acetamido)-8-oxo-3-(trifluoromethylsulfonyloxy)-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (55 mg, 0.074 mmol, 1.0 eq) in THF (1 mL) at O⁰C, a solution Of CH₂N₂ in Et₂O (10 mL, 0.74 mol, 10 eq) was added. The resulted suspension was stirred for 6 hrs. The reaction mixture was concentrated in vacuo to get the crude product. The crude product was purified by column chromatography on silica gel using PE:EA = 4:1 as an eluent to furnish the desired product as a light yellow solid in 18% yield.

Method G

To a solution of di-tert-butyl-2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene)bis(sulfanediyl)bis(ethane-2,l-diyl)dicarbamate (156 mg) in acetonitrile (10 mL) was added NaBH₄ (14.4 mg). The mixture was stirred at rt for 18 hrs and the mixture was used for next step without purification. (6R,7S,Z)-7-(2-(5- amino-l,2,4-thiadiazol-3-yl)-2-(trityloxyimino)acetamido)-8-oxo-3- (trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (see Method F) was added to the solution and stirred for 3.5 hrs and evaporated to dryness. The residue was taken to column chromatography (PE:EA = 2:1) and 270 mg of (6i?,75',Z)-7-(2-(5-amino-l,2,4-thiadiazol-3-yl)-2-(trityloxyimino)acetamido)-3-(2-((2- (terf-butoxycarbonylamino)ethylthio)methyl)pyridin-3-ylthio)-8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid was obtained as a white solid in 30% yield.

Method H

To a solution of (Z)-2-(5-amino-l,2,4-thiadiazol-3-yl)-2-(trityloxyimino) acetic acid (5.4 g, 12 mmol) in anhydrous acetonitrile, TEA (1.265 g, 12.5 mmoL) was added at O⁰C. The reaction solution was stirred for 10 min. Disulfide (4.9 g, 14.7 mmoL) was added during 30 min to the reaction solution. Then, a solution of triethyphosphite (3.545 g, 21.35 mmoL) in CH₃CN (30 mL) was added during 30 min. The reaction was stirred at rt for 27 hrs and filtered. The solid obtained was washed by CH₃CN (50 mL) three times to get (Z)-5-benzo[<f]thiazol-2-yl-2-(5-amino- 1,2,4- thiadiazol-3-yl)-2-(trityloxyimino)ethanethioate (3.2 g, 46%).

Method I

D ^~ MF

Solvent DMF was added to a solid mixture of (6R,7S,Z)-7-(2-(5-dύoτo- 2-(tritylamino)thiazol-4-yl)-2-(methoxyimmo)acetamido)-8-oxo-3- (trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (2 g, 2.53 mmol) and Bu₄NI (934 mg, 0.25 mmol). Iodomethyl pivalate (12.24 g, 50.6 mmol) and TEA (0.9 mL, 7.6 mmol) were added to the resulting solution at O⁰C in an ice-bath. After 30 min, the ice bath was removed and the solution was stirred for 1 hr at rt. Ethyl acetate was added and washed with water twice and brine once, then dried with MgSO₄ and evaporated under reduced pressure. The residue was dissolved in THF, the petroleum ether was and the solution was filtered. 1.2 g pure product in 54% yield was obtained with column chromatography (PE:EA = 2:1)

Example 9

(67?,7»S)-te^-butyl-7-(ter/-butoxycarbonylamino)-8-oxo-3-(trifluoromethylsulfonyloxy)- 1 -aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate

^DMF '

Step 1 : A mixture of (17?,25)-2-amino-l ,2-diphenylethanol (4.28 g, 20.0 mmol), K₂CO₃ (0.28 g 2.03 mmol) and diethyl carbonate (20 niL, 166 mmol) was heated under reflux for 16 hrs. The resulting mixture was washed with water (10 mL) and extracted with CH₂Cl₂ (300 mL). The organic phase was dried MgSO₄, filtered and concentrated. The residue was recrystallized form toluene to give the desired compound (4S,5i?)-4,5-diphenyioxazolidin-2-one as white solid. Yield 88%, ESI-MS: 240.1 [M⁺]

Step 2: NaH (0.66 g, 60% mineral oil dispersion, 20.8 mmol) was placed in a three necked flask under argon and washed with anhydrous hexane (15 mL). After addition of THF (50 mL) to NaH, a solution of (45',57?)-4,5-diphenyloxazolidin-2-one in

THF was added to the suspension and the mixture was stirred for 2 hrs at rt. Then, ethyl bromoacetate was added dropwise in a period of 30 min, and the mixture was stirred for 30 min. The reaction was quenched with water (100 mL) and extracted with CH₂Cl_2. The combined extracts were washed with water, dried over MgSO₄, filtered and concentrated. The residue was purified by silica gel column chromatography to give ethyl-2-((4S,5i?)-2-oxo-4,5-diphenyloxazolidin-3-yl)acetate.

A THF (20 mL) solution of ethyl-2-((4S,5i?)-2-oxo-4,5- diphenyloxazolidin-3-yl) acetate was added to a solution of KOH (2.99 g, 53.3 mmol) in H₂O/MeOH/THF (35 mL, H₂O:MeOH:THF = 3:3:8) and the mixture was stirred for 2 hrs at rt. Then, 1 M aq HCl (100 mL) was added to the mixture. The desired product was extracted with Et₂O (3x10OmL) and the combined extracts were washed with sat. aq NaCl (50 mL), dried over MgSO₄, filtered and concentrated. The residue was recrystallized from toluene to give 2-((4S,5i?)-2-oxo-4,5-diphenyloxazolidin-3-yl)acetic acid yield 83%. ESI-MS: 298.1 [M⁺].

Step 3: Glycine t-butyl ester hydrochloride (125 g, 0.75 mol) was treated with 10 N aqueous sodium hydroxide (180 mL) and extracted with dichloromethane.

The dichloromethane solution was back washed with saturated aqueous NaCl, dried by sodium sulfate, filtered and concentrated in vacuum to get the glycine-butyl ester (60 g).

7ert-butyl-2-aminoacetate (31.5 g, 0.24 mol) in dichloromethane was treated sequentially with 1 equivalent of cinnamaldehyde (26.4 g, 0.2 mol) and a desiccating agent, such as magnesium sulfate (70 g), in the amount of about 2 grams of desiccating agent per gram of starting amino acid ester or amide. The reaction was stirred at ambient temperature until all of the reactants were consumed as measured by thin layer chromatography. The reactions were typically complete after 3 hrs. The reaction mixture was then filtered and the filter cake was washed with dichloromethane. The filtrate was concentrated under reduced pressure to provide the desired imine that was used as is in the subsequent step.

Step 4: 2-((45,5i?)-2-oxo-4,5-diphenyloxazolidin-3-yl)acetic acid (5.95 g, 20 mmol) was dissolved in CH₂Cl₂. Then, DMF (0.04 mL, 0.6 mmol) was added, followed by COCl₂ (2.6 mL, 30 mmol). The reaction mixture was stirred for 1.5 hrs at rt and concentrated. The product was used for next step without further purification. Triethylamine (4.18 mL, 30.0 mmol) was added at -78⁰C to a solution of the acid chloride (6.32 g, 20.0 mmol) in dry methylene chloride (100 mL). After 20 min, a solution of the imine (4.91 g, 20.0 mmol) in dry CH₂Cl₂ (50 mL) was added dropwise at the same temperature. The cooling bath was removed and the resulting mixture was stirred under nitrogen atmosphere at O⁰C for 2 hrs. Then, the reaction mixture was successively washed with water 100 mL, 1 N HCl (50 mL), saturated aqueous solution of NaHCO₃ (100 mL). The organic layer was dried over MgSO₄, filtered and concentrated to afford a crude material, which was washed by little CH₃OH to afford a white solid tert-butyl-2-((35^r,4i?)-2-oxo-3-((46',5i?)-2-oxo-4,5-diphenyloxazolidin-3-yl)- 4-((£)-styryl)azetidin-l-yl)acetate. ESI-MS: 525.1 [M⁺]. ¹H NMR (300 MHz, DMSO- d₆): δ 7.46-6.91 (m, 15H), 6.80 (d, 15.6Hz, IH), 6.37 (dd, 8.1/15.9 Hz, IH), 5.93 (d, 8.1Hz, IH,), 5.28 (d, 8.1Hz, IH), 4.60-4.50 (m, 2H), 4.60 (d, 17.7 Hz, IH), 3.77 (d, 18.0 Hz, IH), 1.358 (s, 9H).

Step 5: Pearlman's catalyst (2 g) and

dicarbonate (6.5 g, 30 mmol) were added successively to a solution of the corresponding tert-butyl-2-((3S,47?)- 2-oxo-3-((45',5i?)-2-oxo-4,5-diphenyloxazolidin-3-yl)-4-((E)-styryl)azetidin-l-yl)acetate (1 mmol) in THF (30 mL). The resulting mixture was stirred at rt under a hydrogen atmosphere (120 psi) for 48 hrs. Then, the mixture was filtered through Celite. After evaporation of the filtrate under reduced pressure, the resulting crude was crystallization by methanol to give 2-((3S,4i?)-3-(terr-butoxycarbonylammo)-2-oxo-4- phenethylazetidin-1 -yl) acetate (2.63 g, 65%). ESI-MS: 405.2 [M⁺]

Step 6: To a mixture of the fert-butyl-2-((35,4/?)-3-(tert- butoxycarbonylamino)-2-oxo-4-phenethylazetidin-l-yl)acetate (2.1 g, 5.19 mmol) in carbon tetrachloride (30 mL), acetonitrile (30 mL), and water (45 mL) was added at rt periodic acid (17.24 g, 75.26 mmol). The biphasic mixture was stirred until both phases became clear, and ruthenium trichloride hydrate (236 mg, 1.05 mmol) was added. Stirring was continued until no starting material was detected by TLC (4 hrs). The reaction mixture was cooled down to 0°C, and diethyl ether (300 mL) was added with vigorous stirring for 10 min. The organic phase was separated and the aqueous layer extracted with diethyl ether (2x150 mL). The combined organic layers were washed with brine (100 mL), dried, filtered, and concentrated. The resulting crude was purified by chromatography (CH₂C1₂:EA = 2:1) to give 3-((2/?,3S)-l-(2-tert-butoxy-2-oxoethyl)- 3-(ter£-butoxycarbonylamino)-4-oxoazetidin-2-yl) propanoic acid (1.2 g, 62%). ESI- MS: 373.2 [M⁺]

Step 7: To a cold (0⁰C) solution of (6.8 g, 16.83 mmol) of 3-((2R,35)-l- (2-tert-butoxy-2-oxoethyl)-3-(tert-butoxycarbonylamino)-4-oxoazetidin-2-yl)propanoic acid in 300 niL of methylene chloride maintained under nitrogen were added 103.7 mg (0.85 mmol) of dimethylaminopyridine, thiophenol (2.32 g, 21.04 mmol), and dicyclohexylcarbodiimide (DCC) (4.34 g, 21.04 mmol). The mixture was stirred at O⁰C for 10 minutes and at rt for 6 hrs. The mixture was poured into 400 mL of methylene chloride and the mixture washed with an aqueous sodium bicarbonate solution (50% of saturated), with 1 M hydrochloric acid, and with saturated sodium bicarbonate solution. The organic phase was dried over sodium sulfate, filtered and evaporated to dryness to yield the title compound as partly crystalline oil. The resulting crude was purified by chromatography (CH₂C1₂:EA = 4:1) to give tert-buty\-2-((3S,4R)-3-(tert- butoxycarbonylamino)-2-oxo-4-(3-oxo-3-(phenylthio)propyl)azetidin-l -yl) acetate (7.5 g, 89%). ESI-MS: 465.2 [M⁺]

Step 8: To a solution of 18.12 g (39 mmol) of tert-butyl-2-((35,4Λ)-3- (fert-butoxycarbonylamino)-2-oxo-4-(3-oxo-3 -(phenyl thio)propyl)azeti din- l-yl)acetate in 300 mL of anhydrous THF and maintained under argon at -78° C was added 156 mL (156 mmol) of lithium hexamethyldisilazane (1M/L) (also maintained under argon at - 78°C). After about 6 hrs, the mixture was poured into 1000 mL of aqueous ammonium chloride (50% of saturation) and the pH was adjusted to 3 with 1 M HCl aqueous. The acidified mixture was extracted three times with 800 mL of portions of methylene chloride. The extracts was combined, washed with brine, dried over sodium sulfate, filtered and concentrated by evaporation. The residue was initially chromatographed over silica using hexane-ethyl acetate (ca 3:1, v/v), followed by a (2:1, v/v). mixture of the same solvents for elution of the product. The desired fraction was evaporated to dryness to provide (6i?,75)-ter?-butyl-7-(tert-butoxycarbonylamino)-3-hydroxy-8-oxo-l- aza-bicyclo-[4.2.0]oct-2-ene-2-carboxylate (10.2 g, 74%). ESI-MS: 377.1 [M⁺]

Step 9: A CH₂Cl₂ solution of trifluoromethanesulfonic anhydride (338.4 mg, 1.2 mmol) was rapidly added to a solution of (6R,7S)-tert-bxιty\-7-(tert- butoxycarbonylamino)-3-hydroxy-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate (354 mg, 1 mmol) and DIPEA (193 mg, 1.5 mmol) in CH₂Cl₂ (5 mL) at -40 °C. After 15 min, the reaction mixture was poured into a saturated aqueous solution of NaHCO₃ (10 mL). The resulting mixture was extracted with CH₂Cl₂ (3x20 mL). The extracts were combined, washed with brine (1x5 mL), dried (MgSO₄), filtered and concentrated to give 438 mg (91%) of (6i?,75)-ter?-butyl-7-(ter?-butoxycarbonylamino)-8-oxo-3- (trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate as a white solid. ESI-MS: 486.2 [M⁺]. ¹H NMR (300 MHz, DMSO-J₆): δ 7.71 (d, 6.9Hz, IH), 5.20 (dd, 4.2/6.9Hz, IH), 3.85 (dd, 4.2/8.4 Hz, IH), 2.62 (d, 2.7Hz, 2H), 1.90-1.80 (m, 2H), 1.46 (s, 9H), 1.38 (s, 9H)

Example 10

(Z)-5-benzo[<f|thiazol-2-yl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (trityloxyimino)ethanethioate

tπethylphosphite

Step 1 : SOCl₂ (200 mL, 2.74 mol) was slowly added to methanol (400 mL) during 1.5 hrs at O⁰C. Then, (Z)-2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (methoxyimino)acetic acid 1 (61 g, 0.30 mol) was added in one portion and the reaction mixture was stirred for 24 hrs at 7O⁰C. Concentration gave a white solid which was partitioned between ethyl acetate (500 mL x 3) and water (200 mL). The organic phase was washed (saturated NaHCO₃, water), dried on Na₂SO₄ and concentrated to give 56 g of (Z)-methyl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetate 2 as a white solid in 85% yield. This product was used without further purification.

Step 2: A solution of (Z)-methyl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (methoxyimino)acetate 2 (60 g, 0.28 mol) and NH₂OH-HCl (140 g, 1.98 mol) in methanol (400 mL) and H₂O (200 mL) was stirred at 100⁰C for 24 hrs. Concentration gave a yellow syrup which was partitioned between ethyl acetate (IL) and water (400 mL). The aqueous layer was extracted with ethyl acetate (2x1 L). The organic phase was dried on NaSO₄, filtered and concentrated to dry. The crude solid was crystallized from DCM/PE (20:1, 1 L) 5 times, the product was collected and 20 g of (Z)-methyl-2-(5- amino-l,2,4-thiadiazol-3-yl)-2-(hydroxyimino)acetate 3 was obtained as a white solid in 45% yield. The product was used without further purification.

Step 3: To a solution of (Z)-methyl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (hydroxyimino)acetate 3 (1O g, 0.05 mol) in 50 mL THF at O⁰C was added 5.5 g TEA, stirred 10 minutes. Then, 14 g of trityl chloride was added in at O⁰C and the reaction solution was stirred at this temperature for 2 hrs. Concentration gave a white solid which was partitioned between ethyl acetate (500 mL) and water (200 mL). The aqueous layer was extracted with ethyl acetate (2x500 mL). The organic phase was washed with 1 % NaOH aqueous solution (200 mL) three times. The organic phase was dried over NaSO₄, filtered and concentrated to dry. The solid obtained was crystallized from petroleum ether (1 L). The product was collected and (Z)-methyl-2-(5-amino- l,2,4-thiadiazol-3-yl)-2-(trityloxyimino)acetate 4 (15 g) was obtained as a white solid in 68% yield. The product was used without further purification.

Step 4: A solution of (Z)-methyl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (trityloxyimino)acetate 4 (15 g, 33.8 mmol) in 80 mL of 2.5 M NaOH and 40 mL ethanol was heated to gentle reflux for 2 hrs. The reaction solution was cooled down and THF (40 mL) was added in. Then, adjusted reaction solution to pH = 3 by 5 % aq. HCl. The whole reaction solution was extracted with ethyl acetate (100 mL). The organic phase was dried on Na₂SO₄, filtered and concentrated. The crude (Z)-2-(5- amino-l,2,4-thiadiazol-3-yl)-2-(trityloxyimino)acetic acid 5 (12 g, 28.0 mmol) was obtained as white solid in 70% yield. The product was used without further purification. Step 5: To a solution of (Z)-2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (trityloxyimino) acetic acid 5 (5.4 g, 12 mmol) in anhydrous acetonitrile TEA (1.265 g, 12.5 mmoL) was added in at O⁰C. The reaction solution was stirred for 10 min. Disulfide (4.9 g, 14.7 mmoL) was added during 30 min to the reaction solution. Then, a solution of triethyphosphite (3.545 g, 21.35 mmoL) in CH₃CN (30 mL) was added during 30 min. The reaction was stirred at rt for 27 hrs and filtered. The solid obtained was washed by CH₃CN (50 mL) three times to get (Z)-S-benzo[<i]thiazol-2-yl-2-(5- amino-l,2,4-thiadiazol-3-yl)-2-(trityloxyimino)ethanethioate 6 (3.2 g, 46%).

Example 11

(Z)-5-benzo[ύT]thiazol-2-yl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2- (methoxyimino)ethanethioate

(Z)-S-benzo[<f]thiazol-2-yl-2-(5-amino-l,2,4-thiadiazol-3-yl)-2-

(methoxyimino)ethanethioate 2 was prepared from (Z)-2-(5-amino-l,2,4-thiadiazol-3- yl)-2-(methoxyimino) acetic acid 1 in 40% yield by Method H. The product was used without further purification. ESI-MS: 352.4 [M+H].

Example 12

(Z)->S-benzo[d]thiazol-2-yl-2-(5-chloro-2-(tritylamino)thiazol-4-yl)-2- (trityloxyimino)ethanethioate

Step 1 : To a solution of (Z)-ethyl-2-(2-aminothiazol-4-yl)-2- (hydroxyimino)acetate 1 (21.5 g, 0.1 mol) in 100 mL DMF, Et₃N (30.6 mL, 0.22 mol) was added. Then, TrCl (64 g, 0.22 mol) was added during 20 minutes, the reaction solution was stirred at 5O⁰C for 48 hrs until LC-MS indicated the reaction was over. The reaction solution was slowly poured into water (600 mL). (Z)-ethyl-2-(2- (tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetate 2 was obtained as a white solid in 85% yield. The resulting product was used without further purification. Step 2: To a solution of (Z)-ethyl-2-(2-(tritylamino)thiazol-4-yl)-2-

(trityloxyimino) acetate 2 (14.5 g 20.7 mmol) in H₂O (10 mL) and dioxane (80 mL), NaOH aqueous (1.7 g, 41.4 mmol) was added in. The reaction solution was refluxed for 24 hrs until LC-MS indicated there no starting material existed. Then, water (200 mL) was added under stirring. The mixture was cooled down to a temperature between O⁰C to 5⁰C under stirring and the precipitated solid was filtered, washed by dioxane and dried under vacuum to give 10.0 g of (Z)-2-(2-(tritylamino)thiazol-4-yl)-2- (trityloxyimino) acetic acid 3 in 72% yield as a white solid. The resulting product was used without further purification.

Step 3: To a solution of (Z)-2-(2-(tritylamino)thiazol-4-yl)-2- (trityloxyimino)acetic acid 3 (67 g, 0.1 mol) in 400 mL DMF, NCS (25 g, 0.19 mol) was added during 5 minutes. The reaction mixture was stirred at O⁰C for 3 hrs. To the reaction solution, 600 mL of water was added and the whole reaction solution was extracted with 300 mL of ethyl acetate. The organic layer was washed with 200 mL of saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, filtered and concentrated to dry. The residue was crystallized from ethyl acetate to give crude (Z)-2-(5-chloro-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetic acid as a white solid. The resulting product was purified by column chromatography (50% EtOAc in petroleum ester) to give (Z)-2-(5-chloro-2-(tritylamino)thiazol-4-yl)-2- (trityloxyimino)acetic acid 4 as a white solid (76 g, 80%).

Step 4: (Z)-^-benzo[d]thiazol-2-yl-2-(5-chloro-2-(tritylamino)thiazol-4- yl)-2-(trityloxyimino)ethanethioate 5 was prepared from (Z)-2-(5-chloro-2-(tritylamino) thiazol-4-yl)-2-(trityloxyimino)acetic acid 4 according to Method H. The resulting product was purified by column chromatography (20% DCM in petroleum ester) in 20% yield as a white solid. ESI-MS: 8653.2 [M+H]. The compound may be used in methods similar to those of Methods A-I.

Example 13

(Z)-S-benzo[d]thiazol-2-yl-2-(2-amino-5-chlorothiazol-4-yl)-2- (methoxyimino)ethanethioate

Step 1 : (Z)-ethyl-2-(2-amino-5-chlorothiazol-4-yl)-2- (methoxyimino)acetate 2 was prepared from (Z)-ethyl-2-(2-aminothiazol-4-yl)-2- (methoxyimino)acetate 1 as set forth in Example 12. The resulting product was purified by column chromatography (50% EtOAc in petroleum ester) in 80% yield.

Step 2 : (Z)-S-benzo[d]thiazol-2-yl-2-(2-amino-5-chlorothiazol-4-yl)-2- (methoxyimino)ethanethioate 3 was prepared from (Z)-ethyl-3-((Z)-amino(methylthio) methyl eneamino)-2-(methoxyimino)propanoate by following Method H. The resulting product (Z)-5-benzo[d]thiazol-2-yl-2-(2-amino-5-chlorothiazol-4-yl)-2-

(methoxyimino)ethanethioate 3 was purified by column chromatography (20% DCM in petroleum ester as eluent) in 16% yield as a white solid. ESI-MS: 345.9 [M+H]. The compound may be used in methods similar to those of Methods A-I.

Example 14 Preparation of l,2-di(pyridine-3-yl)disulfane

Step 1 : NaH (4.0 g, 0.1 mol) was added to 3-hydroxylpyridine 1 (9.5 g, 0.1 mol) in DMF (100 mL) at rt. Then, the reaction mixture was stirred for 10 min and dimethylcarbamothioic chloride (12.4 g, 0.1 mol) was added in one portion. The reaction solution was heated to 8O⁰C for 1 hr. The reaction mixture was diluted with water, extracted with ethyl acetate from water. The combined organic layer was dried (Na₂SO₄), filtered and concentrated. The residue was purified by column chromatography to afford O-pyridin-3-yl-dimethylcarbamothioate 2 as a slight yellow oil (16.5 g, 91%). ¹H NMR (400 MHz, CDCl₃): 8.48 (d, IH), 8.39 (s, IH), 7.45 (d, IH), 7.34 (m, IH), 3.46 (s, 3H), 3.37 (s, 3H).

Step 2: The solution of O-pyridin-3-yl-dimethylcarbamothioate 2 (3.6 g, 20 mmol) in diphenyl ether (100 mL) was heated to reflux for 2 hrs. TLC indicated no 0-pyridin-3-yl-dimethylcarbamothioate existed and concentrated. The residue was purified by column chromatography to afford S-pyridin-3-yldimethylcarbamothioate 3 as a yellow oil (2.8 g, 77%). ¹H NMR (400 MHz, CDCl₃): 8.51 (s, IH), 8.37 (d, IH), 7.67 (d, IH), 7.22 (m, IH), 3.11 (s, 3H), 3.03 (s, 3H).

Step 3: Na (1.8 g, 77 mmol) was added to CH₃OH (10 niL) during 0.5 hrs. The mixture was stirred at rt until all the metal was dissolved. Then, 5-pyridin-3- yldimethylcarbamothioate 3 (2.8 g, 15.4 mmol) was added in and the reaction solution was heated to reflux for 2 hrs, cooled to rt, diluted with water, adjusted to pH = 6 and extracted with ethyl acetate from water_. The organic layer was washed with brine, dried

(Na₂SO₄), filtered and concentrated. 0.9 g pyridine-3 -thiol 4 was obtained as yellow oil.

¹H NMR (400 MHz, CDCl₃): 8.51 (s, IH), 8.37 (d, IH), 7.67 (d, IH), 7.22 (m, IH), 3.0 (s, IH).

Step 4: Pyridine-3 -thiol 4 was purified by column chromatography, 1,2- di(pyridine-3-yl)disulfane 5 was formed in process of purification. 0.65 g oil was obtained, yield 38.4%. ¹H NMR (400 MHz, CDCl₃): 8.68 (s, 2H), 8.51 (d, 2H), 7.83 (d, 2H), 7.28 (m, 2H).

Example 15 Preparation of 4,5-dimethylthiazole-2-thiol

Step 1 : Bromine (6.8 mL, 132 mmol) was added to a solution of 4,5- dimethylthiazole 1 (4.7 mL, 44 mmol) at O⁰C, dropwise and stirred at rt overnight. The reaction was diluted with water and extracted with ethyl acetate. The organic layer was dried over sodium sulfate, filtered and concentrated. The residue was purified by column chromatography to afford 3.9 g clear oil, yield 47%.

Step 2: The solution of 2-bromo-4,5-dimethylthiazole 2 (3.9 g, 20.3 mmol) in ethanol (10 mL) was added to the solution of thiourea (7.6 g, 100 mmol) in ethanol (100 mL) at 8O⁰C dropwise. After the addition, the mixture was heated to reflux for another 2 hrs and concentrated. The resiude was purified by column chromatography (PE:EA = 2:1) to afford 1.3 g 4,5-dimethylthiazole-2-thiol 3 as a white solid, yield 44%. ESI-MS: 146.2 [M+H]

Example 16

Preparation of Sodium l,2,3-thiazole-5-thiolate

Na₂S

2

A mixture of 5-chloro-l,2,3-thiadiazole 1 (0.24 g, 1.99 mmol),

Na₂S-9H₂O (0.48 g, 2.0 mmol) and ethanol (10 mL) was heated to reflux for 2 hrs and concentrated. 500 mg sodium l,2,3-thiazole-5-thiolate 2 was obtained as a white solid, yield 100%. ESI-MS: 140.1 [M⁺]

Example 17

Preparation of 1 ,2-di(thiazol-4-yl)disulfane

Step 1 : Na (0.69 g, 30 mmol) was added to a solution of ^-butylthiol

(3.38 mL, 30 mmol) at it portionwise and stirred for 0.5 hrs. Then, 4-bromothiazole 1 (0.49 g, 3.0 mmol) was added and the mixture was heated to reflux overnight. LC-MS indicate desired product formed and the reaction was concentrated. The residue was dissolved in ethyl acetate, filtered through silica gel and the filtrate was concentrated again. The residue was used for the next step directly. Step 2: The residue from last step was dissolved in cone, hydrochloride, the resulting mixture was heated to 12O⁰C for 24 hrs until LC-MS indicate no A-(tert- butylthio)thiazole 2 existed. The reaction solvent was concentrated, ammonia was added to the residue, concentrated again, purified by column chromatography (PE:EA = 1 :1) to afford 24 mg 1 ,2-di(thiazol-4-yl)disulfane 3 as a white solid, yield 6.9%. ESI- MS: 233.2 [M+H]

Example 18 Preparation of ter?-butyl-2-((4-mercaptopyridin-3-yl)methylthio)ethyl carbamate

), DMF ) c

H₃OH h

Step 1 : LDA (0.11 mmol) was added to 4-chloropyridine 1 (15 g, 0.1 mol) in THF (250 mL) dropwise at -6O⁰C and stirred at this temperature for 1 hr. Then, DMF (9.3 mL, 0.12 mol) was added and stirred at rt overnight. The product was extracted with ethyl acetate from water. The combined organic layer was dried

(Na₂SO₄), filtered and concentrated. The residue was purified by column chromatography (PE:EA = 10:1) to afford 4.6 g white solid, yield 65%. ¹H NMR (400 MHz, CDCl₃):10.51 (s, IH), 9.05 (s, IH), 8.08 (d, IH), 7.45 (d, IH).

Step 2: The mixture of 4-chloronicotinaldehyde 2 (4.6 g, 32.6 mmol), 2- methyl-2-propanethiol (4.4 mL, 32.6 mmol), K₂CO₃ (9.0 g, 65.2 mmol) and DMF (70 mL) was stirred at 100⁰C for 12 hrs until TLC indicate no 4-chloronicotinaldehyde was existed. The reaction mixture was diluted with water, extracted with ethyl acetate and the organic layer was concentrated. The residue was purified by column chromatography (PE:EA = 12:1) to afford 6.3 g clear oil, yield 99%. ¹H NMR (400 MHz, CDCl₃): 10.63 (s, IH), 9.03 (s, IH), 8.65 (d, IH), 7.50 (d, IH), 1.40 (s, 9H). Step 3: NaBH₄ (0.38 g, 10.0 mmol) was added to 4-(tert- butylthio)nicotinaldehyde 3 (0.97 g, 5.0 mmol) in CH₃OH (10 mL) portionwise. The mixture was stirred overnight at rt. The reaction mixture was diluted with water, extracted with ethyl acetate. The organic layer was concentrated and the residue was purified by column chromatography (PE:EA = 2:1-0:1) to afford 0.9 g yellow oil, yield 91.4%. ESI-MS:m/z 198.1 (M+H).

Step 4: SOCl₂ 0.45 mL (6.15 mmol) was added to the solution of the (4- (tert-butylthio)pyridine-3-yl)methanol 4 (0.8 g, 4.1 mmol) in DMF (15 mL) dropwise at O⁰C and stirred at rt for 1 hr. The reaction mixture was diluted with water, extracted with ethyl acetate and the organic layer was concentrated. The residue was purified by column chromatography (PE:EA = 5:1) to afford 0.80 g brown oil, yield 90.5%. ESI- MS: m/z 216.0 [M+H].

Step 5: The mixture of the 4-(/ert-butylthio)-3-(chloromethyl)pyridine 5 (0.8 g, 4.1 mmol), N-Boc-aminoethanethiol 3.46 mL (20.5 mmol), NaI 0.15 g(1.0 mmol) and DMF (15 mL) was stirred at rt for 1 hr. The reaction mixture was diluted with water and extracted with ethyl acetate. The organic layer was concentrated and the residue was purified by column chromatography (PE:EA = 2:1) to afford 1.39 g oil, yield 96%. ¹H NMR (400 MHz, CDCl₃): 8.56 (s, IH), 8.41 (d, IH), 7.44 (d, IH), 4.96 (s, IH), 4.12 (s, 2H), 3.35 (m, 2H), 2.61 (m, 2H), 1.40 (m, 9H), 1.27(m, 9H).

Step 6: rer/-butyl-2-((4-(te/^-butylthio)pyridine-3- yl)methylthio)ethylcarbamate 6 was dissolved in concentrated HCl, heated to reflux for 24 hrs until LC-MS indicated no fcrt-butyl-2-((4-(terr-butylthio)pyridine-3- yl)methylthio)ethylcarbamate was existed. The reaction mixture was concentrated and the residue was used for the next step directly.

Step 7: BoC₂O (0.56 g, 3.4 mmol) was added to the solution of Et₃N

(0.48 mL, 2.55 mmol) and 3-((2-aminoethylthio)methyl)pyridine-4-thiol 7 (0.85 mmol) in CH₃OH. The reaction mixture was diluted with water and extracted with ethyl acetate. The organic layer was concentrated and the residue was purified by column chromatography to afford 0.48 g yellow oil, yield 93%. ESI-MS:m/z 401.2 (M+H).

Step 8: The mixture of fert-butyl-2-((4-(fert-butoxycarbonylthio)- pyridine-3-yl)methylthio)ethylcarbamate 8 (200 mg, 0.5 mmol), CH₃ONa (10 mmol), CH₃OH (40 mL) was heated to reflux overnight until TLC indicate no tert-buty\-2-((4- (fer?-butoxycarbonylthio)pyridine-3-yl)methylthio)ethylcarbamate existed. The reaction mixture was diluted with water and the water layer was adjusted to pH = 6 with concentrated HCl, extracted with ethyl acetate from water. The organic layer was concentrated and the residue was purified by column chromatography to afford 0.48 g of 9 as a yellow oil, yield 73%. ¹H NMR (400 MHz, CDCl₃): 7.85 (s, IH), 7.52(m, IH), 7.46 (m, IH), 5.26 (s, IH), 3.97 (s, 2H), 3.35 (m, 2H), 2.65 (m, 2H), 1.44 (s, 9H).

Example 19 Preparation of l,2-bis(5-methylthiophen-2-yl)disulfane

Step 1 : Thiophene 1 (4.4 mL, 51 mmol) was added to a solution of ClSO₂OH (10 mL, 155 mmol) in CH₂Cl₂ (100 mL) at O⁰C during 0.5 hrs. The reaction solution was stirred at this temperature for another 3 hrs. Then, the reaction mixture was poured into ice-water and extracted with CH₂Cl₂ twice. The organic layer was washed with brine, concentrated and 6.0 g 5-methylthiophene-2-sulfonyl chloride 2 was obtained as a light oil, yield 59.5%. Step 2: The solution of 5-methylthiophene-2-sulfonyl chloride 2 (1.2 g, 6.1 mmol) in THF (10 niL) was added to LiAlH₄ (0.93 g, 24.4 mmol) in THF (50 mL) at -6O⁰C during 20 minutes. The reaction solution was stirred at rt for 1 hr, quenched with Na₂SO₄-IOH₂O and filtered. The filtrate was concentrated and the residue was purified by column chromatography (PE:EA = 5:1) to afford 0.6 g l,2-bis(5- methylthiophen-2-yl)disulfane 3 as a yellow oil, yield 76%. ¹H NMR (400Hz, CDCl₃): 6.96 (d, 2H), 6.66 (d, 2H), 2.50 (s, 6H).

Example 20 Preparation of Di-tert-butyl-2,2'-(3,3'-disulfanediylbis(pyridine-3,2-diyl))bis(ethane-

2, 1 -diyl)dicarbamate

I CX N CN

Step 1 : m-Chloroperbenzoic acid (1O g, 85%, 49 mmol) was added to a solution of 3-bromopyridine 1 (4.74 g, 30 mmol) in CH₂Cl₂ (5OmL) portion-wise. The reaction solution was stirred at rt for 1 hr. TLC indicated there was no starting material. Then, Na₂S₂O₃ (3.0 g, 19 mmol) was added into the reaction mixture. The resulting mixture was filtered. The filtrate was concentrated, purified by column chromatography with ethyl acetate as eluent and 3 -bromopyri dine- 1 -oxide 2 was obtained as a light yellow oil (5.0 g, 96%).

Step 2: The mixture of 3-bromopyridine-l-oxide 2 (3.48 g, 20mmol), TMSCN (5.94 g, 60 mmol), Et₃N (5.05 mL, 40 mmol) and CH₃CN (30 mL) was heated to reflux for 4h until TLC indicated no 3-bromopyridine-l-oxide 2 existed. The reaction mixture was concentrated and the residue was purified by column chromatography (PE:EA = 10:1). 0.3 g 5-bromopicolinonitrile / 3.0 g 3-bromopicolinonitrile 3 were obtained as a white solid, yield 82.0% Step 3: NaH (0.9 g, 22.5 mmol) was suspended in dry THF, 2.53 mL t- butylthiol (22.5 mmol) was added to the suspension, the resulting mixture was heated to 5O⁰C for 1 hr until H₂ evolution ceased. To the white suspension 2-cyano-3- bromopyridine (2.74 g, 15 mmol) was added and the reaction was heated to reflux for 1.5 hrs under N₂. LC-MS indicated no 3-bromopicolinonitrile existed and the reaction was filtered through silica gel. The filtrate was concentrated and the residue was purified by column chromatography (PE:EA = 5:1), 2.88 g 3-(tert- butylthio)picolinonitrile 4 was obtained as a light oil in yield 99%.

Step 4: NaOH 5.2 g (130 mmol) was dissolved in 5 mL H₂O and 5 mL ethanol. To this solution 2.5 g 3-(tert-butylthio)picolinonitrile 4 (13 mmol) was added in. The mixture was heated to reflux for 1 hr, at the same time N₂ was bubbled into the solution to remove the NH₃ evolved. Then, the reaction was cooled down to rt, diluted with water and extracted with ethyl acetate. The aqueous layer was adjusted to pH = 2, and extracted with ethyl acetate from the water. The organic layer was washed with brine, dried over sodium sulfide and concentrated. 2.38 g solid 5 was obtained, yield 87%.

Step 5: To a solution of 3-(tert-butylthio)picolinic acid 5 (0.53 g, 2.5 mmol) in DMF (10 mL), CH₃I (0.23 mL, 3.75 mmol) and K₂CO₃ (0.69 g, 5.0 mmol) was added. The mixture was stirred overnight at rt and extracted with ethyl acetate from sat. aq. Na₂CO_3. The organic layer was washed with brine and concentrated. The residue was purified by column chromatography (PE:EA = 5:1) and 0.45 g methy\-3-(tert- butylthio)picolinate 6 was obtained in yield 80% as a light oil. Step 6: NaBH₄ (0.38 g, 10 mmol) was added to the solution of CaCl₂ (0.56 g, 5.0 mmol) and methyl-3-(fert-butylthio)picolinate 6 (0.45 g, 2.5 mmol) in ethanol (10 mL) portion-wise. Then, the reaction mixture was stirred at rt overnight and extracted with ethyl acetate from sat. aq. Na₂CO₃. The organic layer was washed with brine, concentrated and the residue was purified by column chromatography (PE:EA = 2:1), 0.40 g yellow oil 7 was obtained in yield 82%.

Step 7: SOCl₂ (0.45 mL, 6.15 mmol) was added to the solution of the (3- (fert-butylthio)pyridin-2-yl)methanol 7 (0.8 g, 4.1 mmol) in DMF (15 mL) drop-wise at O⁰C. The reaction solution was stirred at rt for 1 hr, extracted with ethyl acetate from sat. aq. Na₂CO₃. The organic layer was washed with brine, concentrated and the residue was purified by column chromatography (PE:EA = 10:1). 0.80 g oil 8 was obtained in yield 90.5%

Step 8: The mixture of the 3-(tert-butylthio)-2-(chloromethyl)pyridine 8 (4.4 g, 20.4 mmol), NaCN (2.0 g, 40.8 mmol) and DMSO (40 mL) was heated to 6O⁰C for 2 hrs. Then, the desired product was extracted with ethyl acetate from water. The organic layer was washed with brine and concentrated. The residue was purified by column chromatography (PE:EA = 2:1) and 3.4 g slight yellow oil 9 was obtained in yield 81%.

Step 9: NaBH₄ (0.18 g, 4.8 mmol) was added to the suspension Of NiCl₂ (0.13 g, 0.96 mmol) and 2-(3-(tert-butylthio)pyridin-2-yl)acetonitrile 9 (0.1 g, 0.48 mmol) in CH₃OH (15 mL) portion-wise. The reaction solution was stirred at rt overnight. The product was extracted with ethyl acetate from water. The organic layer was washed with brine and concentrated. 0.05 g oil 10 was obtained yield 51%.

Step 10: 2-(3-(fert-butylthio)pyridin-2-yl)ethanamine 10 was dissolved in concentrated HCl, heated to reflux for 24 hrs until LC-MS indicate no starting materials existed. The reaction mixture was concentrated and the residue was used for the next step directly.

Step 11 : The crude 2-(2-aminoethyl)pyridine-3 -thiol 11 from last step was dissolved in ammonia and air was bubbled into the reaction solution until LC-MS indicated no 2-(2-aminoethyl)pyridine-3 -thiol existed. The reaction mixture was concentrated and residue was used for the next step directly. Step 12: BoC₂O 0.56 g (3.4 mmol) was added to the solution Of Et₃N (0.48 mL, 2.55 mmol) and 2,2'-(3,3'-disulfanediylbis(pyridine-3,2-diyl))diethanamine 12 (0.85 mmol) in CH₃OH. The mixture was stirred for 1 hr at rt. Then, the reaction mixture was diluted with water, extracted with ethyl acetate The organic layer was washed with brine and concentrated. The residue was purified by column chromatography with ethyl acetate as eluent and 0.48 g white solid 13 was obtained yield 93%. ESI-MS: 507.7 [M+H]. ¹H NMR (400 MHz, CDCl₃): 8.40 (m, 2H), 7.77 (m, 2H), 7.13 (m, 2H), 3.62 (m, 4H), 3.13 (m, 4H), 1.43 (s, 18H).

Example 21

Preparation of Di-tert-butyl-3,3'-(3,3'-disulfanediylbis(pyridine-3,2-diyl))bis(propane-

3 , 1 -diyl)dicarbamate

Step 1 : n-BuLi (5.6 mL, 13.9 mmol) was added to CH₃CN (7.2 mL, 139 mmol) in THF at -6O⁰C, dropwise, The mixture was stirred for 4 hrs at this temperature, then 3-(fc/-t-butylthio)-2-(chloromethyl)pyridine 1 (3.0 g, 13.9 mmol) was added, stirred for another 2 hrs and quenched with water at this temperature. Then, the reaction mixture was extracted with ethyl acetate from water. The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with PE:EA = 5:1 as eluent, 0.8 g oil was obtained, yield 26%.

Step 2: NaBH₄ (0.18 g, 4.8 mmol) was added to the suspension Of NiCl₂ (0.13 g, 0.96 mmol) and 3-(3-(tert-butylthio)pyridin-2-yl)propanenitrile 2 (0.1 g, 0.48 mmol) in CH₃OH (15 mL) portion-wise. Then, the reaction mixture was stirred at rt overnight and extracted with ethyl acetate from water. The organic layer was washed with brine and concentrated. 0.05 g oil was obtained, yield 50.5%

Step 3: 3-(3-(tert-butylthio)pyridin-2-yl)propylamine 3 was dissolved in cone. HCl, heated to reflux for 24 hrs until LC-MS indicated no starting material existed. The reaction mixture was concentrated, used for the next step directly.

Step 4: The crude product from last step was dissolved in ammonia, air was bubbled in until LC-MS indicated no 2-(3-aminopropyl)pyridine-3 -thiol 4 existed, concentrated , used for the next step directly. Step 5: BoC₂O (0.56 g, 3.4 mmol) was added to the solution of Et₃N

(0.48 mL, 2.55 mmol) and 4-(3-((2-(3-aminopropyl)pyridin-3-yl)disulfanyl)pyridin-2- yl)butan-l -amine 5 (0.85 mmol) in CH₃OH, the mixture was stirred for 1 hr at rt. Then, the reaction mixture was diluted with water and extracted with ethyl acetate The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with ethyl acetate as eluent, 0.48 g white solid 6 was obtained, yield 93%. ESI-MS: 579.6 [M+H]. ¹H NMR (400 MHz, CDCl₃): 8.40 (m, 2H), 7.78 (m, 2H), 7.14 (m, 2H), 4.86 (s, 2H), 3.19 (m, 4H), 2.98 (m, 4H), 1.94 (m, 4H), 1.47 (s, 18H).

Example 22

Preparation of 3,3'-disulfanediyldipyridin-2-amine

5

Step 1 : A mixture of 3-(tert-butylthio)picolinic acid 1 (10 g, 47 mmol),

DPPA (12 mL, 56.4 mmol), Et₃N (7.9 mL, 56.4 mmol) and tolune (300 mL) was stirred overnight at 100⁰C. TLC indicated no starting material existed and the reaction mixture was used for the next step directly.

Step 2: To the tolune solution from last step, aqueous NaOH was added, the mixture was heated to reflux for 2 hrs, cooled to rt, extracted with ethyl acetate from water, the organic layer was washed with brine, concentrated and the residue was purified by column chromatography with PE:EA = 5:1 as eluent, 3.8 g solid was obtained, yield 44%.

Step 3: 3-(fert-butylthio)pyridin-2-amine 3 (360 mg, 2 mmol) was dissolved in concentrate HCl, heated to reflux for 24 hrs until LC-MS indicated no 3- (fert-butylthio)pyridin-2-amine 3 existed. The reaction mixture was concentrated and the residue was used for the next step directly.

Step 4: The crude product 4 from last step was dissolved in ammonia, air was bubbled in until LC-MS indicated no starting material existed. The solution was filtered, 170 mg 3,3'-disulfanediyldipyridin-2-amine 5 as a slight yellow solid was obtained, yield 68%. ESI-MS: 251.2 [M+H]. ¹H NMR (400 MHz, CDCl₃): 8.08 (m,

2H), 7.34 (m, 2H), 6.53 (m, 2H), 5.23 (s, 6H).

Example 23

Preparation of Di-ter£-butyl-2,2'-(3,3'-disulfanediylbis(pyridine-3,2-diyl)bis (methyl ene))bis(sulfanediyl)bis(ethane-2, 1 -diyl)dicarbamate

NHBoc

Step 1 : A mixture of 3-(fert-butylthio)-2-(chloromethyl)pyridine 1 (0.8 g, 4.1 mmol) (obtained from example 20 step 7), N-Boc-aminoethanethiol (3.46 mL, 20.5 mmol), NaI (0.15 g, 1.0 mmol) and DMF (15 mL) was stirred at rt for 1 hr. Then, the reaction mixture was extracted with ethyl acetate from sat. aq. Na₂CO₃. The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with PE:EA = 2:1 as eluent, 1.39 g of tert-buty\-2-((3-(tert- butylthio)pyridin-2-yl)methylthio)ethylcarbamate 2 was obtained as a slight oil, yield 95.5%.

Step 2: tert-butyl-2-((3-(tert-butylthio)pyridin-2- yl)methylthio)ethylcarbamate 2 was dissolved in concentrated HCl, heated to reflux for

24 hrs until LC-MS indicated no starting material existed. The reaction mixture was concentrated, and slight yellow solid 2-((2-aminoethyl thio)m ethyl )pyridine-3 -thiol 3 was obtained, which was used for the next step directly.

Step 3: The crude 2-((2-aminoethylthio)methyl)pyridine-3-thiol 3 was dissolved in ammonia and air was bubbled in until LC-MS indicated no starting material existed. The reaction mixture was concentrated, and slight yellow solid 2,2'- (3,3'-disulfanediylbis(pyridine-3,2-diyl)bis(methylene))bis(sulfanediyl)diethanamine 4 was obtained, which was used for the next step directly.

Step 4: Boc₂O (0.56 g, 3.4 mmol) was added to the solution of Et₃N

(0.48 mL, 2.55 mmol) and 2,2'-(3,3'-disulfanediylbis(pyridme-3,2- diyl)bis(methylene))bis(sulfanediyl) diethanamine 4 (0.85 mmol) in CH₃OH. The mixture was stirred for 1 hr at rt, diluted with water and extracted with ethyl acetate_. The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with ethyl acetate as eluent, 0.48 g yellow solid di-fert-butyl

2,2'-(3,3'-disulfanediylbis(pyridine-3,2-diyl)bis(methylene))bis(sulfanediyl)bis(ethane- 2,l-diyl)dicarbamate 5 was obtained, yield 93%. ESI-MS: 600.06 [M+H]. ¹H NMR

(400 MHz, CDCl₃): 8.36 (s, 2H), 7.92 (m, 2H), 7.18 (m, 2H), 5.12 (s, 2H), 3.98 (s, 4H),

3.30 (s, 4H), 2.64 (s, 4H), 1.42 (s, 18H).

Example 24 Preparation of di-/ert-butyl-3,3'-(3,3'-disulfanediylbis(pyridine-3,2-diyl) bis(methylene))bis(sulfanediyl)dipyrrolidine- 1 -carboxylate

Δ 5

Step 1 : A mixture of 3-(terf-butylthio)-2-(chloromethyl)pyridine 1 (0.8 g, 4.1 mmol), N-Boc-aminoethanethiol (3.46 mL, 20.5 mmol), NaI (0.15 g, 1.0 mmol) and DMF (15 mL) was stirred at rt for 1 hr. Then, the reaction mixture was extracted with ethyl acetate from sat. aq. Na₂CO₃. The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with PE:EA = 2:1 as eluent, 1.39 g oil was obtained, yield 96%.

Step 2: tert-butyl-3-((3-(tert-butylthio)pyridin-2- yl)methylthio)pyrrolidine- 1 -carboxylate 2 was dissolved in concentrate HCl, heated to reflux for 24 hrs until LC-MS indicated no starting material existed. The reaction mixture was concentrated, used for the next step directly.

Step 3: The crude product from last step was dissolved in ammonia, air was bubbled into it, until LC-MS indicated no 2-((pyrrolidin-3-ylthio)methyl)pyridine- 3-thiol 3 existed. The reaction mixture was concentrated, used for the next step directly.

Step 4: BoC₂O (0.56 g, 3.4 mmol) was added to the solution of Et₃N (0.48 mL, 2.55 mmol) and l,2-bis(2-((pyrrolidin-3-ylthio)methyl)pyridin-3-yl)disulfane 4 (0.85 mmol) in CH₃OH and the mixture was stirred for 1 hr at rt. Then, the reaction mixture was diluted with water, extracted with ethyl acetate The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with ethyl acetate as eluent, 0.48 g of di-ter;-butyl-3,3'-(3,3'- disulfanediylbis(pyridine-3,2-diyl) bis(methylene))bis(sulfanediyl)dipyrrolidine-l- carboxylate 5 was obtained as a white solid, yield 93%. ESI-MS: 652.0 [M+H]. ¹H NMR (400 MHz, CDCl₃): 8.36 (s, 2H), 7.91 (m, 2H), 7.19 (m, 2H), 3.98 (s, 4H), 3.60 (m, 2H), 3.640 (m, 2H), 3.30 (s, 4H), 3.10 (m, 2H), 2.15 (m, 2H), 1.83 (m, 2H), 1.43 (s, 18H).

Example 25

Preparation of di-tert-buty\ 2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene))bis(sulfanediyl)bis(ethane-2, 1 -diyl)bis(methyl carbamate)

Step 1 : A mixture of 3-(ter?-butylthio)-2-(chloromethyl)pyridine 1 (0.8 g, 4.1 mmol), N-Boc aminoethanethiol (3.46 mL, 20.5 mmol), NaI (0.15 g, 1.0 mmol) and DMF (15 mL) was stirred at rt for 1 hr. Then, the reaction mixture was extracted with ethyl acetate from sat. aq. Na₂CO₃. The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with PE:EA = 2:1 as eluent, 1.39 g oil was obtained, yield 96%.

Step 2: NaH (0.65 g, 16.2 mmol) was added to the solution of tert-butyl 2-((3-(tert-butylthio)pyridin-2-yl)methylthio)ethylcarbamate 2 (2.9 g, 8.1 mmol) in

THF, stirred for 0.5 hr, then CH₃I (0.56 mL, 8.9 mmol) was added. The mixture was stirred at rt overnight. Then, the reaction mixture was extracted with ethyl acetate from water, the organic layer was washed with brine, concentrated and the residue was purified by column chromatography with PE:EA = 2:1 as eluent, 2.27 g of tert-buty\ 2- ((3-(tert-butylthio)pyridin-2-yl)methylthio)ethyl(methyl)carbamate 3 was obtained as a slight oil, yield 76%.

Step 3: tert-butyl-2-((3-(fert-butylthio)pyridin-2- yl)methylthio)ethyl(methyl)carbamate 3 was dissolved in concentrate HCl, heated to reflux for 24 hrs until LC-MS indicated no fert-butyl-2-((3-(terr-butylthio)pyridin-2- yl)methylthio)ethyl(methyl)carbamate 3 existed. The reaction mixture was concentrated and residue was used for the next step directly.

Step 4: The crude product from last step was dissolved in ammonia, air was bubbled into the reaction solution until LC-MS indicated no 2-((2- (methylamino)ethylthio)methyl)pyridine-3 -thiol 4 existed. The reaction mixture was concentrated, used for the next step directly.

Step 5: BoC₂O (0.56 g, 3.4 mmol) was added to the solution Of Et₃N (0.48 mL, 2.55 mmol) and 2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene))bis(sulfanediyl)bis(N-methylethanamine) 5 (0.85 mmol) in CH₃OH, the mixture was stirred for 1 hr at rt. The reaction mixture was diluted with water, extracted with ethyl acetate_, the organic layer was washed with brine, concentrated and the residue was purified by column chromatography with ethyl acetate as eluent. 0.48 g of 2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene))bis(sulfanediyl)bis(ethane-2, 1 -diyl)bis(methyl carbamate) 6 was obtained as a yellow solid, yield 93%. ESI-MS: 628.1 [M+H]. ¹H NMR (400 MHz, CDCl₃): 8.36 (s, 2H), 7.94 (m, 2H), 7.21 (m, 2H), 4.11 (s, 4H), 3.36 (s, 4H), 2.84 (s, 6H), 2.66 (s, 4H), 1.45 (s, 18H).

Example 26

Preparation of di-ter;-butyl-3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene)dicarbamate

Step 1 : A mixture of 3-(ter/-butylthio)-2-(chloromethyl)pyridine 1 (0.8 g, 4.1 mmol) and ammonia (410 mmol) was heated to 12O⁰C in a sealed tube for 2 hrs. The reaction mixture was concentrated, used for the next step directly.

Step 2: (3-(tert-butylthio)pyridin-2-yl)methanamine 2 was dissolved in cone. HCl, heated to reflux for 24 hrs until LC-MS indicated no starting material existed. The reaction mixture was concentrated, used for the next step directly.

Step 3: The crude product 2-(aminomethyl)pyridine-3 -thiol 3 from step 2 was dissolved in ammonia, air was bubbled into it until LC-MS indicated no starting material existed, concentrated, used for next step directly. Step 4: Boc₂O (0.56 g, 3.4 mmol) was added to the solution Of Et₃N

(0.48 mL, 2.55 mmol) and 3,3'-disulfanediylbis(pyridine-3,2-diyl)dimethanamine 4 (0.85 mmol) in CH₃OH, the mixture was stirred for 1 hr at rt. The reaction mixture was diluted with water, extracted with ethyl acetate The organic layer was washed with brine, concentrated and the residue was purified by column chromatography with ethyl acetate as eluent, 0.48 g di-tert-butyl-3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene)di carbamate 5 was obtained as a slight yellow solid, yield 93%. ESI- MS: 479.6 [M+H]. ¹H NMR (400 MHz, CDCl₃): 8.43 (m, 2H), 7.80 (m, 2H), 7.18 (m, 2H), 5.98 (s, 2H), 4.58 (s, 4H), 1.49 (s, 18H).

Example 27

1 ,2-bis(5-chloro-l ,3,4-thiadiazol-2-yl) disulfane

Step 1 : Aqueous hydrogen peroxide (1.3 g, 30%, 11.25 mmol) was added dropwise to a solution of 5-amino-l,3,4-thiadiazole-2-thiol 1 (100 mg, 0.75 mmol) in MeOH (20 mL) during 5 min. The resulting bright yellow solution was stirred until precipitation of the product was complete. After filtration, 5,5'- disulfanediylbis(l,3,4-thiadiazol-2-amine) 2 was obtained as a yellow solid (900 mg, yield 91%) . The product was used without further purification.

Step 2: A solution of 5,5'-disulfanediylbis(l,3,4-thiadiazol-2- amine) 2 (890mg) in cone. HCl (20 mL) and H₂O (12 mL) was treated with NaCl-ice and cooled to -1O⁰C, then NaNO₂ (0.5 g) in H₂O (8 mL) was added slowly. The reaction mixture was stirred for 2 hrs at -10 ⁰C, then CuCl was added slowly. The mixture was heated to 50-55 ⁰C for another 2 hrs, cooled and dried with H₂O and

CH₂Cl₂, washed with brine, dried over Na₂SO₄, and concentrated to get l,2-bis(5- chloro-l,3,4-thiadiazol-2-yl)disulfane 3 (500 mg, yield 49%). ESI-MS: m/z 302 [M+H].

Example 28 5-methylthiazole-2 -thiol

n-BuLι(1 1eq )

Step 1 : 1 ,2-di-fert-butyldisulfane (4.4 mL, 51 mmol) was added to a solution of 5-methylthiazole 1 (10 mL, 155 mmol) in THF (100 mL) at -60 ⁰C during 0.5 hrs. The reaction solution was stirred at this temperature for another 3 hrs. Then, the reaction mixture was poured into ice-water and extracted with CH₂Cl₂ twice. The organic layer was washed with brine, concentrated, and 2-(ter£-butylthio)-5- methylthiazole 2 was obtained as a light oil (6.0 g, 20.7%).

Step 2: The solution of 2-(tert-butylthio)-5-methylthiazole 2 (1.1 g, 6.1 mmol) in con. HCl (10 mL) was heated to reflux for 24 hrs, the reaction was filtered, the filtrate was concentrated, and the residue was purified by column chromatography (PE:EA = 2:1) to afford 0.6 g of 5-methylthiazole-2-thiol 3 as a yellow solid (yield 75%). ¹H NMR (400Hz, CDCl₃): 7.42 (s, IH), 3.0. (s, IH), 2.35 (s, 3H).

Example 29 Iodomethyl pivalate

Sodium iodide (67.5 g, 448.2 mmol) was added in one portion to a solution of 2,2-dimethylpropanoic acid chloromethyl ester 1 (45 g, 300 mmol) in 150 mL dry acetonitrile at rt under nitrogen. The heterogeneous reaction was stirred at rt for

18 hrs, then filtered and concentrated in vacuo. The residue was partitioned between ethyl acetate and 5% sodium bisulfite. The organic layer was washed with 5% sodium bisulfite and water, then dried over Mg₂SO₄, filtered and evaporated to get 56 g of pure product 2 with 77% yield. ¹H NMR (400 MHz, chloroform-d): 1.20 (s, 9H), 5.93 (s,

2H).

Example 30 l,r-(5,5'-disulfanediylbis(l ,3,4-thiadiazole-5,2-diyl))dipyrrolidin-2-one

Step 1 : Aqueous hydrogen peroxide (127.5 mg, 30%, 1.125 mmol) was added dropwise to a solution of 5-amino-l,3,4-thiadiazole-2-thiol 1 (100 mg, 0.75 mmol) in MeOH (20 mL) during 5 min. The resulting bright yellow solution was stirred until precipitation of the product was complete. Collection furnished the disulfide, 5,5'- disulfanediylbis(l,3,4-thiadiazol-2-amine) 2, as a yellow solid (90 mg, yield 91%). The product was used without further purification. ESI-MS: m/z 264 [M+H].

Step 2: To a solution of 5,5'-disulfanediylbis(l,3,4-thiadiazol-2-amine) 2 (100 mg, 0.375 mmol) in anhydrous toluene (5 mL) at rt was added 4-bromobutanoyl chloride (139 mg, 0.75 mmol) by syringe, causing precipitation. The reaction mixture was refluxed for 1 hr. After standing at rt overnight, the product was filtered to afford N,N'-(5,5'-disulfanediylbis(l,3,4-thiadiazole-5,2-diyl))bis(4-bromobutanamide) 3 as a yellow solid (168.7 mg, yield 80%). The product was used without further purification. ESI-MS: m/z 562 [M+H]. Step 3: To a solution of N,N'-(5,5'-disulfanediylbis(l,3,4-thiadiazole-5,2- diyl))bis(4-bromobutanamide) 3 (152 mg, 0.27 mmol) in anhydrous THF (50 mL) at 0 ⁰C was added J-BuOK (45.4 mg, 0.405 mmol). After being stirred at 0 ⁰C for 30 min, saturated NH₄Cl aqueous solution was added and the mixture was extracted by ethyl acetate. The combined organic layers were washed with brine, dried over Na₂SO₄, filtered and solvent was removed under pressure to afford 1,1 '-(5, 5'- disulfanediylbis(l,3,4-thiadiazole-5,2-diyl))dipyrrolidin-2-one 4 as a yellow solid (75 mg, yield 70%). The product was used without further purification. ESI-MS: m/z 401 [M+H].

Example 31

5-(trifiuoromethyl)-l,3,4-thiadiazole-2-thiol

Step 1 : A solution of 5-(trifluoromethyl)-l,3,4-thiadiazol-2- amine 1 (1.7 g) in HBr (75 mL) and H₂O (50 mL) was treated with NaCl-ice and cooled to -10 ⁰C, NaNO₂ (1.5 g) in H₂O (25 mL) was added slowly. The reaction mixture was stirred for 2 hrs at -10 ⁰C. The mixture was extracted with ethyl acetate, washed with brine, dried over MgSO₄, and concentrated. 2-bromo-5-(trifluoromethyl)- 1,3,4- thiadiazole 2 (1.16 g ) was obtained. The product was used in next step without further purification.

Step 2: The mixture of 2-bromo-5-(trifluoromethyl)- 1,3,4- thiadiazole 2 (1.15 g), thiourea (1.2 g) and ethanol (15 mL) was heated to reflux for 1 hr, concentrated, and 5-(trifluoromethyl)-l,3,4-thiadiazole-2-thiol 3 was obtained as a yellow solid (800 mg, 86%). ESI-MS: 186 [M + H].

Example 32 5-(trifluoromethyl)thiazole-2-thiol

H₂

step 6 step 7

Step 1 : To a stirred THF (20 mL) solution of methylsulfonylbenzene (1.60 g, 10 mmol) under N₂ at O ⁰C was added NaH (60%, 600 mg, 15 mmol) in portions after which the resulting suspension was stirred at 0 ⁰C for 10 min, and then treated dropwise with ethyl trifluoroacetate (3.60 mL, 30 mmol) at 0 ⁰C.

After 2 hrs under reflux, the resulting solution was poured into saturated aqueous NaCl

(250 mL) and extracted with Et₂O (100 mL x 4). The combined extracts were dried over MgSO₄, and evaporated under reduced pressure to give l,l,l-trifluoro-3-

(phenylsulfonyl)propan-2-one (1.80 g). The product was used without further purification in next step.

Step 2: NaBH₄ (2.50 g, 10 mmol) was added to a solution of l,l,l-trifluoro-3-(phenylsulfonyl)propan-2-one (1.80 g) in MeOH (20 mL). After stirring overnight at it, the solution was poured into saturated NaCl (200 mL) and extracted with Et₂O (100 mL x 4). The combined extracts were dried over MgSO₄ and evaporated under reduced pressure. The residue was recrystallized from Et₂O-hexane to give l,l,l-trifluoro-3-(phenylsulfonyl)propan-2-ol (1.40 g, 57%). Step 3: To a stirred solution of l,l,l-trifluoro-3- (phenylsulfonyl)propan-2-ol (1.40 g, 5.7 mmol) and Et₃N (1.60 mL, 11 mmol) in CH₂Cl₂ (20 mL), 4-methylbenzene-l-sulfonyl chloride (1.08 g, 5.7 mmol) was added in portions. The reaction mixture was heated to reflux for 2 hrs, then treated with DBU (868 mg, 5.7 mmol) and heated under reflux for another 1 hr. The solution was then poured into saturated aqueous NaHCO₃ (200 mL) and extracted with CH₂Cl₂ (100 mL x 4). The combined extracts were washed with HCl (1 M, 100 mL x 2), dried over MgSO₄, and evaporated under reduced pressure. The residue was recrystallized from Et₂O-hexane to give (E)-(3,3,3-trifluoroprop-l-enylsulfonyl)benzene as a white solid (890 mg, 67%).

Step 4: To a cooled solution (-78 °C) consisting of 12 mmol of BuLi in anhydrous THF was added 12 mmol of tert-BuOOH in anhydrous octane. After stirring for 1 hr at -78 °C, 2.35 g (10 mmol) of (£)-(3,3,3-trifluoroprop-l- enylsulfonyl)benzene was added dropwise. The mixture was stirred at -78 ⁰C for 1 hr and then quenched with 10% HCl. After the usual work-up and chromatography on silica gel, 1.8 g (72%) of 2-(phenylsulfonyl)-3-(trifluoromethyl)oxirane was obtained.

Step 5: A solution consisting of 1.0 g of 2-(phenylsulfonyl)-3- (trifluoromethyl)oxirane and 2 equiv of thiourea in 4 mL of dimethylformamide was heated overnight at 90 ⁰C. After cooling, 40 mL Of CH₂Cl₂ was added and the dark solution washed successively with water and brine. Charcoal was then added and after filtration and evaporation of the solvent, the residue was chromatographed on silica gel to get 4-(trifluoromethyl)thiazol-2-amine (200 mg, yield 30%).

Step 6: To a solution of 5-(trifluoromethyl)thiazol-2-amine (3.3 g, 20 mmol) in cone. HCl (10 mL) at 0 ⁰C, NaNO₂ (2.1 g, 30.4 mmol) was added in. The reaction solution was stirred for 2 hrs, and then potassium O-ethyl carbonodithioate in water (20 mL) was added. The mixture was stirred at 5 ⁰C for 12 hrs, and the whole reaction solution was extracted with 300 mL of ethyl acetate. The organic layer was washed with 200 mL of saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated to dry. The residue was purified by column chromatography (50% EtOAc in petroleum ester) to give O-ethyl-5-5- (trifluoromethyl)thiazol-2-yl carbonodithioate (1.0 g, 52% yield) as a yellow oil. Step 7: To a solution of 0-ethyl-S-5-(trifluoromethyl)thiazol-2-yl carbonodithioate (0.27 g, 1.0 mmol) in 10 mL ethanol, KOH (25 mg, 1.0 mmol) was added during 5 minutes. The reaction mixture was stirred at 80 ⁰C for 3 hrs. Then the reaction solution was cooled to rt, poured into ice water, adjusted to pH = 3 with diluted hydrochloride, and the whole reaction solution was extracted with 300 mL of ethyl acetate. The organic layer was washed with 200 mL of saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated. The residue was purified by column chromatography (50% EtOAc in petroleum ester) to give 5-(trifluoromethyl)thiazole-2-thiol as a white solid (0.16 g, 90%).

Example 33

(Z)-5-benzo[d]thiazol-2-yl-2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-

(trityloxyimino)ethanethioate

Step 1 : To a solution of 1 (43 g, 0.2 moL) in 300 mL DMF was added 63 mL TEA. The mixture was stirred for 10 min, then 123 g of trityl chloride was added and the mixture was kept at 50 ⁰C for 72 hrs. The mixture was concentrated and extracted with acetic ether. The acetic ether was washed with 1% NaOH solution three times, the organic layer was dried over Na₂SO₄, filtered and the filtrate was concentrated under reduced pressure. The residue was dried in vacuum overnight to provide (Z)-ethyl-2-(2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetate 2 (120 g, yield 85%).

Step 2: To a solution of 2 (175 g, 0.25 mol) in about 1000 mL of 1,4- dioxane was added NaOH (4 g) in 10 mL H₂O. The mixture was kept at 100 ⁰C overnight. After the reaction was completed, water (2 L) was added to the reaction mixture. Then, the precipitate was isolated. The filter cake was washed with ethyl acetate (50 mL x 5). The precipitates were combined and dried in air or vacuo to get (Z)-2-(2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetic acid 3 (135 g, yield 80%) Step 3: An oven-dried flask under inert atmosphere was charged with dicarboxylic acid 3 (3.0 mmol) and anhydrous powdered K₂CO₃ (9.0 mmol) in dry DMF and stirred at it for 10 minutes. Alkenyl bromide (7.5 mmol) and a catalytic amount of tetrabutylammonium iodide (TBAI) were added to the above reaction mixture. The reaction mixture was stirred at rt for 1 hr. To the reaction mixture, water (200 mL) was added and extracted with dichloromethane (4 x 50 mL). The organic layers were combined and washed with water (3 x 200 mL). Finally, the organic layers were dried over Na₂SO₄, evaporated and followed by silica gel (100-200 mesh) column purification to afford the respective dialkenated product, (Z)-allyl-2-(2- (tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetate 4 (1.9 g, yield 90%) Step 4: In 10 mL of DMF was dissolved 1 g of 4. To this solution, 0.32 g of N-bromosuccinimide was added and the mixture was stirred at rt for 1 hr. To the reaction mixture were added 2x10 mL of water and 30 mL of ethyl acetate, and the mixture was shaken. The organic layer was separated, washed with 20 mL of saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, and then concentrated. The residue was crystallized from ethyl acetate to give 0.9 g (77% yield) of (Z)-allyl-2-(5-iodo-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetate 5. Step 5: 5 was dissolved in DMF and A and CuI were added. The mixture was heated at 85 ⁰C for 4 hrs. The mixture was cooled and then ether was added. The reaction mixture was extracted with H₂O.brine, the organic layer was dried over Na₂SO₄ and evaporated under reduced pressure to yield (Z)-allyl-2-(5- (trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetate 6.

Step 6: 700 mg of 6 was dissolved in CH₂Cl₂ To the resulting solution were added 900 mg of potassium 2-ethylhexanoate, 47 mg of PPh₃ and 53 mg of Pd(PPh₃)₄ and the mixture was stirred at normal temperature for 1 hr. After the reaction completed, the reaction solution was washed with saturated saline solution, dried over anhydrous magnesiam sulfate and then distilled under reduced pressure to remove the solvent, to get 300 mg of (Z)-2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2- (trityloxyimino)acetic acid 7.

Step 7: To a solution of 7 (4.273 g, 5.48 mmol) and PPh₃ (2.871 g, 10.96 mmol) dissolved in 10 mL DCM under N₂ was added disulfide (3.62 g, 10.96 mmol) by small portions at rt. After that, the reaction mixture was stirred for 1 hr at rt, then the mixture was evaporated and purified by flash chromatography to afford the dialkenated product, (Z)-5'-benzo[d]thiazol-2-yl-2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)- 2-(trityloxyimino)ethanethioate 8 (2.385 g, 49%).

Example 34

Di-tert-butyl 2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene))bis(sulfanediyl)bis(ethane-2,l-diyl)dicarbamate

σ B^Dr^I r IM

f-BuSH, NaH NaOH, EtOH

THF, reflux N CN H_∑O, reflux

NHBoc

K₂CO₃, NaI cone. HCI

DMF, 23⁰C, 48 h 10O⁰C, 12 h

Step 1 : ra-Chloroperbenzoic acid (10 g, 85%, 49 mmol) was added to a solution of 3-bromopyridine (4.74 g, 30 mmol) in CH₂Cl₂ (50 mL) portion-wise. The reaction solution was stirred at rt for 1 hr, TLC indicated there was no starting material. Then, Na₂S₂O₃ (3.0 g, 19 mmol) was added into the reaction mixture. The resulting mixture was filtered. The filtrate was concentrated, purified by column chromatography with ethyl acetate as eluent, and 3-bromopyridine-l-oxide was obtained as a slight yellow oil (5.0 g, 95.6%).

Step 2: A mixture of 3-brornopyridine-l-oxide (3.48 g, 20 rnrnoϊ), TMSCN (5.94 g, 60 mmol), Et₃N (5.05 mL, 40 mmol) and CH₃CN (30 mL) was heated to reflux for 4 hrs until TLC indicated no 3-bromopyridine-l-oxide existed, concentrated purified by column chromatography (PE:EA = 10:1) and 0.3 g of 5- bromopicolinonitrile with 3.0 g of 3-bromopicolinonitrile was obtained as a white solid (yield 82%).

Step 3: NaH (0.9 g, 22.5 mmol) was suspended in dry THF, 2.53 mL of t-butylthiol (22.5 mmol) was added to the suspension, the resulting mixture was heated to 5O⁰C for 1 hr until H₂ evolution ceased. To the white suspension, 2-cyano-3- bromopyridine (2.74 g, 15 mmol) was added, the reaction was heated to reflux for 1.5 hrs under N₂, LC-MS indicated no 3-bromopicolinonitrile existed, the reaction was filtered through silica gel, the filtrate was concentrated, and purified by column chromatography (PE:EA = 5:1). 2.88 g of 3-(tert-butylthio)picolinonitrile was obtained as a light oil (yield 99%).

Step 4: NaOH (5.2 g, 130 mmol) was dissolved in 5 mL H₂O and 5 mL ethanol. To this solution 3-(fert-butylthio)picolinonitrile (2.5 g, 13 mmol) was added and the mixture was heated to reflux for 1 hr. At the same time N₂ was bubbled into the solution to remove the evolved NH₃. Then the reaction was cooled to rt, diluted with water, extracted with ethyl acetate, the aqueous layer was adjusted to pH = 2, and extracted with ethyl acetate from the water, washed with brine, dried over sodium sulfide, and concentrated. 2.38 g of solid was obtained (yield 86.9%).

Step 5: To a solution of 3-(terr-butylthio)picolinic acid (0.53 g, 2.5 mmol) in DMF (10 mL), CH₃I (0.23 mL, 3.75 mmol) and K₂CO₃ (0.69 g, 5.0 mmol) was added, the mixture was stirred overnight at rt, extracted with ethyl acetate from sat. Na₂CO₃ solution_, the organic layer was washed with brine, concentrated, and purified by column chromatography (PE:EA = 5:1). 0.45 g of methyl-3-(tert-butylthio)picolinate was obtained as a light oil (yield 80%).

Step 6: NaBH₄ (0.38 g, 10 mmol) was added to the solution of CaCl₂ (0.56 g, 5.0 mmol) and methyl-3-(fert-butylthio)picolinate (0.45 g, 2.5 mmol) in ethanol (10 mL) portion-wise. Then, the reaction mixture was stirred at rt overnight, extracted with ethyl acetate from sat. aq. Na₂CO₃, the organic layer was washed with brine, concentrated, and purified by column chromatography (PE:EA = 2:1). 0.40 g of yellow oil was obtained (yield 81.5%). Step 7: SOCl₂ (0.45 mL, 6.15 mmol) was added to a solution of (3-(tert- butylthio)pyridin-2-yl)methanol (0.8 g, 4.1 mmol) in DMF (15 mL) drop-wise at O⁰C. The reaction solution was stirred at rt for 1 hr, extracted with ethyl acetate from sat. aq. Na₂CO₃, the organic layer was washed with brine, concentrated, and purified by column chromatography (PE:EA = 10:1). 0.80 g of oil was obtained (yield 90.5%).

Step 8: A mixture of 3-(fert-butylthio)-2-(chloromethyl)pyridine (0.8 g, 4.1 mmol), N-Boc-aminoethanethiol (3.46 mL, 20.5 mmol), NaI (0.15 g, 1.0 mmol) and DMF (15 mL) was stirred at rt for 1 hr, then extracted with ethyl acetate from sat. aq. Na₂CO₃, the organic layer was washed with brine, concentrated, and purified by column chromatography with PE:EA = 2:1 as eluent. 1.39 g of tert-buty\-2-((3-(tert- butylthio)pyridin-2-yl)methylthio)ethylcarbamate was obtained as a slight oil (yield 95.5%).

Step 9: tert-butyl-2-((3-(tert-butylthio)pyridin-2- yl)methylthio)ethylcarbamate was dissolved in concentrate HCl, heated to reflux for 24 hrs, until LC-MS indicated no starting material existed, concentrated, and slight yellow solid 2-((2-aminoethylthio)methyl)pyridine-3-thiol was obtained, which was used for the next step directly.

Step 10: The crude 2-((2-aminoethylthio)methyl)pyridine-3-thiol was dissolved in ammonia, air was bubbled in until LC-MS indicated no starting material existed, concentrated, and a slight yellow solid, 2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene))bis(sulfanediyl)diethanamine, was obtained, which was used for the next step directly.

Step 11 : Boc₂O (0.56 g, 3.4 mmol) was added to a solution Of Et₃N (0.48 mL, 2.55 mmol) and 2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene))bis(sulfanediyl)diethanamine (0.85 mmol) in CH₃OH. The mixture was stirred for 1 hr at rt, then, diluted with water, and extracted with ethyl acetate_. The organic layer was washed with brine, concentrated, and purified by column chromatography with ethyl acetate as eluent, 0.48 g of yellow solid di-ter?-butyl-2,2'- (3,3'-disulfanediylbis(pyridine-3,2-diyl)bis(methylene))bis(sulfanediyl)bis(ethane-2,l- diyl)dicarbamate was obtained (yield 93.3%). ESI-MS: 600.06 [M+H]. ¹H NMR (400 MHz, CDCl₃): 8.36 (s, 2H), 7.92 (m, 2H), 7.18 (m, 2H), 5.12 (s, 2H), 3.98 (s, 4H), 3.30 (s, 4H), 2.64 (s, 4H), 1.42 (s, 18H). Example 35 /er/-Butyl-2-((4-mercaptopyridin-3-yl)methylthio)ethylcarbamate

H₃OH h

Step 1 : LDA (0.1 1 mmol) was added to 4-chloropyridine 1 (15 g, 0.1 mol) in THF (250 mL) dropwise at -60 ⁰C and stirred at this temperature for 1 hr. Then, DMF 9.3 mL (0.12 mol) was added, stirred at rt overnight, extracted with ethyl acetate from water, concentrated, and the residue was purified by column chromatography (PE:EA = 10:1) to afford 4.6 g of 2 as a white solid (yield 65.3%). ¹H NMR (400 MHz, CDC1₃):1O.51 (s, IH), 9.05 (s, IH), 8.08 (d, IH), 7.45 (d, IH).

Step 2: A mixture of 4-chloronicotinaldehyde 2 (4.6 g, 32.6 mmol), 2- rriethyl-2-propanethiol (4.4 mL, 32.6 mmol), K₂CO₃ (9.0 g, 65.2 mmol) and DMF (70 mL) was stirred at 100⁰C for 12 hrs until TLC indicate no 4-chloronicotinaldehyde was present, the reaction mixture was diluted with water, extracted with ethyl acetate, the organic layer was concentrated, and the residue was purified by column chromatography (PE:EA = 12:1) to afford 6.3 g of 3 as a clear oil (yield 99.0%). ¹H NMR (400 MHz, CDCl₃): 10.63 (s, IH), 9.03 (s, IH), 8.65 (d, IH), 7.50 (d, IH), 1.40 (s, 9H).

Step 3: NaBH₄ (0.38 g, 10.0 mmol) was added to 4-(tert- butylthio)nicotinaldehyde 3 (0.97 g, 5.0 mmol) in CH₃OH (10 mL) in portions, the mixture was stirred overnight at rt, the reaction mixture was diluted with water, extracted with ethyl acetate, the organic layer was concentrated, and the residue was purified by column chromatography (PE:EA = 2:1-0:1) to afford 0.9 g of 4 as a yellow oil (yield 91.4%). ESI-MS: m/z 198.1 [M+H].

Step 4: SOCl₂ (0.45 mL, 6.15 mmol) was added to a solution of (4-(tert- butylthio)pyridine-3-yl)methanol 4 (0.8 g, 4.1 mmol) in DMF (15 mL) dropwise at 0⁰C, and stirred at rt for 1 hr. The reaction mixture was diluted with water, extracted with ethyl acetate, the organic layer was concentrated, and the residue was purified by column chromatography (PE:EA = 5:1) to afford 0.80 g of 5 as a brown oil (yield 90.5%). ESI-MS: m/z 216.0 [M+H]. Step 5: A mixture of 4-(tert-butylthio)-3-(chloromethyl)pyridine 5 (0.8 g, 4.1 mmol), N-Boc-aminoethanethiol (3.46 mL, 20.5 mmol), NaI (0.15 g, 1.0 mmol) and DMF (15 mL) was stirred at rt for 1 hr, the reaction mixture was diluted with water, extracted with ethyl acetate, the organic layer was concentrated, and the residue was purified by column chromatography (PE:EA = 2:1) to afford 1.39 g of 6 as an oil (yield 95.5%). ¹H NMR (400 MHz, CDCl₃): 8.56 (s, IH), 8.41 (d, IH), 7.44 (d, IH), 4.96 (s, IH), 4.12 (s, 2H), 3.35 (m, 2H), 2.61 (m, 2H), 1.40 (m, 2H), 1.27(m, 2H).

Step 6: tert-Butyl-2-((4-(fcrt-butylthio)pyridine-3- yl)methylthio)ethylcarbamate 6 was dissolved in concentrated HCl, heated to reflux for 24 hrs, until LC-MS indicated no tert-butyl-2-((4-(tert-butylthio)pyridine-3- yl)methylthio)ethylcarbamate was present. The reaction mixture was concentrated and the residue was used for the next step directly.

Step 7: BoC₂O (0.56 g, 3.4 mmol) was added to a solution Of Et₃N (0.48 mL, 2.55 mmol) and 3-((2-aminoethylthio)methyl)pyridine-4-thiol 7 (0.85 mmol) in CH₃OH, the reaction mixture was diluted with water, extracted with ethyl acetate, the organic layer was concentrated, and the residue was purified by column chromatography to afford 0.48 g of 7 as a yellow oil (yield 93.3%). ESI-MS: m/z 401.2 [M+H]. Step 8: A mixture of ferr-butyl-2-((4-(tert-butoxycarbonylfhio)pyridine-

3-yl)methylthio)ethylcarbamate 7 (200 mg, 0.5 mmol), CH₃ONa (10 mmol), and

CH₃OH (40 mL) was heated to reflux overnight, until TLC indicate no ter?-butyl-2-((4-

(ter?-butoxycarbonylthio)pyridine-3-yl)methylthio)ethyl carbamate existed, the reaction mixture was diluted with water, the water layer was adjusted to pH = 6 with concentrated HCl, extracted with ethyl acetate from water, the organic layer was concentrated, and the residue was purified by column chromatography to afford 0.48 g of 8 as a yellow oil (yield 73.3%). ¹H NMR (400 MHz, CDCl₃): 7.85 (s, IH), 7.52(m,

IH), 7.46 (m, IH), 5.26 (s, IH), 3.97 (s, 2H), 3.35 (m, 2H), 2.65 (m, 2H), 1.44 (s, 9H).

Example 36 Pyridin-4-ylmethanethiol

Step 1 : To a solution of 4-(chloromethyl)pyridine 1 (1O g, 66 mmol) in

60 mL ethanol, thiourea (5.8 g, 77 mmol) was added, and then heated at reflux for 1.5 hrs. After cooling, the precipitate was filtered, and washed with ether and dried to give pyridin-4-ylmethyl carbamimidothioate 2 (13.4g) as a white solid in 98% yield.

Step 2: To a solution of sodium hydroxide (1.28 g) in water (10 mL) pyridin-4-ylmethyl carbamimidothioate 2 (2.0 g) was added, and then heated to 70 ⁰C for 30 min. After cooling, acidify with hydrogen chloride solution (4 M) to pH=7.0. Extracted with DCM, dried over Na₂SO₄ and concentrated in vacuum. The residue was purified by column chromatography to afford pyridin-4-ylmethanethiol 3 in 47% yield as a yellow solid. ESI-MS: 126.0 [M+H].

Example 37

(6i?,75',Z)-tert-Butyl-7-(tert-butoxycarbonylamino)-3-(2-(4-methylthiazol-5-yl)vinyl)-8- oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate

Step 1 : (6i?,7»S)-fert-butyl-7-(tert-butoxycarbonylamino)-8-oxo-3- (trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate 1 (400 mg) and Pd(PPh₃)₄ (38 mg, 0.04 eq), LiCl (104 mg , 3 eq), 2,6-di-fcrt-butyl-4-methylphenol (15 mg), and Bu₃SnCHCH₂ (286 mg, 1.1 eq) were dissolved in dry dioxane (15 mL) and refluxed for 3 hrs at 100 ⁰C. After removal of the solvent, the black residue was extracted with CH₂Cl₂ and washed with water, the organic layer was dried over MgSO₄, then concentrated and purified through silica gel. {6R,1 S)-tert-bxxty\-l -(tert- butoxycarbonylamino)-8-oxo-3 -vinyl- 1 -aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate 2 was obtained as a white solid (210 mg, 70%).

Step 2: To a solution of (6R,lS)-tert-hu\y\-l-{tert- butoxycarbonylamino)-8-oxo-3-vinyl-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate 2 (182 mg) in H₂O/acetone (1 :3, 10 mL) was added NaIO₄ (236 mg), then OsO₄/H₂O (3 mL) was added and the solution was kept at rt for 1 hr. When LC-MS showed the reaction was over, the solution was slowly added to Na₂CO_3. After removal of the solvent, the black residue was extracted with CH₂Cl₂ and washed with water, the organic layer was dried over MgSO₄, then concentrated and purified through silica gel. (6i?,75)-tert-butyl-7-(ter?-butoxycarbonylamino)-3-formyl-8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate 3 was obtained as a white solid (55 mg, 30%).

Step 3: K₂CO₃ (90 mg) and 18-Crown-6 (6 mg, 23 μmol) were added to a stirred solution of (6i?,7iS)-tert-butyl-7-(tert-butoxycarbonylamino)-3-formyl-8-oxo-l- aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate 3 (200 mg, 546 mmol) and triphenylpyridin- 4-ylmethylphosphonium bromide (300 mg, 600 mmol) in anhydrous DCM (30 mL). After 3 hrs, more K₂CO₃ (23 mg, 0.17 mmol) was added and stirring was continued for an additional 3 hrs. The mixture was partitioned between DCM (25 mL) and H₂O (10 mL). The organic phase was washed with H₂O (10 mL), before being dried over MgSO₄. Filtration, solvent evaporation, and purification by RP-HPLC gave 90 mg of (6i?,75',Z)-ter^-butyl-7-(ter?-butoxycarbonylamino)-3-(2-(4-methylthiazol-5-yl)vinyl)-8- oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate 4 as a white solid in 45% yield.

Example 38

(6/?,7,S^r,Z)-7-(2-(2-amino-5-(trifluoromethyl)thiazol-4-yl)-2-(hydroxyimino)acetamido)- 3-(2-((2-aminoethylthio)methyl)pyridin-3-ylthio)-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-

2-carboxylic acid

1

Step 1 : te/-r-butyl-2-((3-mercaptopyridin-2-yl)methylthio)ethylcarbamate was prepared from di-/erf-butyl-2,2'-(3,3'-disulfanediylbis(pyridine-3,2- diyl)bis(methylene))bis(sulfanediyl)bis(ethane-2,l-diyl)dicarbamate (100% yield) by following Method G. The slight yellow solution was used without further purification. Step 2: (6i?,75,Z)-benzhydryl-3-(2-((2-(/ert- butoxycarbonylamino)ethylthio)methyl)pyridin-3-ylthio)-8-oxo-7-(2-(5- (trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxyiate was prepared from fcrf-butyl-2-((3- mercaptopyridin-2-yl) methylthio)ethylcarbamate and (6i?,75,Z)-benzhydryl-8-oxo-7-(2- (5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-3-

(trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate in 30% yield by following Method G. The resulting white solid product was purified. Step 3 : (6i?,75,Z)-7-(2-(2-amino-5-(trifluoromethyl)thiazol-4-yl)-2- (hydroxyimino)acetamido)-3-(2-((2-aminoethylthio)methyl)pyridin-3-ylthio)-8-oxo-l- aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid 1 was from (6i?,75',Z)-benzhydryl-3-(2- ((2-(ter/-butoxycarbonylamino)ethylthio)methyl)pyridin-3-ylthio)-8-oxo-7-(2-(5- (trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)- 1 -aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate in 50% yield by following Method E. The resulting white solid product was purified by Prep-HPLC. ESI-MS: m/z 618 [M+H].

Example 39 (6i?,75,E)-7-(2-(2-amino-5-(trifluoromethyl)thiazol-4-yl)-2-(hydroxyimino)acetamido)- 3-(3-((2-aminoethylthio)methyl)pyridin-4-ylthio)-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-

2-carboxylic acid

Step 1 : (6R,7S,Z)-benzhydryl-3-(3-((2-(tert- butoxycarbonylamino)ethylthio)methyl)pyridin-4-ylthio)-8-oxo-7-(2-(5- (trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate was prepared from tert-butyl-2-((4- mercaptopyridin-3-yl)methylthio)ethylcarbamate and (6i?,7iS,Z)-benzhydryl-8-oxo-7-(2- (5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-3-

(trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate in 30% yield by following Method G. The resulting white solid product was purified.

Step 2: (6i?,75,_Jfc)-7-(2-(2-amino-5-(trifluoromethyI)thiazol-4-yi)-2- (hydroxyimino)acetamido)-3-(3-((2-aminoethylthio)methyl)pyridin-4-ylthio)-8-oxo-l- aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid 1 was from (6i?,75,Z)-benzhydryl-3-(3- ((2-(ter^-butoxycarbonylamino)ethylthio)methyl)pyridin-4-ylthio)-8-oxo-7-(2-(5- (trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate in 50% yield by following Method E. The resulting white solid product was purified by Prep-HPLC. ESI-MS: m/z 618 [M+H].

Example 40

(6i?,75',Z)-3-(5-amino-l,3,4-thiadiazol-2-ylthio)-7-(2-(2-amino-5-

(trifluoromethyl)thiazol-4-yl)-2-(hydroxyimino)acetamido)-8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid

1 Step 1 : (6i?,75,E)-8-oxo-7-(2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-

4-yl)-2-(trityloxyimino)acetamido)-3 -(trifluoromethylsulfonyloxy)- 1 -aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid was prepared from (Z)-5-benzo[d]thiazol-2- yl-2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)ethanethioate and (6i?,75)-7-amino-8-oxo-3-(trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2- ene-2-carboxylic acid in 100% yield by following Method B. The resulting white solid product was used without further purification.

Step 2: (6^,75,Z)-benzhydryl-8-oxo-7-(2-(5-(trifluoromethyl)-2- (tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-3-(trifluoromethylsulfonyloxy)- l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate was prepared from (6R,7S,E)-8-oxo-7-(2- (5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-3-

(trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid in 100% yield by following Method C. The resulting white solid product was used without further purification.

Step 3: (6i?,75',Z)-benzhydryl-3-(5-amino-l,3,4-thiadiazol-2-ylthio)-8- oxo-7-(2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)- l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate was prepared from (όi^^^Zj-benzhydryl- 8-oxo-7-(2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2- (trityloxyimino)acetamido)-3-(trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2- ene-2-carboxylate and 5-amino-l,3,4-thiadiazole-2-thiol in 61% yield by following Method D. The resulting white solid product was purified by column chromatography (PE:EA = 2: l as fluent). Step 4: (6i?,7S,Z)-3-(5-amino-l,3,4-thiadiazol-2-ylthio)-7-(2-(2-amino-5-

(trifluoromethyl)thiazol-4-yl)-2-(hydroxyimino)acetamido)-8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid 1 was prepared from (6i?,75,Z)-benzhydryl-3- (5-amino-l,3,4-thiadiazol-2-ylthio)-8-oxo-7-(2-(5-(trifluoromethyl)-2- (tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-l-aza-bicyclo[4.2.0]oct-2-ene- 2-carboxylate in 33% yield by following Method E. ESI-MS: m/z 551 [M+H].

Example 41 (6i?,75,Z)-7-(2-(2-amino-5-(trifluoromethyl)thiazol-4-yl)-2-(hydroxyimino)acetamido)-

8-oxo-3-(pyridin-4-ylthio)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid

1

Step 1 : (67?,75,Z)-benzhydryl-8-oxo-3-(pyridin-4-ylthio)-7-(2-(5- (trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate was prepared from (6./?,7.S',Z)-benzhydryl-8-oxo- 7-(2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-3- (trifluoromethylsulfonyloxy)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate as a slight yellow solid by following Method D. The resulting product was purified by column chromatography (eluting solvent: PE:EA = 4:1) in 80% yield.

Step 2: (6i?,75^r,Z)-7-(2-(2-amino-5-(trifluoromethyl)thiazol-4-yl)-2- (hydroxyimino)acetamido)-8-oxo-3-(pyridin-4-ylthio)-l-aza-bicyclo[4.2.0]oct-2-ene-2- carboxylic acid 1 was prepared from (6i?,75,Z)-benzhydryl 8-oxo-3-(pyridin-4-ylthio)-7- (2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate as a slight yellow solid in 63.5% yield by following Method E. ESI-MS: m/z 529 [M+H].

Example 42 (6i?,75,Z)-3-(l,3,4-thiadiazol-2-ylthio)-7-(2-(2-amino-5-(trifluoromethyl)thiazol-4-yl)- 2-(hydroxyimino)acetamido)-8-oxo-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid

1

Step 1 : (6i?,75,£)-benzhydryl-3-(l,3,4-thiadiazol-2-ylthio)-8-oxo-7-(2- (5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-l -aza- bicyclo[4.2.0]oct-2-ene-2-carboxylate was prepared from (ό^^^iTj-benzhydryl-S-oxo- 7-(2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)-2-(trityloxyimino)acetamido)-3- (trifluoromethylsulfonyloxy)-l -aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate and 1 ,3,4- thiadiazole-2-thiol in 53% yield by following Method D. The resulting white solid product was purified by gel column chromatography (PE:EA = 4:1 as fluent).

Step 2: (6i?,75,Z)-3-(l ,3,4-thiadiazol-2-ylthio)-7-(2-(2-amino-5- (trifluoromethyl)thiazol-4-yl)-2-(hydroxyimino)acetamido)-8-oxo-l-aza- bicyclo[4.2.0]oct-2-ene-2-carboxylic acid 1 was prepared from

(l,3,4-thiadiazol-2-ylthio)-8-oxo-7-(2-(5-(trifluoromethyl)-2-(tritylamino)thiazol-4-yl)- 2-(trityloxyimino)acetamido)-l-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate in 31% yield by following Method E. The resulting white solid product was purified by prep-HPLC. ESI-MS: m/z 536 [M+H].

Example 43 MIC Assay Protocol It is well-established that the effectiveness of β-lactam antibiotics is correlated to the amount of time that the concentration of free (unbound) drug exceeds the MIC. A serum protein binding value of >97% is considered too high for a sufficient free drug concentration to be established in a patient using any practical dosing regime. Furthermore, a compound displaying human serum binding of 70% has ten times the amount of free drug as a compound with 97% serum binding (30% vs 3%).

It will be appreciated that, in any given series of compounds, a spectrum of biological activity will be observed. In its most preferred embodiment, a compound of this invention will demonstrate activity superior to vancomycin or cefotaxime against bacterial infections resistant to conventional β-lactam antibiotics such as methicillin and ampicillin. The following procedures may, without limitation, be used to evaluate the compounds of this invention.

The in vitro MIC for bacterial isolates may be obtained in the following manner: a test compound is incorporated into a series of two-fold dilutions in cation adjusted Mueller-Hinton broth (CAMHB). Different bacterial strains diluted to provide a uniform inoculum are added to the CAMHB containing test compounds. A well without test compound is included for each strain as a growth control. The MIC is defined as the concentration of compound that completely inhibits growth as observed by the naked eye. The procedures used in these experiments are generally those standardized by the Clinical and Laboratory Standards Institute (CLSI), as set forth in the CLSI publication entitled "M7-A7. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard-seventh edition." (2006), which is incorporated by reference as if fully set forth herein. The following exemplifies such a procedure although it is to be understood that modifications of the procedure may be implemented as required.

Two-fold dilutions of the test compounds are prepared in CAMHB at 2x the concentration range to be tested if the compounds are soluble in aqueous solution. Alternately, dimethylsulfoxide (DMSO) is used to prepare two-fold dilutions at 1Ox the concentration range to be tested. Reference drugs such as cefotaxime, vancomycin or imipenem are used as positive controls. A few isolated colonies are retrieved from a pure culture prepared on an agar plate and suspended in PBS until the turbidity of the suspension matches a 0.5 McFarland standard which is equal to approximately 10 CFU/mL. This solution is further diluted in CAMHB to 10⁶CFU/mL if compounds are diluted in CAMHB and 5x10⁵ CFU/mL if compounds are diluted in DMSO. The CAMHB plates containing the compound dilutions are combined in equal volumes with the higher density inoculum, or 10 μL of the DMSO dilutions are added to the lower density inoculum. When S. aureus is the organism being tested and the compound is oxacillin, a beta-lactam or a carbacephem compound of the present invention, 2% NaCl is added to the growth media. The plates are then incubated for 16-20 hrs at 35⁰C. The plates are then observed to determine which concentration of the test compound is the MIC.

Data for certain representative compounds is shown in Table 2 below.

Table 2

* Key:

** MIC Key:

MICs of 1.0 μg/mL or less = A MICs of greater than 1.0 μg/mL to 8.0 μg/mL = B MICs of greater than 8.0 μg/mL = C *** Comparative Compounds:

Comparative Compound 1 is:

Ceftobiprole

Comparative Compound 2 is:

Example 44

Compounds that show superior activity in in vitro tests can then be further evaluated in animal models such as rats and mice. The following is an example of such a test, it being understood that the example is not to be construed as limiting the scope of this invention in any manner whatsoever.

Staphylococcus aureus strain Smith (ATCC 13709, penicillin- susceptible) or strain 76 (methicillin-resistant) is grown overnight at 37°C in brain-heart infusion broth (BHIB). The following morning, it is sub-cultured to fresh BHIB and incubated for 4-5 hrs at 37°C. The cells are harvested by centrifugation, washed twice with PBS, and adjusted to the desired inoculum. The cell suspension is then mixed with an equal volume of sterile 14% hog-gastric mucin (Comber K. R., et al., Antimicrobial Agents and Chemotherapy, 1995, 7(2): 179-185). The inoculum is kept in an ice bath until ready for use (preferable less than 1 hr).

Male Swiss-Webster mice are challenged intraperitoneally with 0.5 mL of the above bacterial suspension of S. aureus strain Smith (LD₅₀). Test compounds are administered subcutaneously in 0.1 mL volumes immediately after inoculation and again 2 hours later. The animals are then observed for 72 hrs. The total dose associated with 50% survival (ED₅₀) is then determined using the probit method (Pasiello, A. P., et al., J. Toxicol. Environ. Health, 1977, 3:797 809).

As noted previously, to be an effective anti-MRSA compound, a carbacephem must exhibit a proper balance of potency versus serum protein binding. The following procedure may be used to evaluate serum binding: compounds are incubated in serum for 10 min at 37°C in a shaking water bath. Then a serum ultrafiltrate is obtained by centrifugation of ultra-filtration units (Amicon Centrifree) for, say, 20 minutes at 25°C. Compound content in the ultrafiltrate is quantified by HPLC using standards prepared in blank ultra- filtrate undergoing similar processing.

The range of utility of the compounds herein can easily be established by those skilled in the art using the disclosures herein and all bacteria within the useful range are within the scope of this invention.

All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification are incorporated herein by reference in their entirety to the extent not inconsistent with the present description.

I l l From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A compound having the following structure (I):

(I) or a stereoisomer, pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

R¹ is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted heteroaryl, optionally substituted heteroarylalkyl and -CC=O)R^{1 a}, wherein:

R^la is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted cycloalkyl, optionally substituted cycloalkylalkyl, optionally substituted heterocyclyl, optionally substituted heterocyclylalkyl, optionally substituted heteroaryl and optionally substituted heteroarylalkyl;

X is selected from -O-, -S-, -C(=O)-, -SCH₂S-, -SCH₂-, -CH₂S-, - SCH=CH-, -CH=CHS-, -OCH₂-, -CH₂O-, optionally substituted alkylene, optionally substituted alkenylene and optionally substituted cycloalkyl;

Ar¹ is

wherein:

R³ is selected from chloro, bromo, fluoro, iodo, cyano, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, - SO₂R^3a, -SOR^3a, -SR^3a, -C(=O)R^3a, -C(=O)NR^3aR^3b, -NR^3aR^3b and -OR³\ wherein:

R^3a is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl; and

R³ is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyciyl, optionally substituted heteroaryl and an amino acid, or R^3a and R^3b, together with the N atom to which they are attached, form an optionally substituted heterocyclyl or an optionally substituted heteroaryl; R⁴ is selected from hydrogen, chloro, bromo, fluoro, iodo, cyano, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, - SO₂R^4a, -SOR^4a, -SR^4a, -C(=O)R^4a, -C(=O)NR^4aR^4b, -NR^4aR^4b and -OR^4a, wherein:

R ,4a^a is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl; and

2. A compound of claim 1 wherein R¹ is hydrogen.

3. A compound of claim 1 wherein R¹ is alkyl and is selected from methyl, ethyl, n-propyl, /so-propyl, n-butyl, tert-butyl, z^'sø-butyl and sec-butyl.

4. A compound of claim 1 wherein R¹ is substituted alkyl and is optionally substituted haloalkyl.

5. A compound of claim 4 wherein R¹ is selected from -CH₂CH₂Cl, -CH₂CH₂F, -CH₂CHF₂, -CH₂CF₃, -CHFCH₂F, -CHFCHF₂, -CHFCF₃, -CH₂F, -CHF₂, - CF₃ and -CH₂CH₂CH₂F.

6. A compound of claim 1 wherein R¹ is substituted alkyl and is optionally substituted alkoxyalkyl or optionally substituted hydroxyalkyl.

7. A compound of claim 6 wherein R¹ is -CH₂CH₂OH, CH₂CH₂OMe or -CH₂CH₂OCF₃.

8. A compound of claim 1 wherein R¹ is substituted alkyl and is CH₂CH₂SMe, -CH₂CH₂SO₂Me, -CH₂CH₂NMe₃, -CH₂CH₂NMe₂ or -CH₂CN.

9. A compound of claim 1 wherein R^! is alkenyl and is CH₂CH=CH₂.

10. A compound of claim 1 wherein R¹ is substituted alkenyl and is optionally substituted haloalkenyl.

11. A compound of claim 10 wherein R¹ is -CH₂CH=CCl₂ or -

CH₂CH=CF₂.

12. A compound of claim 1 wherein R¹ is cycloalkyl and is selected from cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, and cyclohexenyl.

13. A compound of any one of claims 1-12 wherein R 2 i •s hydrogen.

14. A compound of any one of claims 1-12 wherein R² is alkyl and is selected from methyl, ethyl, n-propyl, zso-propyl, rø-butyl, tert-butyl, zso-butyl and sec- butyl.

15. A compound of any one of claims 1-12 wherein:

R² is substituted alkyl and is selected from haloalkyl, - (CH₂)_nOR^2a, -(CH₂)_nN(R^2a)₂, -(CH₂)_nN(R^2a)₃, -(CH₂)_nSOR^2a, -(CH₂)_nSO₂R^2a and - (CH₂)_nCN; n is 1 or 2; and each R^2a is independently optionally substituted alkyl.

16. A compound of claim 15 wherein R² is selected from -CH₂F, - CH₂CN, -CH₂CH₂F, -CH₂CHF₂, -CH₂CF₃, -CH₂CH₂OCH₃, -CH₂CH₂OCF₃, - CH₂CH₂SO₂CH₃, -CH₂CH₂CN, -CH₂CH₂N(CH₃)₃ and -CH₂CH₂N(CH₃)₂.

17. A compound of any one of claims 1-12 wherein R² is cycloalkyl and is selected from cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

18. A compound of any one of claims 1-12 wherein R² is aryl and is phenyl.

19. A compound of any one of claims 1-12 wherein R² is substituted aryl and is substituted phenyl.

20. A compound of any one of claims 1-12 wherein R² is heteroaryl and is a 6-membered ring comprising at least one N atom.

21. A compound of any one of claims 1-20 wherein the compound is a pharmaceutically acceptable salt of structure (I) having the following structure (II): R¹

(H) wherein M is an alkali metal atom.

22. A compound of any one of claims 1-20 wherein the compound is a prodrug of structure (I) having the following structure (III):

(III) wherein R² and Y, taken together, are selected from:

23. A compound of any one of claims 1-20 wherein the compound is a prodrug of structure (I) having the following structure (III):

(III) wherein R and Y, taken together, are selected from:

wherein Y¹ is -CH₂-, -O-, -S-, -SO₂-, -NH-, -NCH₃-, -NCH₂CH₃-, -NCH₂CH₂CH₃- or -NCH₂CF₃-.

24. A compound of any one of claims 1-23 wherein X is -SCH₂- or -

CH₂S-.

25. A compound of any one of claims 1-23 wherein X is -SCH₂S-.

26. A compound of any one of claims 1-23 wherein X is -SCH=CH- or -CH=CHS-.

27. A compound of any one of claims 1-23 wherein X is -O-.

28. A compound of any one of claims 1-23 wherein X is -C(=O)-.

29. A compound of any one of claims 1-23 wherein X is -OCH₂- or - CH₂O-.

30. A compound of any one of claims 1-23 wherein X is alkylene.

31. A compound of claim 30 wherein X is -CH₂- or -CH₂CH₂-.

32. A compound of any one of claims 1-23 wherein X is substituted alkylene.

33. A compound of claim 32 wherein X is selected from -CHF-, - CF₂-, -CHCH₃- and -C(CH₃)₂-.

34. A compound of any one of claims 1-23 wherein X is alkenylene.

35. A compound of claim 34 wherein X is -CH=CH-.

36. A compound of any one of claims 1-23 wherein X is cycloalkyl.

37. A compound of claim 36 wherein X is cyclopropyl.

38. A compound of any one of claims 1-23 wherein X is -S-.

39. A compound of any one of claims 1-38 wherein Ar¹ is selected from:

40. A compound of any one of claims 1-38 wherein Ar¹ is selected from:

41. A compound of any one of claims 1-40 wherein R³ is -NHR^3aR^3b, R^3a is hydrogen and R^3b is an amino acid.

42. A compound of claim 41 wherein R^3b is glycine, alanine or valine.

43. A compound of any one of claims 1-40 wherein R³ is -OR^3a and R^3a is optionally substituted alkyl.

44. A compound of claim 43 wherein R^3a is -CH₃ or -CF₃.

45. A compound of any one of claims 1-40 wherein R³ is substituted alkyl and is optionally substituted haloalkyl.

46. A compound of claim 45 wherein R³ is -CF₃.

47. A compound of any one of claims 1-46 wherein R⁴ is -NHR^4aR^4b, R^4a is hydrogen and R^4b is an amino acid.

48. A compound of claim 47 wherein R^4b is glycine, alanine or valine.

49. A compound of any one of claims 1-46 wherein R⁴ is -OR^4a and

R^4a is optionally substituted alkyl.

50. A compound of claim 49 wherein R 4a^a is -CH₃ or -CF₃.

51. A compound of any one of claims 1-46 wherein R⁴ is substituted alkyl and is optionally substituted haloalkyl.

52. A compound of claim 51 wherein R⁴ is -CF₃.

53. A compound of any one of claims 1-52 wherein Ar 2 is

54. A compound of claim 53 wherein Ar² is selected from:

55. A compound of claim 54 wherein R⁵ is selected from hydrogen, chloro, fluoro, cyano, -CH₃, -CF₃, -SO₂CH₃, -SCH₃, -OCH₃, -OCF₃, -NH₂, -NHCH₃, - N(CH₃)₂, -NHCH₂CH₃, -N(CH₂CH₃)₂, -NHCH(CH₃)₂,

-H ,^NH ' -K ,^N- ' -i-N N-Λ ' -i-N N-

56. A compound of any one of claims 1-52 wherein Ar² is:

wherein: each Z is independently selected from -CR⁵-, -S-, -0-, -N-, -NR⁶- such that the resulting ring is aromatic,

57. A compound of claim 56 wherein Ar² is selected from:

58. A compound of claim 57 wherein R⁵ is selected from hydrogen, chloro, fluoro, cyano, -CH₃, -CF₃, -SO₂CH₃, -SCH₃, -OCH₃, -OCF₃, -NH₂, -NHCH₃, - N(CH₃)₂, -NHCH₂CH₃, -N(CH₂CH₃)₂, -NHCH(CH₃)₂,

V_{N I} \ , -I-N \ , -i-N o , J-N s , -i-N sf°

-N NH , -|-N N- , .|__N/ ^ , J__N/ ^

59. A pharmaceutical composition comprising a compound of any one of claims 1-58, or a stereoisomer, pharmaceutically acceptable salt or prodrug thereof, and a pharmaceutically acceptable carrier, diluent or excipient.

60. A method of treating a bacterial infection in a mammal in need thereof, comprising administering to the mammal an effective amount of a compound of any one of claims 1-58 or a composition of claim 59.

61. The method of claim 60 wherein the bacterial infection is caused by a β-lactam antibiotic-resistant bacterium.

62. The method of claim 61 wherein the β-lactam antibiotic-resistant bacterium is a methicillin-resistant genus Staphylococcus bacterium.