WO2018175954A1

WO2018175954A1 - Synthesis of imidazo[5,1-a]isoindole derivative useful as ido inhibitors

Info

Publication number: WO2018175954A1
Application number: PCT/US2018/024127
Authority: WO
Inventors: Remy Angelaud; Stephan Bachmann; Andreas BEYELER; Diane CARRERA; Rolf Fischer; Maud GUILLEMONT-PLASS; Haiyun HOU; Hans Iding; Anne Katrin KRAFT; Andreas Manns; Roland Meier; Karin Monika NIEDERMANN; Martin OLBRICH; Katarzyna PIECHOWICZ; Pankaj Rege; Travis Paul Remarchuk; Lauren SIROIS; Frederic St-Jean; Jie Xu
Original assignee: F Hoffmann La Roche AG; Genentech Inc; Hoffmann La Roche Inc
Current assignee: F Hoffmann La Roche AG; Genentech Inc; Hoffmann La Roche Inc
Priority date: 2017-03-23
Filing date: 2018-03-23
Publication date: 2018-09-27
Anticipated expiration: 2019-09-23

Abstract

Presently provided is a method of making a compound of the Formula (I) wherein X is halogen, which is useful for modulating the activity of indoleamine 2,3-dioxygenase (IDO) and treating diseases and conditions in which the inhibition of IDO mediated immunosuppression is beneficial.

Description

SYNTHESIS OF IMIDAZO[5,1 -A]ISOINDOLE DERIVATIVE USEFUL AS IDO INHIBITORS

BACKGROUND OF THE INVENTION Field of the Invention

[0001] The present disclosure relates to the synthesis of compounds for inhibition of indoleamine 2,3-dioxygenase.

Summary of the Related Art

[0002] Tryptophan (Trp) is an essential amino acid required for the biosynthesis of proteins, niacin and the neurotransmitter 5-hydroxytryptamine (serotonin). The enzyme indoleamine 2,3-dioxygenase (also known as INDO or IDO) catalyzes the first and rate limiting step in the degradation of L-tryptophan to N-formyl-kynurenine. In human cells, IFN-y stimulation induces activation of IDO, which leads to a depletion of Trp, thereby arresting the growth of Trp-dependent intracellular pathogens such as Toxoplasma gondii and Chlamydia trachomatis. IDO activity also has an antiproliferative effect on many tumor cells, and IDO induction has been observed in vivo during rejection of allogeneic tumors, indicating a possible role for this enzyme in the tumor rejection process.

[0003] Several lines of evidence suggest that IDO is involved in induction of immune tolerance. Studies of mammalian pregnancy, tumor resistance, chronic infections and autoimmune diseases have shown that cells expressing IDO can suppress T-cell responses and promote tolerance. Accelerated Trp catabolism has been observed in diseases and disorders associated with cellular immune activation, such as infection, malignancy, autoimmune diseases and AIDS, as well as during pregnancy. It was proposed that IDO is induced chronically by HIV infection, and is further increased by opportunistic infections, and that the chronic loss of Trp initiates mechanisms responsible for cachexia, dementia and diarrhea and possibly immunosuppression of AIDS patients (Brown, et al, 1991, Adv. Exp. Med. Biol., 294: 425-35). To this end, it has recently been shown that IDO inhibition can enhance the levels of virus-specific T cells and, concomitantly, reduce the number of virally infected macrophages in a mouse model of HIV (Portula et al, 2005, Blood, 106:2382-90).

[0004] Small molecule inhibitors of IDO are being developed to treat or prevent

IDO-related diseases such as those described above. For example, PCT Publication WO 99/29310 reports methods for altering T cell-mediated immunity comprising altering local extracellular concentrations of tryptophan and tryptophan metabolites, using an inhibitor of IDO such as 1-m ethyl -DL-tryptophan, p-(3-benzofuranyl)-DL-alanine, p-[3-benzo(b)thienyl]-DL-alanine, and 6-nitro-L-tryptophan) (Munn, 1999). Reported in WO 03/087347, also published as European Patent 1501918, are methods of making

antigen-presenting cells for enhancing or reducing T cell tolerance (Munn, 2003).

Compounds having indoleamine-2,3-dioxygenase (IDO) inhibitory activity are further reported in WO 2004/094409; and U.S. Patent Application Publication No. 2004/0234623 is directed to methods of treating a subject with a cancer or an infection by the administration of an inhibitor of indoleamine-2,3-dioxygenase in combination with other therapeutic modalities.

[0005] In light of the experimental data indicating a role for IDO in immunosuppression, tumor resistance and/or rejection, chronic infections, HIV-infection, AIDS (including its manifestations such as cachexia, dementia and diarrhea), autoimmune diseases or disorders (such as rheumatoid arthritis), and immunologic tolerance and prevention of fetal rejection in utero, therapeutic agents aimed at suppression of tryptophan degradation by inhibiting IDO activity are desirable. Inhibitors of IDO can be used to activate T cells and therefore enhance T cell activation when the T cells are suppressed by pregnancy, malignancy or a virus such as HIV. Inhibition of IDO may also be an important treatment strategy for patients with neurological or neuropsychiatric diseases or disorders such as depression.

SUMMARY OF THE INVENTION

[0006] We recognized that in light of the experimental data indicating a role for IDO in the indications described above, therapeutic agents aimed at suppression of tryptophan degradation by inhibiting IDO are desirable. The methods herein help meet the current need for IDO modulators.

[0007] In this disclosure, we describe novel methods for the synthesis of compounds that are inhibitors of indoleamine 2,3-dioxygenase.

[0008] In one aspect, the invention provides a method for making a compound of the Formula (I)

(I) wherein X is halogen, the method includes converting a compound of Formula (IX)

(IX)

to a compound of Formula (I).

In embodiment Ii, the method involves

(a) oxidizing a compound of Formula (II),

(Π)

wherein PG is a hydroxyl protecting group, to provide a compound of Formula

(in);

(III)

reducing the ketone of a compound of Formula (III) to provide a compound of Formula (IV),

(IV)

and

(c) reducing the alkene and deprotecting the 4'-hydroxy group of the compound of Formula (IV) to provide a compound of Formula (I).

[0010] In embodiment I₂, converting the compound of Formula (IX) to the compound of Formula (I) involves

(a) reducing the carbonyl in the compound of Formula (IX) to provide a mixture of a compound of Formula (I) and a compound of Formula (Γ);

(I) ( )

and

(b) converting the mixture of a compound of Formula (I) and a compound of

Formula (Γ) to the compound of Formula (I).

[0011] In embodiment I₃, converting the compound of Formula (IX) to the compound of Formula (I) includes

(a) converting a compound of Formula (IX) to a compound of Formula (IXa);

(IXa)

and

(b) converting a compound of Formula (IXa) to a compound of Formula (I).

[0012] All patents and publications cited in this disclosure are area incorporated by reference in their entirety to the extent consistent with the teachings herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 shows the Di-silyl sequence. Two silyl protecting groups are introduced sequentially. Compounds in square brackets are not isolated.

[0014] Figure 2 shows the Direct sequence. Only one silyl protecting group is introduced. No additional protecting group is employed in position 1.

[0015] Figure 3 shows the Mono-silyl sequence. A second TBS-group is introduced in position 1, followed by the removal of the TBS-group at position 4'. Compounds in square brackets are not isolated.

[0016] Figure 4 shows the synthesis of a compound of Formula (I) according to an example embodiment.

[0017] Figure 5 shows the synthesis of a compound of Formula (I) according to an example embodiment.

[0018] Figure 6 shows the synthesis of a compound of Formula (I) according to an example embodiment.

[0019] Figure 7 shows the synthesis of a compound of Formula (I) according to an example embodiment.

[0020] Figure 8 shows the synthesis of a compound of Formula (I) according to an example embodiment.

[0021] Figure 9 shows the synthesis of a compound of Formula (I) according to an example embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] As used herein, "convert" or "converting" means performing a single or multi-step process to transform a first molecule into a second. The step or steps of the process may include, e.g., chemical reactions, purifications, crystallizations, or any other techniques known to one of skill in the art.

[0023] PG may be any suitable hydroxyl protecting group. For example, the hydroxyl can be protected with a TBS group. Other exemplary protecting groups include, without limitation, alkyl ethers, such as methyl, trityl, triphenylmethyl, methoxymethyl, benzyl, p- methoxybenzyl, tetrahydropyranyl (THP); silyl ethers, such as triethylsilyl (TES), tnisopropylsilyl (TIPS), t-Butyldimethylsilyl (TBS) or t-Butyldiphenylsilyl (TBDPS); or esters, such as trifluoroacetyl (TFA), acetyl (Ac), trimethylacetyl (Piv) or benzoyl (Bz). Protecting groups may be selected from suitable protecting groups known in the art, such as those described in "Greene's protective groups in organic synthesis" Wiley-Interscience, New Jersey 2007, 4^th Edition, 189-196.

[0024] In one aspect, the invention presents a method for making a compound of the Formula (I)

(I)

wherein X is halogen. The method may include converting a compound of Formula (IX)

(IX)

to a compound of Formula (I). [0025] In embodiment Ii, the invention provides a method for making a compound of the Formula (I), wherein the method involves

(a) oxidizing a compound of Formula (II),

(Π)

wherein PG is a hydroxyl protecting group, to provide a compound of Formula (ΠΙ),

(III)

(b) reducing the ketone of a compound of Formula (III) to provide a compound of Formula (IV),

(IV)

and

[0026] The synthesis of a compound of Formula (I) through a compound of Formula (IV) is depicted in each of Figures 1 -3. The compound of Formula (IV) can be a common intermediate in the di-silyl sequence (Figure 1), direct sequence (Figure 2) and the mono-silyl sequence (Figure 3). In some embodiments, the formation of the compound of Formula (IV) is the same in each sequence.

Step 1.1 Protection of the 4'-Hydroxy Group

[0027] As shown in Figure 1, the compound of Formula (II) can be provided by protecting the 4'-hydroxy group of the corresponding unprotected compound. For example, the 4'-Hydroxy-ketone can be protected with a TBS group. The synthetic procedure can be carried out with other protecting groups and in a manner known in the art, such as described in "Greene's protective groups in organic synthesis" Wiley-Interscience, New Jersey 2007, 4^th Edition. 189-196. For example, the protecting group may be an alkyl ether, such as methyl, trityl, triphenylmethyl, methoxymethyl, benzyl, p-methoxybenzyl, tetrahydropyranyl (TUP); a silyl ether, such as triethylsilyl (TES), triisopropyl silyl (TIPS), t-Butyldimethylsilyl (TBS) or t-Butyldiphenylsilyl (TBDPS); or an ester, such as trifluoroacetyl (TFA), acetyl (Ac), trimethylacetyl (Piv) or benzoyl (Bz).

Step 2.1 De-hydrogenation

[0028] As shown in Figure 1, the double bond of the compound of Formula (III) is installed in a de-hydrogenation reaction (i.e., an oxidation reaction). For example, oxidizing the compound of Formula (II) may comprise contacting the compound of Formula (II) with an oxidizing composition comprising a periodate. The oxidizing composition may also comprise LiBr, NaBr, or I. The components of the oxidizing composition may be mixed before addition to the reaction mixture or added sequentially. In one embodiment, the oxidizing composition comprises sodium periodate and iodine in acetic acid. In some embodiments, lithium bromide is added to the reaction or to the oxidizing composition. For example, the ratio of NaI0₄/LiBr may be 0.3/0.6 to 1.1/0.005 molar equivalents of the compound of Formula (II), preferably 0.4/0.05 equivalents of the compound of Formula (II). The solvent of the oxidation may also include a mixture of AcOH with other solvents (e.g., 2- MeTHF or ACN), and the oxidation may be performed at a temperature of 20-80 °C, preferably 50-60 °C. A halogenation/elimination sequence may also be used to provide the compound of Formula (III). Oxidation can be accomplished with other oxidizing groups according to known procedures. Step 3.1 Asymmetric Ketone Hydrogenation

[0029] As shown in Figure 1, the compound of Formula (rV) can be provided by reducing the ketone of a compound of Formula (III). For example, reducing the ketone of a compound of Formula (III) comprises contacting the ketone with a Ruthenium catalyst in an atmosphere of hydrogen. The Ruthenium catalyst can be a Ruthenabicyclic complex with chiral diphosphine of type [Ru(daipena)(diphosphine)X] of the formula

wherein, daipena = anion of DAIPEN at the 2-position of an anisyl group, X = anionic ligand, e.g., CI^", Br^", Γ, CH₃SO₃ ^", CF₃CO₂ ^", TfO^", diphosphine = atropisomeric biarylphosphines (e.g., SEGPHOS, BINAP, and MeOBIPHEP); R^N1, R^N2, R^N3, and R^N4 are each independently a hydrogen atom, an optionally substituted C1-C20 alkyl group, an optionally substituted C2- C20 alkenyl group, an optionally substituted C7-C20 alkylaryl group, or an optionally

o_{f R}Nl-N4

substituted C3-C8 cycloalkyl group, provided that at least one is a hydrogen atom;

R^a, and R are each independently a hydrogen atom, an optionally substituted C1-C20 alkyl group, an optionally substituted C2-C20 alkenyl group, an optionally substituted C3-C8 cycloalkyl group, an optionally substituted C7-C20 alkylaryl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group, or R^a, R and R^c combine to form

AT

an alkylene group or an alkylenedioxy group;, n is an integer of 0 to 3; and R is a methoxy group. In one embodiment, the compound is

The complexes may be in part commercially available or prepared in analogy to literature from [Ru(p-cym)Cl₂]₂ (K. Matsumura, N. Arai, K. Hon, T. Saito, N. Sayo, T. Ohkuma, J. Am. Chem. Soc. 2011, J 33, 10696-10699; H. Nara, T. Yokozawa, US9079931B2 July 14, 2015 to Takasago Int. Corp.).

[0030] For example, the Ruthenium catalyst may contain a chiral diphosphine of the formula

R³

wherein

R¹ is lower-alkyl, lower-alkoxy, hydroxy or lower-alkyl-C(0)0-;

R² and R³ are each independently hydrogen, lower-alkyl, lower-alkoxy or di(lower- alkyl)amino; or

R¹ and R² which are attached to the same phenyl group, or R² and R³ which are

attached to the same phenyl group taken together are -X-(CH₂)_r-Y-, wherein X is - O- or -C(0)0-, Y is -O- or -N(lower-alkyl)- and r is an integer from 1 to 6, or a CF₂ group,

or both R¹, taken together, are -0-(CH₂)_r-0- or 0-CH(CH₃)-(CH₂)_r-CH(CH₃)-0-, wherein r is an integer from 1 to 6, or

R¹ and R², or R² and R³, together with the carbon atoms to which they are attached, form a naphthyl, tetrahydronaphthyl or dibenzofuran ring;

R⁴ and R⁵ are each independently lower alkyl, cycloalkyl, phenyl, naphthyl or

heteroaryl, substituted with 0 to 7 substituents independently selected from the group consisting of lower-alkyl, lower-alkoxy, di(lower-alkyl)amino, morpholino, phenyl and tri(lower-alkyl)silyl, carboxy, lower-alkoxycarbonyl;

provided that when R⁴ is phenyl, it is substituted with 0 to 5, preferably 0 to 3 substituents as described above.

[0031] For example, the chiral diphosphine in the ruthenium complex may be BINAP, MeOBIPHEP or SegPhos. [0032] In other embodiments, a more highly active catalyst (e.g., the triflate) can be formed in situ by treatment of the chloro ruthenium complex with sodium triflate

immediately before use.

[0033] The desired configuration of the product at the CH(OH) chiral in position 1 center is (S). Obtaining the (S) configuration of the product at the CH(OH) chiral center at position 1 is achieved by using catalyst containing the (R) configuration at the phosphine ligand (Rp). In contrast, the configuration of the diamine ligand can be (R) or (S) ((RN) or (S_N)). The experiments conducted with catalysts of the opposite configuration at the phosphine ligand afforded the (R)-product.

[0034] In some embodiments, the solvent in the ketone reduction may be methanol, ethanol, 2-propanol, dichloromethane, THF, ethyl acetate, toluene or a combination thereof. In some embodiments, the solvent is a 2-propanol/dichlorom ethane mixture.

[0035] In some embodiments, the base in the ketone reduction may be KOtBu, DBU (K. Matsumura, N. Arai, K. Hori, T. Saito, N. Sayo, T. Ohkuma, J. Am. Chem. Soc. 2011, 133, 10696-10699), KOtBu, LiOH, triethylamine, DBU (H. Nara, T. Yokozawa, US9079931B2 July 14, 2015 to Takasago Int. Corp), Cs₂C0₃, K₂C0₃, K₃P0₄, TMG, N- Ethyldiisopropylamine, Dicyclohexylamine, DABCO, DBN. The amount of cisltrans isomerization on the cyclohexyl ring may depend on the base used. In specific examples, the base is Cs₂C0₃, K₂C0₃ or TMG.

[0036] The amount of base added can vary between 0.0005 and 5.0 molar equivalents to substrate. The amount can be adjusted depending on the base type and the substrate quality. In some examples, the molar equivalents of base to substrate is 0.005-0.5.

[0037] In some embodiments, the enantiomeric ratio (e.r.) of the product of the ketone reduction is greater or equal to 97.5:2.5. In other embodiments, the e.r. is greater than or equal to 99.5:0.5.

[0038] In some embodiments, the compound of Formula (IV) is crystallized to provide a compound of Formula (IV) in greater than 90: 10, 95:5, 96:4, 97:3, 98:2, or 99: 1 enantiomeric ratio (e.r.) before reducing the alkene and deprotecting the 4'-hydroxy group of the compound of Formula (IV) to provide a compound of Formula (I).

[0039] The asymmetric ketone reduction can be accomplished under other conditions according to known procedures. Di-silyl Sequence

[0040] In some embodiments, reducing the alkene and deprotecting the 4'-hydroxy group of the compound of Formula (IV) is conducted by

(cla) protecting the 1 -hydroxy group of the compound of Formula (IV) to provide a compound of Formula (IVa),

(IVa)

and

(clb) reducing the alkene of the compound of Formula (IVa) and deprotecting the 1- hydroxy and 4'-hydroxy groups to provide a compound of Formula (I).

Step 4.1 Protection of Intermediate 4'-TBS-En-ol in Position 1

[0041] In some embodiments, the product of the asymmetric hydrogenation may be protected with one of following groups: TBS ("Greene's protective groups in organic synthesis" Wiley-Interscience, New Jersey 2007, 4^th Edition. 189-196) (see Example 4), TES ("Greene's protective groups in organic synthesis" Wiley-Interscience, New Jersey 2007, 4^th Edition. 178-180) (see Example 5), Piv ("Greene's protective groups in organic synthesis" Wiley-Interscience, New Jersey 2007, 4^th Edition. 250-252) (see Example 6), Ac ("Greene's protective groups in organic synthesis" Wiley-Interscience, New Jersey 2007, 4^th Edition. 223-224) (see Example 7). The synthetic procedure can be carried out in analogy to typical literature procedures.

Step 5a.l Diastereoselective Reduction of Alkene

[0042] The exocyclic double bond can be reduced selectively if the allylic hydroxy function in position 1 is protected with a sterically demanding protecting group (e.g., acetyl, pivaloyl, triethylsilyl, tert-butyldimethylsilyl).

[0043] The catalyst used in the heterogeneous hydrogenation of the alkene can be Pd, Pt, Rh or Ni. In some embodiments, the catalyst is Pd or Pt, while in other embodiment, the catalyst is Pd. [0044] The solvent used in the heterogeneous hydrogenation of the alkene can be cpme, tbme, iPrOAc, EtOAc, MeOH, iPrOH, THF, 2-MeTHF. In some embodiments, the solvent is cpme.

[0045] The temperature of the heterogeneous hydrogenation of the alkene can be about 25 to about 40 °C, at a hydrogen pressure of about 1 to about 50 bar.

[0046] The addition of a base may improve the diastereo selectivity of the heterogeneous reduction of the alkene. The base may be 2,6-lutidine, 3,5-lutidine, 1,8- diazabicyclo[5.4.0]undec-7-ene, pyridine, imidazole, triethylamine, tetramethylguanidine, diisopropylethylamine, diisopropylamine, dicylohexylmethylamine, aniline, benzylamine, l,4-diazobicyclo[2.2.2]octane, ammonia. In some embodiments, the base is selected from 2,6-lutidine, pyridine and l,8-diazabicyclo[5.4.0]undec-7-ene. (see Example Het3.01-3.03).

Step 5b.l Deprotection of DiTBS- API

[0047] The deprotection of DiTBS- API may be performed in analogy to classic methods. ("Greene's protective groups in organic synthesis" Wiley-Interscience, New Jersey 2007, 4^th Edition. 196-206). In some embodiments, the conditions may be selected from (a) T=60 °C, 2h THF/H₂0: HC1, (b) AcOH, (c) HBF₄-Et₂0, (d) ^TsOH, (e) CH₃S0₂OH, (f) CF₃S0₂OH, (g) H₃P0₄, (h) NaI0₄, (i) LiBF₄ and (j) BF₃-Et₂0. In certain embodiments, the deprotection conditions may be selected from (a) T=60 °C, 2h THF/H₂0: HC1, (b) pTsOU and (c)

CF₃S0₂OH. In other embodiments, the deprotection conditions may include 1-5 NHC1 aq.

Step 6.1 Salt Formation

[0048] In some embodiments, the exocyclic double bond is reduced in step 5a.1 with a diastereomeric ratio (d.r.) of greater than or equal to 93 :7. Finally, during the final API salt formation, d.r. enrichment may be achieved by crystallization.

Direct Sequence

[0049] In some embodiments, reducing the alkene and deprotecting the 4'-hydroxy group of the compound of Formula (rV) are performed simultaneously to provide a compound of Formula (I).

Step 4.2 Diastereoselective Reduction of Alkene

[0050] Reducing the alkene of the compound of Formula (VI) may include contacting the alkene with a catalyst in an atmosphere of hydrogen. Under comparable conditions as in step 5a. l 4 -TBS-En-ol is reduced to API as a mixture of the desired (1R,5 ^"S) and the undesired (1R,5^"R) diastereomer in a ratio of 1 :2. This unfavorable ratio can be reversed and the desired diastereoisomer formed as major product (in a ratio up to 84: 16) if acids are added to the heterogeneous hydrogenation or the reaction is run in acetic acid as solvent, (see Example Het4.01-Het4.05)

[0051] The catalyst used in the heterogeneous reduction of the alkene can be Pd, Pt, Rh, Ni or Co. In some embodiments, the catalyst is Pd or Pt, while in other embodiment, the catalyst is Pd.

[0052] The solvent used in the heterogeneous reduction of the alkene can be i-PrOAc, iPrOH, 2-MeTHF, methanol, AcOH, ethanol, methanol/H₂0 or MeOH.

[0053] The temperature of the heterogeneous reduction of the alkene can be about 25 to about 80 °C. In some embodiments, the temperature of the heterogeneous reduction of the alkene can be about 25 to about 40 °C.

[0054] The pressure of the heterogeneous reduction of the alkene can be about 2 to about 250 bar. In some embodiments, the pressure of the heterogeneous reduction of the alkene can be about 80 to about 120 bar.

[0055] The acid used in the heterogeneous reduction of the alkene can be AcOH, phosphoric acid, ascorbic acid, citric acid, tartaric acid, camphor- 10-sulfonic acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, p- toluenesulfonic acid. In some embodiments, the acid used in the heterogeneous reduction of the alkene is methanesulfonic acid.

[0056] In some embodiments, depending on the acid used, the protecting group stays intact or is (partially) cleaved during the reaction. In some embodiments, using

methansulfonic acid provides the best di stereo selctivity and the TBS-group is completely removed. Thus, an additional deprotection step is not necessary.

Step 5.2 Free Basing

[0057] Free base API can be obtained by the addition of aqueous sodium hydroxide to the mesylate salt (or alternatively aqueous ammonium hydroxide could also been used). See Example 13.

Mono-silyl Sequence

[0058] In other embodiments, reducing the alkene and deprotecting the 4'-hydroxy group of the compound of Formula (rV) is conducted by

(c2a) protecting the 1 -hydroxy group of the compound of Formula (IV) and

deprotecting the 4'-hydroxyl group of the compound of Formula (rV) to provide a compound of Formula (IVb),

(IVb)

(c2b) reducing the alkene of the compound of Formula (IVb) to provide a compound of Formula (IVb),

(IVb)

and

(c2c) deprotecting the 1 -hydroxy group of a compound of Formula (IVb) to provide a compound of Formula (I).

Step 4b.3 Mono Deprotection in Position 4' of Intermediate DiTBS-En-ol

[0059] In some embodiments, DiTBS-En-ol is not isolated, but in a one-pot procedure is converted to intermediate 1-TBS-En-ol by the addition of phosphoric acid.

Step 5.3 Diastereoselective Reduction of Alkene

[0060] The solvent used can be cpme, 2-MeTHF, iPrOAc, MeOH, iPrOH, 1-propanol. In some embodiments, the solvent is MeOH.

[0061] The heterogeneous reduction of the alkene may also include a base. The base can be DBU, 2,6-lutidine or triethylamine.

[0062] In some embodiments, the heterogeneous reduction of the alkene is performed at about 40 °C. Step 6.3 TBS-Deprotection

[0063] In some embodiments, TBS-deprotection of the 4' position in MeOH with methanesulfonic acid and d.r. enrichment through crystallization of the mesylate salt can be performed (see Example 12).

[0064] The method may further include crystallizing the compound of Formula (I) from a solution to provide a crystalline salt of a compound of Formula (I). The crystalline salt may be formed from any pharmaceutically acceptable salt known in the art. For example, the crystalline salt of Formula (I) may be a phosphoric acid salt or a methanesulfonic acid salt.

[0065] The method may further include forming a free base of the compound of Formula (I). This method may include contacting the crystalline salt of a compound of Formula (I) with a base in solution to provide a free base of a compound of Formula (I).

[0066] In some embodiments, the compound of Formula (I) is isolated as a mixture of diastereomers in a ratio of 90: 10 or greater.

[0067] In some embodiments, the compound of Formula (I) is isolated in an overall yield of 30 % or greater.

[0068] In some embodiments, the compound of Formula (I) has a purity of 90 % or greater.

[0069] In some embodiments, the compound of Formula (I) has a purity of 91 % or greater, 92 % or greater, 93 % or greater, 94 % or greater, 95 % or greater, 96 % or greater, 97 % or greater, 98 % or greater or 99 % or greater.

[0070] In all formulae described herein PG is a protecting group that remains intact during the manipulation of the chemical structure, and is easily removed without significantly affecting the other functional groups of the molecule. In some examples PG is acetyl, pivaloyl or a silyl protecting group. For example, PG can be triethylsilyl or a tert- butydimethylsilyl.

[0071] In embodiment I₂, converting the compound of Formula (IX) to the compound of Formula (I) may involve

(I) ( )

and

(b) converting the mixture of a compound of Formula (I) and a compound of

Formula (Γ) to the compound of Formula (I).

[0072] In some embodiments, the reducing agent used to reduce the carbonyl in the compound of Formula (IX) to provide a mixture of a compound of Formula (I) and a compound of Formula (Γ) may be any boron or aluminum reducing agent known in the art, such as NaBH₄, BH₃, Li A1H₄, RedAl, LiAlH(OtBu)₃, selectride, as well as any other suitable reducing agent known in the art. In some embodiments, LiAlH(OtBu)₃ may be used, and may result in diastereoselectivities of >97%.

[0073] In embodiments where a boron reducing agent is used, the solvent may be MeOH, EtOH, i-PrOH, n-PrOH, THF, 2-Me-THF, DCM, TBME, CPME, dioxane, toluene or mixtures thereof. In embodiments where an aluminum reducing agent is used, the solvent may be THF, 2-Me-THF, CPME, TBME, dioxane, DCM, toluene or mixtures thereof. In some embodiments, a mixture of THF/2-Me-THF may be used, and may improve the diastereoselectivity of the reaction. For example, a reduction in THF may provide a diastereoselectivity of 94-95%, where a reduction performed in THF/2-Me-THF may provide a diastereoselectivity of >97%.

[0074] The stoichiometry of the reducing agent may range from about 0.3-5 equiv. for boron reducing reagents, and about 1.0-5.0 equiv. for aluminum reducing reagents. In some embodiments, about 0.3-1 equiv. of boron reducing reagent may be used. In other embodiments, about 1.0-1.3 equiv. or about 1.1 equiv. of aluminum reducing may be used.

[0075] The temperature of the reduction may range from about -30 °C to about 50 °C. In some embodiments, the temperature may range from about -15 °C to about 25 °C, or from about -15 °C to about 0 °C.

[0076] In some embodiments, the method further includes (a) treating the mixture of the compound of Formula (I) and the compound of

Formula (Γ) with a chiral acid to form a diastereoselective salt; and

(b) treating the diastereoselective salt with a base to provide the compound of

Formula (I).

[0077] In some embodiments, diastereomeric salt formation may be accomplished by using various chiral acids. For example, the chiral acid may be tartaric acid or derivatives thereof, such as dibenzoyl tartaric acid or ditoluoyl tartaric acid. In other embodiments, the chiral acid may be mandelic acid or camphorsulfonic acid. The chiral acid may be used in about 0.9-10 equiv., or about 0.95-1.5 equiv. or about 1.0-1.2 equiv. The solvents use for the diastereomeric salt formation include alcohols such as MeOH, EtOH, n-PrOH, 2-PrOH, n- BuOH, s-BuOH, tBuOH, t-Amyl alcohol or mixtures thereof. The diastereomeric salt formation may be performed at a temperature of about 0-100 °C, or about 40-70 °C, or about

45-55 °C.

[0078] In some embodiments, treating the diastereoselective salt with a base to provide the compound of Formula (I) may be performed with any free basing reagent known in the art. For example, the free basing agent may be an aqueous solution of an inorganic base, such as NaOH, KOH, Li OH, Ca(OH)₂,Na/K/LiHC0₃, Na/K/Li₂C0₃, NaAmberlyst A21 Resin, etc. The free basing may be performed in any organic solvent, water, or any aqueous inorganic base described above. In certain embodiments, the free basing may be performed in aqueous NaOH. The free basing agent may be used in about 1.95-10 equiv., about 2-3 equiv., or about 2.5 equiv. The free basing may be performed at a temperature of about 0- 50°C, about 5-25°C, or about 15-20°C.

[0079] In some embodiments, the method further includes cleaving a hydroxyl protecting group, PG, from a compound of Formula (II)

[0080] In some embodiments, the method further includes reacting a compound of Formula (V)

(V)

wherein

PG is a hydroxyl protecting group, and

each R" is independently a Ci-C₆ alkyl group, a compound of Formula (VI)

(VI)

to provide a compound of Formula (II).

[0081] In some embodiments, the method further includes

(a) esterifying a compound of the structure

to provide a compound of Formula (Va)

(Va)

wherein R is a Ci-C₆ alkyl group;

(b) protecting the 4'-hydroxy group of the compound of Formula (Va) to provide a compound of Formula (Vb);

(Vb)

and

(d) converting the compound of Formula (Vb) to a compound of Formula (V).

[0082] In some embodiments, esterification may be performed with an acid, such as HC1, MsOH or TsOH, in an alcoholic solvent, such as ethanol. Toluene may be used for the workup following the esterification, as well as for the subsequent protection of the 4'- hydroxyl group. In some embodiments, the protecting group (PG) of the compound of Formula (Vb) may be a silyl group, such as TBS. The esterification may be performed at about 30-40°, and the subsequent silylation at about 70-80°C. The compound of Formula (Vb) may be obtained by short-path distillation.

[0083] In some embodiments the converting of the compound of Formula (Vb) to a compound of Formula (V) involves treating the compound of Formula (Vb) with an alkyl phosphonate (e.g., dimethylmethyl phosphonate) under basic conditions. In some

embodiments where LiHMDS is be used as the base, low temperatures may not be needed. In other embodiments, the phosphonate (compound of Formula (V)) may not be isolated and the crude product may be taken on to react with a compound of Formula (VI). In other embodiments, following the reaction of a compound of Formula (V) with a compound of Formula (VI) to provide a compound of Formula (II), the protecting group on the compound of Formula (II) may be cleaved in situ to provide a compound of Formula (IX). Under these conditions, the compound of Formula (IX) may be provided from a compound of Formula (Vb) without the isolation of any intermediates.

[0084] In some embodiments, the method further includes

(a) converting a compound of Formula (Via)

(Via)

to a compound of Formula (VIb) X

(VIb)

wherein X is a halogen; and

(b) reacting the compound of Formula (VIb) with a compound of Formula (Vic),

(Vic)

wherein X is a halogen,

to provide the compound of Formula (VI).

[0085] In embodiment I₃, converting the compound of Formula (IX) to the compound of Formula (I) may involve

(a) converting a compound of Formula (I a compound of Formula (IXa);

(IXa)

and

(b) converting a compound of Formula (IXa) to a compound of Formula (I).

[0086] Converting a compound of Formula (IX) to a compound of Formula (IXa) may include

(a) treating the mixture of the compound of Formula (IX) with a chiral acid to form a diastereoselective salt; and

(b) treating the diastereoselective salt with a base to provide the compound of

Formula (IXa).

[0087] In some embodiments, diastereomeric salt formation may be accomplished by using various chiral acids. For example, the chiral acid may be tartaric acid or derivatives thereof, such as dibenzoyl tartaric acid or ditoluoyl tartaric acid. In other embodiments, the chiral acid may be mandelic acid or camphorsulfonic acid. The chiral acid may be used in about 0.9-10 equiv., or about 0.95-1.5 equiv. or about 1.0-1.2 equiv. The solvents use for the diastereomeric salt formation include alcohols such as MeOH, EtOH, n-PrOH, 2-PrOH, n- BuOH, s-BuOH, tBuOH, t-Amyl alcohol or mixtures thereof. The diastereomeric salt formation may be performed at a temperature of about 0-100 °C, or about 40-70 °C, or about 45-55 °C. In some embodiments, the diastereomeric salt formation may be carried out in EtOH or IPA at a temperature from about 60 °C to 80 °C.

[0088] In some embodiments, treating the diastereoselective salt with a base to provide the compound of Formula (IXa) may be performed with any free basing reagent known in the art. For example, the free basing agent may be an aqueous solution of an inorganic base, such as NaOH, KOH, Li OH, Ca(OH)₂,Na/K/LiHC0₃, Na/K/Li₂C0₃, NaAmberlyst A21 Resin, etc. The free basing may be performed in any organic solvent, water, or any aqueous inorganic base described above. In certain embodiments, the free basing may be performed in aqueous NaOH. The free basing agent may be used in about 1.95-10 equiv., about 2-3 equiv., or about 2.5 equiv. The free basing may be performed at a temperature of about 0- 50°C, about 5-25°C, or about 15-20°C. In some embodiments, the free basing may be carried out in DCM with an aqueous solution of Na/Li/KHC0₃ or Na/Li/KH_xP0₄ at a temperature of about 0 °C to about 40 °C. In some embodiments, slurrying of the free base in MeTHF, toluene, IP Ac or EtOAc may increase the resulting enantiomeric excess.

[0089] In some embodiments, converting the compound of Formula (IX) to the compound of Formula (IXa) may involve treating the compound of Formula (IX) with (L)- Dibenzoyl tartaric acid salt and K₂HP0₄.

[0090] In some embodiments, converting the compound of Formula (IXa) to a compound of Formula (I) may involve reducing the carbonyl in the compound of Formula (IXa). In some embodiments, reducing the carbonyl in the compound of Formula (IXa) may involve treating the compound of Formula (IXa) with an aluminum or boron reducing agent.

[0091] The reducing agent may include BH₃/(R)-2-methyl-CBS-oxazaborolidine, NaBH₄, LiAlH₄, RedAl, Li AlH(OtBu)₃, selectride, etc. In some embodiments, using LiAlH(OtBu)₃ as the reducing reagent may provide a compound of Formula (I) in a diastereo selectivity of about >97%.

[0092] In embodiments where a boron reducing agent is used, the solvent may be MeOH, EtOH, i-PrOH, n-PrOH, THF, 2-Me-THF, DCM, TBME, CPME, dioxane, toluene or mixtures thereof. In embodiments where an aluminum reducing agent is used, the solvent may be THF, 2-Me-THF, CPME, TBME, dioxane, DCM, toluene or mixtures thereof. In some embodiments, a mixture of THF/2-Me-THF may be used, and may improve the diastereoselectivity of the reaction. For example, a reduction in THF may provide a diastereoselectivity of 94-95%, where a reduction performed in TFIF/2-Me-TFIF may provide a diastereoselectivity of >97%.

[0093] The stoichiometry of the reducing agent may range from about 0.3-5 equiv. for boron reducing reagents, and about 1.0-5.0 equiv. for aluminum reducing reagents. In some embodiments, about 0.3-1 equiv. of boron reducing reagent may be used. In other embodiments, about 1.0-1.3 equiv. or about 1.1 equiv. of aluminum reducing may be used.

[0094] The temperature of the reduction may range from about -30 °C to about 50 °C. In some embodiments, the temperature may range from about -15 °C to about 25 °C, or from about -15 °C to about 0 °C.

[0095] In some embodiments, the method may further include reducing the 4'-carbonyl group of a compound of Formula (VIII)

(VIII)

to provide the compound of Formula (IX).

[0096] In some embodiments, reducing the 4'-carbonyl group of the compound of Formula (VIII) to provide the compound of Formula (IX) may involve treating the compound of Formula (VIII) with a ketoreductase. In some embodiments, the stereoselective reduction provides the trans-product in 95% yield with a purity >95a%. A low enzyme loading (substrate /enzyme up to 200 [w/w]) and low NAD cofactor loading (substrate /cofactor up to 2000 [w/w]) may be used, and the pH of the reaction may range from about 6.0 to about 8.0. The reduction may also include a buffer, such as phosphate buffer of about 50-250 mM. The reduction may be performed at a temperature of about 20 °C to about 50 °C, and may include a beneficial additive, such as 2-propanol, butanol and glycine. In some embodiments, the additive is 2-Propanol in about 5 to about 25 weight percent.

[0097] In some embodiments, the method may further include reacting a compound of Formula (VII)

(VII)

wherein

each R' is independently Ci-C₆ alkyl or both R' combine with the oxygen atoms to which they are attached to form a 5- or 6-membered dioxanyl ring, and

each R" is independently a Ci-C₆ alkyl group,

with a compound of Formula (VI)

(VI)

to provide the compound of Formula (VIII).

[0098] In some embodiments, the compound of Formula (VII) is formed from an alkyl 4- oxocyclohexanecarboxylate. First, the ketone of the alkyl 4-oxocyclohexanecarboxylate (e.g., ethyl 4-oxocyclohexanecarboxylate) may be protected, for example, with as an acetal. The reaction may be run in EtOH, THF, MTBE or toluene with or without alkylorthoformate and in presence of a strong acid, such as H₂SO₄, HQ or pTsOH, and at a temperature of about 20 to about 80 °C. The compound of Formula (VII) can then be formed by treating the protected alkyl 4-oxocyclohexanecarboxylate with an alkyl phosphonate (e.g.,

dimethylmethyl phosphonate) under basic conditions. For example, the protected alkyl 4- oxocyclohexanecarboxylate may be treated with a base at a temperature of about -80 °C to about -20 °C, in a solvent such as MeTHF, THF or toluene. Suitable bases include, but are not limited to BuLi, LDA and LHMDS.

[0099] In some embodiments, reacting a compound of Formula (VII) with reacting a compound of Formula (VI) to provide a compound of Formula (VIII) is performed in a solvent (e.g., THF, MeTHF, toluene, etc.) in the presence of a base (e.g., NaOH, or

Li/K/Na₂C0₃) at a temperature of about 40 °C to about 80 °C. In some embodiments, an acid (e.g., H₂S0₄, HC1, AcOH, etc.) can be used in water for the deprotection of the acetal.

[0100] In some embodiments, the method may further include converting a compound of Formula (Via)

CHO

(Via)

a compound of Formula (VIb)

(VIb)

wherein X is a halogen; and

(b) reacting the compound of F ) with a compound of Formula (Vic)

(Vic)

wherein X is a halogen,

to provide the compound of Formula (VI).

[0101] In some embodiments, the conversion of a compound of Formula (Via) to a compound of Formula (VIb) is performed at about -40 °C to about 0 °C, in MeTHF, TUF or toluene.

[0102] In some embodiments, reacting of the compound of Formula (VIb) and the compound of Formula (Vic) to provide the compound of Formula (VI) may be performed through a palladium catalyzed cross-coupling, such as the Suzuki-Miyaura cross-coupling reaction. In some embodiments, a zero valent palladium species (Pd(0)) is used, which may be applied directly (e.g. as commercial Pd(0) complexes such as Pd(PPh₃)₄, Pd(PCy₃)₂, Pd(PtBu₃)₂ or similar Pd(0) complexes) or may be formed from a palladium source in combination with either a phosphine ligand and/or a base such as (KOtBu, KOH, NaOAc, K₃P0₄, K₂C0₃, Hiinig's base, Et₃, Pr₃, etc.). The palladium source may be selected from, for example, [PdCl(X)]₂ (X= allyl, cinnamyl, crotyl, etc.), [Pd(X)PR₃] (R= alkyl or aryl), [Pd(X)(Y)] (Y= cyclopentadienyl, p-cymyl, etc.), Pd(dba)₂, Pd₂(dba)₃, Pd(OAc)₂, PdZ₂ (Z= CI, Br, I), Pd₂Z₂(PR₃)₂, Pd(TFA)₂ or any other suitable Pd complexes.

[0103] The palladium catalyzed cross-coupling may also employ a ligand, which may be used in combination with [PdCl(allyl)]₂ or as a Pd pre-catalyst. Suitable ligands include, for example, mono (e.g. XPhos, CataCXiumA, Amphos (=bis(di-tert-butyl(4- dimethylaminophenyl)phosphine)- and diphosphine (e.g. DPPP, DPPF) as well as HC (IPr). In some embodiments, the ligand is Amphos or di-tert-butylphenylphospine. In some embodiments, the catalyst system is an in situ formed Pd complex from Pd2(dba)3/Amphos As one of ordinary skill in the art would appreciate, the catalytic system may be further refined by exploring different palladium pre-catalysts in oxidation state 0 and II with and without pre-bound ligand.

[0104] The solvent used in the palladium catalyzed cross-coupling may include methanol, ethanol, iso-propanol, dioxane, 2-methyltetrahydrofuran, tetrahydrofuran, toluene, tert- butylmethyl ether, acetone, dimethyl carbonate, acetonitrile, N-methyl-2-pyrrolidone, isopropyl acetate, propylene carbonate, mixtures thereof and water mixtures thereof. In some embodiments, the solvent may be a mixture of methanol, water and a co-solvent selected from any of the solvents listed directly above. For example, the solvent for the palladium catalyzed cross-coupling may be methanol/water/THF.

[0105] The base used in the palladium catalyzed cross-coupling may include an inorganic base, such as M₂C0₃, MO Ac, MHC0₃, M₃P0₄, MH₂P0₄, MOH, tBuOM or MPiv (where "M" is a alkali earth metal), an organic base, such as tetramethylguanidine, N,N- diisopropylethylamine, triethylamine, l,4-diazobicyclo[2.2.2]octane, tripropylamine, triphenylamine, lutidine, pyridine, tributylamine, NMM, or tert-butylamine, or a combination thereof. In some embodiments, the base is present in about 1.0 to about 2.5 molar

equivalents, or. In some embodiments, the base is 1.3 equivalents of N,N- dii sopropyl ethyl amine .

[0106] In some embodiments, the palladium catalyzed cross-coupling may be performed at a temperature of about 60-80 °C, for up to about 24h, and at a substrate/catalyst ratio of up to about 200.

[0107] In some embodiments, the method may further include

(a) reacting a compound of Formula (VII)

(VII)

wherein each R' is independently Ci-C₆ alkyl or both R' combine with the oxygen atoms to which they are attached to form a 5- or 6- membered dioxanyl ring, and

each R" is independently a Ci-C₆ alkyl group,

a compound of Formula (VI)

(VI)

to provide the compound of Formula (VIII)

(VIII)

and

(b) reducing the 4'-carbonyl group of the compound of Formula (VIII) to provide the compound of Formula (IX).

In some embodiments, the method may further include

(a) reacting a compound of Formula (V)

(V)

wherein

PG is a hydroxyl protecting group, and

each R" is independently a Ci-C₆ alkyl group,

a compound of Formula (VI)

(VI)

to provide a compound of Formula (II)

(Π)

and

(b) cleaving a hydroxyl protecting group, PG, from the compound of Formula (II) to provide the compound of Formula (IX).

[0109] In certain embodiments, X is F, CI, or Br. In certain embodiments, X is F.

[0110] In certain embodiments PG may be TBS.

[0111] In some embodiments, the compound of Formula (I) is isolated as a mixture of diastereomers in a ratio of about 90: 10 or greater, about 91 :9 or greater, about 92:8 or greater, about 93 :7 or greater, about 94:6 or greater, about 95:5 or greater, about 96:4 or greater, about 97:3 or greater, about 98:2 or greater, or about 99: 1 or greater.

[0112] In some embodiments, the compound of Formula (I) is

[0113] In some embodiments, wet-milling (high-sheer mixing) of the compound of Formula (I) is performed to control (and diminish) particle size control. Wet-milling may be performed by single-pass or multiple-pass of a suspension through rotor-stator equipment typically controlled by a pump. The suspension temperature increases to a certain degree. This suspension a) may be isolated directly, or b) may be tempered at a certain (potentially elevated) temperature in order to manipulate particle size distribution. The resulting suspension is then cooled and isolated.

[0114] The following examples are offered for illustrative purposes, and are not intended to limit the disclosure in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results. The example compounds below were found to be inhibitors of IDO according to one or more of the assays described herein.

EXAMPLES

General Experimentals.

[0115] All reagents and solvents were purchased from commercial sources. All commercial reagents and solvents were used as received without further purification. The reactions were monitored using analytical thin layer chromatography (TLC), HPLC or hydrogen uptake. All reactions were performed under an inert atmosphere (e.g., nitrogen, argon). The reactions with gases under pressure were carried out in stainless steel autoclaves equipped with magnetic or mechanical stirring (depending on size), sensors for temperature and pressure measurements and software for their control, overpressure valve or breaking disc.

[0116] 4'-Hydroxy-ketone of general Formula II is an intermediate of the current synthesis of the API according to International Patent Application Publication No.

WO2012/142237.

[0117] Abbreviations

pCym ^-cymene

DBN l,5-diazobicyclo[4.3.0]non-5-ene

DBU l,8-diazobicyclo[4.5.0]undec-7-ene

KOfBu Potassium tert-butoxide

TMG 1 , 1 ,3 ,3 -tetram ethyl guani dine

pTsOH /?ara-toluenesulfonic acid

TBSC1 tert-butyl(dimethyl)silyl chloride

TBSOTf tert-butyl(dimethyl)silyl triflate

OAc acetate

OTf triflate

TFA trifluoro acetate

Xyl 3,5-dimethylphenyl, 3,5-xylyl

Piv pivoyl

TBS tert-butyl(dimethyl)silyl

TES triethylsilyl

d.r. diastereomeric ratio

S/C substrate-to-catalyst molar ratio

(S)-Rucy-XylBINAP RuCl((5)-daipena)((5)-XylBINAP)

2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-

4'-Hydroxy-ketone

1 -(4-hydroxycyclohexyl)ethanone

\-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-

4'-TBS-ketone

fluoro-5H-imidazo[l,5-b]isoindol-5- yl)ethanone

(2Z)-l-[4-[tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-

4'-TBS-Enone

fluoroimidazol[l,5-b]isoindol-5- ylidene)ethanone l-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-

4'-TBS-En-ol

fluoroimidazo[l,5-b]isoindol-5- ylidne)ethanol

tert-butyl-[(l S, 2Z)]-l-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-

DiTBS-En-ol

fluoroimidazol[l,5-b]isoindol-5- ylidene)ethoxy]-dimethyl-silane

[(lR)-l-[4-[tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-[(5S)-

DiTBS-API

6-fluoro-5H-imidazol[l,5-b]isoindol-5- yl]ethanol

4-((R)-2-[(5)-6-fluoro-5H-imidazo[l,5-

Free base API b]isoindol-5-yl]-l- hydroxy ethyl ] cy cl ohexanol

4-[(l S,2Z)-l -[tert-butyl(dimethyl)silyl]oxy-

1-TBS-En-ol 2-(6-fluoroimidazo[l,5-b]isoindol-5- ylidene)ethyl]cycl ohexanol

4-[(lR)-l-[tert-butyl(dimethyl)silyl]oxy-2-

1-TBS-API [(5S)-6-fluoro-5H-imidazo[l,5-b]isoindol-5- yl]ethyl]cyclohexanol

(S)-6-fluoro-5-((R)-2-hydroxy-2-

API MeS0₃H ((lr,4R)-4-hydroxycyclohexyl)ethyl)-5H- imidazo[5, l-a]isoindol-2-ium mesylate

[(IS, 2Z)-\ -[4-[tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6- l-Ac-4"-TBS-En-ol

fluoroimidazol[l,5-b]isoindol-5- yli dene)ethyl ] acetate

[(1R, 2Z)-l-[4-[tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6- l-Piv-4"-TBS-En-ol

fluoroimidazol[l,5-b]isoindol-5- ylidene)ethyl]2,2-dimethylpropanoate tert-butyl-[4-(l S, 2Z)-2-(6- fluoroimidazol[l,5-b]isoindol-5-ylidene)-l- l-TES-4"-TBS-En-ol

triethylsilyloxy-ethyl]cyclohexoyl]-dimethyl- silane

[0118] Acronyms of diphosphine ligands

Synthetic approaches to the hydrogenation substrate TBS-Enone

Example 1: l-[4-[fert-butyl(dimethyl)silyl]oxycvclohexyl1-2-(6-fluoroimidazol[L5- b]i soindol -5 -yPethanone (4'-TBS-ketone)

[0119] Under inert atmosphere in a 50L reactor 3.50 kg (11.1 mol) 4'-hydroxy-ketone and 1.3 kg (19.1 mol) imidazole were dissolved in a mixture of 19.5 kg 2-methyltetrahydrofuran and 5.5 kg DMSO at 60 °C. A solution of 2.36 kg (15.7 mol) fert-butyldimethylchlorosilane in 4.4 kg 2-methyltetrahydrofuran was added within 15 min. After complete conversion (sat. ketone <0.5%) 5.8 kg water were added and the phases were separated. The organic phase was washed with water at 60 °C. After a solvent exchange to n-heptane the product is crystallized upon cooling to 0 °C. The crystals were filtered off and washed with cold n- heptane. After drying 3.9 kg (83%) of product was obtained as a white solid with a purity of 99.7% m/m. LC-MS of reference reaction MH⁺ = 429.2384

Example 2: (2Z)-l-[4-[fert-butyl(dimethyl)silylloxycyclohexyll-2-(6-fluoroimidazol[L5- bli soindol -5 -ylidene)ethanone (4'-TBS-Enone)

[0120] In 25 ml 3-neck flask equipped with magnet stirring bar, thermometer, reflux condenser and argon inlet 1.07 g (0.95 mmol) l-[4-tert-butyl(dimethyl)silyl]oxycyclohexyl]- 2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)ethanone were dissolved in 10 ml acetic acid, 269 mg (1.25 mmol) sodium (meta) periodate was added. The suspension was heated to 60 °C and 3.4 mg (0.013 mmol) iodine were added. The mixture was aged at 60 °C for 2 h, after which time the starting material was less than 1 area% (short: < la%). After cooling to 11-14 °C a solution made of 0.45 g ascorbic acid in 5 ml water was added dropwise. The mixture was diluted with 2-PrOAc and the organic phase was washed with aq. NaCl solution. The aqueous phases were back-extracted with 2-PrOAc. The combined organic phase were evaporated under reduced pressure; the crude product was filtered through silica gel and recrystallized from 2-PrOH/water to afford 0.67 g (62%) of the title compound in a purity of 96.9 % according to HPLC. LC-MS of reference reaction M⁺ = 426.21521

Example 3: (2Z)-l-[4-[fert-butyl(dimethyl)silylloxycyclohexyll-2-(6-fluoroimidazol[L5- b^"|i soindol -5 -ylidene)ethanone (4'-TBS-Enone)

[0121] In a 50 L reactor 1.67 kg (3.90 mol) l-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)ethanone, 334 g (1.56 mol) sodium (meta) periodate and 16.7 g (0.2 mol) lithium bromide (powder) were suspended in 4.4 kg acetic acid and 3.6 kg 2-methyltetrahydrofuran. The mixture was heated to 60 °C until starting material was < 2.5% (approx. 3h). After cooling to 5-10 °C the mixture was neutralized by addition onto a mixture of freshly prepared 10.0 kg of 28% sodium hydroxide aq. solution, 8.4 kg water and 7.1 kg 2-MeTHF. The phases were separated and the organic phase was washed twice with sodium thiosulfate solution 10% aq and water. The organic phase was treated with charcoal and the title compound was crystallized by solvent exchanged to ^-heptane. The solids were filtered off, washed and dried to afford 1.25kg (71%) corr.) of product as a yellow solid with a purity of 99.3% according to HPLC. LC-MS of reference reaction M⁺ = 426.21521 Preparation of Catalysts

[0122] Complexes [RuCl((S)-daipena)((S)-Xyl-Binap)] and [RuCl((R)-daipena)((R)-Xyl- Binap)] were purchased from Strem, while [Ru(OTf)((S)-daipena)((S)-Xyl-Binap)],

[RuCl((S)-daipena)((S)-Xyl-Segphos) and [RuCl((5)-daipena)((5)-Xyl-MeOBIPHEP)] were in analogy to literature procedures (K. Matsumura, N. Arai, K. Hori, T. Saito, N. Sayo, T. Ohkuma, J. Am. Chem. Soc. 2011, J 33, 10696-10699; H. Nara, T. Yokozawa, US9079931B2 July 14, 2015 to Takasago Int. Corp.).

Example Catalyst 1

rRuCl((R)-daipena)((R)-3.5-iPr-MeOBIPHEP)l

[0123] Under Ar a 250 mL Schlenk flask was charged with 5.00 g (5.44 mmol) (R)-3,5- iPr-MeOBIPHEP, 1.71 g (2.74 mmol) [Ru(pCym)Cl₂]₂ and 20 mL methanol. The mixture was stirred for 30 min at room temperature and then heated to 60 °C for 1 h. The resulting yellow solution was cooled to ambient temperature. Then 1.89 g (6.01 mmol) (R)-daipen, 0.58 mL (5.57 mmol) diethylamine and 0.20 mL (10.9 mmol) water were added. The mixture was heated to 60 °C and stirred for 23 h. Then the resulting suspension was cooled for 1 h in an ice-bath and filtered. The filter cake was washed with cold methanol and dried to afford 5.37 g (72%) of the titled compound as pale yellow crystals. MS: M⁺ 1368.62829

Example Catalyst 2

rRuCl((y)-daipena)((R)-3.5-iPr-MeOBIPHEP)l

[0124] Under Ar a 50 mL Schlenk flask was charged with 1.10 g (1.2 mmol) (R)-3,5-iPr- MeOBIPHEP, 376 mg (0.60 mmol) [Ru(pCym)Cl₂]₂ and 18 mL methanol. The mixture was stirred for 30 min at room temperature and then heated to 50 °C for 1 h. The resulting yellow solution was cooled to ambient temperature. Then 415 mg (1.32 mmol) (^-daipen, 128 uL (1.23 mmol) diethylamine and 43.2 uL (2.4 mmol) water were added. The mixture was heated to 60 °C and stirred for 22h. Then the resulting suspension was cooled for lh in an ice-bath and filtered. The filter cake was washed with cold methanol and dried to afford 1.25g (77%) of the titled compound as yellow crystals. MS: M⁺ 1368.62938

Example Catalyst 3

rRu(OTf)((R)-daipena)((R)-3.5-iPr-MeOBIPHEP)l

[0125] In a glove box (0₂ content < 2 ppm ) to a solution of 1.00 g (0.73 mmol) of

[RuCl((R)-daipena)((R)-3,5-iPr-MeOBIPHEP)] in 10 mL dichloromethane 192 mg (1.1 mmol) sodium trifluoromethanesulphonate were added. After 2 h the suspension is filtered, the solid was washed with 6 mL dichloromethane. Then 37.8 mg (0.147 mmol) silver trifluoromethanesulfonate were added to the filtrate. The mixture was stirred for 2 h, followed by removal of the volatiles under reduced pressure. The residue was taken up in dichloromethane, solids were filtered off and the solution was filtered through silica gel. Removal of the solvent afforded 0.96 g (89%) of the title compound. MS: M⁺ 1482.61965

Example Catalyst 4

rRu(TFA)((R)-daipena)((R)-3.5-iPr-MeOBIPHEP)l

[0126] In a glove box (0₂ content < 2 ppm ) 100 mg (0.073 mmol) of [RuCl((R)- daipena)((R)-3,5-iPr-MeOBIPHEP)] were dissolved in 1 mL dichloromethane, then 18.1 mg (0.080 mmol) silver trifluoroacetate was added with aid of 1 mL dichloromethane. The mixture was stirred for 2 h followed by removal of the volatiles under reduced pressure. The residue was taken up in dichloromethane, solids were filtered off and the solution was filtered through silica gel. Removal of the solvent afforded 45 mg (42%) of the title compound. MS: M⁺ 1446.64559

Example Catalyst 5

rRu(OMs)((R)-daipena)((R)-3.5-iPr-MeOBIPHEP)l

[0127] In a glove box (0₂ content < 2 ppm ) a solution of 100 mg (0.073 mmol ) of

[RuCl((R)-daipena)((R)-3,5-iPr-MeOBIPHEP] in 1 mL dichloromethane was treated with 16.6 mg (0.080 mmol) silver methanesulphonate added with aid of 1 mL dichloromethane. The mixture was stirred for 2 h, followed by removal of the volatiles under reduced pressure. The residue was taken up in dichloromethane, solids were filtered off and the solution was filtered through silica gel. Removal of the solvent afforded 31 mg (30%) of the title compound. MS: M⁺ 1482.64439

Example Catalyst 6

rRuCK(R)-daipena)((R)-3.5-iPr-4-MeO-MeOBIPHEP)l

[0128] All manipulations were carried out under an Ar-atmosphere. A 10 mL Schlenk tube was charged with 90 mg (0.087mmol) (R)-3,5-iPr-4-MeO-MeOBIPHEP, 26.5 mg (0.043 mmol) [Ru(pCym)Cl₂]₂ and 1.5 mL methanol. After stirring at 50 °C for 2 h, the mixture was cooled to room temperature and 29.9 mg (0.095 mmol) (R)-daipen followed by 9.0 μL (0.0.087 mmol) diethylamine were added. The mixture was stirred at 60 °C for additional 18 h, cooled to room temperature and the volatiles removed under reduced pressure. The residue was filtered through silica gel (eluent: toluene). After removal of the solvent the residue was stirred in «-pentane, filtered and dried to afford 35 mg (27%) of the titled compound. MS: M⁺ 1488.67083

Example Catalyst 7

rRu(OTf)((y)-daipena)((y)-3.5-Me-4-MeO-MeOBIPHEP)l

[0129] All manipulations were carried out under an Ar-atmosphere. A 10 mL Schlenk tube was charged under argon with 90 mg (0.11 mmol) (5)-3,5-Me,4-MeO-MeOBIPHEP, 33.8 mg (0.055 mmol) [Ru(pCym)Cl₂]2 and 1.5 mL methanol. The mixture was stirred at 60 °C for 3.5 h and then cooled to room temperature. 52.1 mg (0.166 mmol) (^-daipen and 11.5 μL (0.11 mmol) diethylamine were added. After stirring at 60 °C for additional 18 h, the reaction mixture was cooled to ambient temperature and the volatiles removed under reduced pressure. The residue was filtered over silica (eluent: toluene, toluene/EtOAc) and the solvent removed under reduced pressure. The residue was extracted with toluene/water, and the toluene phase was washed with aq. Na₂S0₄. After re-dissolution in toluene the residue was filtered over silica (eluent: toluene, toluene/EtOAc) to obtain the crude intermediate product [RuCl((5)-daipena)((5)-3,5-Me-4-MeO-MeOBIPHEP)] after removal of the solvent. Without further purification 20.5 mg (0.078 mmol) silver trifluoromethanesulfonate and 1 mL toluene were added. After stirring for 1.5 h, the solids were filtered off and the solution was filtered through silica gel (toluene, toluene/EtOAc). Removal of the solvent afforded 41 mg (27%) of the title compound. MS: M⁺ 1378.40782

Example Catalyst 8

rRuOTf((y)-daipena)((y)-3.4.5-Me-MeOBIPHEP)l

[0130] In a glove box (0₂ content < 2 ppm ) a 10 mL Schlenk tube was charged with 120 mg (0.16 mmol) (S)-3,4,5-Me-MeOBIPHEP, 48.9 mg (0.08 mmol) [Ru(pCym)Cl₂]₂ and 2 mL methanol. The Schlenk tube was sealed and the mixture was stirred at 60 °C for 4 h. Under Ar 55.3 mg (0.18 mmol) (<S)-daipen, 16.7 μL (0.16 mmol) diethylamine and 5.76 μL (0.32 mmol) water were added. After stirring at 60 °C for additional 18 h, the reaction mixture was cooled to r.t. and the volatiles removed under reduced pressure. In a glove box (0₂ content < 2 ppm ) the residue is filtered through silica (eluent: toluene, toluene/EtOAc) to obtain the crude intermediate product RuCl[(,S daipena][(S 3,4,5-Me-MeOBIPHEP] after removal of the solvent. Without further purification the residue is dissolved in 1 mL dcm, and 17.1 mg (0.067 mmol) silver trifluoromethanesulfonate with 1 mL dcm is added. After stirring for 2 h, the solids were filtered off and the solution was filtered through silica gel. Removal of the solvent afforded 31 mg (14.8%) of the title compound. MS: M⁺ 1314.43027 Asymmetric Hydrogenation of 4'-TBS-Enone

Example AH1

(£2Z)-1 4-fert-butyl(dimethyl)silyl1ox

ylidene)ethanol (4'-TBS-En-ol)

[0131] In-situ catalyst preparation: In a glove box (0₂ content < 2 ppm ) 21.83 mg (0.016 mmol) of [RuCl((R)-daipena)((R)-3,5-iPr-MeOBIPHEP)] and 28.15 mg (160 μιηοΐ) NaOTf were added in 5 ml of toluene in a 10 ml flask. The resulting suspension was stirred for 1.5 h. (In-situ preparation of [RuOTf((R)-daipena)((R)-3,5-iPr-MeOBIPHEP] has not been described in K. Matsumura, N. Arai, K. Hon, T. Saito, N. Sayo, T. Ohkuma J. Am. Chem. Soc. 2011, J 33, 10696-10699).

[0132] Hydrogenation: a 50 ml stainless steel autoclave was charged in the same glove box with 3.45 g (8.0 mmol) of (2Z)-l-[4-[tert-butyl(dimethyl)silyl]oxycyclohexyl]-2-(6- fluoroimidazol[l,5-b]isoindol-5-ylidene)ethanone, 25 ml of toluene and the catalyst suspension. After rinsing the catalyst-flask with additional 4.5 ml toluene, 508 μΙ_, (4.0 mmol) TMG were added. The autoclave was sealed and the hydrogenation was run under stirring at 40°C under 20 bar of hydrogen. After 18 h the autoclave was opened, the solution was transferred into a 150 mL round-bottomed flask, treated with charcoal and filtered through a filter aid pad. After solvent exchange to acetonitrile, crystallization and drying, the title compound was isolated in 82% (2.83 g) with a purity of 98.8% and a S/R enantiomeric ratio of 97.5/2.5 as off-white crystals. MS: M⁺ = 428.2313

Example AH2 (S/C 50 Rucy-Xyl-Binap)

[0133] In a glove box (0₂ content < 2 ppm ) a 35 ml stainless steel autoclave with glass inlet and a magnetic stirring bar was charged with 50 mg (0.12 mmol) of (2Z)-l-[4-[tert- butyl(dimethyl)silyl]-oxycyclohexyl]-2-(6-fluoroimidazol[l,5-b]isoindol-5-ylidene)ethanone, 2.72 mg (2.3 μιηοΐ) (S)-Rucy-XylBINAP, 1.75 μΐ (11.5 μιηοΐ) DBU and 2 ml of iPrOH. The asymmetric hydrogenation was run for 19 h at 25 °C under 40 bar of hydrogen. Afterwards the pressure was released from the autoclave and the reaction mixture was analyzed as described in Example AH1 to determine the conversion and the ee of the resulting TBS-En- ol. The conversion was 99.8 a%, 97.3 a% yield, 91 :9 e.r. R.

Examples AH3.01 to AH3.17 (biphosphine, solvent)

[0134] In a manner analogous to Example AH2 the following hydrogenations were performed with (2Z)-l-[4-[/ert-butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazol[l,5- b]isoindol-5-ylidene)ethanone as substrate in the presence of ruthenium complexes of general formula [RuX(daipena)(diphosphine)] as the catalyst in various solvents. After 20 h the reaction mixture was analyzed as described in Example AHl to determine the conversion and the enantiomeric ratio (e.r.) of the resulting TBS-En-ol. The obtained results are reported in Table 1.

Table 1

Conv. Yield of

Example Ratio

Catalyst Solvent % TBS-En-ol

No. S:R

HPLC %HPLC

RuCl((S

AH3.09 daipena)((R)-3,5-iPr- 2-PrOH 99.8 97.5 98.1/1.9

MeOBIPHEP)

RuOTf((R)-

AH3.10 daipena)((R)-3,5-iPr- toluene 99.1 96.1 97.3/2.7

MeOBIPHEP)

Ru(TFA)((R)-

AID .1 1 daipena)((R)-3,5-iPr- 2-PrOH 99.9 96.0 96.1/3.9

MeOBIPHEP)

Ru(TFA)((R)-

AH3.12 daipena)((R)-3,5-iPr- toluene 77.9 65.8 96.7/3.3

MeOBIPHEP)

Ru(MsO)((R)-

AH3.13 daipena)((R)-3,5-iPr- 2-PrOH >99.9 97.6 96.0/4.0

MeOBIPHEP)

Ru(MsO)((R)-

AH3.14 daipena)((R)-3,5-iPr- toluene 63.3 51.5 96.5/3.5

MeOBIPHEP)

RuCl((R)- daipena)((R)-3,5-

AH3.15 2-PrOH 78.7 55.0 99.8/0.2 iPr,4-MeO- MeOBIPHEP)

RuOTf((5)- daipena)((,S)-3,5-

AH3.16 toluene >99.9 98.2 12.3/87.7

Me,4-MeO- MeOBIPHEP)

RuOTf((5)-

AH3.17 daipena)((,S)-3 ,4, 5 - toluene 99.9 97.5 10.5/89.5

Me-MeOBIPHEP) Example AH4.01 to AH4.06

[0135] In a manner analogous to Example AH2 the following hydrogenations were performed with (2Z)-l-[4-[tert-butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazol[l,5- b]isoindol-5-ylidene)ethanone as substrate in the presence of (,S)-Rucy-Xyl-BINAP as the catalyst and 0.1 molar equiv. base. After 20 h, the reaction mixture was analyzed as described in Example AHl to determine the conversion and the enantiomeric ratio of the resulting TBS- En-ol. The obtained results are reported in Table 2.

Table 2

Example AH5

(₎5',2Z)-l-[4-fert-butyl(dimethyl)silylloxycyclohexyll-2-(6-fluoroimidazo[L5-blisoindol-5- ylidene)ethanol

[0136] Under Argon a 2L stainless steel autoclave was charged with a solution of 113 g (249 mmol, 94% pure) of (2Z)-l-[4-[tert-butyl(dimethyl)silyl]oxycyclohexyl]-2-(6- fluoroimidazol[l,5-b]isoindol-5-ylidene)ethanone in 520 mL iPrOH and 105 mL DCM. After rinsing with additional 400 mL iPrOH, 815 mg caesium carbonate (2.5 mmol) was added. The autoclave was sealed, rendered inert and the atmosphere was changed to hydrogen. At 25 °C a solution of 344 mg of (R)-Rucy-3,5-iPr-MeOBIPHEP (0.25 mmol) in 50 mL iPrOH and 3 mL DCM was added. The hydrogenation was performed at 25°C under 40 bar of hydrogen pressure. After 3 h the autoclave was opened, the solution was transferred (rinsing with iPrOH 80 mL) into a 2L flask containing 0.84 mL ethylendiamine (12.4 mmol), treated with charcoal and filtered through a filter aid pad. The solution is concentrated under reduced pressure, water is added and seeded. After crystallization and drying, the title compound was isolated in 84% (90.4 g) with a purity of 99.2% and a S/R enantiomeric ratio of 99.7/0.3 as off-white crystals.

Example AH6

(₎5',2Z)-l-r4-fert-butyl(dimethyl)silyl1oxycvclohexyl1-2-(6-fluoroimidazorL5-b1isoindol-5- ylidene)ethanol

[0137] Under Argon a 2L stainless steel autoclave was charged with a solution of 113.6 g (250 mmol, 94% pure) of (2Z)-l-[4-[/er/-butyl(dimethyl)silyl]oxycyclohexyl]-2-(6- fluoroimidazol[l,5-b]isoindol-5-ylidene)ethanone in 520 mL iPrOH and 105 mL DCM. After rinsing with additional 400 mL iPrOH, 815 mg caesium carbonate (2.5 mmol) was added. The autoclave was sealed, rendered inert and the atmosphere was changed to hydrogen. At 25 °C a solution of 343 mg of (R_P,S_N)-Rucy-3,5-iPr-MeOBIPHEP (0.25 mmol) in 50 mL iPrOH and 3 mL DCM was added. The hydrogenation was performed at 25°C under 40 bar of hydrogen pressure. After 3.5 h the autoclave was opened, the solution was transferred (rinsing with iPrOH 80 mL) into a 2L flask containing 0.84 mL ethylendiamine (12.4 mmol), treated with charcoal and filtered through a filter aid pad. The solution is concentrated under reduced pressure, water is added and seeded. After crystallization and drying, the title compound was isolated in 77% (83.0 g) with a purity of 99.2% and a S/R enantiomeric ratio of 99.9/0.1 as light yellow crystals.

Synthesis of the substrate for diastereoselective reductions Example 4

fert-butyl-|Yl S, 2Z)l-l-[4-fert-butyl(dimethyl)silylloxycyclohexyll-2-(6-fluoroimidazol[L5- Misoindol-5-ylidene)ethoxy1-dimethyl-silane (DiTBS-En-ol)

[0138] Under Ar in a 750 mL 4-neck flask 25 g (58.8 mmol) (l S,2Z)-l-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazo[l,5-^]isoindol-5-ylidne)ethanol were dissolved in 500 mL 2-methyltetrahydrofuran 14.8 ml (41.2 mmol) 2,6-lutidine and 18.4 ml (26.1 mmol) TBSOTf were added at 24 to 26 °C. After stirring for 4.5 h at 25 °C, the solution was diluted with 500 ml n-heptane, washed with each 150 ml half saturated brine, with 150 ml 10% phosphoric acid and 200 ml half saturated NaHC0₃ solution. The organic layer was concentrated and the residue was filtered through silica using a mixture of ethyl acetate/heptane (ratio 19: 1 to 7:3). After removal of the solvent and drying under reduced pressure 31.5 g (99.5%) of the title compound with a purity of 98.7 % according to HPLC were isolated. LC-MS: 542

Example 5

tert-butyl-[4-(lS, 2Z)-2-(6-fluoroimidazol[L5- >lisoindol-5-ylidene)-l-triethylsilyloxy- ethyl lcyclohexoyll-dim ethyl - si 1 ane (l-TES-4'-TBS-En-ol)

[0139] Under Ar a solution of 0.25 g (0.58 mmol) (l S,2Z)-l-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazo[l,5-b]isoindol-5-ylidene)ethanol in 2.5 mL dichloromethane was treated at 0 °C with 141 μΐ (0.82 mmol) triethylchlorosilane and 67.8 mg (0.99 mmol) imidazole. After 30 min the mixture was allowed to warm to room temperature. The solid was filtered off and the volatiles of the filtrate were removed under reduced pressure. The residue was purified by silica chromatography (DCM,

DCM/acetonitrile) to yield after removal of the solvents 0.25 g (80%) of the title compound with a purity of >98% according to HPLC. GC-MS: 542.4

Example 6

|Y1R, 2Z)-l-[4-[tert-butyl(dimethyl)silylloxycyclohexyll-2-(6-fluoroimidazol[L5- )lisoindol- 5-ylidene)ethvH2,2-dimethylpropanoate (l-Piv-4'-TBS-En-ol)

[0140] Under Ar a solution of 0.14 g (0.33 mmol) (R,2Z)-l-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazo[l,5-^]isoindol-5-ylidne)ethanol in 2.8 mL dichloromethane was treated with 31.6 μΐ (0.39 mmol) pyridine, 80.3 μΐ (0.39 mmol) pivalic anhydride and 2.0 mg (0.0.16 mmol)4-dimethylaminopyridine. The mixture was stirred at 40 °C for 22 h, cooled to room temperature, washed with water until neutral. The water phases extracted with DCM. The volatiles of the combined organic phases were removed under reduced pressure and the residue was purified by silica gel chromatography (DCM/EtOAc) to afford after solvent removal 156 mg (93%) of the title compound with a purity of >98% according to HPLC. MS of reference reaction M⁺= 512.2879

Example 7

IY1S, 2Z)-l-r4-rtert-butyl(dimethyl)silyl1oxycvclohexyl1-2-(6-fluoroimidazoirL5-b1isoindol- 5-ylidene)ethyllacetate ( 1 - Ac-4^* -TB S-En-ol)

[0141] Under Ar a solution of 0.10 g (0.21 mmol) (S,2Z)-\-[4-tert- butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazo[l,5-b]isoindol-5-ylidene)ethanol in 10 mL dichloromethane was treated with 25.2 μΐ (0.31 mmol) pyridine and 29.8 μΐ (0.31 mmol) acetic anhydride. The mixture was stirred at ambient temperature for 18 h, washed with water and brine. The water phases extracted with CH₂CI₂, the combined organic phases were dried over sodium sulfate, the volatiles were removed under reduced pressure and the residue was purified by silica gel chromatography (CH₂Cl₂/MeOH) to afford after solvent removal 78 mg (91%) of the title compound with a purity of 94% according to HPLC. MS: M⁺ = 471.2472

Example 8

4-r(l S.2Z)-l-rfert-butyl(dimethvnsilyl1oxy-2-(6-fluoroimidazori.5-b1isoindol-5- yl idene)ethyl ] cy cl ohexanol

[0142] Under Ar a 2500 mL 4 neck flask was charged with 104 g (243 mmol) 4-[(l S,2Z)- l-[tert-butyl(dimethyl)silyl]oxy-2-(6-fluoroimidazo[l,5-b]isoindol-5- ylidene)ethyl]cyclohexanol dissolved in 1200 mL 2-methyltetrahydrofuran, 63.7 ml (547 mmol) 2,6-lutidine and 73.7 ml (321 mmol) TBS triflate at 24 to 28 °C. After stirring for 3 h at 25 °C, 150 g (1.3 mol) phosphoric acid 85% dissolved in 485 ml water were added and the biphasic mixture was vigorously stirred for 20 h. The mixture was diluted with 1200 ml ethyl acetate and the layers separated. The organic layer was washed with 500 ml half saturated brine, 500 ml saturated NaHC0₃ solution, dried over 63 g Na₂S0₄, filtered and evaporated. The residue was filtered through silica using ethyl acetate/heptane (ratio 1 : 1 to pure ethyl acetate). After removal of the solvent the residue was dissolved in 200 ml diisopropylether at 60 °C. To the clear solution 150 ml n-heptane were slowly added, the clear solution was seeded and cooled to 0 °C with stirring. The crystals were collected washed with 40 ml ice cold n-heptane and dried at 45 °C for 5h to afford 99.6g (95.8%) of the title compound with a purity of 99.8 % according to HPLC. MS: M⁺ = 428.2295

Example 9

4-r(l S.2Z)-l-rfert-butyl(dimethvnsilyl1oxy-2-(6-fluoroimidazori.5-Misoindol-5- yl idene)ethyl 1 cycl ohexanol

[0143] Under Ar a 500 mL 4 neck flask was charged with 25.4 g (59.3 mmol) 4-[(l S,2Z)- l-[tert-butyl(dimethyl)silyl]oxy-2-(6-fluoroimidazo[l,5-b]isoindol-5- ylidene)ethyl]cyclohexanol, 200 mL acetonitrile and 15.6 g (146 mmol) 2,6-lutidine dissolved in 20 ml DMF. The suspension was heated to 52 °C, then a solution of 21 g (139 mmol) TBS chloride in 70 ml acetonitrile was added. After stirring for 19 h at 52 °C, most acetonitrile was evaporated and substituted by 200 ml 2-methyltetrahydrofuran. 150 g (306 mmol) phosphoric acid 20% were added and the biphasic mixture was vigorously stirred for 6.7 h. Acetonitrile was evaporated and the residue diluted with 250 ml ethyl acetate, washed with 100 ml half saturated brine and 100 ml saturated NaHC0₃ solution. The water layers were re-extracted consecutively with 150 ml ethyl acetate. The organic layers were combined washed with 100 ml saturated NaHC0₃ solution, filtered and evaporated. The residue was filtered through silica using ethyl acetate/heptane (ratio 1 : 1 to pure ethyl acetate). After removal of the solvent the residue was dissolved in 50 ml diisopropylether at 60 °C. To the clear solution 80 ml n-heptane were slowly added, the clear solution was seeded and cooled to 25 °C. The crystals were collected, washed with 10 ml ice cold n-heptane and dried at 45 °C for 5h to afford 20.75 g (81.7%) of the title compound with a purity of 100 % according to HPLC. MS: M⁺ = 428.2296

Heterogeneous hydrogenation

Hetl

fert-butyl-r(lR)-l-r4-rfert-butyl(dimethvnsilyl1oxycvclohexyl1-2-r(5y)-(6-fluoro-5H- imidazorL5-Misoindol-5-yl)ethoxy1-dimethyl-silane (Di TBS -API)

[0144] Under Ar a glass vial was charged with 50 mg (0.092 mmol) DiTBS-En-ol, 1 mL cpme, and 20.9 mg Pd/C 5% (ca. 50% H₂0). The vial was sealed and the hydrogenation was run under shaking at 5 bar for 4 h. After cooling and pressure release the suspension was filtered, washed and the volatiles were removed under reduced pressure to afford 44 mg (89%) of the title compound with a d.r. (1R,5"S)/(1R,5"R) of 89.6/10.4 according to HPLC. MS: M⁺ =544.3331

Example Het2.01-Het2.04

[0145] In a manner analogous to Example Hetl the following hydrogenations were performed with different substrates in thf as a solvent. After the catalyst was filtered off the d.r. of the resulting solution was determined by HPLC. The obtained results are reported in Table 3.

Table 3

544.3322 (0.54

Het02.03^1} l-TES-4'-TBS-En-ol 81 82: 18

mDa)

514.304 (1.31

Het02.04²⁾ l-Piv-4'-TBS-En-ol 70 90: 10

mDa)

LC-MS: MH⁺

Het02.05³⁾ l-Ac-4'-TBS-En-ol 39 rsp. 36⁵⁾ 53 :47⁵⁾

=473.3

1) 42 mg Pd/C wet; 2) 105 mg substrate with 64 mg Pd/C 5% wet; 3) 74 mg substrate with

45 mg Pd/C 5% wet; 4) d.r. ratio of (1R,5S) to (1R, 5R), 5) the configuration of the single diastereomers is not unambiguously assigned.

Example Het3.01-Het3.03

[0146] In a manner analogous to Example Hetl the following hydrogenations were performed with the addition of 0.1 molar equiv. of base. After the catalyst was filtered off the d.r. of the resulting solution was determined by HPLC. The obtained results are reported in Table 4.

Table 4

1) d.r. ratio of (1R,5S) to (1R, 5R)

Example Het4.01-Het4.05

(lR)-l-r4-tert-butyl(dimethvnsilyl1oxycvclohexyl1-2-r(5S)-(6-fluoro-5H-imidazori.5- bli soindol -5 -yl)1 ethanol

[0147] Under Argon a glass vial was charged with 50 mg (0.12 mmol) 4'-TBS-En-ol,l mL AcOH and catalyst (S/C 20). The vial was sealed and the hydrogenation was run under shaking at 5 bar for 4 h at 40 °C. After cooling and pressure release the suspension was filtered and the d.r. of the resulting solution was determined by HPLC. The obtained results are reported in Table 5. Table 5

1) reaction run at 80 bar hydrogen pressure, 2) d.r. ratio of (1R,5S) to (1R, 5R)

Example Het5.01-Het5.05

(lR)-l-r4-tert-butyl(dimethvnsilylloxycvclohexyll-2-r(5S)-(6-fluoro-5H-imidazori.5- bli soindol -5 -yl)l ethanol

[0148] Under Ar a glass vial was charged with 23.5 mg Pt nPtnZr0₂/Al₂0₃ 4.79%, 50 mg (0.12 mmol) 4'-TBS-En-ol,l mL MeOH and 2 molar equiv. acid. The vial was sealed and the hydrogenation was run under shaking at 5 bar for 4 h at 40 °C. After cooling and pressure release the suspension was filtered and the d.r. of the resulting solution was determined by HPLC. The obtained results are reported in Table 6.

Table 6

1) d.r. ratio of (1R,5S) to (1R, 5R), 2)∑ free base API + 4'-TBS-En-ol, ca. 90%

deprotection, 3)∑ free base API + 4'-TBS-En-ol >95% deprotection Het6

4-r(lRV irfert-butyl(dimethvnsilylloxy-2-r(5S)-(6-fluoro-5H-imidazori.5-blisoindol-5- vniethyllcvclohexanol (1-TBS-API)

[0149] A 185 mL stainless steel autoclave was charged with 1.0 g Pd/C 5% (ca. 59% H₂0) and 10 mL MeOH, 10.0 g (23.3 mmol) 4-[(l S,2Z)-l-[tert-butyl(dimethyl)silyl]oxy-2- (6-fluoroimidazo[l,5-b]isoindol-5-ylidene)ethyl]cyclohexanol and 90 mL MeOH were added, followed by 176 μL (1.17 mmol) l,8-diazobicyclo[5.4.0]undec-7-ene. The autoclave was sealed and the hydrogenation was run at 40 °C under 10 bar of hydrogen. After 1.5 h the autoclave was cooled to ambient temperature and the pressure released. The catalyst was filtered off, rinsed with total 60 mL methanol and the filtrate was concentrated. The solution was heated to 55 °C and a total of 90 mL water was added dropwise, the resulting suspension was allowed to cool to room temperature, the crystals were filtered off, washed with H₂0/MeOH 7/3 and dried to obtain 8.69 g (86%) of the titled compound in 99.1% purity (HPLC area).

[0150] MS: M⁺ 430.2464 API synthesis as free base or salt Example 10

4-((R)-2-r(,5 -6-fluoro-5H-imidazorL5-b1isoindol-5-yl1-l-hvdroxyethyl1cvclohexanol

[0151] A 380 mL stainless steel autoclave was charged with 24.85 g (45.8 mmol) tert- butyl-[(l S, 2Z)]-l-[4-/er/-butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazol[l,5- b]isoindol-5-ylidene)ethoxy]-dimethyl-silane, 2.38 g Pd/C 5% (ca. 59% H₂0), 0.70 mL (4.58 mmol) l,8-diazobicyclo[5.4.0]undec-7-en and 210 mL cpme. The autoclave was sealed and the hydrogenation was run at 40 °C under 5 bar of hydrogen. After 2.5 h the autoclave was cooled to ambient temperature and the pressure released. The catalyst was filtered off and rinsed with 90 mL cpme to obtain as an intermediate solution ter/-butyl-[(lR)-l-[4-[/ert- butyl(dimethyl)silyl]oxycyclohexyl]-2-[(5S)-(6-fluoro-5H-imidazo[l,5-^]isoindol-5- yl)ethoxy]-dimethyl-silane as a mixture of diastereomers (d.r. 93.3 :6.7) in 91.5a% purity (HPLC area). The solution was concentrated to 168 g and dropwise added to 57 ml (228 mmol) cold (1-5 °C) 4N HC1 aq. After complete addition the biphasic mixture was stirred for 3.5 h at 1-5 °C and then warmed to room temperature. The phases were separated and organic phase was extracted with water, the water phases were washed with cpme. The combined aqueous phases were charcoal treated, cooled to 2 °C and 2-methyltetrahydrofuran (5 mL) added, followed by the slow addition of 20.5 mL aq. H₄OH (25%). The suspension was filtered and the solid washed with cold water (100 mL). After drying 13.31 g (92%) of the title compound were isolated in a purity of 92.3% according to HPLC.

Example 11

fS)-6-fluoro-5-((R)-2-hvdroxy-2-((lr.4R)-4-hvdroxycvclohexynethvn-5H-imidazor5.1- alisoindol-2-ium mesylate

[0152] A 185 mL stainless steel autoclave was charged under argon with 10.00 g (23.1 mmol) (2Z)-l-[4-[tert-butyl(dimethyl)silyl]oxycyclohexyl]-2-(6-fluoroimidazol[l,5- b]isoindol-5-ylidene)ethanone in 70 mL methanol. 2.96 mL (45.1 mmol) methansulfonic acid were slowly added under stirring, after addition was completed, 0.50 g nPtnZr0₂/Al₂0₃ 4.79%) and 5 mL MeOH were added, the autoclave was sealed and the hydrogenation was run at 30 °C under 80 bar of hydrogen. After 3h the autoclave was cooled to ambient temperature and the pressure released. The catalyst was filtered off and rinsed with 25 mL MeOH to obtain the title compound in solution as a mixture of diastereomers (d.r. 84: 16) in 82.4a%> purity (HPLC area). The solvent was exchanged to 2-propanol (75 mL) and at 40 °C 2 mg seeding crystals were added to the solution, which was then slowly cooled to 5 °C. The suspension was filtered and the crystals washed with total 20 mL cold iPrOAc/iPrOH and dried to yield 6.36 g (67%>) of the titled compound in 98.9%> according to HPLC.

Example 12

4-((R)-2-[(,5^r)-6-fluoro-5H-imidazo[L5-blisoindol-5-yll-l-hydroxyethyllcyclohexanol

[0153] Under Ar a 250 mL 4 neck flask was charged with 15.3 mL hydrochloric acid (3M, 46 mmol). 8.0 g (18.4 mmol) 4-[(lR)- l [tert-butyl(dimethyl)silyl]oxy-2-[(5S)-(6-fluoro- 5H-imidazo[l,5-b]isoindol-5-yl)]ethyl]cyclohexanol 1-TBS-API in 50 mL dichloromethane were added dropwise. After complete addition the biphasic mixture was stirred for 2.5 h at 36 °C and then cooled to room temperature. The phases were separated, the aqueous phase was washed with dcm (20 mL) and charcoal treated, followed by the slow addition of ca. 3.5 mL aq. H₄OH (25%)). The suspension was filtered and the solid washed with water and heptane. After drying 5.24 g (89%>) of the title compound was isolated in a purity of 99.1%> according to HPLC.

Example 13

[0154] Under Ar in a 200 mL 3 neck flask 1 1.92 g (28.8 mmol) (S)-6-fluoro-5-((R)-2- hydroxy-2-((lr,4R)-4-hydroxycyclohexyl)ethyl)-5H-imidazo[5, l-a]isoindol-2-ium mesylate (API MeS0₃H) were dissolved in 72 mL water and 17.3 ml (34.5 mmol) 2M NaOH aq. were added dropwise. After stirring lh at room temperature the suspension was filtered. The filtercake was wash with 24 mL water, 48 mL heptane and dried to afford 8.96 g (98%) of the title compound in 99.1% purity according to HPLC.

Example 14

fS)-6-fluoro-5-((R)-2-hvdroxy-2-((lr.4R)-4-hvdroxycvclohexynethvn-5H-imidazor5.1- a^"|isoindol-2-ium dihydrogene phosphate hydrate

[0155] A suspension of 6.5 g (20.54 mmol, 92.3% purity) 4-((R)-2-[(S)-6-fluoro-5H- imidazo[l,5-b]isoindol-5-yl]-l-hydroxyethyl]cyclohexanol in EtOH / water was dissolved by addition of an aqueous solution of 1.50 mL phosphoric acid 85% at 50°C. The product crystallized after cooling to 0°C, was isolated by filtration and dried to afford 7.04 g (79%) title compound in 99.0% purity.

[0156] Certain steps in the syntheses described herein may be performed in accordance with the methods disclosed in International Patent Application Publication No.

WO2012/142237 ("the '237 PCT publication").

General Example 1: Synthesis of a Compound of Formula (V)

[0157] The compound of Formula (V) may be prepared in accordance with the methods of the '237 PCT publication, Tetrahedron, Asymmetry 16 (2005) 3682-3689, methods known to one of skill in the art, and/or the following synthetic schemes:

Formula (Va) Formula (vb) OTBS OTBS

Formula (Vb) Formula (V)

General Example 2: Synthesis of a Compound of Formula (VI) from a Compound of Formula (VIb) and a Compound of Formula (Vic)

[0158] The compound of Formula (VI) may be prepared in accordance with the following synthetic scheme:

X

Formula (VIb) Formula (Vic)

Formula (VI)

General Example 3: Synthesis of a Compound of Formula (VIb) from a Compound of Formula (Via')

[0159] The compound of Formula (VIb) may be prepared in accordance with the following synthetic scheme:

Formula (Via¹) Formula (Via")

Formula (VIb)

General Example 4: Synthesis of a Compound of Formula (II) from a Compound of Formula (V) and Formula (IV)

[0160] The compound of Formula (II) may be prepared in accordance with the methods of the '237 PCT publication, methods known to one of skill in the art, and/or the following synthetic scheme:

Formula (V) Formula (Π)

General Example 5: Synthesis of a Compound of Formula (II) from a Compound of Formula (II)

[0161] The compound of Formula (I) may be prepared in accordance with the methods of the '237 PCT publication, methods known to one of skill in the art, and/or the following synthetic scheme: Formula (IX)

Chiral

crystallization

Chiral Chiral o H o H

Formula (I) Formula (I)

[0162] Examples 15-22 described the synthesis of a compound of Formula (I) as depicted in Figure 7

Example 15: Synthesis of trans-ethyl-4-[tert-butyl(dimethyl)silyl]oxycyclohexane carboxylate

[0163] To a mixture of 4-hydroxycyclohexanecarboxylic acid (30 g, 208.1 mmol) in EtOH (90 mL) was added a solution of HC1 (2.15 g) in EtOH (60 mL), the resulting solution was heated to 35-40 °C and stirred for 6h. The mixture was cooled and the solvent was partially removed, toluene (180 mL) was added and the solvents were partially removed. Then toluene (180 mL) and an aqueous solution of NaHC0₃ (5%, 80 mL) was slowly added at 20-30 °C. The phases were separated, the aqueous phase was extracted with toluene, the organic phases were washed twice with water and the combined organic phases were concentrated under vacuum to a total volume of ca. 100 mL. This solution was added at 20- 30 °C to imidazole (20.1 g), diluted with toluene (20 mL) and the mixture was heated to 60 °C. To the clear solution a solution of TBSC1 (35.7 g) in toluene (52 mL) was added, the reaction mixture was heated to 70-80 °C and stirred for 9h. Then, the reaction mixture was cooled to 40-50 °C, EtOH (37 mL) was added and the mixture was stirred for 30-40 min. The reaction mixture was cooled to 20-30 °C and then aqueous acetic acid (5%, 120 mL) was added. Then the phases were separated, the organic phase was washed twice with water (134 mL) and the organic phase was concentrated to dryness under vacuum (50 °C, <0.1 mbar) to yield the crude product (53.53 g, 87.5% yield) as yellow oil.

[0164] On a larger scale batch (3.43 kg) this oil was distilled (short-path distillation, 150° C, 5 mbar) to give the pure product (3.042 kg, 88.6% yield). 1H NMR (600 MHz, CHLOROF ORM-<f) δ ppm 4.09 (q, 2 H), 3.51 - 3.58 (m, 1 H), 2.20 (tt, 1 H), 1.91 - 1.98 (m, 2 H), 1.85 - 1.90 (m, 2 H), 1.41 - 1.50 (m, 2 H), 1.18 - 1.36 (m, 8 H), 0.79 - 0.94 (m, 11 H), 0.03 (s, 6 H). MS (EI⁺): m/z = 287.3 ([M+H]⁺)

Example 16: Synthesis of trans-l-[4-[tert-butyl(dimethyl)silyl]oxycyclohexyl]-2- dimethoxyphosphoryl-ethanone (Step 2)

STEP 2

[0165] To a mixture of trans-ethyl -4- [tert- butyl(dimethyl)silyl]oxycyclohexanecarboxylate (45.0 g) and Dimethylmethyl phosphonate (21.56 g) in n-heptane (120 mL) was added at -5 to-5 °C a solution of LiHMDS (261.9 g, 1.5M in THF) and the mixture was stirred for 2h. This reaction mixture was added at -5 °C to 20°C to a mixture of water (150 mL), n-heptane (50 mL) and acetic acid (54.5 g), the mixture was allowed to warm to ambient temperature and stirred for 30 min. The pH was adjusted to pH 6.0-7.0 with additional acetic acid if necessary and the phases were separated. The organic phase was washed with water (90 mL), the phases were separated and the organic phase was concentrated to dryness under vacuum to yield the product as a colorless oil (56.8 g, 99.7% yield). 1H NMR (600 MHz, CHLOROF ORM-<f) δ ppm 3.78 (d, 6 H), 3.49 - 3 (m, 1 H), 3.06 - 3.18 (m, 2 H), 2.43 - 2.57 (m, 1 H), 1.85 - 1.98 (m, 4 H), 1.29 - 1.45 (m H), 0.88 (s, 9 H). HR-MS: m/z = 365.1908 ([M+H]⁺). Example 17: Synthesis of (trans)-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-l-(4- hydroxycyclohex l)ethanone (step 2')

[0166] To a mixture of trans-ethyl -4- [tert- butyl(dimethyl)silyl]oxycyclohexanecarboxylate (45.0 g) and Dimethylmethyl phosphonate (21.56 g) in n-heptane (120 mL) was added at -5 to 5 °C a solution of LiHMDS (261.9 g, 1.5M in THF) and the mixture was stirred for 2h. This reaction mixture was added at -5 °C to 20 °C to a mixture of water (150 mL), n-heptane (50 mL) and acetic acid (54.5 g), the mixture was allowed to warm to ambient temperature and stirred for 30 min. The pH was adjusted to pH 6.0-7.0 with additional acetic acid if necessary and the phases were separated. The organic phase was washed with water (90 mL), the phases were separated and the organic phase was concentrated to dryness under vacuum. To the concentrate, THF (156 mL) was added and this THF solution was added under stirring at ambient temperature to a mixture of 2-fluoro-6-(lH-imidazol-4-yl)benzaldehyde (25.4 g) in THF (106 mL) and K₂C0₃ (73.9 g) in water. The resulting bi-phasic mixture was heated to 50 °C and stirred for 15h. Then the reaction mixture was cooled to 20-30 °C and the phases were separated. To the organic phase, water (147 mL) and HC1 (37%, 22.6 g) were added, the mixture was stirred for lh, followed by the addition of anisole (85 mL). The phases were separated and the aqueous phase was washed with anisole (127 mL). To the aqueous phase was added anisole (203 mL) and K₃P0₄ (30% aqu. solution, 161.3 g) over a period of 10-20 min. At a pH of 8-10 the emulsion was heated to 60 °C, the phases were separated, the organic phase was cooled to 48 °C, seeding crystals were added, and the mixture was cooled to 45°C and stirred for 5h. Then the suspension was cooled to -5 °C, stirred for 2h, the obtained crystals were filtered off, washed with EtOAc (38 mL) and dried under vacuum to give the title compound (35.7 g, 85% yield).

Example 18: Synthesis of (trans)-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-l-(4- hydroxycyclohexyl)ethanone (Step 3)

O H

H

d) HCI (aq.) rt, 1 h

e) K₃P0₄

f) cryst. from anisole

[0167] To a mixture of 2-fluoro-6-(lH-imidazol-4-yl)benzaldehyde (18 g) in THF (75 mL) was added at ambient temperature a solution of K₂C0₃ (52.4 g) in water (198 mL). Then a solution of trans-l-[4-[tert-butyl(dimethyl)silyl]oxycyclohexyl]-2-dimethoxyphosphoryl- ethanone (36.2 g) in THF (132 mL) was added and the bi-phasic mixture was heated to 50 °C for 15h. Then the reaction mixture was cooled to 20-30 °C, water (183 mL) and HCI (37%, 28.3 g) were added and the mixture was stirred for lh. Afterwards, anisole (60 mL) was added, the phases were separated and the aqueous phase was washed with anisole (90 mL). To the aqueous phase, anisole (144 mL) and an aqueous solution of K₃P0₄ (30%, 208 g) were added over a period of 20-30 min. At a pH of 8-10 the emulsion was heated to 60 °C, the phases were separated, the organic phase was cooled to 48 °C, seeding crystals were added, and the mixture was stirred for 5h. Then the suspension was cooled to -5 °C, stirred for 2h, the obtained crystals were filtered off, washed with EtOAc (27 mL) and dried under vacuum to give the title compound (25.3 g, 85% yield). 1H MR (600 MHz, DMSO-i/6) δ ppm 7.57 (t, 1 H), 7.42 - 7.49 (m, 2 H), 7.18 (s, 1 H), 7.08 - 7.14 (m, 1 H), 5.80 (dd, 1 H), 4.54 (d, 1 H), 3.51 (dd, 1 H), 3.08 (dd, 1 H), 2.36 (tt, 1 H), 1.74 -1.93 (m, 4 H), 0.99 - 1.41 (m, 4 H). HR- MS : m/z = 315.1517 ([M+H]⁺). Example 19: Synthesis of (±)-4-(2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l- hydroxyethyl)-trans-cyclohexanol

(LiAlH(OtBu)₃ procedure) / THF as solvent

[0168] To a solution of (trans)-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-l-(4- hydroxycyclohexyl)ethanone (80 g, 254.4 mmol) in THF (800 ml) was added at an internal temperature of -13to -3 °C a solution of LiAlH(OtBu)₃ in THF (1M, 280 mL, 280 mmol, 1.1 equiv.) over a period of 30 min. The clear yellow solution was stirred for lh to achieve full conversion. Then the reaction mixture was quenched with MeOH (133 mL) and solvent was reduced under vacuum to a total volume of 250 mL. Then MeOH (800 mL) was added and the solvent was reduced under vacuum to a total volume of 600 mL. The light yellow solution was cooled to 5 °C and the resulting white suspension was stirred overnight. The crystals were filtered off and washed with an ice cold mixture of MeOH/iPrOH and dried under vacuum to give the title compound (63.03 g, 73.5% yield) as white crystals. ¹H- MR (d6- DMSO, 400 MHz): δ 7.94 (s, 1 H), 7.52-7.30 (m, 2 H), 7.16 (s, 1 H), 7.1 1 -6.99 (m, 1 H), 5.66-5.46 (m, 1 H), 4.57 (d, 1 H), 4.43 (d, 1 H), 3.42-3.31 (m, 1 H), 3.30-3.20 (m, 1 H), 2.36- 2.19 (m, 1 H), 1.95-1.46 (m, 5 H), 1.22-0.91 (m, 5 H). MS: m/z 317.17 ([M+H]⁺).

2-Me-THF as solvent (preferred)

[0169] To a solution of (trans)-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-l-(4- hydroxycyclohexyl)ethanone (2.6 kg, 8.27 mol) in 2-Me-THF (7.5 L) was added at an internal temperature of -13 to -3 °C a solution of LiAlH(OtBu)₃ in THF (1M, 9.3 L) over a period of 1-3 h. The transfer line was washed with 2-Me-THF (0.34 L) and the clear yellow solution was stirred for lh to achieve full conversion. The reaction mixture was quenched with MeOH (1.9 L) and solvent was removed under vacuum. Then, MeOH (25.3 L) was added and the solvent was reduced under vacuum to a total volume of 15 L. The light yellow solution was cooled to 0°C and the resulting white suspension was stirred overnight. The crystals were filtered off and washed with an ice cold MeOH. The white crude product was treated with NaOH (aq., 28%, 15.8 L) and the suspension was stirred at 20-25 °C for 3h. Then the product was filtered off, washed with water (30 L) and dried under vacuum to give the title compound (2.0 kg, 78.8 % yield) as white crystals.

(RedAl = sodium bis(2-methoxyethoxy)aluminiumhydride)

[0170] To a suspension of (trans)-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-l-(4- hydroxycyclohexyl)ethanone (50 g, 159.1 mmol) in CH₂C1₂ (450 mL) was added at an internal temperature of sodium bis(2-methoxyethoxy)aluminum hydride (70% solution in toluene, 67.6 mL, 238.6 mmol, 1.5 equiv.) over a period of 30-60 min. The yellowish reaction mixture was stirred for l-2h followed by the addition of NaOH (10% aq.) and water at 0-25 °C whereupon the crude product precipitated. The thick white suspension was stirred at 25 °C for lh, the crude product was filtered off, washed with water and dried under vacuum to yield the light beige crude product. This crude product was treated with MeOH and the suspension was refluxed for 30 min, MeOH was removed under vacuum to a total volume of 130 mL, seeded and cooled to 0 °C, whereupon the product precipitated. The suspension was stirred at 3-10 °C overnight, the crystals were filtered off, washed with cold MeOH and dried under vacuum to yield the title compound as white crystals (23.7g, 47.1% yield).

Example 20: Synthesis of (lR,5S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(-4- hydroxycyclohexyl)ethanol (D)-dibenzoyl tartaric acid salt

A: 6V

[0171] To a solution of (±)-4-(2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l- hydroxyethyl)-trans-cyclohexanol (3.4 kg, 10.75 mol) in a mixture of MeOH (8.1 kg)/iPrOH (5.3 kg) in a 40 L reactor was added at an internal temperature of 40-50 °C a solution of D- (+)-Dibenzoyl tartaric acid monohydrate (4.4 kg, 11.69 mol, 1.1 equiv.) in MeOH (2.7 kg). After the addition of 40% of this solution, seeding crystals (34 g in 260 mL iPrOH) were added and the reaction mixture was stirred for 30 min. Then the remaining 60% of the (D)- Dibenzoyl tartaric acid monohydrate solution was added. Then the suspension was cooled to 20-25 °C over a period of 2h and the white suspension was stirred for lh. Then, the crystals were filtered off, washed twice with iPrOH and dried under vacuum to yield the title compound (3.04 kg, 41.9% yield) as white crystals. 1H MR (400 MHz, CDC1₃): δ 8.14 (s, 1 H), 8.01 (td, 4 H), 7.72 (tt, 2 H), 7.59 (t, 4 H), 7.47-7.44 (m, 2 H), 7.27 (s, 1 H), 7.11 (ddd, 1 H), 5.85 (s, 2 H), 5.63 (t, 1 H), 3.39 (dt, 1 H), 3.29-3.23 (m, 1 H), 2.31 (dt, 1 H), 1.91 (ddd, 1 H), 1.83-1.81 (m, 2 H), 1.68-1.65 (m, 1 H), 1.55-1.54 (m, 1 H), 1.13-0.95 (m, 5 H). HR-MS: m/z 317.1656 ([M+H]⁺).

B: 9V

[0172] In a similar experiment (3.4 kg scale) to the one described above but with 9V of solvents the product was isolated in an analogue way as white crystals (2.91 kg) in 40.2% yield.

Sequential addition of (D)-Dibenzoyl tartaric acid monohydrate

[0173] To a suspension of (±)-4-(2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l- hydroxyethyl)-trans-cyclohexanol (100 g, 316.1 mmol) in MeOH (332.6 g) was added at 20- 25 °C, iPrOH (219.8 g) and 10% (10 mL) of a solution of D-(+)-Dibenzoyl tartaric acid monohydrate (130.0 g) in MeOH (79.2 g). Then the suspension was heated to 40-45 °C, 35% (35 mL) of the D-(+)-Dibenzoyl tartaric acid monohydrate solution was added and the mixture was stirred until a yellow-orange solution was obtained. Then, seeding crystals (lg in 7.9 g iPrOH) were added and the resulting suspension was stirred for 15-45 min and the remaining 55% (55 mL) of the D-(+)-Dibenzoyl tartaric acid monohydrate solution was added. The suspension was stirred for 30-60 min and then cooled to 15-25 °C within 1-2 h. The suspension was stirred for lh, the crystals were filtered off, washed with iPrOH (200 mL) and dried at 50 °C under vacuum to yield the title compound as white solid (90.6 g, 41% yield).

Example 21: Synthesis of (lR,5S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(irans)- 4-hydroxycyclohexyl)ethanol

[0174] To a suspension of (lR,5,S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(/ra«5)- 4-hydroxycyclohexyl)ethanol (D)-dibenzoyl tartaric acid salt (1.74 kg, 2.48 mol) in water (10.5 L) was added at an internal temperature of 20-25 °C a mixture of NaOH (0.92 kg, 28% aq.) and water (1.0 L) over a period of 40 min and the resulting suspension was stirred at 20- 25 °C for 3h. The product was filtered off, washed twice with water and ^-heptane and dried under vacuum to give the title compound (0.73 kg, 93% yield) as white crystals. 1H MR (400 MHz, CDC1₃): δ 7.95 (s, 1 H), 7.44-7.34 (m, 2 H), 7.16 (s, 1 H), 7.10-7.05 (m, 1 H), 5.57 (t, 1 H), 4.59 (d, 1 H), 4.46 (d, 1 H), 3.38-3.34 (m, 1 H), 3.28-3.21 (m, 1 H), 2.29 (dt, 1 H), 1.89 (ddd, 1 H), 1.82-1.76 (m, 2 H), 1.66-1.63 (m, 1 H), 1.54-1.52 (m, 1 H), 1.11-0.94 (m, 5 H). HR-MS: m/z 317.1677 ([M+H]⁺).

Example 22: Synthesis of (lR,5S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(irans)- 4-hydroxycyclohexyl)ethanol monophosphate mono hydrate salt

Crystallization procedure without milling.

[0175] To a suspension of (lR,5,S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(/ra«5)- 4-hydroxycyclohexyl)ethanol (50.0 g) in EtOH (93.9g) and water (44.5 g) was added at ambient temperature, phosphoric acid (85%, 19.3 g) and water (35.1 g). This mixture was heated to 53 °C and the clear solution was polish-filtered, the filter was washed with ethanol (27.3 g) and water (3.0 g) and the reaction mixture was cooled to 39 °C. Then seeding crystals (1.0 g in EtOH (4.28g) and water (0.75 g)) were added, the mixture was aged for 15 min and then cooled to 0 °C over a period of 3.5-4h. To the resulting suspension EtOH (556 g) was added over a period of 60-90 minutes and the suspension was stirred at 0 °C for 6-18h. The product was filtered off, washed with a mixture of EtOH (73.8 g) and water (8.2 g) and dried at 30-40 °C under vacuum to yield the title compound as white solid (64.1 g, 92.4 % yield). 1H MR (600 MHz, DMSO-^6): δ ppm 8.04 (d, J=0.7 Hz, 1 H), 7.43 - 7.46 (m, 1 H), 7.41 - 7.45 (m, 1 H), 7.20 - 7.22 (m, 1 H), 7.09 (ddd, 1 H), 5.59 (t, 1 H), 3.36 - 3.40 (m, 1 H), 3.23 - 3.28 (m, 1 H), 2.30 (dt, 1 H), 1.90 (ddd, 1 H), 1.79 - 1.81 (m, 1 H), 1.79 - 1.81 (m, 1 H), 1.64 - 1.68 (m, 1 H), 1.53 (dt, 1 H), 1.08 - 1.14 (m, 1H), 1.02 - 1.07 (m, 1 H), 1.01 - 1.06 (m, 1 H), 0.98 (br d, 2 H). HR-MS: m/z = 317.1663 ([M+H]⁺). Particle size distribution: d50 = 364 μιη, d90 = 592 μιη.

Crystallization procedure with wet-milling (high-sheer mixing).

[0176] To a suspension of (lR,5,S)-2-(6-fluoro-5H-imidazo[5, l-a]isoindol-5-yl)-l-(tra«5)- 4-hydroxycyclohexyl)ethanol (30.0 g) in EtOH (56.3g) and water (26.7 g) was added at ambient temperature under stirring, phosphoric acid (85%, 11.6 g) and water (21.1 g). This mixture was heated to 55°C and the clear solution was polish-filtered, the filter was washed with ethanol (16.4 g) and water (1.8 g) and the reaction mixture was cooled to 39 °C. Then seeding crystals (0.45 mg in EtOH (2.25 g) and water (0.4 g)) were added, the mixture was aged for 5 min and then cooled to 0°C. To the resulting suspension EtOH (334 g) was added over a period of 60 minutes and the suspension was milled at 0-8 °C. The suspension was then heated to 35 °C, stirred for 2h, cooled to 0 °C and stirred for 14h at 0 °C. The obtained crystals were filtered off, washed with a mixture of EtOH (54 mL) and water (6 mL) and dried at 35 °C under vacuum for 16h to yield the title compound as white solid (36.7 g, 88.5 % yield). Particle size distribution: d50 = 67 μπι, d90 = 127 μπι.

[0177] Examples 23-32 describe the synthesis of a compound of Formula (I) as depicted in Figure 9

Example 23: Synthesis of 3-Fluoro-2-Formyl boronic acid

[0178] To a solution of bis(2-methoxy ethyl) amine (1.1 equiv., 443 mmol, 65.5 mL) in toluene (400 mL) was added at -20°C methyllithium (3.1 M in diethoxymethane, 1.1 equiv., 443 mmol, 143 mL) and the mixture was stirred for 15 min. Then a solution of 2- fluorobenzaldehyde (1.0 equiv., 402 mmol, 50 g) and toluene (100 mL) was added over a period of 35 min at -20 °C and the reaction mixture was stirred for 45 min. Afterwards, methyllithium (3.1 M in diethoxymethane, 1.2 equiv., 483 mmol, 155.9 mL) was added at -20 °C over 30 min, then the reaction mixture was allowed to warm to 0 °C and stirred for 16h. Then the mixture was cooled to -20°C, trimethylb orate (3.0 equiv., 1208 mmol, 138 mL) was added over a period of 1 h and the slurry was then warmed to 0 °C and stirred for 2.5h. This reaction mixture was added at 10 °C to water (500 mL), the resulting bi-phasic slurry was aged for 30 min, allowed to warm to ambient temperature, the solids were filtered off washed with water (200 mL). From the bi-phasic filtrate the layers were allowed to separate and to the aqueous layer MTBE (250 mL) was added. This biphasic mixture was stirred at internal temperature 20-25 °C for 30 min and the phases were separated. The aqueous layer was acidified with sulfuric acid in water (50 wt%, 200mL) to pH 2.3, MBTE (250 mL) was added and the bi-phasic mixture was stirred for 30 min at ambient temperature. After phase separation, the aqueous phase was extracted with MTBE (250 mL) twice. The combined organic phases were washed with water (100 mL) and the bi-phasic mixture was stirred for 30 min at ambient temperature. The phases were separated and the organic phase was heated to 45°C and the mixture was concentrated to ca. 5V under vacuum. Then toluene (500 mL) was added and the mixture was concentrated to a content of <5 w% of TBME in toluene. Then water (100 mL) was added and the mixture was allowed to stir for 1 h at 45 °C. Then the mixture was warmed to 60 °C and allowed to stir for an additional 1 h. Then, the mixture was cooled to 25 °C, and the stirring solids were aged for 1 h then filtered. The wet cake was dried at ambient temperature under a stream of nitrogen overnight yielding the product as off- white solid (48.0% yield).

[0179] Rework of Mother Liquor and Second Crop

[0180] The mother liquor from the filtration above was concentrated down to dryness, and then to this solid (10.0 g), boiling isopropyl acetate (25 mL) was added and the resulting slurry was filtered. To the filtrate at 85 °C, water (0.8 mL) and hot heptane (74 mL) were added slowly. During heptane addition, the product began to crystallize. The hot suspension was allowed to cool to 25 °C overnight, cooled to 0 °C and stirred for lh. The crystals were filtered, combined with the second crop crystals obtained earlier, and washed with pentane (10 mL). The combined yellow solid was reslurried in toluene (60 mL) and dried at 50 °C in a vacuum oven for 3h. The product was obtained in 9.0% yield. 1H- MR (600 MHz, DMSO-i/6, mixture of open/closed form in solution) δ ppm 10.30 (s, 1 H), 9.47 (s, 1 H), 8.01 (br s, 1 H), 7.61 - 7.76 (m, 1 H), 7.40 - 7.55 (m, 2 H), 7.22 - 7.36 (m, 2 H), 7.06 - 7.21 (m, 1 H), 6.24 - 6.41 (m, 1 H). HR-MS: m/z = 213.0374 ([M+HCOO]-).

Example 24: Synthesis of 2-fluoro-6-(lH-imidazol-4-yl)benzaldehyde

[0181] To a solution of 4-bromo-lH-imidazole (40.0 g, 204.1 mmol) in MeOH (140 mL) was added at ambient temperature, N-ethyldiisopropylamine (35.0 g, 265.4 mmol, 1.3 equiv.) and the mixture was stirred for 30 min. A preformed solution of

tris(dibenzylideneacetone)dipalladium(0) (0.801 g, 673.6 μιηοΐ, 0.0033 equiv.) and 4-(di-tert- butylphosphino)-N,N-dimethylaniline (1.083 g, 4.0 mmol, 0.02 equiv.) in THF (18 mL) was added. Then, a mixture of (3-fluoro-2-formylphenyl) boronic acid (36.0 g, 214.4 mmol, 1.05 equiv.) in MeOH (150 mL) and water (40 mL) was added at ambient temperature over a period of 30-60 min. The reactor was evaporated and refiled with argon 3 times, heated to 80 °C and stirred for 16-20 h. Then, the mixture was cooled to 55 °C over a period of 2h, the solids were filtered over a charcoal filter pad, and washed with methanol (400 mL).

Afterwards, N-acetyl cysteine (1.67 g) was added and the mixture was stirred for 2-16h at 50- 55 °C. Then, methanol was continuously exchanged under vacuum with 2-Me-THF (500 mL), the volume was adjusted to ca. 250 mL, 2-Me-THF (250 mL) and water (190 mL) were added and the mixture was stirred for 15-30 min at 55 °C. The phases were separated and the aqueous layer was washed three times with 2-Me-THF (240 mL). The combined organic layers were treated with water and the biphasic mixture was stirred for 15-30 min at 55 °C. Then, the phases were separated, the organic phase was cooled to 20-25 °C and treated with water (150 mL). Afterwards, the pH was adjusted to >13.6 upon addition of NaOH (30%, ca. 43.6 g) and the bi-phasic mixture was stirred for 15-30 min. The layers were separated, the organic phase was treated with water (100 mL) and NaOH (30%, ca. 9.1 g) to adjust the pH to >13.6 and the bi-phasic mixture was stirred for 15-30 min. The phases were separated and the organic phase was treated with water (100 mL) and NaOH (30%, ca. 6.1 g) to adjust the pH to >13.6 and the bi-phasic mixture was stirred for 15-30 min. The combined aqueous phases were treated with 2-Me-THF (90 mL) and MeOH (30 mL) and sulfuric acid (20%, ca. 88.1 mL) was added over a period of at least 20 min to adjust the pH to 10.5. The resulting suspension was stirred for 1-4 h at 20-25 °C, the product was filtered off and washed with a mixture of water (120 mL), THF (15 mL) MeOH (15 mL) and water (75 mL). The resulting yellow product was dried at 50-55 °C under vacuum to yield the title compound (26.63 g, 68.6% yield). 1H NMR (600 MHz, DMSO-i/6, mixture of open and closed form) δ ppm 12.54 (br s, 1 H), 10.21 (s, 1 H), 8.01 - 8.06 (m, 1 H), 7.91 (s, 1 H), 7.84 (d, 1 H), 7.72 (s, 1 H), 7.61 (br d, 1 H), 7.55 - 7.60 (m, 1 H), 7.48 (td, 1 H), 7.41 (d, 1 H), 7.14 - 7.21 (m, 1 H), 7.14 -7.16 (m, 1 H), 7.09 (t, 1 H), 6.89 - 6.94 (m, 1 H), 6.68 (d, 1 H). HR-MS: m/z 191.0620 (M+H]⁺).

Example 25: Synthesis of ethyl 4,4-diethoxycyclohexanecarboxylate

[0182] A mixture of ethyl 4-oxocyclohexanecarboxylate (5.0 kg, 29.4 mol), EtOH (15 L), triethylorthoformate (4.8 kg, 32.4 mol) and p-TsOH.H20 (50.4 g, 270 mmol) was heated to 50-55 °C and stirred for 2h. Then the mixture was cooled to 20-25 °C and triethylamine (595 g, 5.88 mol) was added. The mixture was concentrated under vacuum at 40-45 °C to 2V, followed by the addition of 2-Me-THF (10 L), the mixture was concentrated under vacuum at 40-45 °C to 2V and filtered. Then, the mixture was concentrated under vacuum to IV followed by the addition of 2-Me-THF (10 L). The mixture was further concentrated under vacuum at 40-45 °C to IV to give the title compound as an oil (7.6 kg, 95.3% yield). 1H

MR (400 MHz, CDC13): δ ppm 4.15 (2 H), 3.46 (m, 4 H), 3.39 (, 4 H), 2.28 (m, 1 H), 1.99 (m, 2 H), 1.80 (m, 2 H), 1.65 (m, 2 H), 1.41 (m, 2 H), 1.21 (m, 3 H), 1.13 (m, 6 H).

Example 26: Synthesis of l-(4,4-diethoxycyclohexyl)-2-dimethoxyphosphoryl-ethanone

[0183] Formation of LDA: To a mixture of diisopropylamine (950 mL) in 2-MeTHF (1 L) was added at -35 to -45 °C a solution of n-BuLi (2.5 M in n-hexanes, 2.46 L) over a period of 1-2 h. Then the mixture was slowly warmed to -15°C to -5°C for lh.

[0184] To a mixture of ethyl 4,4-diethoxycyclohexanecarboxylate (500 g) in 2-Me-THF (1 L) and MePO(OMe)₂ (281.0 g) in 2-MeTHF (1 L) was added at -55 to -65 °C the above prepared LDA solution over a period of 1-2 h and the resulting reaction mixture was stirred for 15-20 min. Then acetic acid (740 g) in 2-Me-THF (1 L) was added, whereupon the reaction temperature increased to 0 °C. Then water (1.5 L) was added and the mixture was heated to 20-25 °C. The phases were separated and the organic phase was washed with water (1.5 L) and the aqueous phase was back- extracted with isopropylacetate (2x1 L). The combined organic phases were concentrated to IV to get the product as an oily solution (in ca. 85% yield). 1H- MR (400 MHz, CDC13): δ ppm 3.77 (s, 3 H), 3.76 (s, 3H), 3.47 (m, 2 H), 3.39 (m, 2 H), 3.17 (s, 1 H), 3.11 (s, 1H), 2.57 (m, 1H), 2.06-1.75 (m, 4 H), 1.58 (m, 2H), 1.30 (m, 2 H), 1.14 (m, 6 H).

Example 27: Synthesis of 4-[2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5- yl)acetyl] cyclohexanone

[0185] To a mixture of aldehyde (1.0 equiv., 210 mmol, 40.0 g), phosphonate (1.2 equiv., 252 mmol, 121 g) in water (160 mL) and 2-Me-THF was added at 20-25 °C a solution of NaOH (6.0 equiv., 1.262 mol, 51.0 g) in water (240 mL) over a period of 15 min. Then the reaction mixture was heated to 50-60 °C over a period of 30 min and stirred for lh.

Afterwards, the bi-phasic mixture was cooled to 20-25 °C, the layers were separated and the organic phase was washed twice with sodium chloride solution (18 w%, 320 mL). The organic phase was washed twice at 20-25 °C with sulfuric acid (3 M, 260 mL), the layers were separated and the combined aqueous phases were diluted with water (325 mL) and 2- Me-THF (24 mL). Then the pH was adjusted at 25-30 °C with ammonium hydroxide in water (15 w% solution, 325 mL) to pH 4-4.5. Then seeding crystals were added and the pH was adjusted with ammonium hydroxide in water (15 wt% solution, 1.0 V, 81 mL) to pH 8.5. The resulting white suspension was stirred overnight, the product was filtered off, washed with water (407 mL) and n-heptane (163 mL) and the dried under vacuum to yield the title compound as an off-white solid (60.34 g, 92% yield). 1H MR (400 MHz, DMSO-^6) δ ppm 7.61 (s, 1 H), 7.47 (m, 2 H), 7.19 (s, 1 H), 7.13 (m, 1 H), 5.84 (m, 1 H), 3.61 (m, 1 H), 3.24- 3.16 (m, 1 H), 2.95 (m, 1 H), 2.39 (m, 2 H), 2.37 (m, 2 H), 2.23 (m, 2 H), 1.73 (m, 1H).

Example 28: Synthesis of (trans)-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-l-(4- hydroxycyclohexyl)ethanone

[0186] A mixture of 4-(2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)acetyl)cyclohexanone (50 g, 160 mmol), degassed 2-Propanol (125 mL), a degassed aqueous buffer solution (KPI (200 mM) and MgC12 (2 mM), pH 7.2, 375 mL) and NAD (25 mg, 0.038 mmol) in buffer solution were heated to 50°C and stirred for 10 min. The pH was adjusted to 7.2 with H3P04 (85%), then KRED (250 mg,) in buffer solution (1 mL) was added and the reaction was stirred for 23h. Then, the reaction mixture was cooled and the light yellow suspension was partially concentrated under vacuum at 45°C. Then the suspension was cooled to 5°C and stirred overnight. The obtained crystals were filtered off, washed with cold water (300 mL) and cold n-heptane (300 mL) and dried under vacuum to give the product as off-white crystals (47.55 g, 94.5% yield). 1H NMR (600 MHz, DMSO-^6) δ ppm 7.57 (t, 1 H), 7.42 - 7.49 (m, 2 H), 7.18 (s, 1 H), 7.08 - 7.14 (m, 1 H), 5.80 (dd, 1 H), 4.54 (d, 1 H), 3.51 (dd, 1 H), 3.08 (dd, 1 H), 2.36 (tt, 1 H), 1.74 -1.93 (m, 4 H), 0.99 - 1.41 (m, 4 H). HR-MS: m/z = 315.1517 ([M+H]⁺).

[0187] Example 7: Synthesis of trans- l-(4-hydroxycyclohexyl)-2-[(5S)-6-fluoro-5H- imidazo[l,5-b]isoindol-5-yl]ethanone (L)-Dibenzoyl tartaric acid salt

[0188] To a solution of (trans)-2-(6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl)-l-(4- hydroxycyclohexyl)ethanone (50.0 g, 159.1 mmol, 1.0 equiv.) in EtOH (150 mL) was added at 70 °C a solution of (L)-Dibenzoyl tartaric acid (79.8 g, 222.7 mmol, 1.4 equiv.) in EtOH (150 mL) over a period of lh. The obtained mixture was heated to 73 °C and stirred for 9h. The resulting suspension was cooled to 20 °C and stirred for 8h, the product was filtered off, washed with EtOH (80 mL) and dried under vacuum to yield the product as white crystals (95.13 g, 88.9% yield). 1H-NMR (600 MHz, DMSO-^6 ) δ ppm 12.14 - 15.42 (m, 1 H), 7.97 - 8.07 (m, 4 H), 7.69 - 7.77 (m, 3 H), 7.56 - 7.64 (m, 4 H), 7.41 - 7.52 (m, 2 H), 7.26 (s, 1 H), 7.09 - 7.19 (m, 1 H), 5.79 - 5.92 (m, 3 H), 4.36 - 4.69 (m, 1 H), 3.48 - 3.58 (m, 1 H), 3.27 - 3.35 (m, 2 H), 3.12 (dd, J=18.4, 9.1 Hz, 2 H), 2.30 - 2.41 (m, 1 H), 1.76 - 1.89 (m, 4 H), 1.04 - 1.37 (m, 4 H). HR-MS: m/z 315.1513 ([M+H]⁺).

Example 29: trans-l-(4-hydroxycyclohexyl)-2-[(5S)-6-fluoro-5H-imidazo[l,5-b]isoindol- 5-yl]ethanone

[0189] To a suspension of trans- l-(4-hydroxycy clohexyl)-2-[(5 S)-6-fluoro-5H- imidazo[l,5-b]isoindol-5-yl]ethanone (L)-Dibenzoyltartaric acid salt (80.0 g, 118.9 mmol,

1.0 equiv.) in water (256 mL) and 2-Me-THF (18 mL) was added at 11 °C a solution of K2HP04 (68.4 g in 112 g water, 392.5 mmol, 3.3 equiv.) over 1 h and the mixture was stirred for 20 min. Then the solid was filtered off, washed with water (200 mL) and n-heptane (200 mL) and the wet cake was then dissolved in 2-Me-THF (350 mL). Then the phases were separated, the organic phase was concentrated and to the resulting suspension was added at 28 °C over a period of 3h MTBE (190 g). The mixture was cooled to 20 °C over a period of 3h, stirred for 3 h, the product was filtered off, washed with MTBE/2-Me-THF (2: 1, 60 mL) and dried under vacuum to yield the product as white crystals (28.3 g, 76% yield). 1H- MR (600 MHz, DMSO-^6 ) δ ppm 7.57 (t, J=0.6 Hz, 1 H), 7.42 - 7.49 (m, 2 H), 7.18 (s, 1 H), 7.07 - 7.15 (m, 1 H), 5.80 (dd, J=9.1, 3.0 Hz, 1 H), 4.54 (d, J=4.4 Hz, 1 H), 3.51 (dd, J=18.4,

3.1 Hz, 1 H), 3.08 (dd, J=18.4, 9.2 Hz, 1 H), 2.30 - 2.41 (m, 1 H), 1.74 - 1.92 (m, 4 H), 1.01 - 1.40 (m, 4 H). HR-MS: m/z 315.1515 ([M+H]⁺).

Example 30: (lR,5S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(trans)-4- hydroxycyclohexyl)ethanol

[0190] To a suspension of trans- l-(4-hydroxycy clohexyl)-2-[(5 S)-6-fluoro-5H- imidazo[l,5-b]isoindol-5-yl]ethanone (50.0 g, 159.1 mmol, 1.0 equiv.) in 2-Me-THF (375 mL) was added at -10° C over a period of lh LiAlH(OtBu)3 (1M in THF, 175 mL, 175 mmol, 1.1 equiv.) and the resulting reaction mixture was stirred for 1.5 h. This reaction mixture was added at 0 °C to H2S04 (20 wt% aqu., 214.5 g) over a period of 15 min and the reaction mixture was allowed to warm to 23° C and stirred for lh. Then, the phases were separated, the organic layer was cooled to 15 °C and H2S04 (96 wt% aqu., 3.9 g) in water (100 mL) was added. The bi-phasic mixture was stirred for 15 min, the phases were separated. To the combined aqueous phases, citric acid (38.2 g) in water (100 mL) and 2-Me- THF (500 mL) was added and the pH was adjusted upon addition of NaOH (28% aqu.

solution, 155.6 g). After the addition of EtOH (25 mL), the bi-phasic mixture was heated to 50 °C and the phases were separated. The organic phase was concentrated and water was replaced by azeotropic distillation with 2-Me-THF (250 mL) and MeOH (250 mL). Then 250 mL MeOH were added, the solution was polish filtered, and then concentrated at 50 °C under vacuum to 150 mL. MeOH (25 mL) was added and then MTBE (750 mL) was added over 1 h. The mixture was stirred at 50 °C for lh, then cooled to -20 °C over a period of 7h and stirred for 3h at -20 °C. The title compound was filtered off, washed with MTBE (150 mL) and dried under vacuum to yield the product (42.0 g, 83.5% yield). 1H- MR (600 MHz, DMSO-^6 ) δ ppm 7.94 (s, 1 H), 7.36 - 7.48 (m, 2 H), 7.16 (s, 1 H), 7.02 - 7.12 (m, 1 H), 5.57 (t, J=5.1 Hz, 1 H), 4.56 (d, J=5.6 Hz, 1 H), 4.42 (d, J=4.4 Hz, 1 H), 3.34 - 3.42 (m, 1 H), 3.19 - 3.29 (m, 1 H), 2.23 - 2.33 (m, 1 H), 1.75 - 1.97 (m, 3 H), 1.61 - 1.72 (m, 1 H), 1.46 - 1.58 (m, 1 H), 0.89 - 1.15 (m, 5 H). HR-MS: m/z 317.1679 ([M+H]⁺).

Example 31: (lR,5S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(trans)-4- hydroxycyclohexyl)ethanol (CBS reduction)

[0191] Reactor 1 (2 L) was charged under inert atmosphere with trans- 1 -(4- hydroxycyclohexyl)-2-[(5S)-6-fluoro-5H-imidazo[l,5-b]isoindol-5-yl]ethanone (80 g, 254.5 mmol, 1.0 equiv.) and tetrahydrofuran (15 vol, 1200 mL). Reactor 2 (2.5 L) with overhead stirrer was charged under inert atmosphere with borane-THF complex in THF (2.2 equiv., 559.8 mmol, 1 mol/L, 560 mL) followed by a solution of (R)-2-methyl-CBS-oxazaborolidine (0.1 equiv., 25.45 mmol, 7.053g) in THF (0.35 vol, 28 mL), and mixed for 15 min at r.t., then cooled down to -20 °C. Contents of reactor 1 were added via pump to the reactor 2 over 5h, at -20 °C and then aged at -20 °C overnight (the reaction is usually complete at the end of addition, but can be let for 18 h at -20 °C). Reaction was quenched with methanol (3 vol, 240 mL) added dropwise at -15 °C over lh, followed by aqueous H2S04 (4 vol, 2 mol/L, 320 mL) added dropwise at -10 °C over 40 min. Next the reaction was warmed to r.t. and concentrated under vacuum to -350 mL (-35 °C jacket temperature) and water (250 mL) was added to reach a final volume of -600 mL. Then aqueous NH40H (3.15 vol, ~15w%, 255 mL) was added at 10-15 °C until pH reached -8 (measure with a pH meter probe) and the title compound crystallized out. The slurry was aged for 45 min at r.t., solid was filtered, cake washed with water (7 vol, 560 mL), and dried to provide 78 g (88.8% corrected yield).

Example 32: Synthesis of (lR,5S)-2-(6-fluoro-5H-imidazo[5,l-a]isoindol-5-yl)-l-(trans)- 4-hydroxycyclohexyl)ethanol monophosphate mono hydrate salt Crystallization procedure without milling.

[0192] To a suspension of (lR,5S)-2-(6-fluoro-5H-imidazo[5, l-a]isoindol-5-yl)-l-(trans)- 4-hydroxycyclohexyl)ethanol (50.0 g) in EtOH (93.9g) and water (44.5 g) was added at ambient temperature, phosphoric acid (85%, 19.3 g) and water (35.1 g). This mixture was heated to 53 °C and the clear solution was polish -filtered, the filter was washed with ethanol (27.3 g) and water (3.0 g) and the reaction mixture was cooled to 39 °C. Then seeding crystals (1.0 g in EtOH (4.28g) and water (0.75 g)) were added, the mixture was aged for 15 min and then cooled to 0 °C over a period of 3.5-4h. To the resulting suspension EtOH (556 g) was added over a period of 60-90 minutes and the suspension was stirred at 0 °C for 6-18h. The product was filtered off, washed with a mixture of EtOH (73.8 g) and water (8.2 g) and dried at 30-40 °C under vacuum to yield the title compound as white solid (64.1 g, 92.4 % yield). 1H MR (600 MHz, DMSO-^6): δ ppm 8.04 (d, J=0.7 Hz, 1 H), 7.43 - 7.46 (m, 1 H), 7.41 - 7.45 (m, 1 H), 7.20 - 7.22 (m, 1 H), 7.09 (ddd, 1 H), 5.59 (t, 1 H), 3.36 - 3.40 (m, 1 H), 3.23 - 3.28 (m, 1 H), 2.30 (dt, 1 H), 1.90 (ddd, 1 H), 1.79 - 1.81 (m, 1 H), 1.79 - 1.81 (m, 1 H), 1.64 - 1.68 (m, 1 H), 1.53 (dt, 1 H), 1.08 - 1.14 (m, 1H), 1.02 - 1.07 (m, 1 H), 1.01 - 1.06 (m, 1 H), 0.98 (br d, 2 H). HR-MS: m/z = 317.1663 ([M+H]⁺). Particle size distribution: d50 = 364 μιη, d90 = 592 μιη.

Crystallization procedure with wet-milling (high-sheer mixing).

[0193] To a suspension of (lR,5S)-2-(6-fluoro-5H-imidazo[5, l-a]isoindol-5-yl)-l-(trans)- 4-hydroxycyclohexyl)ethanol (30.0 g) in EtOH (56.3g) and water (26.7 g) was added at ambient temperature under stirring, phosphoric acid (85%, 11.6 g) and water (21.1 g). This mixture was heated to 55°C and the clear solution was polish-filtered, the filter was washed with ethanol (16.4 g) and water (1.8 g) and the reaction mixture was cooled to 39 °C. Then seeding crystals (0.45 mg in EtOH (2.25 g) and water (0.4 g)) were added, the mixture was aged for 5 min and then cooled to 0°C. To the resulting suspension EtOH (334 g) was added over a period of 60 minutes and the suspension was milled at 0-8 °C. The suspension was then heated to 35 °C, stirred for 2h, cooled to 0 °C and stirred for 14h at 0 °C. The obtained crystals were filtered off, washed with a mixture of EtOH (54 mL) and water (6 mL) and dried at 35 °C under vacuum for 16h to yield the title compound as white solid (36.7 g, 88.5 % yield). Particle size distribution: d50 = 67 μπι, d90 = 127 μπι.

Claims

We Claim:

1. A method for making a compound of Formula (I):

(I)

wherein X is halogen, the method comprising converting a compound of Formula (IX)

(IX)

to a compound of Formula (I).

The method of claim 1, wherein converting the compound of Formula (IX) to the compound of Formula (I) comprises

(I) ( )

and (b) converting the mixture of a compound of Formula (I) and a compound of Formula (Γ) to the compound of Formula (I).

(a) converting a compound of For a compound of Formula (IXa);

(IXa)

and

(b) converting a compound of Formula (IXa) to a compound of Formula (I).

The method of claim 2, wherein reducing the carbonyl in the compound of Formula (IX) comprises treating the compound of Formula (IX) with an aluminum or boron reducing agent.

The method of claim 2, further comprising

(a) treating the mixture of the compound of Formula (I) and the compound of

Formula (Γ) with a chiral acid to form a diastereoselective salt; and

(b) treating the diastereoselective salt with a base to provide the compound of

Formula (I).

The method of claim 2, further comprising cleaving a hydroxyl protecting group, PG, from a compound of Formula (II)

(Π)

to provide the compound of Formula (IX). The method of claim 6, further comprising reacting a compound of Formula (V)

(V)

wherein

PG is a hydroxyl protecting group, and

each R" is independently a Ci-C₆ alkyl group,

a compound of Formula (VI)

(VI)

to provide a compound of Formula (II).

The method of claim 7, further comprising:

(a) esterifying a compound of the structure

to provide a compound of Formula (Va)

(Va)

wherein R is a Ci-C₆ alkyl group;

(Vb)

and

(d) converting the compound of Formula (Vb) to a compound of Formula (V).

9. The method of claim 8, wherein the converting of the compound of Formula (Vb) to a compound of Formula (V) comprises treating the compound of Formula (Vb) with an alkyl phosphonate under basic conditions.

10. The method of claim 7, further comprising

(a) converting a compound of Formula (Via)

(Via)

to a compound of Formula (VIb)

(VIb)

wherein X is a halogen; and

(b) reacting the compound of F ) with a compound of Formula (Vic),

(Vic)

wherein X is a halogen,

to provide the compound of Formula (VI).

11. The method of claim 3, wherein converting the compound of Formula (IX) to the compound of Formula (IXa) comprises treating the compound of Formula (IX) with (L)-Dibenzoyltartaric acid salt and K₂HPO₄.

12. The method of claim 3, wherein converting the compound of Formula (IXa) to a compound of Formula (I) comprises reducing the carbonyl in the compound of Formula (IXa).

13. The method of claim 12, wherein reducing the carbonyl in the compound of Formula (IXa) comprises treating the compound of Formula (IXa) with an aluminum or boron reducing agent.

14. The method of claim 3, further comprising reducing the 4'-carbonyl group of a

compound of Formula (VIII)

(VIII)

to provide the compound of Formula (IX).

15. The method of claim 14, wherein reducing the 4'-carbonyl group of the compound of Formula (VIII) to provide the compound of Formula (IX) comprises treating the compound of Formula (VIII) with a ketoreductase.

16. The method of claim 15, further comprising reacting a compound of Formula (VII)

(VII)

wherein

each R' is independently Ci-C₆ alkyl or both R' combine with the oxygen atoms to which they are attached to form a 5- or 6- membered dioxanyl ring, and

each R" is independently a Ci-C₆ alkyl group, with a compound of Formula (VI)

(VI)

to provide the compound of Formula (VIII).

The method of claim 11, further comprising

(a) converting a compound of Formula (Via)

(Via)

a compound of Formula (VIb)

(VIb)

wherein X is a halogen; and

(b) reacting the compound of Formula (VIb) with a compound of Formula (Vic)

(Vic)

wherein X is a halogen,

to provide the compound of Formula (VI).

The method of claim 17, wherein the reacting of the compound of Formula (Via) and the compound of Formula (VIb) comprises a palladium catalyst.

The method of claim 2, further comprising (a) reacting a compound of Formula (VII)

(VII)

wherein

each R" is independently a Ci-C₆ alkyl group,

with a compound of Formula (VI)

(VI)

to provide the compound of Formula (VIII)

(VIII)

and

The method of claim 3, further comprising

(a) reacting a compound of Formula (V)

(V)

wherein

PG is a hydroxyl protecting group, and

each R" is independently a Ci-C₆ alkyl group,

a compound of Formula (VI)

(VI)

to provide a compound of Formula (II)

(Π)

and

The method of claim 1, wherein the compound of Formula (I) is isolated as a mixture of diastereomers in a ratio of 97:3 or greater. The method of claim 1, wherein the compound of Formula (I)