High-purity 2'-deoxy-2',2'-difluorotetrahydrouridine and method for producing the same

Abstract

The present invention relates to a method for synthesizing 2'-deoxy-2',2'-difluorotetrahydrouridine with improved purity and a uniform particle size distribution. In particular, the method of the present invention includes crystallization and isolation procedures that provide synthetic reaction intermediates. The present invention further includes compositions that include the final compound in a highly purified form, with fewer impurities and lower levels of individual and total impurities.

Description

Technical Field

[0001] Declaration of Priority This application claims the benefit of U.S. Provisional Application Serial No. 62 / 912,317, filed October 8, 2019, the entire contents of which are incorporated herein by reference.

Background Art

[0002] The present invention relates to a method for synthesizing 2'-deoxy-2',2'-difluorotetrahydrouridine having improved purity and a uniform particle size distribution. In particular, the method of the present invention includes crystallization and isolation procedures that provide synthetic reaction intermediates and final compounds in high purity form.

[0003] Some important chemotherapeutic compounds are analogs of the nucleotide cytidine, including, for example, decitabine, gemcitabine, 5-azacytidine, ara(C), tiazacytidine, 5-fluoro-2'-deoxycytidine, and cytochlor. As analogs of cytidine, the compounds are subject to degradation by the enzyme cytidine deaminase (CDA), which degrades the compounds into inactive metabolites. The presence of CDA limits the effectiveness of cytidine analogs, requiring higher and / or more frequent dosing of the analogs to achieve a therapeutic effect.

[0004] One approach to overcoming this problem is to co-administer a CDA inhibitor with the cytidine analog, thereby blocking the degradation of the analog. One class of CDA inhibitors is the 2'-deoxy-2',2'-difluorotetrahydrouridine compounds. U.S. Patent No. 8,268,800, which is incorporated herein by reference in its entirety, discloses compounds of this class, including Compound 1 below.

Chemical Formula

[0005] There is a need for a more efficient process for manufacturing CDA inhibitors, such as 2'-deoxy-2',2'-difluorotetrahydrouridine, for use in methods of treating cancer and other disorders. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0006] The present invention relates to the development of a more efficient method for synthesizing 2'-deoxy-2',2'-difluorotetrahydrouridine compounds and intermediates involved in the synthesis. Previous synthetic methods in the art were inconvenient due to the use of an inefficient transfer hydrogenation process and the use of preparative HPLC for isolating the final compound. The inventors of the present invention have developed a synthetic method with improved efficiency that achieves the ability of the final compound to be purified by precipitation or crystallization, for example, crystallization-induced diastereoselective transformation (CIDT) (see International Patent Publication No. 2015 / 066162 pamphlet) where a mixture of epimers is converted to the desired compound, thus resulting in an increased yield of the desired epimer. The present invention improves this method by reducing impurities, improving yield, shortening reaction time, and / or otherwise improving the conditions for production on an industrial scale.

[0007] Another aspect of the present invention relates to a method for producing the following compound 1 (named ((4R)-1-[(2R,4R,5R)-3,3-difluoro-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl]-4-hydroxytetrahydropyrimidin-2(1H)-one)) or a salt thereof. CHEMICAL FORMULA The method comprises (a) hydrogenating a compound of formula IV below to produce a compound of formula IIa below, [Chemistry] Here, R is a hydroxyl protecting group. [Chemistry] (b) Reducing the compound of formula IIa to produce a compound of formula IIIa below. [Chemistry] (c) Deprotecting the compound of formula IIIa to produce compound 2 below. [Chemistry] And (d) Precipitating or crystallizing the compound 2 in the presence of a catalyst to produce compound 1 below or a salt thereof. [Chemistry] including the steps of wherein the method includes one or more of the following optional combinations (i) The hydrogenation step (a) is carried out using a palladium catalyst under a hydrogen atmosphere; (ii) The reduction step (b) is carried out at a temperature of about -12°C to about -5°C; (iii) The deprotection step (c) is carried out in the presence of an organic base; and / or (iv) The post-treatment of the deprotected compound from the deprotection step (c) is carried out under non-aqueous conditions. In some embodiments, the present invention further includes a step where the final product is recrystallized, the recrystallization is carried out at a pH of about 6.0 to about 7.4, and the final product is dissolved at a temperature of about 50°C to about 55°C to form a solution, and then the solution is cooled to about 5°C.

[0008] Still another aspect of the present invention relates to the following high-purity Compound 1 (e.g., Compound 1 having a purity of at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or at least about 99.9%) or a salt thereof.

Chemical formula

[0009] The high-purity Compound 1 can be produced by the method of the present invention. Another aspect of the present invention relates to Compound 1 containing a smaller number of impurities and / or lower levels of individual impurities and total impurities as compared to Compound 1 produced by conventional methods.

Mode for Carrying Out the Invention

[0010] The present invention will be described below with reference to the accompanying examples in which embodiments of the present invention are shown. However, the present invention can be embodied in many different forms and should not be construed as limited to the embodiments described herein.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the detailed description herein are for the purpose of describing particular embodiments only and are not intended to limit the present invention.

[0012] Unless the context otherwise indicates, it is specifically intended that the various features of the invention described herein can be used in any combination. Further, the invention also contemplates that in some embodiments of the invention, any feature or combination of features described herein can be excluded or omitted. For purposes of illustration, if the specification of the present application states that a composition contains components A, B, and C, it is specifically intended that any one or combination of A, B, or C can be omitted and discarded either singly or in any combination.

[0013] For the purposes of this specification, where there is any ambiguity between a written chemical name and a depicted chemical structure, the depicted chemical structure shall prevail.

[0014] Definitions

[0015] As used herein, "a", "an", or "the" can mean one or more. For example, "a" compound can mean a single compound or a plurality of compounds.

[0016] Also, as used herein, "and / or" refers to any and all possible combinations of one or more of the recited related items, and includes them, and where interpreted as an alternative ("or") does not include combinations and includes them.

[0017] When referring to measurable values, such as amounts of dosages (e.g., amounts of compounds), etc., the term "about" as used herein is meant to include variations of ±10%, ±5%, ±1%, ±0.5%, or even ±0.1% of the specified amount.

[0018] As used herein, the terms "comprise", "comprises" and "comprising" are intended to specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, actions, elements, and / or groups thereof.

[0019] As used herein, the transitional phrase "consisting essentially of" is to be interpreted as the claim encompassing the specified materials or steps, and those materials or steps that do not materially affect the basic and novel characteristics of the invention recited in the claim. Thus, the term "consisting essentially of" as used in a claim or the description of the invention is not intended to be interpreted as equivalent to "comprising".

[0020] As used herein, the terms "increase", "increases", "increased", "increasing", and like terms denote an increase of at least about 25%, at least about 50%, at least about 75%, at least about 100%, at least about 150%, at least about 200%, at least about 300%, at least about 400%, at least about 500%.

[0021] As used herein, the terms "reduce", "reduces", "reduced", "reduction", and like terms can mean a reduction of at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 35%, at least about 50%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 97%. In certain embodiments, the reduction results in no or essentially no (i.e., even a small amount, such as less than about 10% or even less than 5%) detectable activity or amount.

[0022] The term "the salt" includes pharmaceutically acceptable salts. The term "pharmaceutically acceptable salts" generally means non-toxic salts of the compounds used in the present invention, which are prepared by reacting the free acid with a suitable organic or inorganic base, or the free base with a suitable organic or inorganic acid. Examples of such salts include, but are not limited to, acetate, benzenesulfonate, benzoate, bicarbonate, bisulfate, bitartrate, borate, bromide, calcium, calcium edetate, camsylate, carbonate, chloride, clubranate, citrate, dihydrochloride, edetate, edisylic acid salt, estolate, esylate, fumarate, gluceptate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate, hydrabamine, hydrobromide, hydrochloride, hydroxynapthoate, iodide, isothionate, lactate, lactobionate, laurate, malate, maleate, mandelate, mesylate, methyl bromide, methyl nitrate, methyl sulfate, mucate, napsylate, nitrate, oleate, oxalate, pamoate, palmitate, pantothenate, phosphate / diphosphate, polygalacturonate, potassium, salicylate, sodium, stearate, subacetate, succinate, tannate, tartrate, teoclate, tosylate, triethiodide, and valerate.

[0023] As used herein, the term "Bronsted-Lowry base" refers to a species having the ability to accept a proton.

[0024] As used herein, the term "hydroxyl protecting group" can be any suitable hydroxyl protecting group, i.e., a labile chemical moiety known in the art for protecting a hydroxyl group against unwanted reactions during synthetic procedures. After one or more of such synthetic procedures, the blocking groups described herein can be selectively removed. See, e.g., A. Isidro-Llobet et al., Amino Acid-Protecting Groups, Chem. Rev. 109:2455-2504 (2009) and T. Greene and P. Wuts, Protective Groups in Organic Synthesis (3d Ed. 1999). In some embodiments, the hydroxyl protecting group is an acid-stable hydroxyl protecting group. Examples of hydroxyl protecting groups include, but are not limited to, alkyl, cycloalkyl, arylalkyl, aryl, ether, ester, cyclic ether, cyclic ester, acetal, cyclic acetal, ketal, and cyclic ketal groups, where the protecting group can be removed under acidic or basic conditions such that it is replaced by a hydrogen atom. Specific hydroxyl protecting groups include, but are not limited to, methyl, ethyl, acetate, ethyl acetate, propionate, ethylene glycol, propylene glycol, 4-methoxybenzyl, benzyl, trityl, trimethylsilyl, tetrahydropyranyl, and benzoyl. Other hydroxyl protecting groups include methoxymethyl (MOM), methylthiomethyl (MTM), t-butylthiomethyl, (phenyldimethylsilyl)methoxymethyl (SMOM), benzyloxymethyl (BOM), p-methoxybenzyloxymethyl (PMBM), (4-methoxyphenoxy)methyl (p-AOM), guaiacolmethyl (GUM), t-butoxymethyl, 4-pentenyl-oxymethyl (POM), siloxymethyl, 2-methoxyethoxymethyl (MEM), 2,2,2-trichloroethoxymethyl, bis(2-chloroethoxy)methyl, 2-(trimethylsilyl)ethoxymethyl (SEMOR), tetrahydropyranyl (THP), 3-bromotetrahydropyranyl, tetrahydrothiopyranyl, 1-methoxycyclohexyl, 4-methoxytetrahydropyranyl (MTHP), 4-methoxytetrahydrothiopyranyl, 4-methoxytetrahydrothiopyranyl S,S-dioxide, 1-[(2-chloro-4-methyl)phenyl]-4-methoxypiperidin-4-yl (CTMP), 1,4-dioxan-2-yl, tetrahydrofuranyl, tetrahydrothiofuranyl, 2,3,3a,4,5,6,7,7a-octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, 1-methyl-1-methoxyethyl, 1-methyl-1-benzyloxyethyl, 1-methyl-1-benzyloxy-2-fluoroethyl, 2,2,2-trichloroethyl, 2-trimethylsilylethyl, 2-(phenylselenyl)ethyl, t-butyl, allyl, p-chlorophenyl, p-methoxyphenyl, 2,4-dinitrophenyl, benzyl, p-methoxybenzyl, 3,4-dimethoxybenzyl, o-nitrobenzyl, p-nitrobenzyl, p-halobenzyl, 2,6-dichlorobenzyl, p-cyanobenzyl, p-phenylbenzyl, 2-picolyl, 4-picolyl, 3-methyl-2-picolyl N-oxide, diphenylmethyl, p,p'-dinitrobenzhydryl, 5-dibenzosuberil, triphenylmethyl, α-naphthyldiphenylmethyl, p-methoxyphenyldiphenylmethyl, di(p-methoxyphenyl)phenylmethyl, tri(p-methoxyphenyl)methyl, 4-(4'-bromophenacyloxyphenyl)diphenylmethyl, 4,4',4''-tris(4,5-dichlorophthalimidophenyl)methyl, 4,4',4''-tris(levulinoyloxyphenyl)methyl, 4,4',4''-tris(benzoyloxyphenyl)methyl, 3-(imidazol-1-yl)bis(4',4''-dimethoxyphenyl)methyl, 1,1-bis(4-methoxyphenyl)-1'-pyrenylmethyl, 9-anthryl, 9-(9-phenyl)xanthenyl, 9-(9-phenyl-10-oxo)anthryl, 1,3 - benzodithiolan - 2 - yl, benzisothiazolyl S,S - dioxide, trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), dimethylisopropylsilyl (IPDMS), diethylisopropylsilyl (DEIPS), dimethyltexylsilyl, t - butyldimethylsilyl (TBDMS), t - butyldiphenylsilyl (TBDPS), tribenzylsilyl, tri - p - xylylsilyl, triphenylsilyl, diphenylmethylsilyl (DPMS), t - butylmethoxyphenylsilyl (TBMPS), formate, benzoylformate, acetate, chloroacetate, dichloroacetate, trichloroacetate, trifluoroacetate, methoxyacetate, triphenylmethoxyacetate, phenoxyacetate, p - chlorophenoxyacetate, 3 - phenylpropionate, 4 - oxopentanoate (levulinate), 4,4 - (ethylenedithio)pentanoate (levulinoyl dithioacetal), pivaloate, adamantoate, crotonate, 4 - methoxycrotonate, benzoate, p - phenylbenzoate, 2,4,6 - trimethylbenzoate (mesitoate), alkyl methyl carbonate, 9 - fluorenylmethyl carbonate (Fmoc), alkyl ethyl carbonate, alkyl 2,2,2 - trichloroethyl carbonate (Troc), 2 - (trimethylsilyl)ethyl carbonate (TMSEC), 2 - (phenylsulfonyl)ethyl carbonate (Psec); 2 - (triphenylphosphonio)ethyl carbonate (Peoc), alkyl isobutyl carbonate, alkyl vinyl carbonate alkyl allyl carbonate, alkyl p - nitrophenyl carbonate, alkyl benzyl carbonate, alkyl p - methoxybenzyl carbonate, alkyl 3,4-Dimethoxybenzyl carbonate, alkyl o-nitrobenzyl carbonate, alkyl p-nitrobenzyl carbonate, alkyl S-benzyl thiocarbonate, 4-ethoxy-1-naphthyl carbonate, methyl dithiocarbonate, 2-iodobenzoate, 4-azidobutyrate, 4-nitro-4-methylpentanoate, o-(dibromomethyl)benzoate, 2-formylbenzenesulfonate, 2-(methylthiomethoxy)ethyl, 4-(methylthiomethoxy)butyrate, 2-(methylthiomethoxymethyl)benzoate, 2,6-dichloro-4-methylphenoxyacetate, 2,6-dichloro-4-(1,1,3,3-tetramethylbutyl)phenoxyacetate, 2,4-bis(1,1-dimethylpropyl)phenoxyacetate, chlorodiphenylacetate, isobutyrate, monosuccinoate, (E)-2-methyl-2-butenoate, o-(methoxycarbonyl)benzoate, α-naphthoate, nitrate, alkyl N,N,N',N'-tetramethylphosphorodiamidate, alkyl N-phenylcarbamate, borate, dimethylphosphinothioyl, alkyl 2,4-dinitrophenylsulfenate, sulfate, methanesulfonate (mesylate), benzylsulfonate, and tosylate (Ts), including but not limited to these. Methods for protecting and deprotecting hydroxyl groups are well known and can be found, for example, in Protective Groups in Organic Synthesis (T. Green and P. Wuts; 3rd Edition; John Wiley and Sons, 1999).

[0025]

Chemical formula

[0026]

Chemical formula

[0027] As used herein, the term "g / g" refers to grams per gram of substrate. The substrate is defined as 1 equivalent within each process, and all other aspects within the process are defined relative to the substrate.

[0028] The term "enantiomer" refers to stereoisomers of a compound that are mirror images of each other and cannot be superimposed. In this application, unless otherwise stated or indicated, the chemical names of compounds refer to mixtures of all possible stereochemically isomeric forms.

[0029] The term "diastereomer" refers to stereoisomers of a compound that have different configurations at one or more stereocenters but are not mirror images of each other (and thus are not enantiomers).

[0030] The term "epimer" refers to two diastereomers that differ from each other at only one stereocenter.

[0031] The term "alkyl" means a straight-chain or branched-chain hydrocarbon chain containing 1 to 12 carbon atoms, such as 1 to 6 or 1 to 4 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, etc.

[0032] The term "aryl" refers to an aromatic monocyclic ring system of 5 to 8 members or a bicyclic ring system of 8 to 12 members. The term also includes aromatic bicyclic ring systems in which a hydrogen atom is attached to one, two, or three of the ring carbons at one of the rings (e.g., a partially saturated ring). Examples of aryl groups include phenyl, naphthyl, etc.

[0033] The term "acyl" means an alkyl or aryl group bonded to a carbonyl group. Examples of acyl groups include formyl, acetyl, propionyl, acrylyl, benzoyl, etc.

[0034] As used herein, the term "benzoyl" refers to the acyl of benzoic acid (bonded through the carbonyl carbon) and has the following structure. [Chemical formula]

[0035] Compound

[0036] One aspect of the present invention relates to Compound 1 (or a salt thereof) produced by the method of the present invention, particularly Compound 1 in free base form having a high purity (e.g., epimeric purity or a small amount of impurities, solvents, reaction by-products and / or decomposition products). Another aspect of the present invention relates to Compound 1 having a purity of at least about 80% by weight, such as at least about 85% by weight, at least about 90% by weight, at least about 95% by weight, at least about 96% by weight, at least about 97% by weight, at least about 98% by weight, at least about 99% by weight, at least about 99.5% by weight, or at least about 99.9% by weight. In some embodiments, Compound 1 contains less than about 20% by weight, such as less than about 15% by weight, less than about 10% by weight, less than about 5% by weight, less than about 4% by weight, less than about 3% by weight, less than about 2% by weight, less than about 1% by weight, less than about 0.9% by weight, less than about 0.8% by weight, less than about 0.7% by weight, less than about 0.6% by weight, less than about 0.5% by weight, less than about 0.4% by weight, less than about 0.3% by weight, less than about 0.2% by weight, or less than about 0.1% by weight, of impurities, solvents, reaction by-products and / or decomposition products, such as the impurities shown in Tables 1 and 4 below. In some embodiments, Compound 1 contains less than 20% by weight, such as less than about 15% by weight, less than about 10% by weight, less than about 5% by weight, less than about 4% by weight, less than about 3% by weight, less than about 2% by weight, less than about 1% by weight, less than about 0.9% by weight, less than about 0.8% by weight, less than about 0.7% by weight, less than about 0.6% by weight, less than about 0.5% by weight, less than about 0.4% by weight, less than about 0.3% by weight, less than about 0.2% by weight, or less than about 0.1% by weight, of its corresponding enantiomer and / or epimer of Compound 1.Another further aspect of the present invention relates to Compound 1 having a molar ratio of the desired epimer (Compound 1) to another epimer (Compound 6) of at least about 60:40, such as at least about 70:30, at least about 80:20, at least about 90:10, at least about 95:5, at least about 96:4, at least about 97:3, at least about 98:2, or at least about 99:1, for example, having an epimer purity of at least about 60 wt%, such as at least about 70 wt%, about 80 wt%, at least about 90 wt%, at least about 95 wt%, at least about 96 wt%, at least about 97 wt%, at least about 98 wt%, at least or at least about 99 wt%, for example, 99.5 wt% or 99.9 wt%.

[0037] In some embodiments, Compound 1 (or a salt thereof) produced by the method of the present invention contains less than 20 different measurable impurities, such as less than 15 impurities, such as less than 15, less than 14, less than 13, less than 12, less than 11, less than 10, less than 9, less than 8, less than 7, or less than 6, for example, less than 5 purity. As used herein, "measurable impurities" refers to impurities that can be detected by methods routinely used in the art for testing chemical purity, such as HPLC or mass spectrometry. Measurable impurities are impurities present in an amount greater than 0.03 wt%.

[0038] In some embodiments, Compound 1 (or a salt thereof) produced by the method of the present invention contains less than about 4.0 wt% of the epimer Compound 6, such as less than about 3.5 wt%, less than about 3.0 wt%, less than about 2.5 wt%, less than about 2.0 wt%, less than about 1.9 wt%, less than about 1.8 wt%, less than about 1.7 wt%, less than about 1.6 wt%, less than about 1.5 wt%, less than about 1.4 wt%, less than about 1.3 wt%, less than about 1.2 wt%, less than about 1.1 wt%, or less than about 1.0 wt%.

[0039] In some embodiments, Compound 1 (or a salt thereof) produced by the method of the present invention contains less than about 2.5% by weight of total impurities excluding epimeric Compound 6, for example, less than about 2.0% by weight, less than about 1.9% by weight, less than about 1.8% by weight, less than about 1.7% by weight, less than about 1.6% by weight, less than about 1.5% by weight, less than about 1.4% by weight, less than about 1.3% by weight, less than about 1.2% by weight, less than about 1.1% by weight, less than about 1.0% by weight, less than about 0.9% by weight, less than about 0.8% by weight, less than about 0.7% by weight, less than about 0.6% by weight, or less than about 0.5% by weight.

[0040] In some embodiments, Compound 1 (or a salt thereof) produced by the method of the present invention contains less than about 1.0% by weight of any individual impurity, including or excluding epimeric Compound 6, for example, less than about 1.0% by weight, less than about 0.95% by weight, less than about 0.9% by weight, less than about 0.85% by weight, less than about 0.8% by weight, less than about 0.75% by weight, less than about 0.7% by weight, less than about 0.65% by weight, less than about 0.6% by weight, less than about 0.55% by weight, less than about 0.5% by weight, less than about 0.45% by weight, less than about 0.4% by weight, less than about 0.35% by weight, less than about 0.3% by weight, less than about 0.25% by weight, less than about 0.2% by weight, less than about 0.15% by weight, or less than about 0.1% by weight.

[0041] A compound described herein may contain one or more chiral centers or, alternatively, may exist as multiple stereoisomers. The scope of the present invention includes pure stereoisomers as well as mixtures of stereoisomers, such as purified enantiomers / diastereomers / epimers, enantiomerically / diastereomerically / epimerically enriched mixtures, or racemates. In some embodiments, the compound has a stereochemical purity of at least about 80%, for example, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99%.

[0042] The compounds of the present invention can also, in some cases, exist as tautomers, for example, amide / iminol tautomers. Although only one delocalized resonance structure can be depicted, all such forms are contemplated within the scope of the present invention.

[0043] As described above, the compounds disclosed herein can be prepared in the form of their pharmaceutically acceptable salts. Pharmaceutically acceptable salts are salts that retain the desired biological activity of the parent compound and do not impart undesired toxicological effects. Examples of such salts include (a) acid addition salts formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid, etc.; and organic acids such as acetic acid, oxalic acid, tartaric acid, succinic acid, maleic acid, fumaric acid, gluconic acid, citric acid, malic acid, ascorbic acid, benzoic acid, tannic acid, palmitic acid, alginic acid, polyglutamic acid, naphthalenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, naphthalenedisulfonic acid, polygalacturonic acid, etc.; (b) salts formed with elemental anions such as chlorine, bromine, and iodine; and (c) salts with bases such as ammonium salts, alkali metal salts such as sodium and potassium alkali metal salts, alkaline earth metal salts such as calcium and magnesium alkaline earth metal salts, organic bases such as dicyclohexylamine and N-methyl-D-glucamine. In one embodiment, the compounds disclosed herein are prepared in the form of the free base.

[0044] It is also understood that the compositions herein include compounds and combinations with water, as in the case of hydrates, or other components, as in the case of solvates, in stoichiometric or non-stoichiometric amounts.

[0045] Synthesis Method Still another aspect of the present invention relates to a method for producing the following Compound 1 or a salt thereof.

Chemical Formula

Chemical formula

[0046] In one embodiment, the method produces compound 1.

[0047] The method utilizes crystallization-induced diastereoselective transformation (CIDT) to provide enhanced production of the desired epimer (Compound 1). Any suitable catalyst can be used in this method. As used herein with respect to the precipitation or crystallization step, the term "catalyst" refers to a compound that promotes the equilibrium between Compound 6 and Compound 1 when present in a sub-stoichiometric amount relative to Compound 2. Without being limited by mechanism, Compound 1 and its epimer Compound 6 are thought to be in equilibrium with the open aldehyde structure of the compound as an intermediate. The catalyst promotes the ring-opening of Compound 6 to its aldehyde form, thereby increasing the conversion from one epimer to the other, and is thought to act by equilibrating the amounts of Compound 1 and Compound 6 in solution, such that, depending on the use of a suitable solvent, Compound 1 preferentially precipitates or crystallizes from the solution. The catalyst is present in a catalytically effective amount. In some embodiments, the catalyst can be an acid, for example, an inorganic acid, for example, an organic acid, for example acetic acid or trifluoroacetic acid. In other embodiments, the catalyst can be a base, for example a Bronsted-Lowry base, for example a weak base (one that does not ionize completely in an aqueous solution). In other embodiments, the catalyst can be diisopropylethylamine or ammonium hydroxide. In some embodiments, the base has a basicity of 10 or more in the solvent. In some embodiments, for example, as reported in Bordwell, Acc. Chem. Res. 21:456 1988); Crampton, J. Chem. Res. (S) 22 (1997); Kaliurand et al., J. Org. Chem. 65(19):6202 (2000); Kaljurand et al, J. Org. Chem. 70(3):1019 (2005), the base has a pKa of 10 or more in a solvent, for example, DMSO. In some embodiments, the catalyst is a strong base.In some embodiments, the catalyst is a sterically hindered strong base, for example, a strong base, such as a strong base with low nucleophilicity. In some embodiments, the catalyst is 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU). The DBU can be present in any effective amount, for example, for example, about 1 mol% to about 20 mol%, for example, about 2 mol% to about 15 mol%, for example, about 5 mol% to about 10 mol%, for example, about 5 mol%, or for example, about 10 mol%, for example, about 1 mol%, about 2 mol%, about 3 mol%, about 4 mol%, about 5 mol%, about 6 mol%, about 7 mol%, about 8 mol%, about 9 mol%, about 10 mol%, about 11 mol%, about 12 mol%, about 13 mol%, about 14 mol%, about 15 mol%, about 16 mol%, about 17 mol%, about 18 mol%, about 19 mol%, or about 20 mol%.

[0048] Any solvent or combination of solvents that causes preferential precipitation or crystallization of Compound 1 over Compound 6 can be used. In one embodiment, the solvent is a solvent in which Compound 6 has a higher solubility than Compound 1. In some embodiments, the solution used to form the solution of Compound 2 comprises, consists essentially of, or consists of an organic solvent. In some embodiments, the solution comprises, consists essentially of, or consists of water or an aqueous solvent. In some embodiments, the solvent is a protic solvent. In some embodiments, the solvent is miscible with water. In certain embodiments, the solution is acetonitrile, acetone, tetrahydrofuran, dimethyl sulfoxide, or methanol. In certain embodiments, the solution is an aqueous solution of acetonitrile, an aqueous solution of acetone, an aqueous solution of tetrahydrofuran, an aqueous solution of dimethyl sulfoxide, or an aqueous solution of methanol. In certain embodiments, the solution is an aqueous solution of acetonitrile.

[0049] Precipitation or crystallization can be carried out for a time sufficient for an appropriate amount of Compound 1 to form, for example, from about 0.5 days to about 14 days, for example, about 1 to about 4 days, for example, about 2 to about 3 days, for example, about 3 to about 10 days, for example, about 4 to about 6 days. Precipitation or crystallization can be carried out at any appropriate temperature, for example, at approximately room temperature, optionally at a temperature of about 0 °C to about 10 °C. After precipitation or crystallization is complete, the precipitate can be collected, for example, by filtration, and washed, for example, with an aqueous acetonitrile solution and / or acetonitrile, optionally an aqueous acetonitrile solution and / or acetonitrile cooled to a temperature of about 0 °C to about 10 °C. Next, the precipitate can be dried, for example, under vacuum, at a temperature lower than about 45 °C. The progress of the reaction can be monitored, for example, by sampling the supernatant of the reaction mixture and determining the ratio of Compound 1 to Compound 6. Completion of the reaction is indicated by the presence of a 50:50 mixture of Compound 1 and Compound 6 in the supernatant. If this ratio has not been achieved, additional catalyst can be added and the reaction can be continued until completion.

[0050] Subsequent to precipitation or crystallization, Compound 1 can optionally be further purified by recrystallization or slurrying from, for example, an aqueous acetonitrile solution, with the addition of an acid, for example, trifluoroacetic acid. For example, the precipitate can be resuspended in water:acetonitrile at a ratio of about 1:2 to about 1:10 (volume / volume), heated to about 35 - 45 °C, and then cooled to about 0 °C. The resulting precipitate is washed with water:acetonitrile at a ratio of about 1:2 to about 1:10 (volume / volume), and then washed with acetonitrile, optionally cooled to a temperature of about 0 °C to about 10 °C. In certain embodiments, Compound 1 can optionally be further purified by other methods known in the art, such as HPLC.

[0051] In some embodiments, Compound 1 is further purified by recrystallization in acetone and water adjusted to a pH of about 6.0 to about 7.4 (e.g., about 6, about 6.1, about 6.2, about 6.3, about 6.4, about 6.5, about 6.6, about 6.7, about 6.8, about 6.9, about 7, about 7.1, about 7.2, about 7.3, or about 7.4, or any value or range therein) using, for example, formic acid solution alone or in combination with DBU solution. In some embodiments, the mixture is further heated, for example, to a temperature of about 50 °C to about 55 °C, at a rate of, for example, 0.5 to 1.5 °C / min, until complete dissolution is observed, filtered, washed with a mixture of acetone and water, and then cooled, for example, to a temperature of about 33 °C to about 43 °C, at a rate of, for example, 0.1 to 0.5 °C / min, seeded, and further cooled, for example, to about -10 °C to about 0 °C, at a rate of, for example, 0.1 to 0.5 °C / min, and then allowed to stand, and thereafter further preparation (e.g., filtration, washing, and drying) is performed as known in the art. In some embodiments, the recrystallization mixture is further heated to about 53 °C, filtered clear, and then cooled to a temperature of about 35 °C, seeded, cooled to a temperature of about -5 °C, and allowed to stand (e.g., aged) for about 12 to about 16 hours (e.g., about 12, about 13, about 14, about 15, or about 16 hours, or any value or range therein). The inventors of the present invention have found that the specific recrystallization parameters disclosed herein, such as higher temperatures and / or a specific range of pH, produce a higher purity product, improve the particle size distribution, and avoid dimerization impurities. In some embodiments, the method of the present invention produces a compound having a more uniform particle size distribution, such as a unimodal particle size distribution, centered, for example, at about 100 to 200 μm, for example, about 130 μm. In some embodiments, at least 50% of the particles have a size of 20 μm to 300 μm, for example, at least 60%, 70%, 80%, or 90%.

[0052] The molar ratio of Compound 1 (i.e., the desired epimer) to the epimer of Compound 1 (e.g., Compound 6) after precipitation or crystallization can be at least about 60:about 40, such as at least about 70:about 30, about 80:about 20, about 90:about 10, about 95:about 5, or about 98:about 2. The molar ratio of the desired epimer (Compound 1) to the other epimer (Compound 6) after the second purification step (e.g., recrystallization or slurrying) can be at least about 80:about 20, such as at least about 90:about 10, about 95:about 5, or about 98:about 2.

[0053] Another aspect of the present invention relates to a method for producing the following compound or a salt thereof 1.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0054] The starting compound of formula IV can be obtained commercially, for example, from Aurora Fine Chemicals (San Diego, CA), or can be synthesized by known methods, for example, by the methods described in Wheeler et al., J. Labeled Compounds Radiopharm. 29:583 (1991) and Chou et al., Synthesis 6:565 (1992), which are incorporated herein by reference in their entirety.

[0055] The hydrogenation of the compound of formula IV in step (a) to produce the compound of formula IIa can be carried out by methods known in the art, such as those disclosed in U.S. Patent No. 8,268,800 and / or Patent Publication International Patent Publication No. 2015 / 066162 pamphlet, the disclosures of which are incorporated herein by reference in their entirety. For example, this step can be carried out under catalytic transfer hydrogenation conditions, for example in the presence of palladium on carbon (Pd / C), for example in the presence of about 5% Pd / C. The amount of catalyst used in the hydrogenation step (a), for example Pd / C, can be any catalytically effective amount, for example a catalyst amount of 0.1 part by weight or less per 1 part by weight of the compound of formula IV. In some embodiments, the amount of Pd / C used in the hydrogenation step (a) can be, for example, about 0.025 to about 0.05 parts of Pd / C per 1 part by weight of the compound of formula IV. The hydrogenation can be effected by heating the compound of formula IV to reflux in a solvent, for example in an aqueous ethyl acetate solution, with, for example, formic acid and hydrochloric acid, or with hydrogen (for example at a hydrogen pressure of about 2 to about 4 bar) and optionally acetic acid. The hydrogenation can be carried out at a temperature of about 0 °C to about 100 °C, for example about 50 °C to about 80 °C, for example about 63 °C to about 77 °C, for example for about 0.5 to about 48 hours, at about 68 °C, for example for about 5 to about 24 hours, about 10 to about 20 hours, or about 15 to about 20 hours, or any value or range therein, for example about 24 hours. The reagents used to affect the hydrogenation (for example, palladium and charcoal) can be added after the reaction mixture has been brought to an elevated temperature (for example, about 50 °C to about 80 °C, or about 68 °C). After completion, the catalyst can be removed, for example, by filtration at, for example, about 60 °C to about 70 °C, and can be washed, for example, with ethyl acetate. After separation of the organic layer, it can be washed, for example, with an aqueous potassium carbonate solution, an aqueous sodium bicarbonate solution, and / or an aqueous NaCl solution.The volume of the organic layer can be reduced (e.g., by distillation), and heated (e.g., at about 70 °C) until the residue is dissolved, and cooled (e.g., to about 45 °C to about 55 °C), seeded with the product, and can be stirred, e.g., for about 1 hour, e.g., at about 45 °C to about 55 °C. The volume of the reaction mixture can be reduced (e.g., by distillation), and methyl tert-butyl ether is slowly added at a temperature of about 40 °C to about 50 °C, then the reaction mixture is slowly cooled to about 0 °C to about 10 °C. The resulting suspension can be stirred, e.g., for about 2 to about 16 hours, and then filtered. The filtrate can be washed, e.g., with methyl tert-butyl ether and optionally cooled to about 0 °C to about 10 °C.

[0056] Alternatively, the filtrate from the hydrogenation reaction can be washed (e.g., with acetic acid), heated (e.g., to about 80 °C) to dissolve, and water (e.g., preheated to about 80 °C) can be added. After cooling, the precipitate can be collected by filtration, washed (e.g., with water and ethanol), and dried.

[0057] The solvent used in the hydrogenation step (a) herein can be any conventional solvent that does not adversely affect the reaction. Non-limiting examples of such solvents for hydrogenation include water, alcohols (e.g., methanol, ethanol, isopropanol, n-butanol, trifluoroethanol, ethylene glycol), ethers (e.g., tetrahydrofuran, dioxane, diethyl ether, diglyme), esters (e.g., methyl acetate, ethyl acetate), other organic solvents, and / or a mixed solvent of two or more solvents disclosed herein. The reaction can preferably be carried out in the presence of an organic acid, e.g., formic acid, acetic acid, oxalic acid, maleic acid, fumaric acid, malic acid, tartaric acid, citric acid, succinic acid, and / or benzoic acid. In some embodiments, the hydrogenation can be carried out in a mixed solvent containing ethyl acetate, acetic acid, and water.

[0058] In some embodiments, the hydrogenation can be carried out under an increased pressure (relative to atmospheric pressure), for example, from about 0.1 to about 1 megapascal (MPa), for example, about 0.1 MPa, about 0.15 MPa, about 0.2 MPa, about 0.25 MPa, about 0.3 MPa, about 0.35 MPa, about 0.4 MPa, about 0.45 MPa, about 0.5 MPa, about 0.55 MPa, about 0.6 MPa, about 0.65 MPa, about 0.7 MPa, about 0.75 MPa, about 0.8 MPa, about 0.85 MPa, about 0.9 MPa, about 0.95 MPa, about 0.96 MPa, about 0.97 MPa, about 0.98 MPa, about 0.99 MPa, about 1 MPa, or any value or range therein. In some embodiments, the hydrogenation step (a) can be carried out under ambient (e.g., ordinary, e.g., normal) pressure. In some embodiments, the hydrogenation step (a) can be carried out under an increased pressure of about 0.1 to about 0.85 MPa, or about 0.15 to about 0.73 MPa, or about 0.1 to about 0.5 MPa.

[0059] The reduction of the compound of formula IIa to the compound of formula IIIa in step (b) can be carried out by methods known in the art, such as those disclosed in U.S. Patent No. 8,268,800 and / or International Patent Publication No. WO 2015 / 066162 pamphlet. For example, the reduction can be carried out using a reducing agent, such as sodium borohydride, in an organic solvent, such as a mixture of methylene chloride and ethanol. The reduction can be carried out at any suitable temperature, for example, from about -5°C to about 10°C, for example, from about 0°C to about 5°C, for about 0.5 to 3 hours, for example, about 1.5 hours.

[0060] In some embodiments, the reduction can be carried out at a temperature of from about -12°C to about -3°C, such as about -12°C, about -11°C, about -10°C, about -9°C, about -8°C, about -7°C, about -6°C, about -5°C, about -4°C, or about -3°C, or any value or range therebetween. In some embodiments, the reduction can be carried out at a temperature of from about -11°C to about -3°C, from about -12°C to about -5°C, from about -11°C to about -5°C, or from about -10°C to about -6°C, or at a temperature of about -8°C. The present invention is based in part on the surprising discovery that unusually low temperature conditions (e.g., a temperature of from about -11°C to about -5°C) minimize the formation of impurities, such as DPU and DCU and indirectly CYU (which is generated by the conversion of DCU in a subsequent step), but not limited thereto, which are not further purged in the formation of Compound 1. Exemplary impurity structures are shown in Table 1 below.

[0061]

Table 1

[0062] The reduction can optionally be carried out in the presence of cerium trichloride. In one embodiment, the amount of cerium chloride is about 50 mol% (e.g., 50 mol%). In another embodiment, the amount of cerium chloride is about 20 mol% or about 10 mol% (e.g., 20 mol% or 10 mol%). Following the addition of cerium(III) chloride, the reaction mixture can be heated (e.g., to about 15°C to about 25°C) before being cooled, for example, for about 20 minutes.

[0063] Subsequent to this reduction, the reaction can be quenched, for example, with acetone and the solution can be neutralized with an acid, for example, citric acid. The organic layer containing the compound of formula IIIa is separated and can be washed, for example, with water. The organic layer is heated (for example, to about 20 °C to about 30 °C) and the pH can be adjusted with an acid (for example, citric acid), and thus the process is repeated until the pH stabilizes. The organic layer can be washed (for example, with sodium bicarbonate) at a temperature of, for example, about 20 °C to about 35 °C and then can be washed with water at a temperature of about 0 °C to about 10 °C. The volume of the organic phase can be reduced (for example, by distillation), methyl tert-butyl ether can be added, and the resulting precipitate can be collected, washed with methyl tert-butyl ether, cooled to about 0 °C to about 10 °C, and dried.

[0064] The deprotection of the compound of formula IIIA to produce compound 2 in step (c) is carried out by methods known in the art, such as those disclosed in U.S. Patent No. 8,268,800 and / or International Patent Publication No. WO 2015 / 066162 pamphlet. For example, the deprotection can be carried out in the presence of a weak base, such as ammonium hydroxide, in a solvent, such as methanol. In some embodiments, the deprotection can be carried out in the presence of one or more bases selected from the group consisting of organic bases such as DBU, trimethylamine, N,N-dimethyl-4-aminopyridine (DMAP), and 1,3-diazabicyclo[2.2.2]octane (DABCO). In some embodiments, the deprotection can be carried out in the presence of ammonia, in a solvent, such as methanol, at a temperature of about 20°C to about 30°C. The amount of the organic base used in the deprotection is an amount that is necessary and should not be limited as long as it does not cause any adverse effects, such as side reactions. In some embodiments, the amount of the organic base used in the deprotection is about 0.01 to about 2.2 moles per mole of the compound of formula IIIa (e.g., about 0.01 mole, about 0.02 mole, about 0.03 mole, about 0.04 mole, about 0.05 mole, about 0.1 mole, about 0.2 mole, about 0.3 mole, about 0.4 mole, about 0.5 mole, about 0.6 mole, about 0.7 mole, about 0.8 mole, about 0.9 mole, about 1.0 mole, about 1.1 mole, about 1.2 mole, about 1.3 mole, about 1.4 mole, about 1.5 mole, about 1.6 mole, about 1.7 mole, about 1.8 mole, about 1.9 mole, about 2.0 mole, about 2.1 mole, about 2.15 mole, about 2.16 mole, about 2.17 mole, about 2.18 mole, about 2.19 mole, or about 2.2 moles per mole of the compound of formula IIIa, or any value or range therein). For example, in some embodiments, the deprotection step (c) can be carried out in the presence of about 0.01 to about 2.2 moles of an organic base per mole of the compound of formula IIIa, or about 0.05 to about 2.0 moles of an organic base per mole of the compound of formula IIIa, or about 1.0 to about 1.9 moles of an organic base per mole of the compound of formula IIIa. The deprotection can be carried out for about 12 to about 48 hours, such as about 24 hours.Following deprotection, the mixture is concentrated, dissolved in an aqueous solvent, such as water, and can be washed with an organic solvent, such as ethyl acetate.

[0065] In some embodiments, after deprotection, the workup can be carried out under non-aqueous conditions, for example using an evaporative solvent exchange process. The inventors of the present invention have discovered that the use of a non-aqueous evaporative solvent exchange process forms a non-tacky solid and avoids hydrolysis instability and dimer formation. In some embodiments, after deprotection, it can be further milled to remove impurities, such as genotoxic impurities, such as benzamide, but not limited thereto. In some embodiments, deprotection in the non-aqueous workup can be carried out using isopropanol and / or acetonitrile.

[0066] In some embodiments, the non-aqueous workup can be carried out by reducing the volume of the reaction mixture (e.g., by distillation under reduced pressure), adding methanol and continuing to reduce the volume, adding isopropanol and acetonitrile, and continuing to reduce the volume, and then adding acetonitrile and continuing to reduce the volume. Next, the reaction product can be cooled to, for example, about 0 °C to about 10 °C for, for example, 1 to 2 hours and maintained for, for example, 1 to 6 hours. The solid product can be collected and washed with acetonitrile.

[0067] The precipitation or crystallization of compound 2 to form compound 1 in step (d) can be carried out as described above.

[0068] In some embodiments, the precipitation or crystallization of compound 2 in step (d) to form compound 1 can proceed by suspending the compound, optionally under cooling, in the presence of DBU, acetic acid, trifluoroacetic acid, diisopropylethylamine, and / or ammonium hydroxide.

[0069] In some embodiments, the method of the present invention may include steps (a) to (d), wherein the reduction step (b) is carried out at a temperature of about -12°C to about -3°C, thereby minimizing the formation of DCU and DPU and, indirectly, CYU. CYU is not successfully purged from the remaining synthesis. In some embodiments, the method of the present invention may further include performing a work-up of the compound deprotected in the deprotection step (c) under non-aqueous conditions (e.g., evaporation solvent exchange), thereby producing a non-tacky solid and / or avoiding the formation of dimers. In some embodiments, the method of the present invention may include that the deprotection step (c) may further include a grinding step, thereby removing genotoxic impurities, such as benzamide. In some embodiments, the method of the present invention may further include recrystallizing the final product, wherein the recrystallization is carried out at a pH of about 6.0 to about 7.4 and at a temperature of about 50°C to about 55°C.

[0070] In some embodiments, the method of the present invention may include steps (a) to (d), wherein the hydrogenation step (a) is carried out using a palladium catalyst under a hydrogen atmosphere, and / or the deprotection step (c) is carried out in the presence of an organic base. In particular, with respect to step (a), International Patent Publication No. WO 2015 / 066162 pamphlet discloses that, like the improved method disclosed in US Patent No. 8,268,800, the hydroxyl group is protected and then, in the presence of a substantial amount of Pd / C, a hydrogenation step is carried out using a large amount of formic acid, resulting in successful high-yield hydrogenation. However, the improved process from International Patent Publication No. WO 2015 / 066162 pamphlet still has other drawbacks from the perspective of industrial production. For example, a large amount of expensive Pd / C is used, and a large amount of formic acid, which is not suitable as a reagent for industrial production, is used. The present invention enables the hydrogenation step (a) to be carried out in a high yield and high purity by carrying out the hydrogenation step under a hydrogen atmosphere in the presence of a catalytic amount of a palladium catalyst. In addition, the deprotection reaction of International Patent Publication No. WO 2015 / 066162 pamphlet needs to be carried out using ammonia over a long period of time, which is troublesome for industrial-scale production and generates impurities that are difficult to remove. Compared with the specification of US Patent No. 8,268,800, the hydrogenation step is carried out using an unprotected hydroxyl group in the presence of a large amount of expensive rhodium catalyst, resulting in, for example, high manufacturing costs, low-purity products, and difficulties in purification by chromatography. The problems of International Patent Publication No. WO 2015 / 066162 pamphlet and the specification of US Patent No. 8,268,800 are overcome by the present invention disclosed herein.

[0071] Use

[0072] Compound 1 produced by the present invention or a pharmaceutically acceptable salt thereof can inhibit CDA activity. Compound 1 or a pharmaceutically acceptable salt thereof can be in the form of a pharmaceutical composition, for example, together with pharmaceutically acceptable additives. In some embodiments, Compound 1 or a pharmaceutically acceptable salt thereof can be used in combination with a CDA substrate agent, such as a CDA substrate agent that can be used to treat cancer, in a method for treating cancer in a subject in need thereof. Examples of CDA substrate agents include, but are not limited to, decitabine, 5-azacitidine, gemcitabine, ara-C, tesacytidine, 5-fluoro-2'-deoxycytidine, and cytochlor. In some embodiments, the cancer can be selected from the group consisting of hematological cancers and solid cancers. In certain embodiments, the hematological cancer can be myelodysplastic syndrome or leukemia, such as acute myeloid leukemia or chronic myeloid leukemia. In certain embodiments, the solid cancer can be pancreatic cancer, ovarian cancer, peritoneal cancer, non-small cell lung cancer, metastatic breast cancer, bladder cancer, squamous cell carcinoma, transitional cell carcinoma, adenocarcinoma, gynecological cancer, fallopian tube carcinoma, liver cancer, hepatocellular carcinoma, lung cancer, cervical cancer, genitourinary cancer, or gastrointestinal cancer. In some embodiments, Compound 1 or a pharmaceutically acceptable salt thereof can be administered substantially simultaneously with the CDA substrate agent, optionally in a single unit dosage form or in multiple individual unit dosage forms, before or after the CDA substrate agent. Embodiments according to the present invention are described in the following non-limiting examples.

[0073] Example

[0074] Example 1. Hydrogenation step (a) The hydrogenation of the compound of formula IV (1 equivalent) in step (a) for producing the compound of formula IIa was carried out at a temperature of 63 °C to 77 °C for at least 12 hours using hydrogen at a hydrogen pressure of 2 to 4 bar and acetic acid (80%, 2.62 g / g) in ethyl acetate (8.97 g / g) in the presence of Pd / C (5%, 0.05 g / g) in water (1.98 g / g). After completion, the catalyst was removed by filtration, and the filter cake was washed with ethyl acetate (6.73 g / g). After cooling, the filtrate was washed with an aqueous potassium carbonate solution. The organic layer was washed with an aqueous sodium bicarbonate solution (7% weight / weight, 5.38 g / g) and then with an aqueous NaCl solution (10% weight / weight, 3 g / g). The organic layer was distilled to a residual volume of about 8 volumes, heated to 70 °C until the residue was dissolved, and then cooled to 45 °C to 55 °C. The reaction product was seeded with the compound of formula IIa, and the reaction mixture was distilled to a residual volume of about 2 volumes, and methyl tert-butyl ether (4.44 g / g) was slowly added at a temperature of 40 °C to 50 °C. After cooling the mixture, the precipitated crystals were collected on a filter, washed with methyl tert-butyl ether (1.48 g / g) cooled to 0 °C to 10 °C, and the product was dried to obtain the compound of formula IIa. Yield: 86%. Chemical purity: 98.9%.

[0075] Example 2. Reduction Impurities during Reduction Step (b) The compound of formula IIa (1 equivalent) was dissolved in dichloromethane (14.6 g / g) and stirred. Ethanol (5.83 g / g) was added and the reaction mixture was cooled to -5 °C to 5 °C. Cerium(III) chloride heptahydrate (0.08 g / g) was added and the reaction was heated to 15 °C to 25 °C. Next, water (0.68 g / g) was added and the reaction was stirred for at least 20 minutes. Then it was cooled to 0 °C to -11 °C. Sodium borohydride (0.11 g / g) was added portionwise while maintaining the temperature between 0 °C and -11 °C and stirred until the reaction was complete. Acetone (0.73 g / g) was added and the temperature was maintained between 0 °C and -11 °C. An aqueous solution of citric acid (3.7 - 4.4%, weight / weight) was slowly added until the pH reached 6.5 - 7.5. The phases were allowed to settle and the aqueous phase was separated. The organic phase was washed with an aqueous solution of sodium bicarbonate and then further washed with water. The phases were separated and the organic phase was further washed with water. The organic phase was distilled under vacuum at 35 °C or below until it reached about 2 volumes, then methyl tert-butyl ether (7.38 g / g) was added and distilled under vacuum at 35 °C or below until it reached 4.8 volumes. Further methyl tert-butyl ether (2.67 g / g) was added and the reaction mixture was cooled to 0 °C to 10 °C over 4 hours or more. Further methyl tert-butyl ether (0.89 g / g) was added and the reaction mixture was stirred at this temperature, then the solid product was isolated and washed with methyl tert-butyl ether (1.46 g / g) pre-cooled to 0 °C to 10 °C, and the product was dried to give formula IIIa. Yield: 76%. Chemical purity: 93%.

[0076] The processes of Entry Nos. 1 - 5 were carried out in the same manner as above except that the reduction temperature was changed to 0 °C, -3 °C, -5 °C, -8 °C and -11 °C respectively. As shown in Table 2 below, the formation of DCU, DPU and CYU was minimized by the low temperature. The structures of the impurities are shown in Table 1.

[0077]

Table 2

[0078] Example 3. Improvement in the deprotection step (c) Deprotection was carried out in a solution of ammonia (0.87 g / g) in methanol (4.95 g / g). The compound of formula IIIa (1 equivalent) and further methanol (1.58 kg / kg) were added. The reaction mixture was adjusted to 20 °C - 30 °C and stirred at this temperature until completion. Workup was carried out by distilling the reaction mixture under reduced pressure until the residual volume was about 3 volumes. Methanol (1.58 g / g) was added and distillation was continued under reduced pressure until the residual volume was about 3 volumes. Isopropanol (1.92 g / g) was added, followed by acetonitrile (3.93 g / g), and distillation was continued under reduced pressure until the residual volume was about 3 volumes. Acetonitrile (5.51 g / g) was added and distilled under reduced pressure until a residual volume of 5 volumes was reached. Further, acetonitrile (1.58 g / g) was added and distilled under reduced pressure until a residual volume of about 5 volumes was reached. After the mixture was cooled, the solid product was isolated and washed with acetonitrile (1.56 g / g) pre-cooled to 0 °C - 10 °C. The wet product was mixed with acetonitrile (2.37 g / g). After the mixture was cooled, the wet product was dried to give Compound 2. Yield: 87%. Chemical purity: 97%.

[0079] Reference Example 4. Original deprotection step (c) Deprotection was carried out by treatment with ammonia (7.0 M in methanol, 25 equivalents). The mixture was stirred at 25 °C for 27 hours and then concentrated under reduced pressure. The residue was dissolved in water (6.3 volumes) and washed twice with ethyl acetate (5.7 volumes each). The aqueous layer was concentrated under reduced pressure at a temperature below 35 °C to give Compound 2 (95% yield).

[0080] Continuing forward using typical process conditions, compound 2 generated from the original deprotection conditions typically resulted in compound 1 with overall low purity and a significantly high number of impurities. See Table 3, entries 1 and 2 below.

[0081] Example 5. Very specific crystallization conditions at high temperature Conditions for the crystallization of compound 1 to improve purity were tested. It was found that very specific crystallization conditions produced a very pure substance, improved the control of the particle size distribution within an optimal (monomodal) range, reduced the level of acetonitrile, and avoided dimerization impurities. The specific conditions include an adjustment to a higher temperature and pH used.

[0082] The preferred process for the recrystallization of compound 1 was carried out by mixing compound 2 (1 equivalent), 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU, 0.028 g / g), acetonitrile (5.02 g / g) and water (0.73 g / g), and stirring at 15 °C to 25 °C for 2 hours. The mixture was cooled to 0 °C to 10 °C over 1 hour or more and maintained at this temperature for 1 to 8 hours. The solid product was collected by filtration and washed with acetonitrile:water (0.21 g / g:0.033 g / g) cooled to 0 °C to 10 °C. The wet product and acetonitrile (2.36 g / g) were stirred at 0 °C to 10 °C for 30 minutes to 8 hours. The solid product was collected and washed with acetonitrile (0.78 g / g) cooled to 0 °C to 10 °C. The wet product was dried to give crude compound 1. Yield: 80%. Chemical purity: 94%.

[0083] Crude compound 1 (1 equivalent), acetone (6.26 g / g), and water (2 g / g) were mixed at a temperature of 20 °C to 30 °C. The pH of the reaction mixture was adjusted to 6.0 to 7.5 with an aqueous solution of formic acid (0.0076 g / g formic acid in 1.25 g / g water). If necessary, an aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene DBU (0.041 g / g DBU in 0.78 g / g water) can be used to adjust the pH to the target range. The reaction mixture was heated to 50 °C to 55 °C until complete dissolution was observed and then filtered into a reactor set at 40 °C to 50 °C and washed with a mixture of water (0.1 g / g) and acetone (0.31 g / g). The solution was cooled to 33 °C to 43 °C and seeded with 0.005 g / g of compound 1. The reaction was maintained at this temperature before being cooled to -10 °C to 0 °C. The suspension was maintained at -10 °C to 0 °C for 12 to 16 hours and separated by filtration. The product was washed with acetone (0.78 g / g) and dried to give compound 1. Yield: 61%. Chemical purity excluding epimers: 99.6%. The compound 6 of the following formula, which is an epimer of compound 1, was produced in the following ratio. Compound 1: Compound 6 = 99.6:0.4. (PSD: D(0.9) = 252 μm, D(0.5) = 125 μm, D(0.1) = 21 μm).

[0084] Example 6. Comparison with the original production process Crude compound 1 (1 equivalent) was suspended in a mixture of acetone (2.5 ml / g) and water (2.5 ml / g) and stirred at 25 ± 2 °C for 2 hours. The mixture was cooled to 5 ± 2 °C, stirred for 2 hours, and then filtered. The filter cake was rinsed with acetone (2 x 0.55 ml / g) and dried in vacuo at 55 °C. Compound 1 was obtained in 67% yield. Chemical purity excluding epimers: 99.4%. The compound 6 of the following formula, which is an epimer of compound 1, was produced in the following ratio. Compound 1: Compound 6 = 98.7:1.3.

[0085] The overall purity and the ratio of Compound 1 to Compound 6 are lower in the original process compared to the updated purification process. The impurity profile is shown in Table 3. The structures of the monitored impurities are shown in Table 4.

[0086]

Table 3

[0087]

Table 4

[0088] Example 7. Alternative Methods for Steps (a) to (c) Process (a):

[0089]

Chemical Formula

[0090] Compound (2-1) (20.0 g, 42.4 mmol), a mixture of ethyl acetate (200 mL), acetic acid (80 mL) and water (50 mL) were dissolved with stirring at 50 - 60 °C under a nitrogen atmosphere, and then 0.2 g of Pd / C (10 wt%, 5 wt% on dry basis, 50% water-wetted, NEs-5DR type) was added thereto, and the atmosphere in the reaction vessel was replaced with nitrogen. Subsequently, the atmosphere was replaced with hydrogen, and the reaction mixture was stirred at 50 - 60 °C under an increased pressure of hydrogen (0.5 MPa) for 18 hours. The reaction mixture was filtered, and the residue on the filter was washed with 20 mL of 80% acetic acid. The ethyl acetate in the filtrate was removed under vacuum (100 Torr, 50 °C). The residue was heated to 80 °C to dissolve it, and 400 mL of water pre-heated to 80 °C was added thereto. After the mixture was cooled, the precipitated crystals were collected on a filter, washed with water and ethanol, and dried to obtain 19.24 g of Compound (3-1) (yield: 95.6%, chemical purity: 98.4%).

[0091] Process (b) and Process (c)

[0092]

Chem.

[0093] Synthesis of Compound (4-1) : Compound (3-1) (19.0 g, 40.0 mmol) was dissolved in methylene chloride (228 mL) with stirring. Ethanol (152 mL) and cerium(III) chloride heptahydrate (1.49 g, 4.0 mmol) were added to the solution, and the mixture was cooled to a temperature below 6 °C. A solution of sodium borohydride (3.77 g, 100 mmol) in water (19 mL) was added dropwise to the cooled mixture while maintaining the temperature below 6 °C. After the addition, the reaction mixture was reacted at a temperature below 6 °C for 2 hours. While maintaining the temperature of the reaction mixture below 6 °C, the reaction mixture was quenched with 9.5 mL of acetone with stirring, and then 114 mL of 0.5 M aqueous hydrochloric acid was added thereto to adjust the quenched mixture to pH 7 while maintaining the temperature below 6 °C. After the mixture was warmed to 30 - 40 °C, 114 mL of saturated aqueous sodium bicarbonate solution was added to the mixture. The mixture was separated in a separatory funnel, the organic layer was washed with 114 mL of water, and the solvent was removed under vacuum (50 Torr, 40 °C). The resulting compound (4-1) was used in the next step without purification.

[0094] Synthesis of Compound 5 : To the compound (4-1) obtained in step (b), methanol (190 mL) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (0.30 mL, 2.0 mmol) were added, and the mixture was warmed to 40 °C and stirred at 40 °C for 3 hours. After the reaction, methanol was removed under vacuum (50 Torr, 40 °C), and 95 mL of acetonitrile was added to the residue. After cooling, the precipitated crystals were collected on a filter, washed with cold acetonitrile, and dried to give 8.96 g of compound 5 (yield: 83.4%, chemical purity: 97.1%).

[0095] Step (d)

[0096]

Chem.

[0097] Synthesis of Crude Compound (1) : Compound (5) (0.9 g, 3.35 mmol), acetonitrile (5.8 mL), water (0.65 mL) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (0.025 mL, 0.17 mmol) were suspended, and the suspension was continuously stirred at 20 - 30 °C for 48 h. After cooling, the precipitated crystals were collected on a filter, washed with cooled 90% acetonitrile and then with acetonitrile, and dried to give 0.66 g of Compound 1 (yield: 73.0%, chemical purity: 98.3%). Compound 5: Compound 6 (epimer of Compound 5) = 98.9:1.1.

[0098] Purification of Crude Compound 1: Compound 1 (0.3 g, 1.11 mmol) was suspended in a mixture of acetonitrile (0.96 mL) and water (0.24 mL), and the suspension was stirred for 2 h while heating to 40 - 50 °C. Next, the suspension was stirred at a temperature below 5 °C for 2 h. The obtained precipitate was collected on a filter, washed with cooled 90% acetonitrile and then with acetonitrile, and dried to give 0.66 g of Compound 1 (yield: 73.5%, chemical purity: 99.6%). Compound 6 of the following formula, which is an epimer of Compound 1, was produced in the following ratio. Compound 1: Compound 6 = 99.7:0.3.

[0099]

Chem.

[0100] The total amount of impurities contained in the purified Compound 1 was 0.46% in area percentage. Separately from this, Compound 1 was prepared from the same material and purified by the method disclosed in Patent Document 2 (International Patent Publication No. 2015 / 066162 Pamphlet), but the total amount of impurities in it was more (2.46%) than that of the above process, which means that the process of the present invention can provide a method for preparing Compound 1 in a higher yield.

[0101] Embodiment Embodiments of the present invention include, but are not limited to, the following.

[0102] 1. A method for producing the following Compound 1 or a salt thereof, comprising:

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0103] 2. The method according to embodiment 1, wherein the catalyst is about 1 mol% to about 20 mol% of DBU.

[0104] 3. The method according to embodiment 2, wherein the catalyst is about 5 mol% to about 10 mol% of DBU.

[0105] 4. The method according to embodiment 3, wherein the catalyst is about 5 mol% of DBU.

[0106] 5. The method according to embodiment 1, wherein the catalyst is acetic acid, trifluoroacetic acid, diisopropylethylamine, or ammonium hydroxide.

[0107] 6. The method according to embodiments 1 to 5, wherein the deprotection step (c) further includes a grinding step.

[0108] 7. The method according to embodiments 1 to 6, further including recrystallizing or slurrying Compound 1.

[0109] 8. The method according to embodiment 7, wherein the recrystallization is carried out at a pH of about 6.0 to about 7.4 and a temperature of about 50°C to about 55°C.

[0110] 9. The method according to embodiments 1 to 8, wherein step (d) is carried out in the presence of a solution containing acetonitrile.

[0111] 10. The method according to embodiments 1 to 8, wherein step (d) is carried out in the presence of a solution containing acetone or tetrahydrofuran.

[0112] 11. The method according to any one of embodiments 1 to 10, wherein step (b) is carried out in the presence of CeCl3.

[0113] 12. The method according to any one of embodiments 1 to 11, wherein R is a benzoyl group.

[0114] 13. The method according to any one of embodiments 1 to 12, wherein the palladium catalyst used in step (i) is palladium on carbon (Pd / C).

[0115] 14. The method according to embodiment 13, wherein the amount of Pd / C used in step (i) is a catalytic amount of 0.1 part by weight or less per 1 part by weight of the compound of formula IV.

[0116] 15. The method according to embodiment 13, wherein the amount of Pd / C used in step (i) is 0.025 to 0.05 part by weight per 1 part by weight of the compound of formula IV.

[0117] 16. The method according to any one of embodiments 1 to 15, wherein step (i) is carried out in a mixed solvent containing ethyl acetate, acetic acid and water.

[0118] 17. The method according to any one of embodiments 1 to 16, wherein step (i) is carried out under atmospheric pressure or elevated pressure.

[0119] 18. The method according to any one of embodiments 1 to 17, wherein step (i) is carried out under an elevated pressure of 0.1 to 0.5 MPa.

[0120] 19. The method according to any one of embodiments 1 to 18, wherein the organic base used in step (iii) is one or more bases selected from the group consisting of DBU, triethylamine, DMAP and DABCO.

[0121] 20. The method according to any one of embodiments 1 to 19, wherein the amount of the organic base used in step (iii) is 0.01 to 2.2 moles per 1 mole of the compound of formula IIIa.

[0122] 21. The method according to any one of embodiments 1 to 20, wherein the organic base used in step (iii) is DBU.

[0123] 22. A composition of the following compound 1 or a salt thereof,

Chemical formula

[0124] 23. The composition according to embodiment 24, wherein no impurities are present at a level greater than 0.5 wt%, greater than 0.25 wt%, greater than 0.2 wt%, greater than 0.15 wt%, greater than 0.1 wt%, greater than 0.05 wt%, or greater than 0.01 wt%.

[0125] 24. A composition of the following compound 1 or a salt thereof,

Chemical formula

[0126] 25. The composition according to embodiment 26, containing measurable impurities less than 10, less than 9, less than 8, less than 7, less than 6, or less than 5.

[0127] The above are examples of the present invention and should not be construed as limiting thereof. The present invention is defined by the following claims, and equivalents to the claims are included in the claims.

[0128] All publications, patent applications, patents, and other references cited herein are incorporated by reference in their entirety for the teachings relevant to the sentences and / or paragraphs where the reference is presented.

Claims

1. A method for producing the following compound 1 or a salt thereof, comprising: 【Chemical 01】 (a) hydrogenating a compound of the following formula IV to produce a compound of the following formula IIa, 【Chemical 02】 wherein R is a hydroxyl protecting group; 【Chemical 03】 (b) reducing the compound of formula IIa to produce a compound of the following formula IIIa; 【Chemical 04】 (c) deprotecting the compound of formula IIIa to produce the following compound 2; 【Chemical 05】 and (d) precipitating or crystallizing the compound 2 in the presence of a catalyst to produce the following compound 1 or a salt thereof, 【Chemical 06】 including the steps of wherein the method includes the following (i) the hydrogenation step (a) is carried out using a palladium catalyst under a hydrogen atmosphere; (ii) the reduction step (b) is carried out at a temperature of -12°C to -5°C; (iii) the deprotection step (c) is carried out in the presence of an organic base; and (iv) the post-treatment of the deprotected compound from the deprotection step (c) is carried out under non-aqueous conditions, said method.

2. The method according to claim 1, wherein the catalyst is 1 mol% to 20 mol% of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU).

3. The method according to claim 2, wherein the catalyst is 5 mol% to 10 mol% of DBU.

4. The method according to claim 3, wherein the catalyst is 5 mol% of DBU.

5. The method according to claim 1, wherein the catalyst is acetic acid, trifluoroacetic acid, diisopropylethylamine, or ammonium hydroxide.

6. The method according to claim 1, wherein the deprotection step (c) further includes a step of pulverizing after the deprotection, wherein the pulverization includes removing genotoxic impurities.

7. The method according to claim 6, wherein the genotoxic impurities include benzamide.

8. The method according to claim 1, further including recrystallizing or slurrying compound 1.

9. The method according to claim 8, wherein the recrystallization is carried out at a pH of 6.0 to 7.4, and compound 1 is dissolved at a temperature of 50°C to 55°C to form a solution, and then the solution is cooled to 5°C.

10. The method according to claim 1, wherein step (d) is carried out in the presence of a solution containing acetonitrile.

11. The method according to claim 1, wherein step (d) is carried out in the presence of a solution containing acetone or tetrahydrofuran.

12. Process (b) is carried out in the presence of CeCl 3 The method according to claim 1.

13. The method according to claim 1, wherein R is a benzoyl group.

14. The method according to claim 1, wherein the palladium catalyst used in step (i) is palladium on carbon (Pd / C).

15. The method according to claim 14, wherein the amount of Pd / C used in step (i) is a catalyst amount of 0.1 part by weight or less per 1 part by weight of the compound of formula IV.

16. The method according to claim 14, wherein the amount of Pd / C used in step (i) is 0.025 to 0.05 part by weight per 1 part by weight of the compound of formula IV.

17. The method according to claim 1, wherein step (i) is carried out in a mixed solvent containing ethyl acetate, acetic acid and water.

18. The method according to claim 1, wherein step (i) is carried out under atmospheric pressure or elevated pressure.

19. The method according to claim 1, wherein step (i) is carried out under an elevated pressure of 0.1 to 0.5 MPa.

20. The method according to claim 1, wherein the organic base used in step (iii) is one or more bases selected from the group consisting of DBU, triethylamine, N,N-dimethyl-4-aminopyridine and 1,3-diazabicyclo[2.2.2]octane.

21. The method according to claim 1, wherein the amount of the organic base used in step (iii) is 0.01 to 2.2 moles per 1 mole of the compound of formula IIIa.

22. The method according to claim 1, wherein the organic base used in step (iii) is DBU.

23. A pharmaceutical composition comprising the following compound 1 or a salt thereof, 【Chemical 07】 comprising less than 7 measurable impurities, having no impurities present at a level greater than 1.0% by weight of the composition, and having a purity of at least 90% by weight of the composition for compound 1.

24. The pharmaceutical composition according to claim 23, wherein the composition comprises less than 6 measurable impurities.

25. The pharmaceutical composition according to claim 23 or 24, wherein the composition comprises less than 5 measurable impurities.

26. The pharmaceutical composition according to any one of claims 23 to 25, having no impurities present at a level greater than 0.5% by weight.

27. The pharmaceutical composition according to any one of claims 23 to 26, having no impurities present at a level greater than 0.25% by weight.

28. The pharmaceutical composition according to any one of claims 23 to 27, wherein compound 1 has a purity of at least 99.5% by weight of the composition.

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