Daprodustat and a method for preparing the same cocrystal

Abstract

The present invention provides a crystalline form of daprodustat which is a co-crystal comprising daprodustat free acid and a pharmaceutically acceptable metal salt of daprodustat, wherein the metal salt is an alkali metal salt. The present invention also relates to a method for the preparation of co-crystals of daprodustat in good yield and high purity suitable for industrial scale, pharmaceutical compositions containing them, and their use in therapy. The present invention also provides an efficient process for the preparation of daprodustat or a pharmaceutically or veterinarily acceptable salt thereof in good yield and high purity suitable for industrial scale applications, including improved conditions for the preparation of important intermediates.

Description

Technical Field

[0001] Cross - reference to related applications This application claims priority to European Patent Application EP22382718.9 filed on July 26, 2022, European Patent Application EP22383096.9 filed on November 14, 2022, and European Patent Application EP23382239.4 filed on March 14, 2023.

[0002] The present invention provides a co - crystal comprising daprodustat free acid and a pharmaceutically acceptable metal salt of daprodustat, wherein the metal salt is an alkali metal salt, such as a sodium salt or a potassium salt, in a crystalline form of daprodustat. The present invention also relates to a method for preparing a co - crystal of daprodustat in good yield and high purity, a pharmaceutical composition containing them, and their use in therapy. The present invention also provides an efficient process for preparing daprodustat or a pharmaceutically or veterinarily acceptable salt thereof in good yield and high purity suitable for industrial - scale applications, including improved conditions for preparing important intermediates.

Background Art

[0003] N - [(1,3 - dicyclohexylhexahydro - 2,4,6 - trioxopyrimidin - 5 - yl) carbonyl] glycine, also known as daprodustat, a compound of formula (I), is an oral hypoxia - inducible factor prolyl hydroxylase inhibitor (HIF - PHI) first approved in Japan under the trade name Duvroq in the form of film - coated tablets with dosing strengths of 1, 2, 4, and 6 mg.

[0004]

Chemical formula

[0005] Daprodustat and its tautomer N-[(1,3-dicyclohexyl-6-hydroxy-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)carbonyl]glycine were first disclosed in Patent Document 1, which describes the preparation of daprodustat by using N,N'-dicyclohexylcarbodiimide (DCC) or N,N'-dicyclohexylurea (DCU) as starting materials. This method involves cyclizing the starting material with a malonic acid derivative to obtain 1,3-dicyclohexylbarbituric acid, followed by condensation with ethyl isocyanatoacetate and subsequent ester hydrolysis with an aqueous sodium hydroxide solution in ethanol. DCC is an acute skin irritant in sensitive individuals and is difficult to handle due to its low melting point, and as a result, it is not feasible for industrial use. Alternatively, reacting DCU with malonyl chloride, which is not only unstable and corrosive but also an environmentally unfriendly halogenated reagent.

[0006] Example 18 of Patent Document 1 discloses the preparation of daprodustat from the hydrolysis of a highly ethyl ester intermediate (i.e., ethyl (1,3-dicyclohexyl-6-hydroxy-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbonyl)glycinate) with an aqueous sodium hydroxide solution in ethanol followed by neutralization with hydrochloric acid. Then, according to Method 1 of Example 18, daprodustat is isolated from a mixture of diethyl ether and hexane. Alternatively, according to Method 2 of Example 18, hot filtration is used to isolate daprodustat from acetic acid to remove a small amount of insoluble material. These isolation methods have many drawbacks. For example, diethyl ether is volatile and explosive and is not suitable for use on an industrial scale; hexane is also an inappropriate solvent for industrial use due to its flammability and the safety precautions required for its safe handling; and acetic acid is difficult to remove due to its high boiling point, increasing the cost of the process.

[0007] Patent Document 2 discloses the preparation of the important intermediate 1,3-dicyclohexylbarbituric acid by reacting DCU with malonic acid in the presence of acetic acid and acetic anhydride. However, 1,3-dicyclohexylbarbituric acid is isolated by solvent evaporation, increasing the cost of the process on an industrial scale. Daprodustat is neither disclosed nor prepared.

[0008] In Non-Patent Document 1, which is prior art, the important ethyl isocyanatoacetate is prepared starting from glycine ethyl ester by using phosgene, which is very toxic by acute (short-term) inhalation exposure and is probably a carcinogen. Daprodustat is neither disclosed nor prepared.

[0009] Patent Document 3 discloses solid forms of daprodustat named CS1 and CS9, which have higher purity and lower hygroscopicity compared to the prior art solid form of daprodustat obtained by reproducing the above Method 2 (i.e., from recrystallization in acetic acid). However, the solid forms of CS1 and CS9 are isolated from slow evaporation, which is not feasible on an industrial scale. According to Patent Document 3, the kinetic solubility of CS1 in pure water is 0.014 mg / mL, and for CS9 it is 0.020 mg / mL, suggesting the insufficient water solubility of either form CS1 or form CS9 of daprodustat.

[0010] Patent Document 4 discloses crystalline forms of daprodustat named Form 3 and Form 4. Form 3 is prepared by crystallization from ethylbenzene, and Form 4 is prepared by slurrying daprodustat in diethyl ether. However, Form 3 seems to correspond to the prior art solid form obtained from the above Method 2, and Form 4 seems to correspond to the prior art solid form obtained from the above Method 1.

[0011] Therefore, there is a need to develop a solid form of daprodustat with better solubility to enhance bioavailability that can be easily manufactured on an industrial scale at low energy and low cost. Furthermore, it is also desirable to obtain an efficient and safe process for preparing daprodustat with high purity and high yield that can be easily applied on an industrial scale at low energy, low cost and with good yield.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0013]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0014] Daprodustat is a poorly soluble drug. In the case of poorly soluble drugs, it is important to increase solubility to enhance the bioavailability of the drug, thereby improving the efficacy and safety of daprodustat.

Means for Solving the Problems

[0015] The present invention refers to crystalline forms of daprodustat which are co-crystals comprising daprodustat free acid and pharmaceutically acceptable metal salts of daprodustat, wherein the metal salts are alkali metal salts, such as sodium salts or potassium salts. In particular, a co-crystal comprising daprodustat free acid and the sodium salt of daprodustat is herein referred to as crystalline form N2. In particular, another co-crystal comprising daprodustat free acid and the sodium salt of daprodustat is herein referred to as crystalline form N4. In particular, a co-crystal comprising daprodustat free acid and the potassium salt of daprodustat is herein referred to as crystalline form K2. In particular, another co-crystal comprising daprodustat free acid and the potassium salt of daprodustat is herein referred to as crystalline form K1. Advantageously, these co-crystals of daprodustat have improved properties such as solubility, hygroscopicity and stability as well as manufacturing behavior (compression, flowability, filterability, etc.), thereby being beneficial for the development of pharmaceutical products containing daprodustat.

[0016] Thus, a first aspect of the present invention relates to crystalline forms of daprodustat which are co-crystals comprising daprodustat free acid and pharmaceutically acceptable metal salts of daprodustat, wherein the metal salts are alkali metal salts, such as sodium salts or potassium salts.

[0017] In particular, the present invention relates to crystalline form N2 of daprodustat having an X-ray powder diffraction pattern comprising peaks at 2 theta values of 6.3° ± 0.2°, 7.4° ± 0.2°, 7.6° ± 0.2°, 11.4° ± 0.2° and 16.2° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0018] In particular, the present invention relates to crystalline form N4 having an X-ray powder diffraction pattern comprising peaks at 2 theta values of 6.4° ± 0.2°, 7.4° ± 0.2°, 7.6° ± 0.2°, 13.4° ± 0.2° and 16.7° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0019] In particular, the present invention relates to crystalline form K2 having an X-ray powder diffraction pattern comprising peaks at 2-theta values of 5.5° ± 0.2°, 6.3° ± 0.2°, 7.0° ± 0.2°, 16.8° ± 0.2° and 18.0° ± 0.2°, as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0020] In particular, the present invention relates to crystalline form K1 having an X-ray powder diffraction pattern comprising peaks at 2-theta values of 5.4° ± 0.2°, 7.9° ± 0.2°, 14.6° ± 0.2°, 15.6° ± 0.2° and 17.5° ± 0.2°, as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0021] The second and third aspects of the present invention provide a method for preparing a daptomycin crystalline form as defined herein.

[0022] The fourth aspect of the present invention is a pharmaceutical composition comprising a daptomycin crystalline form as defined herein, in particular a daptomycin crystalline form selected from the group consisting of crystalline form N2, crystalline form N4, crystalline form K2, crystalline form K1, and combinations thereof, and one or more pharmaceutically acceptable carriers, diluents or excipients.

[0023] The fifth aspect refers to a daptomycin crystalline form as defined herein for use in therapy, in particular for the treatment of renal anemia. This aspect can also be formulated as a method for treating renal anemia, which comprises administering to a subject (including humans) in need thereof a daptomycin crystalline form as defined herein and one or more pharmaceutically acceptable carriers, diluents or excipients.

[0024] The use of a daptomycin crystalline form as defined herein for the manufacture of a pharmaceutical composition for the treatment of renal anemia also forms part of the present invention.

[0025] The present invention also provides an efficient and environmentally friendly method for producing daprodustat or a salt thereof in good yield without requiring cumbersome and infeasible purification steps, applicable on an industrial scale and providing high purity conforming to pharmaceutical standards.

[0026] When the inventors hydrolyzed the ester intermediate, ethyl N-[(1,3-dicyclohexyl-6-hydroxy-2,4-dioxo-1,2,3,4-tetrahydro-5-pyrimidinyl)carbonyl]-glycinate according to the conditions disclosed in Example 18 of WO 2007 / 150011 A2 (i.e., in the presence of sodium hydroxide in ethanol followed by neutralization with hydrochloric acid), a daprodustat containing a significant amount of inorganic salts such as sodium chloride, which is difficult to separate by conventional purification techniques such as extraction, was obtained, and subsequently, an additional crystallization step in acetic acid was obtained, which requires hot filtration to remove inorganic materials, when added to a slurry in water.

[0027] Advantageously, the salts formed as by-products from the reaction of a quaternary ammonium hydroxide of the formula N[(C1-C4)alkyl]4OH, preferably tetramethylammonium hydroxide (TMAH), with an acid selected from formic acid, acetic acid, monochloroacetic acid, trichloroacetic acid, and trifluoroacetic acid (TFA) are soluble in the reaction medium that facilitates the isolation of the final daprodustat without requiring cumbersome and infeasible purification steps.

[0028] Accordingly, a sixth aspect of the present invention relates to a method for preparing a daprodustat of formula (I) or a pharmaceutically or veterinarily acceptable salt thereof, comprising converting a compound of formula (VI) to a daprodustat of formula (I) by hydrolysis in the presence of a quaternary ammonium hydroxide of the formula N[(C1-C4)alkyl]4OH, preferably tetramethylammonium hydroxide (TMAH), and a solvent, and optionally converting the daprodustat of formula (I) to a pharmaceutically or veterinarily acceptable salt thereof.

[0029] [Chemical formula] (In the formula, R is unsubstituted or independently selected from the group consisting of (C3-C6) cycloalkyl, heterocycloalkyl, aryl and heteroaryl, and in particular, (C3-C6) cycloalkyl, (C3-C 12 ) heterocycloalkyl, (C6-C 14 ) aryl and (C5-C 12 ) heteroaryl, and is a (C1-C 10 ) alkyl substituted with one or more substituents independently selected from the group consisting of, and preferably, R is ethyl.)

[0030] The compound of formula (VI) can be prepared from 1,3-dicyclohexylbarbituric acid of formula (V) obtained by reacting dicyclohexylurea (DCU) with malonic acid. The inventors have advantageously found that the crystallization of the important intermediate of formula (V) in the presence of a poor solvent, preferably water, avoids the solvent evaporation step for its isolation, which increases the cost of the method and the final cost of the pharmaceutical product.

[0031] Therefore, a seventh aspect of the present invention is a method for preparing the important intermediate 1,3-dicyclohexylbarbituric acid of formula (V), comprising: [Chemical formula] (i) reacting dicyclohexylurea (DCU) with malonic acid in the presence of Ac2O in acetic acid to obtain a compound of formula (V); (ii) adding a poor solvent, preferably water, in an amount of 1 to 10 volumes, preferably 3 to 6 volumes per gram of the compound of formula (V); (iii) optionally heating the mixture of step (ii) at a temperature of 20°C to 85°C, preferably 20°C to 30°C; (iv) isolating the compound of formula (V).

[0032] The eighth aspect of the present invention is a method for preparing a compound of formula (I), or a pharmaceutically or veterinarily acceptable salt thereof, comprising: a1) a step of preparing 1,3-dicyclohexylbarbituric acid of formula (V), comprising: [Chemical formula] (i) reacting dicyclohexylurea (DCU) with malonic acid in the presence of Ac2O in acetic acid to obtain a compound of formula (V); (ii) adding a poor solvent, preferably water, in an amount of 1 to 10 volumes, preferably 3 to 6 volumes per gram of the compound of formula (V); (iii) optionally heating the mixture of step (ii) at a temperature of 20°C to 85°C, preferably 20°C to 30°C; (iv) isolating the compound of formula (V); a2) reacting the 1,3-dicyclohexylbarbituric acid of formula (V) obtained in step (a1) with isocyanatoacetate of formula (IV) in the presence of a base and a solvent to obtain a compound of formula (VI); [Chemical formula] (wherein R is unsubstituted or independently selected from the group consisting of C3-C6 cycloalkyl, heterocycloalkyl, aryl and heteroaryl, especially (C3-C6) cycloalkyl, (C3-C 12 ) heterocycloalkyl, (C6-C 14 ) aryl and (C5-C 12 ) heteroaryl, and is preferably (C1-C 10 ) alkyl substituted with one or more substituents independently selected from the group consisting of, and preferably R is ethyl.) [Chemical formula] (wherein R is as defined above, and preferably R is ethyl) a3) a step of converting the compound of formula (VI) into the daprostatut of formula (I) by hydrolysis in the presence of a base and a solvent; a4) optionally, a step of converting the daprostatut of formula (I) into its pharmaceutically or veterinarily acceptable salt, refers to a method.

[0033] The ninth aspect of the present invention is a method for preparing a compound of formula (VI), comprising

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0034] Advantageously, in a continuous mode process starting from the intermediate of formula (III) from steps (b) and (c) of the present invention (i.e., in a one-pot reaction), by reacting 1,3-dicyclohexylbarbituric acid of formula (V) with the intermediate (IV) which is known to be unstable, the preparation of the important intermediate of formula (VI) after the process according to the ninth aspect, Scheme 1 increases the yield and chemical purity of the compound of formula (VI).

[0035]

Chemical formula

[0036] The tenth aspect of the present invention is a method for preparing daprodustat of formula (I), or a pharmaceutically or veterinarily acceptable salt thereof, comprising

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0037] Definition

[0038] When describing the compounds and methods of the present invention, the following terms have the following meanings unless otherwise indicated.

[0039] The term "about", as used herein, refers to a statistically significant range of values. Such a range can be within the experimental error typical of the standard methods used for the measurement and / or determination of a given value or range. In one embodiment, the range is within ± 5% of the indicated value. In another embodiment, the range is within ± 1% of the indicated value. In yet another embodiment, the range is within ± 0.5% of the indicated value.

[0040] As used herein, "alkyl" means a saturated, non - unsaturated, straight - or branched - chain hydrocarbon radical having 1 to 10 carbon atoms, represented as (C1 - C 10 ) alkyl. Such alkyl groups can be selected from methyl, ethyl, n - propyl, isopropyl, n - butyl, isobutyl, sec - butyl, tert - butyl, straight - or branched - pentyl, straight - or branched - hexyl, straight - or branched - heptyl, straight - or branched - nonyl, or straight - or branched - decyl.

[0041] The term "cycloalkyl" refers to a non - aromatic saturated cyclic hydrocarbon ring containing a specified number of carbon atoms. Thus, for example, the term "C3 - C6 cycloalkyl" refers to a non - aromatic cyclic hydrocarbon ring having 3 to 6 carbon atoms. Exemplary "C3 - C6 cycloalkyl" groups useful in the present invention include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0042] The term "heterocycloalkyl" means a saturated or having one or more degrees of unsaturation and containing one or more hetero - atom substituents independently selected from O, S, and N, and containing a specified number of ring atoms, for example, a non - aromatic heterocyclic ring having 3 to 12 carbon atoms, represented as (C3 - C 12 ) heterocycloalkyl. Such rings may optionally be fused to one or more other "heterocyclic" rings or cycloalkyl rings. Examples of "heterocyclic" moieties include, but are not limited to, aziridine, thiirane, oxirane, azetidine, oxetane, thietane, tetrahydrofuran, pyran, 1,4 - dioxane, 1,3 - dioxane, piperidine, piperazine, 2,4 - piperazinedione, pyrrolidine, imidazolidine, pyrazolidine, morpholine, thiomorpholine, tetrahydrothiopyran, tetrahydrothiophene, etc.

[0043] The term "aryl" means (C6 - C 14)Refers to a monocyclic and polycarbocyclic non-condensed or condensed group having 6 to 14 carbon atoms, optionally substituted, represented as aryl and having at least one aromatic ring conforming to Hückel's rule. (C6-C 14 )Examples of aryl groups are phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, etc.

[0044] The term "heteroaryl" means an aromatic monocyclic ring or polycarbocyclic condensed ring system having 5 to 12 carbon atoms, optionally substituted, represented as heteroaryl, at least one ring conforming to Hückel's rule, having the specified number of ring atoms, and the ring containing at least one heteroatom independently selected from N, O, and S. "(C5-C 12 )Refers to an aromatic monocyclic ring or polycarbocyclic condensed ring system having 5 to 12 carbon atoms, optionally substituted, represented as heteroaryl, at least one ring conforming to Hückel's rule, having the specified number of ring atoms, and the ring containing at least one heteroatom independently selected from N, O, and S. "(C5-C 12 )Examples of "(C5-C

[0045] As used herein, "hydrate" refers to a crystalline form of a molecule that further includes water incorporated into the crystal structure. The water molecules in the hydrate may be present in a regular arrangement and / or an irregular arrangement. The hydrate may contain either a stoichiometric amount or a non-stoichiometric amount of water molecules.

[0046] The term "solvate" refers to a crystalline form of a molecule that further includes solvent molecules incorporated into the crystal structure. When the solvent incorporated into the crystal is water, it is called a hydrate. The solvent molecules in the solvate may be present in a regular arrangement and / or an irregular arrangement. The solvate may contain either a stoichiometric amount or a non-stoichiometric amount of solvent molecules. The solvate may exhibit polymorphism.

[0047] As used herein, the term "cocrystal" is also known as a "crystalline molecular complex" and refers to a crystalline solid composed of two or more distinct chemical species within the same crystal lattice in a defined stoichiometric ratio and having distinct physical, crystallographic, and spectroscopic properties when compared individually to the chemical species. The present crystalline form is a cocrystal comprising the daprodustat free acid, a compound of formula (I), and a pharmaceutically acceptable metal salt of daprodustat, wherein the metal is an alkali metal such as sodium or potassium. The cocrystal can be in the form of a hydrate or a solvate.

[0048] Cocrystals are distinct from "salts" that contain charge-balanced charged species. The species that make up a cocrystal are typically neutral and are generally held together by weak, freely reversible non-covalent interactions. Weak interactions are defined as neither ionic nor covalent bond interactions and include hydrogen bonding, van der Waals forces, p-p interactions, and halogen bonding interactions. Cocrystals can generally be distinguished from salts by the absence of proton transfer between the chemical species. Thus, the cocrystals of the present invention are held together by weak interactions without proton transfer between the daprodustat free acid and the daprodustat metal salt.

[0049] As used herein, the term "particle size" with respect to the crystalline form of daprodustat in the form of needles (i.e., acicular form) refers to the average length of the needles observed in a microscopic image measured by an environmental scanning electron microscope (ESEM).

[0050] As used herein, the term "solvent" refers to water or organic molecules capable of at least partially dissolving another substance (i.e., solute). The solvent may be liquid at room temperature. The organic solvent may be liquid at room temperature. Suitable organic solvents are (C6~C 14 ) aromatic hydrocarbon solvents (e.g., benzene, toluene, o-xylene, m-xylene, and p-xylene), halogenated (C1~C 12) Hydrocarbon solvents (e.g., carbon tetrachloride, 1,2-dichloroethane, dichloromethane, chloroform, etc.), ester solvents (e.g., ethyl formate, methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, ethyl malonate, etc.), ketone solvents (e.g., acetone, methyl ethyl ketone or 2-butanone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 3-pentanone, etc.), (C1~C 12 ) Ether solvents (e.g., diethyl ether, dipropyl ether, diphenyl ether, isopropyl ether, tert-butyl methyl ether, tetrahydrofuran, 1,4-dioxane, etc.), amine solvents (e.g., propylamine, diethylamine, triethylamine, aniline, pyridine), (C1~C 12 ) Alcohol solvents (e.g., methanol, ethanol, isopropanol, 1-propanol, 2-methyl-1-propanol, 1-butanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, tert-butanol, 1-octanol, benzyl alcohol, phenol, trifluoroethanol, glycerol, ethylene glycol, propylene glycol, m-cresol, etc.), acid solvents (e.g., acetic acid, hexanoic acid, etc.), carbon disulfide, nitrobenzene, N,N-dimethylformamide, N,N,-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, acetonitrile, silicone solvents (e.g., silicone oil, polysiloxane, cyclic silicone), and hydrocarbon solvents (e.g., n-pentane, n-hexane, n-heptane, n-octane, paraffin, cyclohexane, methylcyclohexane, decahydronaphthalene, mineral oil, crude oil, etc.) may be included, but are not limited thereto. In some embodiments, the solvent may be formed by a combination of two or more solvents.

[0051] The term "aprotic solvent" as used herein, H +Any molecular solvent that cannot donate, i.e., a compound having no labile hydrogen. Suitable aprotic solvents include, but are not limited to, hydrocarbon solvents (e.g., n-pentane, n-hexane, n-heptane, n-octane, paraffin, cyclohexane, methylcyclohexane, etc.), halogenated hydrocarbon solvents (e.g., 1,2-dichloroethane, dichloromethane, chloroform, etc.), aromatic hydrocarbon solvents (e.g., toluene, o-xylene, m-xylene, and p-xylene, etc.), and ether solvents (e.g., diethyl ether, dipropyl ether, diphenyl ether, isopropyl ether, tert-butyl methyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, etc.), acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or N-methyl-2-pyrrolidone. Preferably, the aprotic solvent is dichloromethane, toluene or tetrahydrofuran.

[0052] The term "(C1-C3) alcohol" as used herein means methanol, ethanol, isopropanol or 1-propanol.

[0053] The terms "one-pot" reaction or "continuous mode" are generally known in the art and refer to a chemical reaction in which starting materials are converted to the final reaction product within a single reaction vessel or container, i.e., there is no intermediate reaction product that is isolated, removed, or purified from the reaction vessel. The "one-pot" reaction or "continuous mode" in its broadest sense still allows for the formation of intermediate products but is further converted to the final product by the addition of further reactants (in situ generation of intermediates). The "one-pot" reaction or "continuous mode" also encompasses reactions within a single reaction vessel ("multi-step" reactions) in which the starting product is converted to the final product through the formation of one or more intermediate products that are formed continuously without further addition of reagents. Thus, the "one-pot" or "continuous mode" process is carried out without isolation and / or purification of one or more intermediate products and is characterized by at least two reaction steps that are appropriately carried out within a single reaction vessel / container. One skilled in the art will understand that a simple transfer of the entire reaction mass at an intermediate stage, without isolating and / or purifying the intermediate product, is still a "one-pot" process or "continuous mode" according to the present invention, especially in that such a process still achieves the technical advantages associated with the one-pot process in that there is no need to isolate and / or purify the in situ formed intermediate.

[0054] The term "hydroacid" (alternatively, binary acid), as used herein, refers to an inorganic acid in which hydrogen is combined with a second non-metallic element such as S, F, Cl, Br, or I. More preferably, the "hydroacid" is selected from the group consisting of hydrochloric acid, hydrobromic acid, and hydroiodic acid.

[0055] The term "inorganic base" refers to hydroxides of alkali metals such as sodium or potassium and alkaline earth metals such as calcium or magnesium, as well as mixtures thereof.

[0056] The term "room temperature" in the context of the present invention refers to a temperature of 15°C to 30°C, preferably 20°C to 25°C.

[0057] As used herein, the term "solvent extraction" refers to a process of separating the components of a mixture by using a solvent that has a greater affinity for one component and can thus separate one component from at least a second component that is less miscible with the solvent than the one component.

[0058] The term "filtration" refers to the act of removing solid particles larger than a predetermined size from a feed containing a mixture of solid particles and a liquid. The expression "filtrate" refers to the mixture excluding the solid particles removed by the filtration process. It will be understood that this mixture may contain solid particles smaller than a predetermined particle size. The expression "filter cake" refers to the residual solid material remaining on the feed side of the filtration element.

[0059] The term "evaporation" refers to the change in the state of a solvent from a liquid to a gas and the removal of that gas from the reactor. Various solvents can be evaporated during the processes disclosed herein. As is known to those skilled in the art, each solvent can have different evaporation times and / or temperatures.

[0060] The term "distillation" refers to a process of separating the component substances from a liquid mixture by selective evaporation and condensation. This can result in an essentially complete separation (substantially pure components) or can be a partial separation that increases the concentration of selected components of the mixture. In either case, the process utilizes the differences in volatility of the components of the mixture.

[0061] As used herein, the term "slurrying" refers to any process of washing, suspending, or dispersing a crude solid product using a solvent.

[0062] The term "phase separation" refers to a solution or mixture having at least two physically distinct regions.

[0063] The term "crystallization" refers to any method known to those skilled in the art, such as crystallization from a single solvent or a combination of solvents, by dissolving a compound, optionally at elevated temperature, and cooling the solution, or removing the solvent from the solution, or both, to precipitate the compound. It further includes methods such as dissolving the compound in a solvent and precipitating it by addition of an "anti-solvent" (i.e., a solvent in which the desired compound has low solubility or insolubility and which can be used to precipitate such compound by adding it to a solution in which the compound is dissolved).

[0064] The term "conventional isolation technique" or "purification", as used herein, refers to a process by which a product can be clarified of extraneous elements, thereby obtaining a purified product. The term "industrial purification" refers to a purification that can be carried out on an industrial scale, such as solvent extraction, filtration, slurrying, washing, phase separation, distillation, centrifugation or crystallization.

[0065] The term "pharmaceutically acceptable metal salt" of daprodustat derived from a pharmaceutically acceptable base includes alkali metals such as sodium or potassium.

[0066] The term "pharmaceutically acceptable" refers to components suitable for use in the pharmaceutical art for the preparation of compositions for medical use. Each component should be "acceptable" in the sense of being compatible with the other components of the composition. When used in contact with human and animal tissues or organs, it should not have excessive toxicity, irritation, allergic reactions, immunogenicity, or other problems or complications commensurate with a reasonable benefit / risk ratio.

[0067] The term "pharmaceutically or veterinarily acceptable salts" refers to salts prepared from bases or acids or their respective conjugated acids or bases that are acceptable for administration to patients such as mammals. Such salts can be derived from pharmaceutically acceptable inorganic or organic bases and pharmaceutically acceptable inorganic or organic acids. Examples of salts of daprodustat derived from pharmaceutically acceptable bases include hydroxides of alkali metals (e.g., sodium or potassium) and alkaline earth metals (e.g., calcium or magnesium) and organic bases such as alkylamines, arylalkylamines, and heterocyclic amines.

Brief Description of the Drawings

[0068] Examples of the present invention are illustrated together with the following drawings.

Figure 1

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Figure 11

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Figure 15

Figure 16

[0069] Any crystalline form that provides an X-ray diffraction pattern substantially identical to that disclosed in the accompanying drawings is within the scope of the present invention. The ability to confirm substantial identity of X-ray diffraction patterns is within the scope of those skilled in the art.

Mode for Carrying Out the Invention

[0070] Detailed Description of the Invention According to a first aspect, the present invention relates to a crystalline form of daprodustat which is a cocrystal comprising daprodustat free acid and a pharmaceutically acceptable metal salt of daprodustat, wherein the metal salt is an alkali metal salt.

[0071] In certain embodiments, the molar ratio of the free acid of daptostat to the metal salt of daptostat in the co-crystal is from 1:3 to 3:1, preferably from 1:2 to 2:1, more preferably about 1:1. In certain embodiments, the molar ratio of the free acid of daptostat to the metal salt of daptostat in the co-crystal is about 2:1. In a preferred embodiment, the molar ratio of the free acid of daptostat to the metal salt of daptostat in the co-crystal is about 1:1.

[0072] In certain embodiments, the present invention relates to a crystalline form of daptostat that is a co-crystal comprising the free acid of daptostat and the sodium salt of daptostat.

[0073] In one embodiment, the present invention relates to a crystalline form of daptostat that is a co-crystal comprising the free acid of daptostat and the sodium salt of daptostat, designated Form N2, having an X-ray powder diffraction pattern comprising peaks at 2-theta values of 6.3° ± 0.2°, 7.4° ± 0.2°, 7.6° ± 0.2°, 11.4° ± 0.2° and 16.2° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0074] In one embodiment, the daptostat of Form N2 further comprises peaks at 2-theta values of 13.0° ± 0.2°, 13.5° ± 0.2°, 14.5° ± 0.2°, 14.8° ± 0.2° and 15.2° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0075] In one embodiment, the daptostat of Form N2 is characterized by XRPD peaks located at 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 of the following approximate positions: 6.3, 7.4, 7.6, 11.4, 13.0, 13.5, 14.5, 14.8, 15.2, 16.2 ± 0.2 degrees of 2-theta as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0076] In certain embodiments, the daprodustat of crystalline form N2 is characterized by an XRPD pattern that matches the pattern shown in Figure 1. In certain embodiments, the daprodustat of crystalline form N2 is characterized in that an XRPD pattern having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 peaks matches the peaks in the pattern of the representative daprodustat of crystalline form N2 provided in Table 1.

[0077]

Table 1

[0078] In certain specific embodiments, the daprodustat of crystalline form N2 is characterized by thermal analysis. A representative DSC plot for crystalline form N2 is shown in Figure 2. In certain specific embodiments, crystalline form N2 is characterized by a DSC plot that includes an endothermic event having a first onset temperature of about 115°C. In certain specific embodiments, crystalline form N2 is further characterized by a DSC plot that further includes a second endothermic event having an onset temperature of about 190°C. In certain specific embodiments, crystalline form N2 is further characterized by a DSC plot that further includes a third endothermic event having an onset temperature of about 201°C. In certain specific embodiments, crystalline form N2 is further characterized by a DSC plot that further includes a fourth endothermic event having an onset temperature of about 228°C.

[0079] A representative TGA plot of the daprostat in crystalline form N2 is also shown in Figure 2. In certain embodiments, the daprostat in crystalline form N2 is characterized by a TGA plot that includes a mass loss of about 4.4% of the total mass of the sample when heated from about 35 °C to about 150 °C. In certain embodiments, the daprostat in crystalline form N2 contains water or other solvents in the crystal lattice. In certain embodiments, the daprostat in crystalline form N2 contains water in the crystal lattice. In certain embodiments, the daprostat in crystalline form N2 contains water in an amount of 0.2 wt% to 10 wt%, preferably 2 wt% to 8 wt%, more preferably 4 wt% to 6 wt% based on the total weight of the crystal. In certain embodiments, the daprostat in crystalline form N2 is a hydrate. In certain embodiments, the daprostat in crystalline form N2 is a hydrate that contains water in an amount of about 4.4% as measured by TGA analysis.

[0080] In certain embodiments, the XRPD pattern of the daprostat in crystalline form N2 does not change substantially after adsorption / desorption analysis. In certain embodiments, crystalline form N2 is stable to humidity. In certain embodiments, the daprostat in crystalline form N2 is slightly hygroscopic according to European Pharmacopoeia 6.0 (5.11).

[0081] In certain embodiments, the daprostat in crystalline form N2 is characterized by proton nuclear magnetic resonance ( 1 1H-NMR) as shown in Figure 3. In certain embodiments, the daprostat in crystalline form N2 is characterized by having a proton NMR spectrum with signal δ (ppm) of 10.13, 4.66, 3.96, 2.31, 1.77, 1.57, and 1.20. In certain embodiments, the daprostat in crystalline form N2 is characterized by having a proton NMR spectrum with signals of 1.20 ppm (m, 6H), 1.57 ppm (m, 6H), 1.77 ppm (m, 4H), 2.31 ppm (m, 4H), 3.96 ppm (d, 2H, J = 6 Hz), 4.66 ppm (m, 2H), and 10.13 ppm (t, 1H, J = 6 Hz).

[0082] In certain embodiments, the daprodustat in crystalline form N2 has the spectrum shown in FIG. 4 and is characterized by an infrared absorption spectrum (FTIR) having peaks at the following wave numbers (cm -1 ) : 691, 761, 789, 840, 895, 924, 966, 1000, 1024, 1057, 1132, 1178, 1237, 1266, 1306, 1338, 1379, 1420, 1444, 1479, 1522, 1586, 1670, 1716, 2849, 2914, 2930, 2973, 3233, 3522, and 3649. Depending on the measuring device, measuring conditions, etc., an error of ±0.5% may be included in the wave number (cm -1 ), but in the present invention, such a level of error is within the allowable range.

[0083] In certain embodiments, the molar ratio of the daprodustat free acid to the sodium salt of daprodustat in crystalline form N2 is from 1:3 to 3:1, preferably from 1:2 to 2:1, more preferably about 1:1. In certain embodiments, the molar ratio of the daprodustat free acid to the sodium salt of daprodustat in crystalline form N2 is about 2:1. In preferred embodiments, the molar ratio of the daprodustat free acid to the sodium salt of daprodustat in crystalline form N2 is about 1:1.

[0084] In certain embodiments, the daprodustat in crystalline form N2 is characterized by its stability profile. In certain embodiments, the daprodustat in crystalline form N2 is stable, for example, its XRPD pattern remains substantially unchanged upon exposure to high temperature, exposure to high humidity, exposure to one or more solvents, and / or upon grinding or pulverizing and compressing.

[0085] In certain embodiments, the daprodustat in crystalline form N2 is maintained at room temperature, in a dry environment at 45 °C and 60 °C, without changing its form for at least one month. In certain embodiments, the daprodustat in crystalline form N2 is maintained without changing its form for at least one month or at least two months under accelerated conditions of 40 °C and 75% relative humidity (RH).

[0086] In certain embodiments, the daprodustat in crystalline form N2 is maintained in water at room temperature for at least one hour without changing its form in the slurry. In other words, the daprodustat in crystalline form N2 does not undergo dissociation (i.e., phase separation into individual components) in the presence of water.

[0087] In certain embodiments, the present invention relates to a crystalline form of daprodustat that is a co-crystal comprising daprodustat free acid and the sodium salt of daprodustat, designated as form N4, having an X-ray powder diffraction (XRPD) pattern that includes peaks at 2 theta values of 6.4° ± 0.2°, 7.4° ± 0.2°, 7.6° ± 0.2°, 13.4° ± 0.2° and 16.7° ± 0.2°, as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0088] In certain embodiments, the daprodustat in crystalline form N4 further includes peaks at 2 theta values of 15.0° ± 0.2°, 26.9° ± 0.2°, 27.5° ± 0.2°, 27.7° ± 0.2° and 28.2° ± 0.2°, as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0089] In certain embodiments, the daprodustat in crystalline form N4 is characterized by XRPD peaks located at 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 of the following approximate positions: 2 theta of 6.4, 7.4, 7.6, 13.4, 15.0, 16.7, 26.9, 27.5, 27.7 and 28.2 ± 0.2 degrees.

[0090] In certain embodiments, the daprodustat of crystalline form N4 is characterized by an XRPD pattern that matches the pattern shown in Figure 5. In some embodiments, the daprodustat of crystalline form N4 is characterized in that an XRPD pattern having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 peaks matches the peaks in the pattern of the representative daprodustat of crystalline form N4 provided in Table 2.

[0091] [Table 2]

[0092] In certain embodiments, a representative DSC / TGA plot for crystalline form N4 is shown in Figure 6. In certain embodiments, the DSC plot for the dapuplostat of crystalline form N4 is characterized by an endothermic event having a first onset temperature of about 107 °C. In certain embodiments, form N4 is further characterized by a DSC plot that includes a second endothermic event having an onset temperature of about 190 °C. In certain embodiments, form N4 is further characterized by a DSC plot that includes a third endothermic event having an onset temperature of about 200 °C. In certain embodiments, form N4 is further characterized by a DSC plot that includes a fourth endothermic event having an onset temperature of about 228 °C. In certain embodiments, the TGA plot for the dapuplostat of crystalline form N4 is characterized by a mass loss of about 4.0% of the total mass of the sample when heated from about 35 °C to about 150 °C. In certain embodiments, the dapuplostat of crystalline form N4 contains water or other solvents in the crystal lattice. In certain embodiments, the dapuplostat of crystalline form N4 contains water in the crystal lattice. In certain embodiments, the dapuplostat of crystalline form N4 contains water in an amount of 0.2 wt% to 10 wt%, preferably 0.2 wt% to 5 wt%, more preferably 2 wt% to 5 wt%, and even more preferably 3.9 wt% to 4.5 wt% based on the total weight of the crystal. In certain embodiments, the dapuplostat of crystalline form N4 is a hydrate. In certain embodiments, the dapuplostat of crystalline form N4 is a hydrate that contains water in an amount of about 4.0% as measured by TGA analysis.

[0093] In certain embodiments, the XRPD pattern of the dapuplostat of crystalline form N4 does not substantially change after adsorption / desorption analysis. In certain embodiments, crystalline form N4 is stable to humidity. In certain embodiments, the dapuplostat of crystalline form N4 is slightly hygroscopic according to European Pharmacopoeia 6.0 (5.11). In certain embodiments, the water content in the dapuplostat of crystalline form N4 is lower than the water content in the dapuplostat of crystalline form N2.

[0094] In certain embodiments, the molar ratio of the free acid of daprostat to the sodium salt of daprostat in crystalline form N4 is from 1:3 to 3:1, preferably from 1:2 to 2:1, more preferably about 1:1. In certain embodiments, the molar ratio of the free acid of daprostat to the sodium salt of daprostat in crystalline form N4 is about 2:1. In preferred embodiments, the molar ratio of the free acid of daprostat to the sodium salt of daprostat in crystalline form N4 is about 1:1.

[0095] In certain embodiments, the daprostat in crystalline form N4 is characterized by its stability profile. In certain embodiments, the daprostat in crystalline form N4 is stable, e.g., its XRPD pattern remains substantially unchanged upon exposure to high temperature, high humidity, one or more solvents, and / or upon grinding or pulverization and compression.

[0096] In certain embodiments, the present invention relates to a crystalline form of daprostat that is a co-crystal comprising the free acid of daprostat and the potassium salt of daprostat.

[0097] In certain embodiments, the present invention relates to a crystalline form of daprostat that is a co-crystal comprising the free acid of daprostat and the potassium salt of daprostat, designated as Form K2, having an X-ray powder diffraction (XRPD) pattern comprising peaks at 2 theta values of 5.5° ± 0.2°, 6.3° ± 0.2°, 7.0° ± 0.2°, 16.8° ± 0.2° and 18.0° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0098] In certain embodiments, the daprostat in crystalline form K2 further comprises peaks at 2 theta values of 7.8° ± 0.2°, 11.8° ± 0.2°, 12.7° ± 0.2°, 13.7° ± 0.2° and 27.6° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0099] In certain embodiments, the daprodustat of crystalline form K2 is characterized by XRPD peaks located at 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 of the following approximate positions: 5.5, 6.3, 7.0, 7.8, 11.8, 12.7, 13.7, 16.8, 18.0, and 27.6 ± 0.2 degrees two-theta.

[0100] In certain embodiments, the daprodustat of crystalline form K2 is characterized by an XRPD pattern that matches the pattern shown in Figure 7. In certain embodiments, the daprodustat of crystalline form K2 is characterized in that an XRPD pattern having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 peaks matches the peaks in the pattern of a representative daprodustat of crystalline form K2 provided in Table 3.

[0101] [Table 3]

[0102] In certain specific embodiments, the daprodustat of crystalline form K2 is characterized by thermal analysis. A representative DSC plot for crystalline form K2 is shown in Figure 8. In certain specific embodiments, crystalline form K2 is characterized by a DSC plot that includes a first endothermic event having an onset temperature of about 33°C. In certain specific embodiments, crystalline form K2 is further characterized by a DSC plot that includes a second endothermic event having an onset temperature of about 248°C.

[0103] A representative TGA plot of the daprodustat in crystalline form K2 is also shown in FIG. 8. In certain embodiments, the daprodustat in crystalline form K2 is characterized by a TGA plot that includes a mass loss of about 5.4% of the total mass of the sample when heated from about 30° C. to about 130° C. In certain embodiments, the daprodustat in crystalline form K2 contains water or other solvents in the crystal lattice. In certain embodiments, the daprodustat in crystalline form K2 contains water in the crystal lattice. In certain embodiments, the daprodustat in crystalline form K2 contains water in an amount of 0.2 wt % to 10 wt %, preferably 2 wt % to 8 wt %, more preferably 4 wt % to 6 wt %, based on the total weight of the crystal. In certain embodiments, the daprodustat in crystalline form K2 is a hydrate. In certain embodiments, the daprodustat in crystalline form K2 is a hydrate that contains water in an amount of about 5.4% as measured by TGA analysis.

[0104] In certain embodiments, the XRPD pattern of the daprodustat in crystalline form K2 does not substantially change after adsorption / desorption analysis. In certain embodiments, crystalline form K2 is stable to humidity.

[0105] In certain embodiments, the daprodustat in crystalline form K2 is characterized by proton nuclear magnetic resonance ( 1 1H-NMR) as shown in FIG. 9. In certain embodiments, the daprodustat in crystalline form K2 is characterized by a proton NMR spectrum having signal δ (ppm) of 10.08, 4.65, 3.93, 2.30, 1.77, 1.57, and 1.20. In certain embodiments, the daprodustat in crystalline form K2 is characterized by a proton NMR spectrum having signals of 1.20 ppm (m, 6H), 1.57 ppm (m, 6H), 1.77 ppm (m, 4H), 2.30 ppm (m, 4H), 3.93 ppm (d, 2H, J = 6 Hz), 4.65 ppm (m, 2H), and 10.08 ppm (t, 1H, J = 6 Hz).

[0106] In certain embodiments, the daptostat of crystalline form K2 has the spectrum shown in FIG. 10 and is characterized by an infrared absorption spectrum (FTIR) having peaks at the following wave numbers (cm -1 -1): 693, 740, 762, 790, 882, 894, 918, 996, 1054, 1134, 1187, 1235, 1258, 1302, 1340, 1378, 1446, 1472, 1506, 1522, 1589, 1669, 2655, 2852, 2935, 2977, 3180, 3477, and 3546. Depending on the measuring device, measuring conditions, etc., there may be an error of ±0.5% in the wave number (cm -1 -1), but in the present invention, such a level of error is within the allowable range.

[0107] In certain embodiments, the molar ratio of the daptostat free acid to the potassium salt of daptostat in crystalline form K2 is from 1:3 to 3:1, preferably from 1:2 to 2:1, more preferably 1:1. In certain embodiments, the molar ratio of the daptostat free acid to the potassium salt of daptostat in crystalline form K2 is about 2:1. In certain embodiments, the molar ratio of the daptostat free acid to the potassium salt of daptostat in crystalline form K2 is about 1:1.

[0108] In certain embodiments, the daptostat of crystalline form K2 is characterized by its stability profile. In certain embodiments, the daptostat of crystalline form K2 is stable; for example, its XRPD pattern remains substantially unchanged upon exposure to high temperature, exposure to high humidity, exposure to one or more solvents, and / or upon grinding or pulverizing and compressing.

[0109] In certain embodiments, the daptostat of crystalline form K2 maintains its form without change for at least one month at room temperature in a dry environment at 45 °C and 60 °C. In certain embodiments, the daptostat of crystalline form K2 maintains its form without change for at least one month or at least two months under accelerated conditions of 40 °C and 75% RH (relative humidity).

[0110] In certain embodiments, the daprostat of crystalline form K2 is maintained without changing its form for at least 12 hours (i.e., overnight) in a drying environment at 45 °C and 60 °C under vacuum.

[0111] In certain embodiments, the daprostat of crystalline form K2 is maintained without changing its form in slurry in water at room temperature for at least 1 hour. In other words, the daprostat of crystalline form K2 does not undergo dissociation (i.e., phase separation into individual components) in the presence of water.

[0112] In certain embodiments, a sample of the daprostat of crystalline form N2 comprises particles having a needle-like (acicular) form. In certain embodiments, a sample of the daprostat of crystalline form N2 comprises acicular crystals as shown in FIG. 11. In certain embodiments, the particles of the daprostat of crystalline form N2 have a size of less than about 300 microns, less than about 250 microns, less than about 200 microns, less than about 150 microns, less than about 100 microns, less than about 50 microns, less than about 25 microns, or less than about 10 microns. In certain embodiments, the particles of the daprostat of crystalline form N2 have a size of 100 - 5 microns, 80 - 5 microns, 60 - 5 microns, 40 - 5 microns, or 30 - 5 microns. In certain embodiments, the particles of the daprostat of crystalline form N2 comprise acicular crystals having the size shown in FIG. 13.

[0113] In certain embodiments, a sample of the daprostatut in crystalline form N4 comprises particles having a needle-like (acicular) morphology. In certain embodiments, the particles of the daprostatut in crystalline form N4 have a size of less than about 300 microns, less than about 250 microns, less than about 200 microns, less than about 150 microns, less than about 100 microns, less than about 50 microns, less than about 25 microns, or less than about 10 microns. In certain embodiments, the particles of the daprostatut in crystalline form N4 have a size of 100 - 5 microns, 80 - 5 microns, 60 - 5 microns, 40 - 5 microns, or 30 - 5 microns.

[0114] In certain embodiments, a sample of the daprostatut in crystalline form K2 comprises particles having a needle-like (acicular) morphology. In certain embodiments, the sample of the daprostatut in crystalline form K2 comprises acicular crystals as shown in FIG. 12. In certain embodiments, the particles of the daprostatut in crystalline form K2 have a size of less than about 300 microns, less than about 250 microns, less than about 200 microns, less than about 150 microns, less than about 100 microns, less than about 50 microns, less than about 25 microns, or less than about 10 microns. In certain embodiments, the particles of the daprostatut in crystalline form N2 have a size of 120 - 10 microns, 90 - 10 microns, 60 - 10 microns, or 30 - 10 microns. In certain embodiments, the particles of the daprostatut in crystalline form K2 comprise acicular crystals having the size shown in FIG. 14.

[0115] In one embodiment, the present invention relates to a crystalline form of daprostatut that is a co-crystal comprising daprostatut free acid and the potassium salt of daprostatut, designated as form K1, having an X-ray powder diffraction (XRPD) pattern comprising peaks at 2 theta values of 5.4° ± 0.2°, 7.9° ± 0.2°, 14.6° ± 0.2°, 15.6° ± 0.2° and 17.5° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0116] In certain embodiments, the daprodustat of crystalline form K1 further comprises peaks at 2-theta values of 10.2° ± 0.2°, 11.3° ± 0.2°, 12.1° ± 0.2°, 15.8° ± 0.2° and 16.2° ± 0.2° as measured with copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature.

[0117] In certain embodiments, the daprodustat of crystalline form K1 is characterized by XRPD peaks located at 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 of the following approximate positions: 5.4, 7.9, 10.2, 11.3, 12.1, 14.6, 15.6, 15.8, 16.2, and 17.5 ± 0.2 degrees of 2-theta.

[0118] In certain embodiments, the daprodustat of crystalline form K1 is characterized by an XRPD pattern that matches the pattern shown in Figure 15. In certain embodiments, the daprodustat of crystalline form K1 is characterized in that an XRPD pattern having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 peaks matches the peaks in the pattern of the representative daprodustat of crystalline form K1 provided in Table 4.

[0119] [Table 4]

[0120] In certain specific embodiments, the daprodustat of crystalline form K1 is characterized by thermal analysis. A representative DSC plot for crystalline form K1 is shown in Figure 16. In certain specific embodiments, crystalline form K1 is characterized by a DSC plot that includes a first endothermic event having an onset temperature of about 56°C. In certain specific embodiments, crystalline form K1 is further characterized by a DSC plot that includes an exothermic event having an onset temperature of about 202°C. In certain specific embodiments, crystalline form K1 is further characterized by a DSC plot that includes two overlapping endothermic events having onset temperatures of about 251°C and about 254°C, respectively.

[0121] A representative TGA plot of the daprostat in crystalline form K1 is also shown in FIG. 16. In certain embodiments, the daprostat in crystalline form K1 is characterized by a TGA plot that includes a mass loss of about 13.2% of the total mass of the sample when heated from about 40° C. to about 130° C. In certain embodiments, the daprostat in crystalline form K1 contains water or other solvents in the crystal lattice. In certain embodiments, the daprostat in crystalline form K1 contains water in the crystal lattice. In certain embodiments, the daprostat in crystalline form K1 is a hydrate. In certain embodiments, the daprostat in crystalline form K1 is a hydrate that contains an amount of water, as measured by TGA analysis, of from 10% to 14%.

[0122] In certain embodiments, the molar ratio of the daprostat free acid to the potassium salt of daprostat in crystalline form K1 is from 1:3 to 3:1, preferably from 1:2 to 2:1, more preferably about 1:1. In certain embodiments, the molar ratio of the daprostat free acid to the potassium salt of daprostat in crystalline form K1 is about 2:1. In certain embodiments, the molar ratio of the daprostat free acid to the potassium salt of daprostat in crystalline form K1 is about 1:1.

[0123] In certain embodiments, a sample of the daprostat in crystalline form K1 comprises particles having a needle-like (acicular) morphology. In certain embodiments, the particles of the daprostat in crystalline form K1 have a size of less than about 300 microns, less than about 250 microns, less than about 200 microns, less than about 150 microns, less than about 100 microns, less than about 50 microns, less than about 25 microns, or less than about 10 microns. In certain embodiments, the particles of the daprostat in crystalline form K1 have a size of from 120 to 10 microns, from 90 to 10 microns, from 60 to 10 microns, or from 30 to 10 microns.

[0124] The present invention further encompasses daprostatins in crystalline form N2, crystalline form N4, crystalline form K2 and crystalline form K1 in pure form or mixed with other materials, such as other polymorphs, solvates or residual reaction solvents or by-products. In particular, the present invention also refers to a mixture comprising the crystalline form of N2 and its crystalline form N4. In particular, the present invention also refers to a mixture comprising the crystalline form of K2 and its crystalline form K1.

[0125] According to a second aspect, the present invention is a method for the preparation of a daprostatine in crystalline form as defined above, comprising: a) providing daprostatine free acid in a solvent or mixture of solvents; b) optionally heating the mixture of step (a) to a suitable temperature, preferably from 70°C to 100°C, more preferably from 75°C to 95°C; c) adding a source in the form of a pharmaceutically acceptable metal inorganic base, preferably an alkali metal inorganic base, in particular a pharmaceutically acceptable metal hydroxide, more preferably an alkali metal hydroxide, in an amount of about 0.5 molar equivalents relative to the daprostatine free acid of step (a); d) optionally cooling the solution obtained from step (c) to room temperature; e) isolating the daprostatine in crystalline form.

[0126] The daprostatine free acid used in (a) can be in the form of its solvate, hydrate, anhydrate, crystalline form or amorphous form. Preferably, the daprostatine free acid is in crystalline form, and even more preferably, the daprostatine free acid used in step (a) is in anhydrous form. The daprostatine solvate used in step (a) can be the diethyl ether solvate prepared in Example 18 of Method 1 of WO 2007 / 150011 A2.

[0127] In certain embodiments, the daprostat stat solvate is a methyl tert-butyl ether solvate, a dioxane solvate, a tetrahydrofuran solvate, a methanol solvate, an ethanol solvate, an isopropanol solvate, a tert-butanol solvate, a dimethylformamide (DMF) solvate, or a dimethyl sulfoxide (DMSO) solvate, all prepared in Table 5 of Example 1.

[0128] Suitable solvents used in step (a) are (C6-C 14 ) aromatic hydrocarbon solvents such as toluene, o-xylene, m-xylene, and p-xylene; halogenated (C1-C 12 ) hydrocarbon solvents such as 1,2-dichloroethane, dichloromethane, chloroform; (C1-C 12 ) ether solvents such as diethyl ether, dipropyl ether, diphenyl ether, isopropyl ether, tert-butyl methyl ether, tetrahydrofuran, 1,4-dioxane; (C1-C 12 ) alcohol solvents such as methanol, ethanol, isopropanol, 1-propanol, 2-methyl-1-propanol, 1-butanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, tert-butanol, 1-octanol, benzyl alcohol, phenol, trifluoroethanol, glycerol, ethylene glycol, propylene glycol, m-cresol; nitrobenzene; N,N-dimethylformamide; N,N,-dimethylacetamide; N-methyl-2-pyrrolidone; or acetonitrile, and may be selected from the group consisting of. In some embodiments, the solvent may be formed by a combination of two or more solvents. In certain embodiments, the solvent used in step (a) is selected from the group consisting of (C1-C6) alcohols, acetonitrile, dichloromethane (DCM), toluene, tetrahydrofuran, and combinations thereof.

[0129] In certain embodiments, the solvent used in step (a) is a mixture of water and another solvent selected from the group consisting of (C1-C6) alcohols, acetonitrile, dichloromethane (DCM), toluene, and tetrahydrofuran. In certain embodiments, the solvent for step (a) is a mixture of (C1-C6) alcohol or acetonitrile and water. In a preferred embodiment, the solvent used in step (a) is a mixture of acetonitrile and water. In a preferred embodiment, the solvent used in step (a) is a mixture of acetonitrile and water in a ratio of 5:1 (v / v) to 15:1 (v / v), preferably 8:1 (v / v) to 12:1 (v / v), more preferably 9:1 (v / v).

[0130] In certain embodiments, the pharmaceutically acceptable metal inorganic base, particularly the metal hydroxide, is an alkali metal inorganic base selected from sodium and potassium inorganic bases. In certain embodiments, the source of the pharmaceutically acceptable metal hydroxide for step (b) is in the form of an alkali metal hydroxide. In certain embodiments, the alkali metal hydroxide is selected from sodium hydroxide and potassium hydroxide. In certain embodiments, the pharmaceutically acceptable metal inorganic base is sodium, providing a co-crystal of sodium daprodustat and the sodium salt of daprodustat. In certain embodiments, the pharmaceutically acceptable metal inorganic base is potassium, providing a co-crystal of sodium daprodustat and the potassium salt of daprodustat.

[0131] In certain embodiments, step (b) is performed to provide a solution. In certain embodiments, step (d) is performed to induce crystallization of the crystalline form. In certain embodiments, prior to performing step (d), crystallization is controlled using daprodustat of the desired crystalline form. In a preferred embodiment, steps (b) and (d) are performed. In a more preferred embodiment, steps (b) and (d) are performed, and seeding with daprodustat of the desired crystalline form is used prior to performing step (d).

[0132] In one embodiment, in a method for the preparation of a crystalline form of daprodustat according to the second aspect, the daprodustat free acid in step (a) is prepared by the method defined in the sixth aspect, or by the method defined in any of the eighth aspects, or by the method defined in the tenth aspect.

[0133] Alternatively, according to the third aspect, the preparation of a crystalline form of daprodustat which is a co-crystal comprising a daprodustat free acid and a pharmaceutically acceptable metal salt of daprodustat, wherein the metal salt is an alkali metal salt such as a sodium salt or a potassium salt, comprises: i. in a solvent or a mixture of solvents, preparing an ester intermediate of formula (VI);

Chemical formula

Chemical formula

[0134] In certain embodiments of the above method, step (iii) comprises adding a source in the form of a pharmaceutically acceptable metal inorganic base, particularly a pharmaceutically acceptable metal hydroxide, preferably an alkali metal inorganic base, more preferably an alkali metal hydroxide, to the ester intermediate of formula (VI) of step (i) (wherein R is as defined above) in an amount of 1.0 - 2.2, preferably 2.0 - 2.2 molar equivalents; and step (iv) comprises adding an acid, preferably a hydrohalic acid such as hydrochloric acid, hydrobromic acid or hydroiodic acid, more preferably hydrochloric acid, to the mixture of step (iii) in an amount of 0.5 - 1.7, preferably 1.5 - 1.7 molar equivalents.

[0135] Advantageously, starting from the ester intermediate of formula (VI) (wherein R is as defined above), the method for the preparation of the crystalline form of daprodustat as defined herein is reproducible and does not generate excess inorganic impurities that are difficult to remove from the final product. The ester intermediate used in step (i) as the starting material can be prepared, as described in WO 2007 / 150011 A2 pamphlet, particularly compound VI where R is ethyl, i.e., N-[(1,3-dicyclohexyl-6-hydroxy-2,4-dioxo-1,2,3,4-tetrahydro-5-pyrimidinyl)carbonyl]glycine prepared in Example 18.

[0136] Suitable solvents for use in step (i) are water, (C1-C 12 ) alcohol solvents such as methanol, ethanol, isopropanol, 1-propanol, 2-methyl-1-propanol, 1-butanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, tert-butanol, 1-octanol, benzyl alcohol, phenol, trifluoroethanol, glycerol, ethylene glycol, propylene glycol, m-cresol; (C1-C 12 ) ether solvents such as diethyl ether, tert-butyldimethyl ether, tetrahydrofuran and dioxane; nitrobenzene; N,N-dimethylformamide; N,N,-dimethylacetamide; N-methyl-2-pyrrolidone; and acetonitrile. In certain embodiments, the solvent can be formed by a combination of two or more solvents. In certain embodiments, the solvent used in step (i) is a (C1-C 12 ) alcohol or acetonitrile. In certain embodiments, the solvent for step (i) is methanol, ethanol, isopropanol, 1-propanol or acetonitrile.

[0137] In certain embodiments, the solvent for step (i) is a mixture of a (C1-C 12 ) alcohol or acetonitrile and water. In certain embodiments, the (C1-C 12 ) alcohol is selected from methanol, ethanol, isopropanol and 1-propanol. In certain embodiments, the solvent used in step (i) is a mixture of ethanol or acetonitrile and water. In certain embodiments, the solvent used in step (i) is a mixture of ethanol or acetonitrile and water in a ratio of 5:1 (v / v) to 15:1 (v / v), preferably 8:1 (v / v) to 12:1 (v / v), more preferably a mixture of acetonitrile and water in a ratio of 9:1 (v / v).

[0138] In certain embodiments, the pharmaceutically acceptable metal salt of step (iii) is an alkali metal salt selected from sodium salts and potassium salts. In certain embodiments, the source of the pharmaceutically acceptable metal inorganic base, particularly the metal hydroxide, in step (iii) is in the form of an alkali metal hydroxide. In certain embodiments, the alkali metal hydroxide is selected from sodium hydroxide and potassium hydroxide. In certain embodiments, the metal hydroxide of step (iii) is added as an aqueous solution. In certain embodiments, the pharmaceutically acceptable metal salt of step (iii) is sodium, providing a co-crystal of the daprodustat free acid and the sodium salt of daprodustat. In certain embodiments, the pharmaceutically acceptable metal salt of step (iii) is potassium, providing a co-crystal of the daprodustat free acid and the potassium salt of daprodustat.

[0139] In certain embodiments, step (iii) further comprises sub-step (iii.1) of completely or partially removing the solvent or mixture of solvents of step (i) by evaporation or distillation, and sub-step (iii.2) of adding a different solvent or mixture of solvents to provide a solution or suspension.

[0140] In certain embodiments, in sub-step (iii.1), the solvent is a (C1-C 12 ) alcohol, which is partially or completely removed by evaporation or distillation, and in sub-step (iii.2), the solvent is a mixture of acetonitrile and water in a ratio of 5:1 (v / v) to 15:1 (v / v), preferably 8:1 (v / v) to 12:1 (v / v), more preferably 9:1 (v / v), to provide a solution or suspension of the corresponding daprodustat alkali metal of formula (Ia) (wherein M is an alkali metal such as sodium or potassium).

[0141] The suitable acids used in step (iv) are inorganic acids or organic acids. Suitable acids have a (water-based) pKa of less than 5, preferably less than 3, more preferably less than 1. Preferably, the acid has a (water-based) pKa of -10 to 5, preferably -10 to 3, more preferably -10 to 1. Examples of suitable acids include, but are not limited to, hydrofluoric acid, hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid, formic acid, acetic acid, dichloroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, and camphorsulfonic acid. Preferably, the acid used in step (iv) is a hydroacid such as hydrochloric acid, hydrobromic acid, or hydroiodic acid, which may be present as a gas or an aqueous solution, or may be generated in situ from an alkylsilyl halide in the presence of a protic solvent, for example. More preferably, the acid used in step (iv) is hydrochloric acid in an aqueous solution.

[0142] In certain embodiments, step (ii) is performed to provide a solution. In certain embodiments, step (v) is performed to induce crystallization of the crystalline form. In certain embodiments, prior to performing step (v), crystallization is controlled using a dapper dustat of the desired crystalline form. In certain embodiments, seeding with a dapper dustat of the desired crystalline form is performed before or during the performance of step (iv). In certain embodiments, seeding with a dapper dustat of the desired crystalline form is performed the number of times necessary to control the dapper dustat of the desired crystalline form. In preferred embodiments, steps (ii) and (v) are performed. In more preferred embodiments, steps (ii) and (v) are performed, and seeding with a dapper dustat of the desired crystalline form is used prior to performing step (v). In preferred embodiments, steps (ii) and (v) are performed, and seeding with a dapper dustat of the desired crystalline form is used before step (v), or before or during the performance of step (iv). In certain embodiments, hot filtration of the mixture obtained in step (iii) may be performed to remove any insoluble material.

[0143] In certain embodiments, the present invention relates to the potassium salt of daprostat, of formula (Ia) wherein M is potassium. In certain embodiments, the potassium salt of daprostat of formula (Ia) wherein M is potassium is in its solvated, hydrated, crystalline or amorphous form.

[0144] In one embodiment, in the method for preparing the crystalline form of daprostat according to the third aspect, the ester intermediate of formula (VI) is prepared by the method defined in the ninth aspect.

[0145] In certain embodiments, the preparation of the crystalline form N2 of daprostat, which is a co-crystal comprising daprostat free acid and the sodium salt of daprostat, i. preparing an ester intermediate of formula (VI) in a solvent or a mixture of solvents;

Chemical formula

[0146] In certain embodiments of the above method, step (iii) comprises adding a source in the form of a pharmaceutically acceptable metal inorganic base, particularly a pharmaceutically acceptable metal hydroxide, preferably an alkali metal inorganic base, more preferably an alkali metal hydroxide, to the ester intermediate of formula (VI) of step (i) (wherein R is as defined above) in an amount of 1.0 to 2.2, preferably 2.0 to 2.2 molar equivalents; and step (iv) comprises adding an acid, preferably a hydrohalic acid such as hydrochloric acid, hydrobromic acid or hydroiodic acid, more preferably hydrochloric acid, to the mixture of step (iii) in an amount of 0.5 to 1.7, preferably 1.5 to 1.7 molar equivalents.

[0147] In certain embodiments, steps (ii) and (v) as defined above are carried out. In certain embodiments, seeding with the crystalline form N2 of daprostat is used to control crystallization before step (v) is carried out.

[0148] In certain embodiments, step (iii) further comprises the sub-steps of: (iii.1) completely or partially removing the solvent or mixture of solvents of step (i) by evaporation or distillation; and (iii.2) adding a different solvent or mixture of solvents to provide a solution or suspension.

[0149] In certain embodiments, in sub-step (iii.1), the solvent is (C1 - C 12) It is an alcohol, which is partially or completely removed by evaporation or distillation, and in the subsequent step (iii.2), the solvent is a mixture of acetonitrile and water in a ratio of 5:1 (v / v) to 15:1 (v / v), preferably 8:1 (v / v) to 12:1 (v / v), more preferably 9:1 (v / v), for providing a solution or suspension of the corresponding daprostatut alkaline metal of formula (Ia) (wherein M is sodium).

[0150] In certain embodiments, the preparation of crystalline form K2 of daprostatut, which is a co-crystal containing daprostatut free acid and the potassium salt of daprostatut, i. A step of preparing an ester intermediate of formula (VI) in a solvent or a mixture of solvents,

Chemical formula

[0151] In certain embodiments of the above method, step (iii) includes adding a source in the form of a pharmaceutically acceptable metal inorganic base, particularly a pharmaceutically acceptable metal hydroxide, preferably an alkali metal inorganic base, more preferably an alkali metal hydroxide, in an amount of 1.0 to 2.2, preferably 2.0 to 2.2 molar equivalents, to the ester intermediate of formula (VI) in step (i) (wherein R is as defined above); and step (iv) includes adding an acid, preferably a hydrohalic acid such as hydrochloric acid, hydrobromic acid or hydroiodic acid, more preferably hydrochloric acid, in an amount of 0.5 to 1.7, preferably 1.5 to 1.7 molar equivalents, to the mixture of step (iii).

[0152] In certain embodiments, steps (ii) and (v) as defined above are performed. In certain embodiments, crystallization is controlled using seeding with the crystalline form K2 of daprostat before step (v) is performed.

[0153] In certain embodiments, step (iii) further includes sub-step (iii.1) completely or partially removing the solvent or mixture of solvents of step (i) by evaporation or distillation, and sub-step (iii.2) adding a different solvent or mixture of solvents to provide a solution or suspension.

[0154] In certain embodiments, in sub-step (iii.1), the solvent is (C1 - C 12) It is an alcohol that is partially or completely removed by evaporation or distillation, and in the subsequent step (iii.2), the solvent is a mixture of acetonitrile and water in a ratio of 5:1 (v / v) to 15:1 (v / v), preferably 8:1 (v / v) to 12:1 (v / v), more preferably 9:1 (v / v), for providing a solution or suspension of the corresponding daprostatut alkaline metal of formula (Ia) (where M is potassium).

[0155] It is also a method for the preparation of crystalline form K1 of daprostatut, which forms part of the present invention and is a co-crystal containing daprostatut free acid and the potassium salt of daprostatut, comprising: i. preparing an ester intermediate of formula (VI) in a solvent or a mixture of solvents;

Chemical formula

[0156] In certain embodiments of the above method, step (iii) involves adding a source in the form of a pharmaceutically acceptable metal inorganic base, particularly a pharmaceutically acceptable metal hydroxide, preferably an alkali metal inorganic base, more preferably an alkali metal hydroxide, to the ester intermediate of formula (VI) of step (i) (wherein R is as defined above) in an amount of 1.0 to 2.2, preferably 2.0 to 2.2 molar equivalents; and step (iv) involves adding an acid, preferably a hydrohalic acid such as hydrochloric acid, hydrobromic acid or hydroiodic acid, more preferably hydrochloric acid, to the mixture of step (iii) in an amount of 0.5 to 1.7, preferably 1.5 to 1.7 molar equivalents.

[0157] In certain specific embodiments, steps (ii) and (v) as defined above are carried out. In certain specific embodiments, seeding with the crystalline form K1 of daprodustat is used to control crystallization before step (v) is carried out.

[0158] In certain specific embodiments, step (iii) further includes a sub-step (iii.1) of completely or partially removing the solvent or mixture of solvents of step (i) by evaporation or distillation, and a sub-step (iii.2) of adding a different solvent or mixture of solvents to provide a solution or suspension.

[0159] In certain specific embodiments, in sub-step (iii.1), the solvent is (C1 - C 12) It is an alcohol that is partially or completely removed by evaporation or distillation, and in the subsequent step (iii.2), the solvent is a mixture of acetonitrile and water in a ratio of 5:1 (v / v) to 15:1 (v / v), preferably 8:1 (v / v) to 12:1 (v / v), more preferably 9:1 (v / v), for providing a solution or suspension of the corresponding daprostat alkali metal of formula (Ia) (wherein M is potassium).

[0160] It also forms part of the present invention and forms a method for the preparation of the daprostat in crystalline form N4, which includes drying the daprostat in crystalline form N2 under vacuum and isolating the daprostat in crystalline form N4. In certain embodiments, the method for the preparation of crystalline form N4 includes drying the daprostat in crystalline form N2 at a temperature of room temperature to 75 °C, preferably 45 °C to 60 °C, under vacuum (about 12 mbar) for at least 6 hours, preferably at least 12 hours, and isolating the daprostat in crystalline form N4. In certain embodiments, the method for the preparation of crystalline form N4 includes drying the daprostat in crystalline form N2 at a temperature of 45 °C to 60 °C under vacuum (about 12 mbar) for at least 6 hours, preferably at least 12 hours, and isolating the daprostat in crystalline form N4.

[0161] The above invention further provides daprostats in crystalline form N2, crystalline form N4, crystalline form K2 and crystalline form K1 in pure form or when mixed with other materials, such as other polymorphs, solvates or residual reaction solvents or by-products. In particular, the above method provides a mixture comprising the crystalline form of N2 and its crystalline form N4. In particular, the above method can provide a mixture of the crystalline form of K2 and its crystalline form K1.

[0162] According to a fourth aspect of the present invention, a pharmaceutical composition comprising a daptomycin in a crystal form selected from the group consisting of crystal form N2, crystal form N4, crystal form K2, crystal form K1, and combinations thereof, and one or more pharmaceutically acceptable carriers, diluents or excipients may further contain a disintegrant, a flow promoter, a lubricant, a binder, a coloring agent, and combinations thereof. In certain embodiments, a pharmaceutical composition comprising a daptomycin in a crystal form selected from the group consisting of crystal form N2, crystal form N4, crystal form K2, crystal form K1 may be a tablet, a dispersible tablet or granules suitable for oral use.

[0163] According to a fifth aspect, a crystal form of daptomycin in a crystal form selected from the group consisting of crystal form N2, crystal form N4, crystal form K2, crystal form K1, and combinations thereof may be particularly suitable for the treatment of symptomatic anemia associated with chronic kidney disease (CKD) in adults undergoing chronic maintenance dialysis or in adults not undergoing dialysis.

[0164] As described above, a sixth aspect of the present invention is a method for preparing a daptomycin of formula (I) or a salt thereof, comprising hydrolyzing a compound of formula (VI) in the presence of a quaternary ammonium hydroxide of formula N[(C1-C4)alkyl]4OH, preferably tetramethylammonium hydroxide (TMAH), and a solvent, and optionally converting the daptomycin of formula (I) to its pharmaceutically or veterinarily acceptable salt.

[0165] In certain embodiments, the amount of the quaternary ammonium hydroxide, preferably tetramethylammonium hydroxide (TMAH), is in a molar ratio of base to the compound of formula (VI) of 1:1 to 4:1, preferably 2:1 to 3:1.

[0166] In certain embodiments, suitable solvents for the sixth aspect are selected from the group consisting of (C1-C3) alcohols, preferably methanol, ethanol or isopropanol; water; and mixtures thereof.

[0167] In one embodiment, the solvent is a mixture of (C1-C3) alcohol, preferably methanol, ethanol or isopropanol, and water in a volume ratio of 10:1 to 1:2, preferably 5:1 to 1:2, and more preferably 10:1 to 5:1.

[0168] In one embodiment of the sixth aspect, after the hydrolysis reaction is completed, an acid selected from formic acid, acetic acid, monochloroacetic acid, trichloroacetic acid and trifluoroacetic acid (TFA), preferably trifluoroacetic acid (TFA), is added.

[0169] In one embodiment, the amount of the acid, preferably trifluoroacetic acid (TFA), is in a molar ratio of acid to the compound of formula (VI) of 1:1 to 4:1, preferably a molar ratio of base to the compound of formula (VI) of 2:1 to 3:1.

[0170] In one embodiment, daprodustat is further purified by slurrying or crystallizing in an organic solvent selected from alcohols, preferably (C1-C3) alcohols, more preferably methanol, ethanol or isopropanol, more preferably ethanol, or acidic solvents such as acetic acid. In one embodiment, daprodustat is purified by crystallization in acetic acid.

[0171] In one embodiment of the sixth aspect, compound (VI) is obtained by reacting a compound of formula (V) with isocyanatoacetate of formula (IV) in the presence of a base and a solvent, and the compound of formula (V) is preferably obtained according to the method of the seventh aspect.

[0172] In one embodiment of the sixth aspect, compound (VI) is preferably obtained from the compound of formula (II) according to the method of the fourth aspect.

[0173] In one embodiment of the sixth aspect, the method further includes the preparation of the daprodustat in the crystalline form as defined above by the method defined in the second aspect of the present invention.

[0174] The seventh aspect of the present invention is a method for preparing 1,3-dicyclohexylbarbituric acid of formula (V), which is an important intermediate, comprising: (i) reacting dicyclohexylurea (DCU) with malonic acid in the presence of Ac2O in acetic acid to obtain a compound of formula (V); (ii) adding a poor solvent, preferably water, in an amount of 1 to 10 volumes, preferably 3 to 6 volumes per gram of the compound of formula (V); (iii) optionally heating the mixture of step (ii) at a temperature of 20 °C to 85 °C, preferably 20 °C to 30 °C; (iv) isolating the compound of formula (V).

[0175] In certain embodiments of the seventh aspect, the compound (V) is reacted with isocyanatoacetate of formula (IV) in the presence of a base and a solvent; and in the presence of a base and a solvent, the compound of formula (VI) is hydrolyzed, preferably according to the method of the sixth aspect, or using NaOH or KOH instead of a quaternary ammonium hydroxide, and then neutralized with an acid such as hydrochloric acid to be further converted to daprostat.

[0176] In certain embodiments of the seventh aspect of the present invention, the molar ratio of malonic acid to dicyclohexylurea (DCU) in step (i) is 2:1 to 1:1, preferably 1.5:1 to 1.1:1.

[0177] In certain embodiments, the molar ratio of Ac2O to dicyclohexylurea (DCU) used in step (i) is 4:1 to 2:1, preferably 3:1 to 2:1.

[0178] In certain embodiments, the mixture of step (i) is heated at a temperature of 70 °C to 95 °C, preferably 85 °C to 90 °C.

[0179] In one embodiment, the amount of the poor solvent, preferably water, in step (ii) is from 1 to 10 volumes, preferably from 3 to 6 volumes per gram of compound (V).

[0180] In one embodiment, the mixture of the compound of formula (V) and the poor solvent, preferably water, in step (ii) is heated at a temperature of 20°C to 85°C, preferably 20°C to 30°C, as the yield increases.

[0181] In one embodiment, the compound of formula (V) is further purified by crystallization or slurrying in an organic solvent selected from (C1-C3) alcohols, preferably methanol, ethanol or isopropanol, more preferably isopropanol.

[0182] In certain embodiments of the eighth aspect, the method further comprises preparing the crystalline form of daprostat as defined above by the method as defined in the second aspect of the present invention.

[0183] The ninth aspect of the present invention is a method for preparing a compound of formula (VI) (wherein R is unsubstituted or independently selected from the group consisting of (C3-C6) cycloalkyl, heterocycloalkyl, aryl and heteroaryl, in particular, (C3-C6) cycloalkyl, (C3-C 12 ) heterocycloalkyl, (C6-C 14 ) aryl and (C5-C 12 ) heteroaryl, and is substituted with one or more substituents independently selected from the group consisting of (C1-C 10 ) alkyl, preferably R is ethyl), comprising a) converting a formamide of formula (II) to an isocyanoacetate of formula (III) (wherein R is as defined above, preferably R is ethyl); b) converting the isocyanoacetate of formula (III) in step (a) to an isocyanatoacetate of formula (IV) (wherein R is as defined above, preferably R is ethyl); c) in the presence of a base and a solvent, reacting the isocyanatoacetate of formula (IV) obtained in step (b) with 1,3-dicyclohexylbarbituric acid of formula (V) to provide a compound of formula (VI); A process is provided which comprises a step of providing a compound of formula (VI), wherein steps (b) and (c) are carried out in a continuous manner.

[0184] In certain embodiments, the formamide of formula (II) is prepared from glycine ethyl ester hydrochloride in the presence of trimethyl orthoformate or triethyl orthoformate. In certain embodiments, the formamide of formula (II) is prepared from glycine ethyl ester hydrochloride in the presence of methyl formate or ethyl formate and a base, preferably an organic base such as TEA. In certain embodiments, the formamide of formula (II) is alternatively prepared from glycine ethyl ester in the presence of methyl formate. In certain embodiments, the formamide of formula (II) is prepared from glycine ethyl ester hydrochloride in the presence of ethyl formate and a base, preferably an organic base such as TEA.

[0185] In certain embodiments, the reaction mixture can be heated at a temperature of 20 °C to 85 °C, preferably 35 °C to 85 °C, more preferably 45 °C to 85 °C for a time sufficient to complete the reaction (e.g., 4 to 48 hours).

[0186] In certain embodiments, when methyl formate or ethyl formate and a base, preferably an organic base such as TEA, are used, the organic salt (e.g., triethylamine hydrochloride) formed in the preparation of the formamide of formula (II) can be removed by adding an organic solvent, preferably an (C6-C 14 ) aromatic hydrocarbon solvent such as toluene. In certain embodiments, the formamide of formula (II) is purified by fractional distillation. In certain embodiments, the formamide of formula (II) is used in the next step without further purification.

[0187] In certain embodiments of the ninth aspect, step (a) is carried out in the presence of a dehydrating agent and a base. Examples of dehydrating agents include, but are not limited to, phosgene, phosphorus oxychloride (POCl3), p-toluenesulfonyl chloride, triphenylphosphine (PPh3) / iodine (I2), Burgess reagent, Appel reagent, or trifluoromethanesulfonic anhydride. Preferably, the dehydrating agent is POCl3. Suitable bases can be organic bases selected from ammonia derivatives such as diethylamine, triethylamine (TEA), N,N-dicyclohexylmethylamine, N,N-dicyclohexylamine, and N,N-diisopropylethylamine (DIPEA), as well as heterocyclic bases such as pyridine and diazabicycloundecene (DBU), and mixtures thereof. Preferably, the base is TEA and DIPEA.

[0188] In certain embodiments, the isocyanoacetate of formula (III) is used in the next step (b) without further purification.

[0189] In certain embodiments, step (b) is carried out in the presence of dimethyl sulfoxide (DMSO) and trifluoroacetic anhydride (TFAA). Alternatively, step (b) is carried out using halogen or acid-catalyzed oxidation with mercury(II) oxide, lead tetraacetate, ozone, dimethyl sulfoxide (DMSO), and pyridine N-oxide.

[0190] In certain embodiments, the temperature used in step (b) is from -20 °C to -40 °C, preferably about -30 °C.

[0191] In certain embodiments, for the preparation of compound (IV), a solution of DMSO in a solvent is added to a solution of compound (III) and trifluoroacetic anhydride in a solvent.

[0192] In certain embodiments, in step (c), the amount of isocyanatoacetate of formula (IV) (preferably where R is ethyl in the formula) to the compound of formula (V) is in a molar ratio of 1:1 to 2:1, preferably 1:1 to 1.5:1, more preferably 1:1 to 1.2:1.

[0193] In certain embodiments, step (c) is carried out in the presence of a base and a solvent to provide a compound of formula (VI). Suitable bases can be organic bases selected from ammonia derivatives such as diethylamine, triethylamine (TEA), N,N-dicyclohexylmethylamine, N,N-dicyclohexylamine and N,N-diisopropylethylamine (DIPEA), and heterocyclic bases such as pyridine and diazabicycloundecene (DBU), and mixtures thereof. Preferably, the base used in step (c) is an organic base selected from TEA or DIPEA. In certain embodiments, the amount of the base can be 1.0 to 3.0, preferably 1.1 to 2.5, more preferably 1.1 to 1.5 molar equivalents relative to the compound of formula (V).

[0194] The solvents suitable for steps (a), (b) and (c) can be aprotic organic solvents. In certain embodiments, the aprotic solvent can be selected from halogenated hydrocarbon solvents (e.g., 1,2-dichloroethane, dichloromethane, chloroform, etc.), aromatic hydrocarbon solvents (e.g., toluene, o-xylene, m-xylene, and p-xylene), and ether solvents (e.g., diethyl ether, dipropyl ether, diphenyl ether, isopropyl ether, tert-butyl methyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, etc.). Preferably, the solvent is dichloromethane, toluene or tetrahydrofuran.

[0195] In certain embodiments, 1,3-dicyclohexylbarbituric acid of formula (V) is added to isocyanatoacetate of formula (IV). In certain embodiments, the compound of formula (V) is added in solid form, or dissolved in a solution, or suspended in an aprotic solvent with or without the presence of a base. In certain embodiments, a solution of isocyanatoacetate of formula (IV) in an aprotic solvent is added to a solution or suspension of the compound of formula (V) in an aprotic solvent. In a preferred embodiment, a solution of the compound of formula (V) in an aprotic solvent is added to a solution of isocyanatoacetate of formula (IV) in an aprotic solvent. The aprotic solvent is defined above for step (c). Preferably, the aprotic solvent is dichloromethane, toluene or tetrahydrofuran.

[0196] In certain embodiments, for the preparation of compound (VI), compound (V) is added into a solution of an aprotic solvent, preferably DCM, with or without the presence of a base. Further, the reaction medium of compound (IV) is added to another vessel containing compound (V) with or without the presence of a base and with or without the presence of an aprotic solvent.

[0197] In certain embodiments of the ninth aspect, compound (VI) is hydrolyzed in the presence of a base and a solvent, preferably according to the method of the sixth aspect, or using NaOH or KOH instead of a quaternary ammonium hydroxide, and then further converted to daprostat by neutralizing with an acid such as hydrochloric acid.

[0198] In certain embodiments of the ninth aspect, the method further comprises the preparation of the daprostat in the crystalline form as defined above by the method as defined in the third aspect of the present invention.

[0199] In certain embodiments, the present invention is a method for preparing daprostat of formula (I), or a pharmaceutically or veterinarily acceptable salt thereof,

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0200] In one embodiment, after the hydrolysis reaction of step (5) is completed, an acid selected from formic acid, acetic acid, monochloroacetic acid, trichloroacetic acid and trifluoroacetic acid (TFA), preferably trifluoroacetic acid (TFA) is added.

[0201] In certain embodiments, the daprostat is further purified by slurrying in an organic solvent selected from alcohols, preferably (C1-C3) alcohols, more preferably methanol, ethanol or isopropanol, and even more preferably ethanol. In another embodiment, the daprostat is further purified by crystallizing in an acid solvent, preferably acetic acid.

[0202] In certain embodiments of the tenth aspect, the method further comprises the preparation of the crystalline form of daprostat as defined above by the method as defined in the second aspect of the invention.

[0203] The present invention will now be further illustrated by way of examples. In no case should they be construed as limiting the scope of the invention as defined in the claims. Unless otherwise indicated, all percentages are by weight and temperatures are in degrees Celsius. [Examples]

[0204] [General method]

[0205] [X-ray powder diffraction (XRPD)] [Sample preparation]: Approximately 20 mg of the as-received sample was prepared in a standard sample holder using two foils of polyacetate. [Data acquisition]: Powder diffraction patterns were acquired using CuKα1 radiation in transmission geometry on a Bruker D8 Advance Series 2Theta / Theta powder diffraction system. This system is equipped with a VÅNTEC-1 single photon counting PSD, a germanium monochromator, a 90-position auto-changer sample stage, a fixed divergence slit and a radial soller. Programs used: Data collection by DIFFRAC plus XRD Commander V.2.5.1 and evaluation by HighScore Plus V.4.9. Measurement conditions: The sample was measured at room temperature in the range of 4° to 40° at 2θ using an angular step of 0.049° and a time per step of 2787 seconds for 0.5 hours.

[0206] One skilled in the art can understand that the powder X-ray diffraction pattern can be obtained with measurement errors that depend on the measurement conditions used. The intensity of the X-ray diffraction pattern can vary depending on the measurement conditions used, and it is generally known that the relative intensity values can vary, for example, by ±30%. It should also be further understood that the relative intensity may also change depending on the experimental conditions, and thus the exact order of intensities should not be taken into account. Furthermore, the measurement error of the diffraction angle of a conventional X-ray diffraction pattern is typically about ±0.2 degrees 2 theta, and the degree of such measurement error should be considered with respect to the aforementioned diffraction angle. As a result, it should be understood that the crystal forms of the present invention are not limited to crystal forms that provide an X-ray diffraction pattern that is exactly the same as the X-ray diffraction pattern shown in the accompanying drawings.

[0207] Differential Scanning Calorimetry (DSC) Sample preparation: Approximately 1 to 4 mg of the sample was weighed into a 40 μL aluminum crucible equipped with a pinhole lid (using an MX5 Mettler Toledo microbalance). Data acquisition: DSC analysis was recorded on a Mettler Toledo DSC822e calorimeter. Program used: Data collection and evaluation by software STARe. Measurement conditions: The sample was heated from 30 to 300 °C at 10 °C / min under dry nitrogen (flow rate: 50 mL / min).

[0208] Thermogravimetric Analysis (TGA) Sample preparation: Approximately 1 to 4 mg of the sample was weighed into a 40 μL aluminum crucible equipped with a pinhole lid (using an MX5 Mettler Toledo microbalance). Data acquisition: Thermogravimetric analysis was recorded on a Mettler Toledo TGA / DSC 3+ with a balance type XP1. Program used: Data collection and evaluation by software STARe. Measurement conditions: The sample was heated from 30 to 300 °C at a rate of 10 °C / min under dry nitrogen (flow rate: 10 mL / min).

[0209] Proton nuclear magnetic resonance ( 1 1H-NMR) Sample preparation: Approximately 2 - 5 mg of the sample was dissolved in 0.7 mL of a deuterated solvent (dimethyl sulfoxide-d6). Data acquisition: Proton nuclear magnetic resonance analysis was recorded on a Bruker 300 NMR spectrometer equipped with a z-gradient 5 mm BBO (Broadband Observe) probe with ATM and an automatic autosampler. Measurement conditions: The sample was analyzed at room temperature.

[0210] Fourier transform infrared spectroscopy (FTIR) FTIR spectra were recorded using an Agilent Technologies Cary 630 FTIR spectrometer equipped with an Agilent Diamond single reflection ATR system, a mid-infrared source as the excitation source, and a DTGS detector. Spectra were acquired at a resolution of 4 cm−1 in the range of 4000 - 650 cm−1 with 32 scans. -1 in the range of 4 cm -1 −1 resolution with 32 scans.

[0211] Dynamic vapor sorption analysis (DVS) Sample preparation: Approximately 5 - 10 mg of the sample was weighed (using an MX5 Mettler Toledo microbalance) into a 150 μL platinum crucible without a lid. Data acquisition: The experiment was carried out on a Mettler Toledo TGA / DSC 1 LF instrument equipped with an LF SDTA FRS2 sensor and connected to a Modular Humidity Generator MHG 32. Data collection and evaluation were performed using STARe software. Measurement conditions: The sample was analyzed according to a humidity cycle of 25 °C (RH: relative humidity) from 5% RH to 90% RH and back to 5% RH in 10% steps for 60 minutes.

[0212] Optical microscopy Sample preparation: The crystals of the sample were immersed in perfluorinated oil. Description of the apparatus: The Zeiss Stemi SV 11 stereomicroscope has variable magnification in the range of 15x to 154x and is equipped with cross-polarizing filters (Carl Zeiss Pol 45517 and 455174) and a l / 2 filter (Carl Zeiss Lambda 455172). For sample illumination, a transmitted cold light source Zeiss KL2500 LCD is used. The size of the crystals can be measured using a standard microslide (5 + 100 / 100 mm, Carl Zeiss 474026).

[0213] Environmental scanning electron microscopy (ESEM) Sample preparation: The sample was attached to an aluminum stub using double-sided carbon conductive tabs. Apparatus: An environmental scanning electron microscope from FEI, model Quanta 600 equipped with EDX (energy-dispersive X-ray spectroscopy) from Oxford Instruments. For the sample morphology image, secondary electrons were collected. Working conditions: Working distance (WD) = 9.9 - 10.3 mm; Accelerating voltage (HV) = 20 kV; Magnification (Mag) = variable (1000x - 4000x).

[0214] Atomic absorption spectrometry (AAS) Apparatus: ICP-OES, Optima 8000 Perkin Elmer Measurement conditions: Wavelength of sodium: 589.592 nm; Wavelength of potassium: 766.490 nm Sample preparation: 25 mg of the sample, 3 mL of concentrated HNO3 and 1 mL of H2O2 were digested in an ultraWAVE Milestone digester. The temperature was heated at 100°C for 5 minutes, 170°C for 10 minutes, and finally 240°C for 10 minutes. The sample was held at this final temperature for 15 minutes. Then, the sample was diluted with 25 mL of 2% HNO3 aqueous solution, followed by a second dilution of 1 mL in 20 mL of 2% HNO3 aqueous solution.

[0215] Example 1: Synthesis of daprostat solvate

[0216] Various daprodustat solvates (Form A, Form B, Form C, Form D, Form E, Form F, Form G and Form H) were prepared as shown in Table 5. All solids obtained herein were crystalline solvates of daprodustat as characterized by XRPD and DSC / TGA analyses.

[0217] [Table 5]

[0218] Common methods:

[0219] Evaporation: A sample of daprodustat (50 mg), obtained by replicating Method 2 of WO 2007 / 150011 A2, was dissolved in a minimum amount of solvent and allowed to evaporate at ambient conditions until a solid was obtained.

[0220] Cooling crystallization: Reproducing Method 2 of WO 2007 / 150011 A2, a sample of daprodustat (50 mg) was dissolved in a minimum amount of solvent at 75°C, and the resulting solution was slowly cooled to room temperature or 4°C to induce crystallization.

[0221] Slurry: A sample of daprodustat (50 mg), obtained by replicating Method 2 of WO 2007 / 150011 A2, was suspended in solvent at 75°C, and the resulting suspension was stirred at this temperature for 2 hours and cooled to room temperature.

[0222] Example 2: Synthesis of co-crystals of daprodustat sodium salt and daprodustat free acid

[0223] A sample of the duprostostat (1 g, 2.54 mmol) obtained by reproducing Method 2 of International Publication No. 2007 / 150011 A2 was suspended in a mixture of acetonitrile and water (9:1 respectively, 55 mL) at 95 °C. An aqueous sodium hydroxide solution (1 M, 0.5 equivalent, 1.28 mL) was added dropwise to the resulting solution, and the resulting suspension was allowed to cool to room temperature. The resulting solid was filtered off and dried under vacuum (2 mbar, 40 °C, 3 hours).

[0224] XRPD (Figure 1): Crystal.

[0225] DSC (Figure 2): Endothermic peaks have onset temperatures of 115 °C (-63 J / g), 190 °C (-11 J / g), 202 °C (-2 J / g) and 228 °C (-39 J / g).

[0226] TGA (Figure 2): 4.4% weight loss from 33 to 150 °C (possible loss of water; 2 theoretical equivalents: 4.3%). Decomposition starts at about 230 °C.

[0227] 1 1H-NMR (300 MHz, DMSO, FIG3): δ (ppm): 10.13 (t, 1H, J = 6 Hz), 4.66 (m, 2H), 3.96 (d, 2H, J = 6 Hz), 2.31 (m, 4H), 1.77 (m, 4H), 1.57 (m, 6H), 1.20 (m, 6H). No residual solvent was detected.

[0228] FTIR: ν (cm -1 , Figure 4): 691, 761, 789, 840, 895, 924, 966, 1000, 1024, 1057, 1132, 1178, 1237, 1266, 1306, 1338, 1379, 1420, 1444, 1479, 1522, 1586, 1670, 1716, 2849, 2914, 2930, 2973, 3233, 3522, 3649.

[0229] DVS: About 0.4% weight gain at relative humidity of 10% - 80% (slightly hygroscopic). No change was observed in XRPD before and after analysis.

[0230] AAS: 2.9% Na (This corresponds to a molar ratio of 1:1 of the free acid of daprodustat to the sodium salt of daprodustat)

[0231] Example 3: Synthesis of a cocrystal of potassium salt of daprodustat and free acid of daprodustat

[0232] A sample of daprodustat (1 g, 2.54 mmol) obtained by reproducing Method 2 of WO 2007 / 150011 A2 pamphlet was suspended in a mixture of acetonitrile and water (9:1 respectively, 55 mL) at 95 °C. An aqueous potassium hydroxide solution (1 M, 0.5 equivalent, 1.28 mL) was added dropwise to the resulting solution, and the resulting suspension was allowed to cool to room temperature. The resulting solid was filtered off and dried under vacuum (2 mbar, 40 °C, 3 hours).

[0233] XRPD (Figure 7): Crystalline

[0234] DSC (Figure 8): Endothermic peaks with onset temperatures of 33 °C (-87 J / g) and 248 °C (-46 J / g)

[0235] TGA (Figure 8): 5.4% weight loss at 27 - 125 °C (possibility of water loss; 2.5 theoretical equivalents: 5.2%). Decomposition starts at about 250 °C

[0236] 1 H-NMR (300 MHz, DMSO, FIG9): δ (ppm): 10.08 (t, 1H, J = 6 Hz), 4.65 (m, 2H), 3.93 (d, 2H, J = 6 Hz), 2.30 (m, 4H), 1.77 (m, 4H), 1.57 (m, 6H), 1.20 (m, 6H). No residual solvent was detected

[0237] FTIR: ν (cm -1, Figure 10): 693,740,762,790,882,894,918,996,1054,1134,1187,1235,1258,1302,1340,1378,1446,1472,1506,1522,1589,1669,2655,2852,2935,2977,3180,3477,3546.

[0238] DVS: Weight gain of approximately 3.9% at relative humidity (hygroscopicity) of 10% - 80%. No change was observed in XRPD before and after analysis.

[0239] AAS: 4.6% K (which corresponds to a molar ratio of 1:1 of the duprostat free acid and the potassium salt of duprostat)

[0240] Example 4: Temperature stability study

[0241] Samples of crystalline N2 and K2 were stored in sealed vials at different temperatures (T), for example, 45°C and 60°C. After some time, the solids were separated and analyzed by XRPD. The results are summarized in Table 6.

[0242] [Table 6]

[0243] Example 5: Solubility study

[0244] Using the solubility test method according to the Chinese Pharmacopoeia, different pH values of different organs in the human body were considered: FeSSIF (fed state simulated intestinal fluid, pH = 5.0), FaSSIF (fasted state simulated intestinal fluid, pH = 6.5) and pure water. Duprostat in the prior art form CS1, crystalline form N2 and crystalline form K2 were suspended in different media at 25°C to obtain saturated solutions. The solutions were sampled at certain time points (1 hour, 4 hours and 24 hours). The concentration values in mg / mL were measured by HPLC. The results are summarized in Table 7.

[0245] [Table 7]

[0246] High Performance Liquid Chromatography (HPLC): Equipment: Agilent Technologies 1200 series Column: Zorbax C18 (50mm×2.1) 1.8μm Eluent: ACN / H2O 6:4 Flow rate: 0.5 ml / min Wavelength: 266 nm Injection volume: 5 μL

[0247] From the results obtained in Table 7, the daptostat of crystalline form N2 showed improved solubility at pH = 6.5 and in pure water compared to the prior art form CS1. Also, the daptostat of crystalline form K2 showed improved solubility at pH = 5.0, pH = 6.5 and in pure water compared to the prior art form CS1.

[0248] Example 6: Drying stability test

[0249] Samples of crystals N2 and K2 were dried overnight in vacuo (12 mbar) at different temperatures (T) in a vacuum drying oven. The resulting solids were analyzed by XRPD. The results are summarized in Table 8. [Table 8]

[0250] As shown in Table 8, the daptostat of crystalline form K2 did not change its form by XRPD analysis. The daptostat of crystalline form N2 was converted to crystalline form N4 characterized by XRPD, DSC / TGA and DVS analyses as shown below.

[0251] XRPD (Figure 5 and Table 2): Crystal (very similar to crystalline form N2).

[0252] DSC (Figure 6): Endothermic peaks have onset temperatures of 107 °C (-62 J / g), 190 °C (-6 J / g), 200 °C (-2 J / g), and 229 °C (-38 J / g).

[0253] TGA (Figure 6): A 4.0% weight loss from 39 °C to 141 °C (possible water loss; 2 theoretical equivalents: 4.3%). Decomposition starts at approximately 220 °C.

[0254] DVS: A weight gain of approximately 0.5% at relative humidities from 10% to 80% (slightly hygroscopic). No change was observed in XRPD before and after analysis.

[0255] Example 7: Slurry experiments

[0256] Samples of crystalline N2 and K2 were suspended in water (100 mg in 1 mL) and stirred at room temperature for 1 hour. The resulting solid was then separated and analyzed by XRPD. As confirmed by XRPD analysis, crystalline form N2 did not change its form. As confirmed by XRPD analysis, crystalline form K2 did not change its form.

[0257] Samples of crystalline N2 and K2 were suspended in water (100 mg in 1 mL) and stirred at three different temperatures of 40 °C, 60 °C, and 80 °C for 30 minutes and 60 minutes. Crystalline form N2 did not change its form in all experiments, as confirmed by XRPD analysis. Crystalline form K2 did not change its form in all experiments, as confirmed by XRPD analysis.

[0258] Example 8: Synthesis of the daptostat of crystalline form N2 from intermediate compound (VI) where R is ethyl

[0259] Ethyl (1,3-dicyclohexyl-2,4,6-trioxohexahydropyrimidine-5-carbonyl) glycinate (5.0 g, 11.9 mmol, 1.0 eq) was suspended in ethanol (20 mL). 1 M aqueous NaOH solution (23.8 mL, 23.8 mmol, 2.0 eq) was added, and the mixture was stirred at 20 - 25 °C for 2 h. The solvent was distilled off under reduced pressure at 40 °C. Acetonitrile (25 mL) was added, and the medium was heated at 40 °C until a solution was obtained, and then the solvent was distilled off under reduced pressure at 40 °C. This operation was repeated once. Acetonitrile (248 mL) and water (10 mL) were added. To the resulting solution, 1 M aqueous solution of HCl (11.9 mL, 11.9 mmol, 1.0 eq) was added at 20 - 25 °C. The white solution was seeded with the daptostat of crystal form N2 (prepared in Example 2). Then, 1 M aqueous solution of HCl (6.0 mL, 6.0 mmol, 0.5 eq) was added at 20 - 25 °C. The white solution was seeded with the daptostat of crystal form N2 (prepared in Example 2) and stirred at 20 - 25 °C for 20 h. The white solid was filtered under reduced pressure. The obtained white solid was suspended in water (100 mL) at 20 - 25 °C for 1 h. The white suspension was filtered and washed with water (2 × 25 mL) under reduced pressure. The obtained white solid was suspended in water (100 mL) at 20 - 25 °C for 1 h again. The white solid was filtered and washed with water (2 × 25 mL) under reduced pressure and dried under reduced pressure at 40 °C for 4 h (3.3 g, 7.8 mmol, yield: 66%).

[0260] XRPD: Daptostat of crystal form N2.

[0261] Example 9: Synthesis of daptostat of crystal form K1 from intermediate compound (VI) where R is ethyl

[0262] Ethyl (1,3-dicyclohexyl-2,4,6-trioxohexahydropyrimidine-5-carbonyl) glycinate (5.0 g, 11.9 mmol, 1.0 equivalent) was suspended in ethanol (20 mL). 1 M aqueous KOH solution (23.8 mL, 23.8 mmol, 2.0 equivalents) was added, and the mixture was stirred at 20 - 25 °C for 2 hours. The solvent was distilled off under reduced pressure at 40 °C. Acetonitrile (25 mL) was added, and the medium was heated at 40 °C until a solution was obtained, and then the solvent was distilled off under reduced pressure at 40 °C. This operation was repeated once. Acetonitrile (248 mL) and water (10 mL) were added. To the resulting solution, 1 M aqueous solution of HCl (11.9 mL, 11.9 mmol, 1.0 equivalent) was added at 20 - 25 °C. The white solution was seeded with daprostat in crystalline form K2. Then, 1 M aqueous solution of HCl (6.0 mL, 6.0 mmol, 0.5 equivalent) was added at 20 - 25 °C. The white solution was seeded with daprostat in crystalline form K2 (prepared in Example 3) and stirred at 20 - 25 °C for 20 hours. The white solid was filtered under reduced pressure. The obtained white solid was suspended in water (100 mL) at 20 - 25 °C for 1 hour. The white suspension was filtered and washed with water (2 × 25 mL) under reduced pressure. The obtained white solid was suspended again in water (100 mL) at 20 - 25 °C for 1 hour. The white solid was filtered, washed with water (2 × 25 mL) under reduced pressure, and dried under reduced pressure at 40 °C for 4 hours (3.1 g, 7.0 mmol, yield: 60%).

[0263] XRPD (Figure 15 and Table 4): Daprostat in crystalline form K1.

[0264] DSC (Figure 16): Endothermic peaks have onset temperatures of 56 °C (-142 J / g) and 251 °C (-76 J / g).

[0265] TGA (Figure 16): 13.2% weight loss from 40 °C to 130 °C. Decomposition starts at about 250 °C.

[0266] KF: 11.57%

[0267] The daprostat of crystalline form K1 obtained above was dried under vacuum at room temperature to obtain the daprostat of crystalline form K2.

[0268] Example 10: Synthesis of 1,3 - dicyclohexylpyrimidine - 2,4,6(1H,3H,5H) - trione (Compound V)

[0269] 1,3 - Dicyclohexylurea (DCU) (175.0 g, 780.0 mmol, 1.0 equivalent) and malonic acid (97.4 g, 936.0 mmol, 1.2 equivalents) were stirred at 20 - 25 °C together with acetic acid (700 mL). To the resulting white suspension, acetic anhydride (199.1 g, 184.0 mL, 1.950 mol, 2.5 equivalents) was added at 20 - 25 °C. The resulting mixture was heated at 80 - 85 °C and stirred at this temperature for 5 hours. Then, the system was cooled to 20 - 25 °C and water (700 mL) was added. The resulting suspension was stirred at 20 - 25 °C for 16 hours. The white solid was separated by filtration under reduced pressure at 20 - 25 °C and washed with a 1:1 mixture of acetic acid and water (2 × 85 mL), water (175 mL), and isopropanol (175 mL). The resulting solid was slurried from isopropanol (1300 mL) at 80 °C and stirred at this temperature for 10 minutes. Then, the mixture was cooled to 20 - 25 °C, stirred at this temperature for 16 hours, and then stirred at 0 - 5 °C for 1 hour. The white solid was separated by filtration under reduced pressure at 0 - 5 °C, washed with ice - cold isopropanol (2 × 100 mL), and dried at 40 - 45 °C.

[0270] Yield: 70% (158.6 g, 542.5 mmol)

[0271] Purity by HPLC: 99.54%

[0272] Example 11: Synthesis of ethyl formylglycinate (Compound II)

[0273] Ethyl glycinate hydrochloride (100.0 g, 716.4 mmol, 1.0 equiv) was mixed with trimethyl orthoformate (300 mL, 291.0 g, 3.8 equiv) at 20 - 25 °C. The resulting white suspension was heated at reflux temperature and stirred at this temperature for 4 hours. Then, the solvent was distilled under reduced pressure at 40 - 75 °C. The obtained brownish residue was purified by fractional distillation under reduced pressure to obtain a transparent oily substance.

[0274] Yield: 86% (80.8 g, 616.2 mmol)

[0275] Purity by HPLC: 98.23%

[0276] Example 12: Synthesis of ethyl formylglycinate (Compound II)

[0277] Ethyl glycinate hydrochloride (25.0 g, 179 mmol, 1.0 equiv) was mixed with ethyl formate (75.0 mL, 69.1 g, 932 mmol, 5.2 equiv) and triethylamine (26.2 mL, 19.0 g, 188 mmol, 1.05 equiv) at 20 - 25 °C. The resulting white suspension was heated at reflux temperature and stirred at this temperature for 24 hours. The reaction medium was cooled to 20 - 25 °C, and the white solid was filtered off and washed with ethyl formate. The solvent of the filtrate was distilled under reduced pressure at 40 °C. The obtained residue was mixed with toluene (100 mL), and the resulting mixture was stirred at 20 - 25 °C for 1 hour. The white solid was filtered off and washed with toluene. Then, the solvent of the filtrate was distilled under reduced pressure at 40 °C. The obtained brownish oily substance was purified by distillation under reduced pressure to obtain a transparent oily substance.

[0278] Yield: 81% (19.0 g, 145 mmol).

[0279] Purity by HPLC: 99.69%

[0280] Example 13: Synthesis of ethyl (1,3 - dicyclohexyl - 6 - hydroxy - 2,4 - dioxo - 1,2,3,4 - tetrahydropyrimidine - 5 - carbonyl) glycinate (Compound VI)

[0281] A solution of ethyl formylglycinate (Compound II, 48.0 g, 366.0 mmol, 1.0 eq) and triethylamine (92.6 g, 128 mL, 915.1 mmol, 2.5 eq) in dichloromethane (288 mL) was cooled to 0 - 5 °C. A solution of phosphorus oxychloride (61.7 g, 37.5 mL, 403 mmol, 1.1 eq) in dichloromethane (96 mL) was slowly added while maintaining the temperature of the system below 5 °C. The resulting mixture was stirred at 0 - 5 °C for 1 hour. At that point, a 10% aqueous solution of potassium carbonate (384 mL) was added at a temperature below 25 °C. Then, the mixture was stirred at 20 - 25 °C for 1 hour. The phases were separated, and the aqueous phase was extracted with dichloromethane (96 mL). The organic phases were combined and washed with a saturated aqueous solution of sodium bicarbonate (96 mL) and water (96 mL). The solvent of the organic phase was distilled off under reduced pressure to obtain a reddish oil corresponding to ethyl 2-isocyanoacetate (Compound III). This oil was used in the next step without further purification.

[0282] A solution of the reddish oil (Compound III) and DMSO (35.7 g, 32.5 mL, 457.5 mmol, 1.25 eq) in dichloromethane (240 mL) was cooled to -30 °C to -35 °C, and a solution of trifluoroacetic anhydride (7.7 g, 5.2 mL, 36.6 mmol, 0.10 eq) in dichloromethane (48 mL) was slowly added. The system was stirred at -35 °C for 30 minutes. Ethyl 2-isocyanatoacetate (Compound IV) was formed in the reaction medium.

[0283] At this point, 1,3-dicyclohexylpyrimidine-2,4,6(1H,3H,5H)-trione (Compound V) (95.8 g, 327.7 mmol, 0.94 equivalent) and diisopropylethylamine (90.1 g, 121 mL, 697.1 mmol, 2.0 equivalents) were added. The resulting solution was stirred at 20 - 25 °C for 16 hours. Then, 3N aqueous hydrochloric acid solution (300 mL) was added, and the mixture was stirred at 20 - 25 °C for 15 minutes. The phases were separated, and the aqueous phase was extracted with dichloromethane (200 mL). The organic phases were combined and washed with saturated aqueous sodium bicarbonate solution (200 mL) and water (200 mL). The solvent of the organic phase was distilled off under reduced pressure and exchanged with isopropanol (1056 mL) to obtain a yellowish suspension, which was heated at reflux temperature to obtain a solution, and this was cooled to 20 - 25 °C. The resulting suspension was stirred at this temperature for 1 hour. The white solid was separated by filtration under reduced pressure at 20 - 25 °C and washed with isopropanol (2 × 100 mL). The white solid was recrystallized from IPA (1000 mL), filtered off, and dried at 40 - 45 °C.

[0284] Yield: 70% (96.7 g, 229.4 mmol)

[0285] Purity by HPLC: 99.66%

[0286] Example 14: Ethyl (1,3-dicyclohexyl-6-hydroxy-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbonyl) glycinate (Compound VI)

[0287] A solution of ethyl formylglycinate (Compound II, 35.0 g, 267 mmol, 1.0 eq) and triethylamine (59.4 g, 81.8 mL, 587 mmol, 2.2 eq) in dichloromethane (210 mL) was cooled to 0 - 5 °C. A solution of phosphorus oxychloride (45.0 g, 27.4 mL, 294 mmol, 1.1 eq) in dichloromethane (70 mL) was slowly added while maintaining the temperature of the reaction medium below 5 °C. The resulting mixture was stirred at 0 - 5 °C for 2 hours. At that point, a 10% aqueous solution of potassium carbonate (350 mL) was added at a temperature below 25 °C. The mixture was then stirred at 20 - 25 °C for 1 hour. The phases were separated and the aqueous phase was extracted twice with dichloromethane (2×70 mL). The organic phases were combined and washed with water (70 mL) and brine (70 mL). The solvent of the organic phase was distilled off under reduced pressure to obtain a reddish oil corresponding to ethyl 2-isocyanoacetate 30 (Compound III). This oil was used in the next step without further purification.

[0288] A mixture of DMSO (24.0 g, 21.8 mL, 308 mmol, 1.2 eq) in dichloromethane (55 mL) was cooled to a temperature of -30 °C to -35 °C. Trifluoroacetic anhydride (5.38 g, 3.62 mL, 25.6 mmol, 0.10 eq) was slowly added at this temperature. Then, a solution of the previously obtained reddish oil (Compound III) in dichloromethane (50 mL) was slowly added while maintaining the temperature at -30 °C to -35 °C. The solution was stirred at this temperature for 30 minutes. Ethyl 2-isocyanatoacetate (Compound IV) was formed in the reaction medium.

[0289] At this point, while maintaining the temperature below 0 °C, a solution of 1,3-dicyclohexylpyrimidine-2,4,6(1H,3H,5H)-trione (Compound V) (59.9 g, 205 mmol, 0.8 eq) and diisopropylethylamine (36.4 g, 49.1 mL, 282 mmol, 1.1 eq) in dichloromethane (120 mL) was added. The resulting solution was stirred at 20 - 25 °C for 4 hours. Then, an aqueous solution (450 mL) of 37% HCl (50 mL) was added, and the mixture was stirred at 20 - 25 °C for 15 minutes. The phases were separated, and the aqueous phase was extracted with dichloromethane (70 mL). The organic phases were combined and washed with water (70 mL) and saturated aqueous sodium bicarbonate solution (70 mL). The solvent of the organic phase was distilled off under reduced pressure and exchanged with isopropanol (700 mL) to obtain a yellowish suspension, which was heated to reflux temperature to obtain a solution, and this was cooled to 20 - 25 °C. The resulting suspension was stirred at this temperature for 16 hours. The white solid was separated by filtration at 20 - 25 °C and washed with isopropanol (3 × 35 mL). The white solid was recrystallized from IPA (6600 mL), filtered, and dried at 40 - 45 °C.

[0290] Yield: 74% (63.5 g, 151 mmol)

[0291] Purity by HPLC: 99.50%

[0292] Example 15: Synthesis of (1,3-Dicyclohexyl-6-hydroxy-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbonyl)glycine (Compound I)

[0293] A suspension of ethyl (1,3-dicyclohexyl-6-hydroxy-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbonyl) glycinate (Compound VI obtained above) (5.0 g, 11.9 mmol, 1.0 equivalent) in ethanol (60 mL) cooled to 0-5 °C was added with an aqueous solution of 25% tetramethylammonium hydroxide (9.0 mL, 26 mmol, 2.2 equivalents) at 0-5 °C. The resulting mixture was heated at 20-25 °C for 1 hour. Then, trifluoroacetic acid (3.0 g, 2.0 mL, 26 mmol, 2.2 equivalents) was added, and the resulting white suspension was stirred at 20-25 °C for 1 hour. The solid was filtered, washed with ethanol (2 × 5 mL), and dried at 40-45 °C.

[0294] Yield 90% (4.2 g, 10.7 mmol)

[0295] Purity by HPLC: 99.93%

Claims

1. A crystalline form of daprodustat which is a co-crystal comprising free acid of daprodustat and a pharmaceutically acceptable metal salt of daprodustat, wherein the metal salt is an alkali metal salt.

2. The crystalline form of daprodustat according to claim 1, wherein the molar ratio of free acid of daprodustat to the metal salt of daprodustat is 1:3 to 3:1, preferably 1:2 to 2:1, more preferably about 1:

1.

3. The crystalline form of daprodustat according to any one of claims 1 to 2, wherein the alkali metal salt is a sodium salt.

4. A co-crystal called Form N2, having an X-ray powder diffraction pattern that includes peaks at 2 theta values of 6.3° ± 0.2°, 7.4° ± 0.2°, 7.6° ± 0.2°, 11.4° ± 0.2° and 16.2° ± 0.2° as measured by Kα radiation of copper having an X-ray wavelength of 1.5406 Å at room temperature, the crystalline form of daprodustat according to claim 3.

5. The crystalline form of daprodustat according to claim 4, wherein the X-ray powder diffraction pattern of the crystal N2 further includes peaks at 2 theta values of 13.0° ± 0.2°, 13.5° ± 0.2°, 14.5° ± 0.2°, 14.8° ± 0.2° and 15.2° ± 0.2° as measured by Kα radiation of copper having an X-ray wavelength of 1.5406 Å at room temperature.

6. The crystalline form of daprodustat according to any one of claims 4 to 5, wherein the crystal N2 contains water in an amount of 0.2% to 10% by weight, preferably 2% to 8% by weight, more preferably 4.0% to 6.0% by weight, based on the total weight of the crystal.

7. A co-crystal called Form N4, having an X-ray powder diffraction pattern that includes peaks at 2 theta values of 6.4° ± 0.2°, 7.4° ± 0.2°, 7.6° ± 0.2°, 13.4° ± 0.2° and 16.7° ± 0.2° as measured by Kα radiation of copper having an X-ray wavelength of 1.5406 Å at room temperature, the crystalline form of daprodustat according to claim 3.

8. The crystalline form of daprodustat according to claim 7, wherein the X-ray powder diffraction pattern of the crystal N4 further includes peaks at 2 theta values of 15.0° ± 0.2°, 26.9° ± 0.2°, 27.5° ± 0.2°, 27.7° ± 0.2° and 28.2° ± 0.2° as measured by Kα radiation of copper having an X-ray wavelength of 1.5406 Å at room temperature.

9. The crystalline N4 contains water in an amount of 0.2% by weight to 5% by weight, preferably 2% by weight to 5% by weight, more preferably 3.9% by weight to 4.5% by weight, based on the total weight of the crystals. The crystalline form of daprostat according to any one of claims 7 to 8.

10. The crystalline form of daprostat according to any one of claims 1 to 2, wherein the alkali metal salt is a potassium salt.

11. It is a eutectic called Form K2 and has an X-ray powder diffraction pattern including peaks with 2-theta values of 5.5° ± 0.2°, 6.3° ± 0.2°, 7.0° ± 0.2°, 16.8° ± 0.2° and 18.0° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature. The crystalline form of daprostat according to claim 10.

12. The X-ray powder diffraction pattern of the crystal K2 further includes peaks with 2-theta values of 7.8° ± 0.2°, 11.8° ± 0.2°, 12.7° ± 0.2°, 13.7° ± 0.2° and 27.6° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature. The crystalline form of daprostat according to claim 11.

13. The crystal K2 contains water in an amount of 0.2% by weight to 10% by weight, preferably 2% by weight to 8% by weight, more preferably 4.0% by weight to 6.0% by weight, based on the total weight of the crystals. The crystalline form of daprostat according to any one of claims 11 to 12.

14. It is a eutectic called Form K1 and has an X-ray powder diffraction pattern including peaks with 2-theta values of 5.4° ± 0.2°, 7.9° ± 0.2°, 14.6° ± 0.2°, 15.6° ± 0.2° and 17.5° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature. The crystalline form of daprostat according to claim 10.

15. The X-ray powder diffraction pattern of the crystal K1 further includes peaks with 2-theta values of 10.2° ± 0.2°, 11.3° ± 0.2°, 12.1° ± 0.2°, 15.8° ± 0.2° and 16.2° ± 0.2° as measured by copper Kα radiation having an X-ray wavelength of 1.5406 Å at room temperature. The crystalline form of daprostat according to claim 14.

16. The crystalline form of daprostatut as claimed in any one of claims 14 to 15, wherein the crystal K1 contains water in an amount of 10% to 14% by weight based on the total weight of the crystals.

17. A method for the preparation of a crystalline form of daprostatut as defined in claims 1 to 16, comprising: a) providing a daprostatut free acid in a solvent or a mixture of solvents; b) optionally, heating the mixture of step (a) to a suitable temperature, preferably from 70°C to 100°C, more preferably from 75°C to 95°C; c) adding a source of a pharmaceutically acceptable metal inorganic base, preferably an alkali metal inorganic base, more preferably in the form of an alkali metal hydroxide, in an amount of about 0.5 molar equivalents relative to the daprostatut free acid of step (a); d) optionally, cooling the solution obtained from step (c) to room temperature; e) isolating the crystalline form of daprostatut.

18. The method according to claim 17, wherein the source of the pharmaceutically acceptable metal inorganic base is a source of an alkali metal inorganic base, preferably the alkali metal inorganic base is an alkali metal hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide.

19. The method according to any one of claims 17 to 18, wherein the solvent used in step (a) is selected from the group consisting of acetonitrile, dichloromethane (DCM), toluene, tetrahydrofuran, and combinations thereof.

20. The method according to any one of claims 17 to 18, wherein the solvent used in step (a) is a mixture of water and another solvent selected from the group consisting of acetonitrile, dichloromethane (DCM), toluene, and tetrahydrofuran, preferably the solvent used in step (a) is a mixture of water and acetonitrile.

21. The method according to any one of claims 14 to 20, wherein steps b) and d) are carried out.

22. A method for the preparation of a crystalline form of daprostatut as defined in claims 1 to 16, comprising: i. preparing an ester intermediate of formula (VI) in a solvent or a mixture of solvents; 【Chemical Formula 1】 (wherein R is unsubstituted or substituted with one or more substituents independently selected from the group consisting of (C ３ ~C ６ ) cycloalkyl, (C ３ ~C １２ ) heterocycloalkyl, (C ６ ~C １４ ) aryl, and (C ５ ~C １２ ) heteroaryl, and is preferably (C １ ~C １０ ) alkyl substituted with ethyl), ii. optionally, heating the mixture of step (i) to an appropriate temperature, preferably from room temperature to 100°C, more preferably from 30°C to 75°C. iii. A source in the form of a pharmaceutically acceptable metal inorganic base, preferably an alkali metal inorganic base, more preferably an alkali metal hydroxide, is added to the ester intermediate of step (i) in an amount of 1.0 to 2.2, preferably 2.0 to 2.2 molar equivalents to form the corresponding alkali metal salt of duprostat of formula (Ia); [Chemical Formula 2] (wherein M is an alkali metal), iv. Adding hydrochloric acid to the mixture of step (iii) in an amount of 0.5 to 1.7, preferably 1.5 to 1.7 molar equivalents; v. Optionally, cooling the mixture obtained from step iv) to room temperature; vi. Isolating the duprostat in the crystalline form; A method comprising.

23. The method according to claim 22, wherein the source of the pharmaceutically acceptable metal inorganic base is an alkali metal inorganic base, preferably the alkali metal inorganic base is an alkali metal hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide.

24. The solvent used in step (i) is a mixture of water and another solvent selected from the group consisting of (C １ -C １２ ) alcohol and acetonitrile. The method according to any one of claims 22 to 23.

25. The aforesaid (C １ ~C １２ ) alcohol is selected from methanol, ethanol, isopropanol and 1-propanol, the method according to claim 24.

26. The method according to any one of claims 22 to 25, wherein steps (ii) and (v) are carried out.

27. Step (iii) is iii. 1) A sub-step of completely or partially removing the solvent or mixture of solvents of step (i) by evaporation or distillation; iii. 2) A sub-step of adding a different solvent or mixture of solvents to provide a solution or suspension; The method according to any one of claims 22 to 26, further comprising.

28. The solvent or mixture of solvents in (iii.1) is a (C １ -C １２ ) alcohol, and the solvent or mixture of solvents in (iii.2) is a mixture of acetonitrile and water in a ratio of 5:1 (v / v) to 15:1 (v / v), preferably 8:1 (v / v) to 12:1 (v / v), more preferably 9:1 (v / v), the method according to claim 27.

29. The method according to any one of claims 22 to 28, further comprising seeding with the desired crystalline form of duprostat before step (v) is carried out, or before or during step (iv) is carried out.

30. A pharmaceutical composition comprising a duprostat in a crystalline form defined in any one of claims 1 to 16, which is a crystalline form selected from the group consisting of crystalline form N2, crystalline form N4, crystalline form K2, and crystalline form K1, and combinations thereof, together with one or more pharmaceutically acceptable carriers, diluents or excipients.

31. A duprostat in a crystalline form defined in any one of claims 1 to 16 for use in the treatment of renal anemia.

32. A compound of formula (VI) is converted to the daprostat of formula (I) by hydrolysis in the presence of a quaternary ammonium hydroxide of formula N[(C １ ~C ４ )alkyl] ４ OH, preferably tetramethylammonium hydroxide (TMAH), and a solvent, and optionally converting the daprostat of formula (I) to its pharmaceutically or veterinarily acceptable salt. A method for preparing a daprostat of formula (I), or a pharmaceutically or veterinarily acceptable salt thereof: [Chemical Formula 3] 【Chemical 4】 (wherein R is unsubstituted or is substituted with one or more substituents independently selected from the group consisting of (C ３ ~C ６ ) cycloalkyl, (C ３ ~C １２ ) heterocycloalkyl, (C ６ ~C １４ ) aryl and (C ５ ~C １２ ) heteroaryl, and is preferably (C １ ~C １０ ) alkyl substituted with ethyl.).

33. The solvent is selected from the group consisting of (C １ -C ３ ) alcohol, preferably methanol, ethanol or isopropanol, water, and mixtures thereof, according to the method of claim 32.

34. The solvent is a mixture of (C １ ~C ３ ) alcohol and water in a volume ratio of 10:1 to 1:2, preferably 5:1 to 1:2, more preferably 10:1 to 5:1, according to the method of claim 33.

35. The method according to any one of claims 32 to 34, wherein after the hydrolysis reaction is completed, an acid selected from formic acid, acetic acid, monochloroacetic acid, trichloroacetic acid and trifluoroacetic acid (TFA), preferably trifluoroacetic acid (TFA) is added.

36. The method according to any one of claims 32 to 35, wherein the compound of formula (VI) is prepared by reacting isocyanatoacetate of formula (IV) with 1,3-dicyclohexylbarbituric acid of formula (V) in the presence of a base and a solvent: 【Chemical Formula 5】 (wherein R is unsubstituted or is substituted with one or more substituents independently selected from the group consisting of C ３ -C ６ cycloalkyl, (C ３ -C １２ ) heterocycloalkyl, (C ６ -C １４ ) aryl and (C ５ -C １２ ) heteroaryl, and is preferably (C １ -C １０ ) alkyl, and preferably, R is ethyl.). 【Chemical Formula 6】

37. The method according to claim 36, wherein the isocyanatoacetate of formula (IV) is prepared from isocyanoacetate of formula (III): 【Chemical Formula 7】 (wherein R is as defined in claim 36, and preferably, R is ethyl).

38. The method according to claim 37, wherein the compound of formula (III) is prepared from formamide of formula (II): 【Chemical 8】 (wherein R is as defined in claim 36, and preferably, R is ethyl),

39. The compound of formula (VI) is a) a step of converting formamide of formula (II) to isocyanoacetate of formula (III); [Chemical Formula 9] (wherein R is as defined in claim 36, and preferably, R is ethyl), b) a step of converting the isocyanoacetate of formula (III) in step (a) to isocyanatoacetate of formula (IV); 【Chemical 10】 (wherein R is as defined in claim 36, and preferably, R is ethyl), c) a step of reacting the isocyanatoacetate of formula (IV) obtained in step (b) with 1,3-dicyclohexylbarbituric acid of formula (V) in the presence of a base and a solvent to obtain the compound of formula (VI), wherein steps (b) and (c) are carried out in a continuous manner, a step of obtaining the compound, 【Chemical 11】 The method according to any one of claims 32 to 35, which is prepared by a method comprising the above steps.

40. The method according to any one of claims 36 to 39, wherein the solvent used in the reaction of the isocyanatoacetate of formula (IV) with 1,3-dicyclohexylbarbituric acid of formula (V) is an aprotic solvent, preferably dichloromethane (DCM), toluene or tetrahydrofuran.

41. The method according to any one of claims 36 to 40, wherein the base used in the reaction of the isocyanatoacetate of formula (IV) with 1,3-dicyclohexylbarbituric acid of formula (V) is an organic base, preferably triethylamine (TEA) or diisopropylamine (DIPEA).

42. The 1,3-dicyclohexylbarbituric acid of formula (V) is (i) Ac in acetic acid ２ A step of reacting dicyclohexylurea (DCU) with malonic acid in the presence of O to obtain a compound of formula (V); (ii) adding a poor solvent, preferably water, in an amount of 1 to 10 volumes, preferably 3 to 6 volumes per gram of compound (V); (iii) optionally heating the mixture of step (ii) at a temperature of 20°C to 85°C, preferably 20°C to 30°C; (iv) isolating the compound of formula (V); The method according to any one of claims 36 to 41, which is prepared by a method comprising

43. The method according to claim 42, wherein step (i) is carried out at a temperature of 70°C to 95°C, preferably 85°C to 90°C.

44. The method according to any one of claims 42 to 43, wherein step (iii) is carried out.

45. The method according to any one of claims 36 to 44, wherein the 1,3-dicyclohexylbarbituric acid of formula (V) is added to the isocyanatoacetate of formula (IV).

46. The method according to any one of claims 37 to 45, wherein the conversion of the isocyanoacetate of formula (III) to the isocyanatoacetate of formula (IV) is carried out in the presence of dimethyl sulfoxide (DMSO) and trifluoroacetic anhydride (TFAA).

47. The method according to any one of claims 37 to 46, wherein the conversion of the isocyanoacetate of formula (III) to the isocyanatoacetate of formula (IV) is carried out at a temperature of -20°C to -40°C, preferably about -30°C.

48. The conversion of the formamide of formula (II) to the isocyanoacetate of formula (III) is carried out in the presence of a dehydrating agent, preferably POCl ３ , and a base, preferably an organic base selected from triethylamine (TEA) or diisopropylamine (DIPEA), according to any one of claims 38 to 47.

49. The method according to any one of claims 38 to 48, wherein the formamide of formula (II) is prepared from glycine ethyl ester hydrochloride in the presence of trimethyl orthoformate or triethyl orthoformate.

50. (i) Ac in acetic acid ２ reacting dicyclohexylurea (DCU) with malonic acid in the presence of O to obtain a compound of formula (V); 【Chemical 12】 (ii) adding a poor solvent, preferably water, in an amount of 1 to 10 volumes, preferably 3 to 6 volumes per gram of compound (V); (iii) optionally heating the mixture of step (ii) at a temperature of 20°C to 85°C, preferably 20°C to 30°C; (iv) isolating the compound of formula (V); A process for preparing 1,3-dicyclohexylbarbituric acid of formula (V) comprising: **Claim 51** A process for preparing a daprostat of formula (I) or a pharmaceutically or veterinarily acceptable salt thereof, comprising: 【Chemical 13】 a1) 1,3-dicyclohexylbarbituric acid of formula (V) is 【Chemical 14】 (i) Ac in acetic acid ２ reacting dicyclohexylurea (DCU) with malonic acid in the presence of O to obtain a compound of formula (V); (ii) adding a poor solvent, preferably water, in an amount of 1 to 10 volumes, preferably 3 to 6 volumes per gram of the compound of formula (V), per gram of the compound of formula (V); (iii) optionally heating the mixture of step (ii) at a temperature of 20°C to 85°C, preferably 20°C to 30°C; (iv) isolating the compound of formula (V); and preparing by a process comprising; a2) reacting 1,3-dicyclohexylbarbituric acid of formula (V) obtained in step (a1) with isocyanatoacetate of formula (IV) in the presence of a base and a solvent to obtain a compound of formula (VI); 【Chemical Formula 15】 (wherein R is unsubstituted or is substituted with one or more substituents independently selected from the group consisting of C ３ -C ６ cycloalkyl, (C ３ -C １２ ) heterocycloalkyl, (C ６ -C １４ ) aryl and (C ５ -C １２ ) heteroaryl, and is preferably (C １ -C １０ ) alkyl substituted with R being ethyl). 【Chemical 16】 (wherein R is as defined above, preferably R is ethyl) a3) converting the compound of formula (VI) to daprostat of formula (I) by hydrolysis in the presence of a base and a solvent; a4) optionally converting the daprostat of formula (I) to its pharmaceutically or veterinarily acceptable salt; A process comprising. **Claim 52** The process according to any one of claims 50 to 51, wherein step (i) is carried out at a temperature of 70°C to 95°C, preferably 85°C to 90°C. **Claim 53** The process according to any one of claims 50 to 52, wherein step (iii) is carried out. **Claim 54** The process according to any one of claims 51 to 53, wherein the solvent used in step (a2) is an aprotic solvent, preferably dichloromethane (DCM), toluene or tetrahydrofuran. **Claim 55** The process according to any one of claims 51 to 54, wherein the base used in step (a2) is an organic base selected from triethylamine (TEA) or diisopropylamine (DIPEA). **Claim 56** The process according to any one of claims 51 to 55, wherein the 1,3-dicyclohexylbarbituric acid of formula (V) is added to the isocyanatoacetate of formula (IV). **Claim 57** The method according to any one of claims 51 to 56, wherein the base used in step (a3) is an inorganic base selected from NaOH and KOH, and is preferably neutralized with an acid such as hydrochloric acid thereafter.

58. The base used in step (a3) is a quaternary ammonium hydroxide of the formula N[(C １ ~C ４ )alkyl] ４ OH, preferably tetramethylammonium hydroxide (TMAH), and the method according to any one of claims 51 to 56.

59. The method according to claim 58, wherein, after the hydrolysis reaction in step (a3) is completed, an acid selected from formic acid, acetic acid, monochloroacetic acid, trichloroacetic acid and trifluoroacetic acid (TFA), preferably trifluoroacetic acid (TFA) is added.

60. The solvent used in step (a3) is selected from the group consisting of (C １ -C ３ ) alcohols, preferably methanol, ethanol or isopropanol, water, and mixtures thereof, according to any one of claims 51 to 59.

61. The solvent used in step (a3) is a mixture of (C １ -C ３ ) alcohol and water in a volume ratio of 10:1 to 1:2, preferably 5:1 to 1:2, more preferably 10:1 to 5:

1. The method according to claim 60.

62. The method according to any one of claims 51 to 61, wherein the isocyanatoacetate of formula (IV) is prepared from the isocyanoacetate of formula (III): 【Chemical 17】 (wherein R is as defined in claim 51, and preferably, R is ethyl).

63. The method according to claim 62, wherein the compound of formula (III) is prepared from the formamide of formula (II): 【Chemical 18】 (wherein R is as defined in claim 51, and preferably, R is ethyl).

64. The method according to claim 63, wherein the formamide of formula (II) is prepared from glycine ethyl ester hydrochloride in the presence of trimethyl orthoformate or ethyl orthoformate.

65. The isocyanatoacetate of formula (IV) is a) a step of converting the formamide of formula (II) into the compound isocyanoacetate of formula (III), 【Chemical Formula 19】 (wherein R is as defined in claim 51, and preferably, R is ethyl), b) a step of converting the isocyanoacetate of formula (III) in step (a) into the isocyanatoacetate of formula (IV), wherein steps (b) and (a) are carried out in a continuous manner, and the converting step, 【Chemical 20】 (wherein R is as defined in claim 51, and preferably, R is ethyl), The method according to any one of claims 51 to 61, which is prepared by a method comprising the above steps.

66. The method according to any one of claims 62 to 65, wherein the conversion of the isocyanoacetate of formula (III) to the isocyanatoacetate of formula (IV) is carried out in the presence of dimethyl sulfoxide (DMSO) and trifluoroacetic anhydride (TFAA).

67. The method according to any one of claims 62 to 66, wherein the conversion of the isocyanoacetate of formula (III) to the isocyanatoacetate of formula (IV) is carried out at a temperature of -20 °C to -40 °C, preferably about -30 °C.

68. The conversion of the formamide of formula (II) to the isocyanoacetate of formula (III) is carried out in the presence of a dehydrating agent, preferably POCl ３ , and a base, preferably an organic base selected from triethylamine (TEA) or diisopropylamine (DIPEA), according to any one of claims 63 to 67.

69. A method for preparing a compound of formula (VI), comprising: 【Chemical 21】 (wherein R is unsubstituted or C ３ -C ６ cycloalkyl, heterocycloalkyl, (C ３ -C １２ ) heterocycloalkyl, (C ６ -C １４ ) aryl and (C ５ -C １２ ) heteroaryl, and is substituted with one or more substituents independently selected from the group consisting of (C １ -C １０ ) alkyl, and preferably, R is ethyl.). a) converting formamide of formula (II) to a compound of formula (III), isocyanoacetate; 【Chemical 22】 (wherein R is as defined above, and preferably, R is ethyl) b) converting the isocyanoacetate of formula (III) obtained in step (a) to an isocyanatoacetate of formula (IV); 【Chemical 23】 (wherein R is as defined above, and preferably, R is ethyl), c) reacting the isocyanatoacetate of formula (IV) obtained in step (b) with 1,3-dicyclohexylbarbituric acid of formula (V) in the presence of a base and a solvent to obtain the compound of formula (VI), wherein steps (b) and (c) are carried out in a continuous manner; 【Chemical 24】 a method comprising the above steps.

70. A method for preparing daprostat of formula (I) or a pharmaceutically or veterinarily acceptable salt thereof, comprising: 【Chemical 25】 b1) converting formamide of formula (II) to a compound of formula (III), isocyanoacetate; 【Chemical 26】 (wherein R is unsubstituted or C ３ ~C ６ cycloalkyl, (C ３ -C ６ ) cycloalkyl, (C ３ ~C １２ ) heterocycloalkyl, (C ６ ~C １４ ) aryl and (C ５ ~C １２ ) heteroaryl, and is substituted with one or more substituents independently selected from the group consisting of (C １ ~C １０ ) alkyl, and preferably R is ethyl), b2) converting the isocyanoacetate of formula (III) obtained in step (b1) to an isocyanatoacetate of formula (IV); 【Chemical 27】 (wherein R is as defined above, and preferably R is ethyl), b3) reacting the isocyanatoacetate of formula (IV) obtained in step (b2) with 1,3-dicyclohexylbarbituric acid of formula (V) in the presence of a base and a solvent to obtain a compound of formula (VI), wherein steps (b2) and (b3) are carried out in a continuous manner; 【Chemical Formula 28】 【Chemical 29】 (wherein R is as defined above, and preferably, R is ethyl), b4) converting the compound of formula (VI) to daprostat of formula (I) by hydrolysis in the presence of a base and a solvent; b5) optionally, converting daprostat of formula (I) to its pharmaceutically or veterinarily acceptable salt. a method comprising the above steps.

71. The method according to any one of claims 69 to 70, wherein the solvent used in the reaction of the isocyanatoacetate of formula (IV) with 1,3-dicyclohexylbarbituric acid of formula (V) is an aprotic solvent, preferably dichloromethane (DCM), toluene or tetrahydrofuran.

72. The method according to any one of claims 69 to 71, wherein the base used in the reaction of the isocyanatoacetate of formula (IV) with 1,3-dicyclohexylbarbituric acid of formula (V) is an organic base selected from triethylamine (TEA) or diisopropylamine (DIPEA).

73. The 1,3-dicyclohexylbarbituric acid of formula (V) is (i) Ac in acetic acid ２ A step of reacting dicyclohexylurea (DCU) with malonic acid in the presence of O to obtain a compound of formula (V); (ii) adding a poor solvent, preferably water, in an amount of 1 to 10 volumes, preferably 3 to 6 volumes per gram of compound (V); (iii) optionally heating the mixture of step (ii) at a temperature of 20°C to 85°C, preferably 20°C to 30°C; (iv) isolating the compound of formula (V); The method according to any one of claims 69 to 72, which is prepared by a method comprising:

74. The method according to claim 73, wherein step (i) is carried out at a temperature of 70°C to 95°C, preferably 85°C to 90°C.

75. The method according to any one of claims 73 to 74, wherein step (ii) is carried out.

76. The method according to any one of claims 69 to 75, wherein the 1,3-dicyclohexylbarbituric acid of formula (V) is added to the isocyanatoacetate of formula (IV).

77. The method according to any one of claims 69 to 76, wherein the conversion of the isocyanoacetate of formula (III) to the isocyanatoacetate of formula (IV) is carried out in the presence of dimethyl sulfoxide (DMSO) and trifluoroacetic anhydride (TFAA).

78. The method according to any one of claims 69 to 77, wherein the conversion of the isocyanoacetate of formula (III) to the isocyanatoacetate of formula (IV) is carried out at a temperature of -20°C to -40°C, preferably about -30°C.

79. The conversion of the formamide of formula (II) to the isocyanoacetate of formula (III) is carried out in the presence of a dehydrating agent, preferably POCl ３ , and a base, preferably an organic base selected from triethylamine (TEA) or diisopropylamine (DIPEA), according to any one of claims 69 to 78.

80. The method according to any one of claims 69 to 79, wherein the formamide of formula (II) is prepared from glycine ethyl ester hydrochloride in the presence of trimethyl orthoformate or ethyl orthoformate.

81. The method according to any one of claims 70 to 80, wherein the base used in step (b4) is an inorganic base selected from NaOH and KOH, and is preferably neutralized with an acid such as hydrochloric acid thereafter.

82. The base used in step (b4) is of the formula N[(C １ ~C ４ )alkyl] ４ OH, a quaternary ammonium hydroxide, preferably tetramethylammonium hydroxide (TMAH), the method according to any one of claims 70 to 80.

83. The method according to claim 82, wherein in step (b4), after the hydrolysis reaction is completed, an acid selected from formic acid, acetic acid, monochloroacetic acid, trichloroacetic acid and trifluoroacetic acid (TFA), preferably trifluoroacetic acid (TFA), is added.

84. The solvent used in step (b4) is selected from the group consisting of (C １ -C ３ ) alcohols, preferably methanol, ethanol or isopropanol, water, and mixtures thereof, the method according to any one of claims 70 to 83.

85. The solvent is a mixture of (C １ ~C ３ ) alcohol and water in a volume ratio of 10:1 to 1:2, preferably 5:1 to 1:2, more preferably 10:1 to 5:1, according to the method of claim 84.

86. The method according to any one of claims 32 to 49, further comprising the preparation of the crystalline form of daprostat defined in any one of claims 1 to 16 by the method defined in any one of claims 17 to 21.

87. The method according to any one of claims 51 to 68, further comprising the preparation of the crystalline form of daprostat defined in any one of claims 1 to 16 by the method defined in any one of claims 17 to 21.

88. The method according to any one of claims 70 to 85, further comprising the preparation of the crystalline form of daprostat defined in any one of claims 1 to 16 by the method defined in any one of claims 17 to 21.

89. The method according to claim 69, further comprising the preparation of the crystalline form of daprostat defined in any one of claims 1 to 16 by the method defined in any one of claims 22 to 29.

90. A method for the preparation of the crystalline form of daprostat according to claims 17 to 21, wherein the daprostat free acid is prepared by the method defined in any one of claims 32 to 49, or by the method defined in any one of claims 51 to 68, or by the method defined in any one of claims 70 to 85.

91. A process for the preparation of the crystalline forms of daptostat described in claims 22 to 29, wherein the ester intermediate of formula (VI) is prepared by the process defined in claim 69.

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