A method for preparing cangrelor intermediate adenosine-2-thione

Abstract

This invention relates to a method for preparing cangrelor intermediate adenosine-2-thione. Specifically, crude adenosine-2-thione is treated with a solvent containing a reducing agent to obtain high-purity adenosine-2-thione in high yield.

Description

Technical Field

[0001] This invention belongs to the pharmaceutical field and relates to a method for preparing the cangrelor intermediate adenosine-2-thione. Background Technology

[0002] Cangrelor (N-[2-(methylthio)ethyl]-2-[(3,3,3-trifluoropropyl)thio]-5'-adenosine monophosphate tetrasodium salt of (dichloromethylene)bisphosphate, cangrelor) is an inhibitor of the adenosine diphosphate (ADP) receptor P2Y12. It inhibits platelet aggregation by inhibiting adenosine cyclase activity. Its indications are percutaneous arterial intervention and arterial syndrome, to prevent thrombosis.

[0003]

[0004] CN1042430C and J.Med.Chem.1999,42,213-220 describe a method for synthesizing cangrelo, including the following steps:

[0005]

[0006] Compound of Formula 1 is prepared by alkylation of adenosine-2-thione, which is crucial to the yield and quality of cangrelor. Adenosine-2-thione is an important intermediate in the synthesis of cangrelor.

[0007]

[0008] The journal article *Nucleosides & Nucleotides*, Volume 12, Issue 1, pp. 1-20, January 1993, discloses a method for preparing this key intermediate using compound 3a. The specific method involves dissolving compound 3a in 25 ml of water, mixing it with 175 ml of methanol and 50 ml of carbon disulfide, heating the mixture at 110°C for 5 hours, cooling, collecting the yellow crystalline solid, washing with water and ethanol, and drying to obtain the intermediate.

[0009]

[0010] US3989682A discloses a method for preparing adenosine-2-thione by performing the above reaction steps under high pressure. On the other hand, CN105893800A also discloses a process for preparing adenosine-2-thione, which involves adding 5 ml of tetrahydrofuran and compound 3 (27 g), 100 ml of methanol, 100 ml of carbon disulfide and 500 ml of dimethyl sulfoxide into a reaction flask, stirring at 140-150 °C for 12 h, then removing the solvent by vacuum distillation, washing with ethanol, water and saturated sodium chloride aqueous solution, and drying to obtain 24 g of product.

[0011] Existing literature focuses more on process operability than on the quality of the resulting samples. However, existing methods inevitably introduce impurities, especially those detected by HPLC with a retention time of approximately 16.7 min, which have been identified as disulfides, as shown below.

[0012]

[0013] Sometimes the crude product contains at least 25% disulfide impurities. The presence of disulfide impurities reduces the process yield and increases the difficulty of subsequent purification processes. Therefore, it is necessary to develop an efficient method for removing disulfide impurities to obtain adenosine-2-thione in high yield. Summary of the Invention

[0014] This invention provides a method for preparing adenosine-2-thione (2-thioadenosine) or its salts, comprising: b) adding crude adenosine-2-thione to an alcohol solution containing a reducing agent, stirring, and filtering; c) adding the sample obtained in step b) to an acidic solution, stirring, and filtering to obtain the target product, i.e., high-purity adenosine-2-thione or its salts.

[0015]

[0016] Furthermore, the method further includes step a) reacting 5-amino-1-β-D-furanose ribosylimidazol-4-carboxamide oxime or its salt optionally with carbon disulfide under alkaline conditions to form crude adenosine-2-thione.

[0017] In some embodiments, the alkaline reagent in step a) is selected from sodium hydroxide or potassium hydroxide. In other embodiments, the solvent used in step a) is selected from, but not limited to, at least one of water, methanol, ethanol, or dimethyl sulfoxide. The methods in US3989682A and CN105893800A are provided as examples, and their contents are incorporated herein by reference.

[0018] Furthermore, in some embodiments, 5-amino-1-β-D-rifuranosylimidazol-4-carboxamide oxime or a salt thereof is reacted with carbon disulfide in an aqueous sodium hydroxide solution in an autoclave to form crude adenosine-2-thione.

[0019] In some embodiments, 5-amino-1-β-D-rifuranosylimidazol-4-carboxamide oxime or its salt (3a) is reacted with carbon disulfide in a sodium hydroxide methanol solution to form crude adenosine-2-thione.

[0020] In other embodiments, 5-amino-1-β-D-ribofuranosylimidazolium-4-carboxamide oxime or its salt (3a) is reacted with carbon disulfide in a sodium hydroxide methanol solution under high pressure to form crude adenosine-2-thione. In some embodiments, the high pressure is 2 to 15 atmospheres, and can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or any two of these values.

[0021] In some embodiments, the molar ratio of 5-amino-1-β-D-furanoribosylimidazolium-4-carboxamide oxime (3a) to carbon disulfide is 1:1 to 1:4, including 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.0, 1:2.2, 1:2.5, 1:3, 1:3.2, 1:3.4, 1:4, or any value between any two numbers.

[0022] On the other hand, the reaction temperature in step a) is 60 to 140°C, including 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C or any value between any two numbers.

[0023] In some embodiments, the applicant discovered that 5-amino-1-β-D-rifuranosylimidazolium-4-carboxamide oxime or its salts, such as its hydrochloride, inevitably generate an impurity with an HPLC retention time of 16.7 min during the preparation of crude adenosine-2-thione with carbon disulfide, especially under high-temperature conditions. Upon separation and identification, this impurity was determined to be a disulfide, specifically a polymer of two molecules of adenosine-2-thione, with the following structural, NMR, and mass spectrometric identification data.

[0024]

[0025] 1 H NMR (400MHz, DMSO-d6): δ8.28(s,2H),7.55(s,4H),5.81(d,J=6.0Hz,2H),5.43(d,J=6.1Hz,2H),5.16(d,J=4.9Hz,2H),4.9 5(t,J=5.6Hz,2H),4.56(q,J=5.7Hz,2H),4.12(q,J=4.4Hz,2H),3.90(q,J=4.1Hz,2H),3.55(ddt,J=49.3,11.9,4.9Hz,4H).

[0026] 13C NMR (101MHz, DMSO-d6): δ161.92,156.27,150.77,139.67,118.15,87.51,86.08,73.89,70.99,62.05,39.95.

[0027] HRMS(ESI)m / z Found:597.1300Calcd.:C 20 H 24 N 10 O8S2:(M+H) + 597.1298.

[0028] In some embodiments, the crude adenosine-2-thione obtained in step a) contains not less than 25% disulfide impurities. In some embodiments, the disulfide impurity content in the crude adenosine-2-thione obtained in step a) is 20%. In some embodiments, the disulfide impurity content in the crude adenosine-2-thione obtained in step a) is 15%. Surprisingly, when the disulfide impurities come into contact with the reducing agent, they undergo degradation and are subsequently converted back into adenosine-2-thione. In some embodiments, the reducing agent in step b) is selected from sodium bisulfite, sodium dithionite, sodium borohydride, potassium borohydride, or hydrazine hydrate. This improves the yield of the process while reducing the difficulty and cost of subsequent purification processes.

[0029]

[0030] On the other hand, the inventors further discovered that different reducing agents have different effects on disulfides, but all are within acceptable ranges. In some embodiments, the reducing agent in step b) is selected from sodium bisulfite. In some embodiments, the reducing agent in step b) is selected from sodium borohydride. In some embodiments, the reducing agent in step b) is selected from hydrazine hydrate.

[0031] On the other hand, in some embodiments, the alcohol solvent in step b) is selected from, but not limited to, at least one of methanol, ethanol, and water. In some embodiments, the alcohol solvent in step b) is selected from methanol.

[0032] Furthermore, maintaining a suitable temperature during stirring in step b) facilitates the decomposition of impurities obtained in step a), such as disulfides. In some embodiments, the temperature during stirring in step b) is maintained between 40 and 100°C, and can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or any value between any two numbers. In other embodiments, the amount of reducing agent added in step b) is expected to be 0.5 to 2 molar amounts of disulfides, and can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, or any value between any two numbers.

[0033] Furthermore, in some other embodiments, the acidic reagent in step c) is selected from hydrochloric acid or sulfuric acid. The presence of the acidic solution can, on the one hand, decompose the excess reducing agent in step b), and on the other hand, further dissolve other impurities to obtain adenosine-2-thione with high purity.

[0034] In some embodiments, the concentration of the acidic solution is selected from 0.1-6 mol / L, including but not limited to 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, or any value between any two numbers.

[0035] In some embodiments, a method for preparing adenosine-2-thione or a salt thereof includes:

[0036]

[0037] a) 5-Amino-1-β-D-ribofuranosylimidazol-4-carboxamide oxime or its salt, such as its hydrochloride, is reacted with carbon disulfide in a sodium hydroxide methanol solution at 60–140 °C to form crude adenosine-2-thione, which is then concentrated.

[0038] b) Add the sample obtained in step a) to an alcohol solution containing a reducing agent, stir, and filter, wherein the reducing agent is selected from sodium bisulfite, sodium dithionite, sodium borohydride, potassium borohydride or hydrazine hydrate, and the alcohol solvent is selected from methanol, ethanol and water;

[0039] c) Add the sample obtained in step b) to an acidic solution, stir, and filter to obtain the target product adenosine-2-thione or its salt, wherein the acidic reagent is selected from hydrochloric acid or sulfuric acid.

[0040] Another aspect of the present invention provides a method for preparing adenosine-2-thione or a salt thereof, comprising the step of converting the compound of formula (II), i.e., the disulfide, into adenosine-2-thione under reducing conditions.

[0041]

[0042] In some embodiments, the reducing agent is selected from, but not limited to, sodium bisulfite, sodium dithionite, sodium borohydride, potassium borohydride, or hydrazine hydrate. In some embodiments, the solvent used is selected from alcohol solvents, including but not limited to at least one of methanol, ethanol, and water. In some embodiments, the reaction temperature is maintained at 40–100°C, and can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or any value between any two of these values.

[0043] In some embodiments, the molar ratio of disulfide to reducing agent is 0.2:1 to 2:1, and can be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2.0:1, or any value between any two numbers. In some embodiments, the molar ratio of disulfide to reducing agent is 0.5:1 to 1.1:1.

[0044] Furthermore, the method for preparing adenosine-2-thione of the present invention further includes the steps of adding the sample obtained in the aforementioned steps to an acidic solution, stirring, and filtering. In some embodiments, the acidic solution is selected from hydrochloric acid or sulfuric acid solution. In other embodiments, the concentration of the acidic solution is selected from 0.1-6 mol / L, including but not limited to 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, or any value between any two numbers.

[0045] On the other hand, the method for preparing adenosine-2-thione or its salts according to the present invention further includes washing and drying steps.

[0046] Furthermore, the purity of adenosine-2-thione or its salt prepared by the method of the present invention is not less than 98%, and can be 98.0%, 98.1%, 98.2%, 98.3%, 98.4%, 98.5%, 98.6%, 98.7%, 98.8%, 98.9%, 99.0%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or higher.

[0047] In another aspect, the present invention provides a method for preparing cangrelor, comprising the aforementioned method steps for preparing adenosine-2-thione or a salt thereof, and a method for preparing cangrelor from adenosine-2-thione or a salt thereof.

[0048]

[0049] In some embodiments, the synthetic methods for preparing cangrelo from adenosine-2-thione or its salts are described in CN1042430C and J.Med.Chem.1999,42,213-220, and the relevant contents are incorporated herein for illustration.

[0050] On the other hand, the present invention also provides a method for preparing cangrelo, comprising the steps of converting the aforementioned disulfide to adenosine-2-thione or a salt thereof, and a method for preparing cangrelo from adenosine-2-thione or a salt thereof.

[0051]

[0052] In addition, the present invention provides the use of disulfides (compounds of formula II) in the preparation of cangrelo.

[0053] The salts of the compounds described in this invention are products of salt formation between the compounds and conventional acids, such as the reaction of adenosine-2-thione with hydrochloric acid to give adenosine-2-thione hydrochloride. Conventional acids include hydrochloric acid, sulfuric acid, or phosphoric acid.

[0054] In this invention, adenosine-2-thione can exist in tautomer form, as shown below.

[0055]

[0056] The term "filtration" in this invention is merely a description of one method of separating solids and liquids, and does not refer to only one specific operation. In actual production, methods such as centrifugation or spin-drying also fall into this category.

[0057] In this invention, the numerical values ​​are instrument measurements and are subject to a certain degree of error. Generally, ±10% is within a reasonable error range. Of course, the context in which the value is used must be considered. For example, in the case of reactor pressure, where the measured error variation does not exceed ±10%, the value can be ±9%, ±8%, ±7%, ±6%, ±5%, ±4%, ±3%, ±2%, or ±1%, preferably ±5%.

[0058] In this invention, “optional” or “optionally” means that the event or circumstances described below may, but do not necessarily, occur, and the description includes the occasion in which the event or circumstances occur or do not occur. Attached Figure Description

[0059] Figure 1 disulfides 1 H NMR spectrum. Detailed Implementation

[0060] The present invention is further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the present invention.

[0061] Experimental methods in the embodiments of this invention that do not specify specific conditions are generally performed under conventional conditions or as recommended by the raw material or product manufacturer. Reagents whose specific source is not specified are commercially available conventional reagents.

[0062] The structure of the compound was determined by nuclear magnetic resonance (NMR) and / or mass spectrometry (MS). NMR shifts (δ) were expressed in 10⁻¹⁰ ohms. -6 The unit (ppm) is given. NMR measurements were performed using a Bruker AVANCE-400 NMR spectrometer, with deuterated dimethyl sulfoxide (DMSO-d6) as the solvent and tetramethylsilane (TMS) as the internal standard.

[0063] HPLC determination was performed using a Thermo U3000 equipped with a DAD detector. The chromatographic column was a Thermo AQ C18 (2.1 × 50 mm, 1.7 μm). The mobile phase consisted of phase A, which was composed of 0.14% Na3PO4 aqueous solution (pH 6), and phase B, which consisted of 0.14% Na3PO4 (pH 6) in methanol aqueous solution (methanol:water 1:1 v / v). The methanol was chromatographic grade, and gradient elution was used. The detection wavelength was 260-300 nm.

[0064] MS measurements were performed using a Waters Micromass Quattro micro API triple quadrupole mass spectrometer, scanning in positive / negative ion mode, with a mass scan range of 120–1300.

[0065] The silica gel plates used for thin-layer chromatography are Yantai Huanghai HSGF254 silica gel plates. The silica gel plates used in thin-layer chromatography (TLC) have a size of 0.2mm ± 0.03mm, and the size used for thin-layer chromatography separation and purification of products is 0.4mm-0.5mm.

[0066] Example 1

[0067]

[0068] In a 10L reactor, 1 kg of 5-amino-1-β-D-rifuranosylimidazolium-4-carboxamide oxime hydrochloride was added to a 2L methanol-water (7:1) solution. Sodium hydroxide was added to adjust the pH to 9-10, and 5L of carbon disulfide was added. The mixture was reacted under high pressure and at 120℃ for 5-6 hours. After cooling to room temperature, the mixture was concentrated to obtain the crude product, and the content was determined to be 85.27% by HPLC.

[0069] The solid obtained in the previous step was added to 4 L of methanol solution, and 152.2 g of sodium borohydride (1.1 equivalents) was added. The mixture was heated to 65-70 °C and stirred for 2-3 h. After cooling, the mixture was filtered and washed with methanol. The solid was then added to 2 L of hydrochloric acid (1 mol / L), heated to 80-90 °C and stirred for 1-2 h. After cooling, the mixture was filtered and washed with purified water. The product was dried under vacuum at 60-80 °C to obtain the target product. HPLC analysis showed a content of 99.1% and a yield of 88%.

[0070] Example 2

[0071]

[0072] In a 500 ml reaction flask, 10 g of 5-amino-1-β-D-ribofuranosylimidazolium-4-carboxamide oxime hydrochloride was added to 200 ml of methanol-water (8:1) solution. Sodium hydroxide was added to adjust the pH to 9-10, and 50 ml of carbon disulfide was added. The mixture was reacted under high pressure at 130 °C for 7 h, cooled to room temperature, and concentrated to obtain the crude product. HPLC analysis showed that the content of adenosine-2-thione was 75.27%. The disulfide was then separated by column chromatography.

[0073] 1 H NMR (400MHz, DMSO-d6): δ8.28(s,2H),7.55(s,4H),5.81(d,J=6.0Hz,2H),5.43(d,J=6.1Hz,2H),5.16(d,J=4.9Hz,2H),4.9 5(t,J=5.6Hz,2H),4.56(q,J=5.7Hz,2H),4.12(q,J=4.4Hz,2H),3.90(q,J=4.1Hz,2H),3.55(ddt,J=49.3,11.9,4.9Hz,4H).

[0074] 13 C NMR (101MHz, DMSO-d6): δ161.92,156.27,150.77,139.67,118.15,87.51,86.08,73.89,70.99,62.05,39.95.

[0075] HRMS(ESI)m / z Found:597.1300Calcd.:C 20 H 24 N 10 O8S2:(M+H) + 597.1298.

[0076] Example 3

[0077]

[0078] 2 g of the disulfide obtained in Example 2 was added to 12 ml of methanol solution and stirred to disperse into a suspension. 0.253 g of sodium borohydride was added, and the mixture was heated to 65–70 °C and stirred for 1–2 h. After cooling, the mixture was filtered and washed with methanol. The resulting solid was then added to a 1 mol / L hydrochloric acid solution, heated to 80–90 °C and stirred for 1–2 h. After cooling, the mixture was filtered and washed with purified water. The product was then vacuum dried at 60–80 °C to obtain 0.90 g of the target product, with a purity of 98.11% as determined by HPLC.

[0079] Example 4

[0080] Take 2g of the disulfide obtained in Example 2, and investigate the effect of different reducing agents on the conversion of disulfide to adenosine-2-thione, referring to the method in Example 3. The specific results are shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] Example 5

[0085]

[0086] 2 kg of disulfide (prepared according to the method in Example 2) was added to 12 L of methanol solution and stirred to disperse into a suspension. 127 g of sodium borohydride was added, and the mixture was heated to 65–70 °C and stirred for 1–3 h. After cooling, the mixture was filtered and washed with methanol. The resulting solid was then added to a 1 mol / L hydrochloric acid solution, heated to 80–90 °C and stirred for 2–3 h. After cooling, the mixture was filtered, washed with purified water, and dried under vacuum at 60–80 °C to obtain 953 g of the target product, with a yield of 95% and a purity of 98.55% as determined by HPLC.

Claims

1. A method for preparing adenosine-2-thione or a salt thereof, comprising the step of converting a compound of formula (II) to adenosine-2-thione under reducing conditions, wherein the reducing agent is selected from sodium bisulfite, sodium dithionite, sodium borohydride, potassium borohydride or hydrazine hydrate, and the reaction solvent is selected from methanol, ethanol and water. 。 2. The method according to claim 1, wherein the reaction temperature is maintained at 40–100°C.

3. The method according to claim 1 or 2, wherein the molar ratio of disulfide to reducing agent is 0.2:1 to 2:

1.

4. The method according to claim 1, further comprising the steps of adding the sample obtained in the foregoing steps to an acidic solution, stirring, and filtering.

5. The method according to claim 4, wherein the acidic reagent is selected from hydrochloric acid or sulfuric acid.

6. The method according to claim 5, wherein the concentration of the acidic solution is selected from 0.1-6 mol / L.

7. The method according to claim 6, wherein the concentration of the acidic solution is selected from 1 mol / L or 2 mol / L.

8. A method for preparing cangrelor, comprising the preparation steps of claims 1-7, and the step of preparing cangrelor from adenosine-2-thione or a salt thereof. 。

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