A synthesis process of remegipam intermediate

Abstract

The invention discloses a synthesis process of a rimegepant intermediate, a compound shown in formula VI, which involves a two-step telescope reaction, wherein the intermediate is not purified, a chiral hydroxyl group is introduced by a ketoreductase catalysis method, and the compound shown in formula V is synthesized, wherein the amino acid sequence of the ketoreductase is shown in SEQ ID No. 1. The three-step yield is as high as 90.1%, and the impurities of the compound shown in formula VI are studied and controlled, and the obtained product has high purity, no unknown impurities greater than 0.10%, and chiral impurities are controlled within 0.15%, which meets the requirements of registration regulations for starting materials, is easy to operate, and is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of pharmaceutical chemistry, and particularly relates to a synthesis process of a remegipam intermediate. Background Art

[0002] Rimegepant is an effective, selective, competitive, orally active calcitonin gene-related peptide (CGRP) antagonist used for the acute treatment of migraine in adults. Its structure is shown below:

[0003]

[0004] (R)-9-Triisopropylsilyloxy-6,7,8,9-tetrahydro-5H-cycloheptyl[b]pyridin-5-one (Compound VI) is the core skeleton of the Remigipam molecule and has a chiral center. The yield, purity, cost, etc. of its preparation process have an important influence on the preparation of Remigipam. Its core part is the compound of formula V with a chiral hydroxyl group introduced.

[0005]

[0006] WO2009126530 reports the synthesis of compound VI, using enzyme reduction of cycloheptane[b]pyridine-5,9-dione to obtain the core compound of formula V, the reaction formula is as follows:

[0007]

[0008] This prior art does not disclose the proportion of (9S)-6,7,8,9-tetrahydro-9-hydroxy-5H-cyclohepta[b]pyridin-5-one in the product obtained by enzyme reduction.

[0009] In 2012, David K. Lealy et al. (Organic Letters, 2012, 14, 4938-4941) reported the synthesis of the compound of formula VI. The core step reported was the introduction of the chiral hydroxyl group of the compound of formula V, using Rh-(R-Binapine)(COD)BF4 and ketoreductase catalyst ES-KRED-119 respectively. The ee values ​​of the reaction products were 99.9% and above 98%, respectively.

[0010]

[0011] The product obtained by keto reductase ES-KRED-119 contains 7% of impurity VII, and the single-step yield of the compound of formula V is only 81%, with an ee value of 99.2%. The author finally chose to use the metal catalyst Rh-(RBinapine)(COD)BF4, which is expensive and not available on the market. The ligand R-Binapine used in the synthesis of Rh-(R-Binapine)(COD)BF4 is also difficult to prepare, and the reaction conditions of its synthesis process are very harsh (such as requiring a hydrogen pressure of up to 100 psi), and the dangerous reagent hexachlorodisilane is used, see Angew.Chem.Int.Ed.2003,42,3509.

[0012] Patent application No. 202110116340.0 filed by Auriate Pharmaceuticals (Tianjin) Co., Ltd. in 2021 reported that the product obtained by asymmetric reduction of cycloheptane [b] pyridine-5,9-dione by Rh-(S-Binap)(COD)BF4 was salified with L-camphorsulfonic acid or D-camphorsulfonic acid, and then split to obtain a high-purity chiral compound, (9R)-6,7,8,9-tetrahydro-9-hydroxy-5H-cycloheptane [b] pyridine-5-one. In addition, CN 113717103A discloses the preparation of (9R)-6,7,8,9-tetrahydro-9-hydroxy-5H-cycloheptane [b] pyridine-5-one by specific metal catalysis in the presence of formic acid, which also uses expensive and unstable metal catalysts.

[0013] The existing technologies generally have the problems of complex reaction processes, low yields, and are not suitable for industrial production. Therefore, there is an urgent need in the art to develop a method for preparing high-purity compound VI that is cost-effective, easy to operate, high in yield, and suitable for industrial production, and the product complies with the impurity research and control requirements of drug registration regulations. Summary of the invention

[0014] The present invention provides a synthesis process of a compound represented by formula VI, which comprises the following steps:

[0015] (1) The compound represented by formula III reacts in an acidic solution to form a compound represented by formula IV;

[0016] (2) using ketoreductase to catalyze the reduction of the compound represented by formula IV to the compound represented by formula V,

[0017] The amino acid sequence of the ketoreductase is shown in SEQ ID No. 1;

[0018] (3) the compound represented by formula V is subjected to hydroxyl protection to generate the compound represented by formula VI,

[0019] The reaction formula is as follows:

[0020]

[0021] Reaction 1:

[0022] The compound represented by Formula IV and the compound represented by Formula V are crude products without purification (for example, without purification by column chromatography or without purification by recrystallization), and are directly used in the next reaction.

[0023] In some preferred embodiments of the present invention, the compound represented by Formula VI is purified by using L-camphorsulfonic acid or D-camphorsulfonic acid as a salt-forming and purification reagent to obtain a high-purity compound VI after being freed.

[0024] In some preferred embodiments of the present invention, the ketoreductase-catalyzed reduction in step (2) is carried out in the presence of a coenzyme selected from NADP+, NADP salt or NADPH. In some more preferred embodiments of the present invention, the coenzyme is selected from NADP salt, such as sodium NADP.

[0025] In some preferred embodiments of the present invention, the ketoreductase catalytic reduction system also includes glucose and glucose dehydrogenase.

[0026] In some preferred embodiments of the present invention, the reaction temperature of the ketoreductase-catalyzed reduction is 4-40° C. In some preferred embodiments of the present invention, the reaction temperature of the ketoreductase-catalyzed reduction is 20-30° C.

[0027] In some preferred embodiments of the present invention, the ketoreductase-catalyzed reduction reaction is carried out in a buffer system at pH 6.0-8.0.

[0028] In some preferred embodiments of the present invention, the buffer is selected from PBS buffer, Tris-HCl buffer or sodium acetate buffer.

[0029] In some preferred embodiments of the present invention, in step (3), the hydroxyl protection reaction comprises the following steps:

[0030] In the presence of a base, the compound represented by formula V is reacted with TIPSCl or TIPSOTf in a solvent to obtain (R)-9-triisopropylsilyloxy-6,7,8,9-tetrahydro-5H-cycloheptyl[b]pyridine-5-one.

[0031] In some preferred embodiments of the present invention, in step (3), the silicon reagent providing a triisopropylsilyl group is selected from TIPSCl.

[0032] In some preferred embodiments of the present invention, in step (3), the solvent is selected from DMF, DMSO, DMAc, THF, 1,4-dioxane, acetonitrile, toluene, or a combination thereof. In some more preferred embodiments of the present invention, in step (3), the solvent is selected from acetonitrile.

[0033] In some preferred embodiments of the present invention, in step (3), the base is selected from DMAP, pyridine, imidazole, DIPEA, DBU, or a combination thereof. In some more preferred embodiments of the present invention, in step (3), the base is selected from DBU.

[0034] In some preferred embodiments of the present invention, in step (3), the temperature of the hydroxyl protection reaction is 40-80° C. In some more preferred embodiments of the present invention, in step (3), the temperature of the hydroxyl protection reaction is 60-70° C.

[0035] The three-step total yield of the synthesis process of the compound represented by formula VI of the present invention is as high as 90.1%, the purity of the compound represented by formula VI is 99.9%, there is no unknown impurity greater than 0.10%, and the chiral impurity is less than 0.15%.

[0036] The present invention also provides a synthesis process of the compound represented by formula V, which comprises the following steps:

[0037] The compound represented by Formula IV is reduced by ketoreductase to obtain the compound represented by Formula V. The reaction formula is as follows:

[0038]

[0039] Wherein, the amino acid sequence of the ketoreductase is shown as SEQ ID No.1.

[0040] In some preferred embodiments of the present invention, the ketoreductase-catalyzed reduction is carried out in the presence of a coenzyme selected from NADP+, NADP salts or NADPH. In some more preferred embodiments of the present invention, the coenzyme is selected from NADP salts, such as sodium NADP.

[0041] In some preferred embodiments of the present invention, the ketoreductase catalyzed reduction reaction system also includes glucose and glucose dehydrogenase.

[0042] In some preferred embodiments of the present invention, the reaction temperature of the ketoreductase catalyzed reduction reaction is 4-40° C. In some more preferred embodiments of the present invention, the reaction temperature of the ketoreductase catalyzed reduction reaction is 20-30° C.

[0043] In some preferred embodiments of the present invention, the ketoreductase-catalyzed reduction reaction is carried out in a buffer system at pH = 6.0 to 8.0, preferably, the buffer is selected from PBS buffer, Tris-HCl buffer or sodium acetate buffer. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The intermediate compound of formula VI of the present invention is1 H-NMR spectrum;

[0045] Figure 2 The enantiomer (VI') of the compound of formula VI of the remegipam intermediate of the present invention 1 H-NMR spectrum;

[0046] Figure 3 The impurity of the compound of formula VIII of the intermediate of remegipam of formula VI of the present invention is 1 H-NMR spectrum;

[0047] Figure 4 is the reverse phase HPLC spectrum of the compound of formula VI of the intermediate of Remigipam of the present invention;

[0048] Figure 5 The normal phase HPLC spectrum of the compound of formula VI of the intermediate of Remigipam of the present invention is shown in FIG.

[0049] Figure 6 The IPC normal phase HPLC spectrum of the compound of formula V of the intermediate of Remigipam of the present invention is shown in FIG. DETAILED DESCRIPTION

[0050] The present inventors have conducted extensive and in-depth research, and through a large number of screenings and tests, have provided a synthesis process for a compound represented by the intermediate formula VI of Remigipan. The synthesis process utilizes a novel ketoreductase to catalyze the reduction of cyclohepta[b]pyridine-5,9-dione to a chiral hydroxy compound, (9R)-6,7,8,9-tetrahydro-9-hydroxy-5H-cyclohepta[b]pyridine-5-one. The crude product of the compound that has not been subjected to column chromatography or recrystallization can be directly used for the preparation of (R)-9-triisopropylsilyloxy-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine-5-one. The preparation process has high yield, high purity, simple operation and is suitable for industrial production. The purity of the final product (R)-9-triisopropylsilyloxy-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine-5-one is greater than 99.9%, and the unknown single impurity is less than 0.10%. Calculated from the raw material (Formula III compound) for preparing cyclohepta[b]pyridine-5,9-dione, the total yield after three-step reaction is as high as 90.1%.

[0051] In the description herein, "room temperature" or "normal temperature" refers to a temperature of 4-40°C, preferably, 25±5°C.

[0052] The ketoreductase used in the present invention is a novel enzyme. A technician introduces a mutation site into the ketoreductase derived from Arthrobacter sp. TS-15, performs activity and stability tests on the mutants, and selects the mutants with higher activity and stability. The ketoreductase used in the present invention (amino acid sequence such as SEQ ID NO.1) catalyzes the reduction of the compound shown in formula IV for 10 hours with a conversion rate greater than 99%, and the ee value of the chiral alcohol product (compound shown in formula V) obtained can reach more than 99.5%. Therefore, the ketoreductase of the present invention is used to catalyze the synthesis of the chiral alcohol compound (compound shown in formula V) from the carbonyl substrate (compound shown in formula IV), thereby realizing the green chemical synthesis of the chiral alcohol compound shown in formula V, and the selectivity is good and the yield is high.

[0053] Based on the amino acid sequence of the ketoreductase provided by the present invention, those skilled in the art can easily obtain the ketoreductase through conventional biotechnology.

[0054] The amino acid sequence of the ketoreductase used in the present invention is as follows:

[0055] MINMRNRVAIVTGGAMGMGNGCARKLAEAGAKVYLIDRSNLVAAAAQDMREAGLNANHVQVDITDQESLTSAYDGIAAAESGRLDVLVNAAGVGDSRMFLDVDDAHYKKVIDVRVRGTWNSCRAAVPHMLSNKHGRII NFGAISGPIVAFPGYTVYALSKGAIFGFTKALASEFAGQNILVNAILPGSMDTPMMRAAMADTNPADPQAVIDEIAAAVPLKRLGTIDDAGNLALFLASDLASYLTGQAIVLDGAFTLAEYQSGGLEAPAETPALVN

[0056] Remigipam intermediate, synthesis process of the compound represented by formula VI

[0057] The method of obtaining the compound of formula VI from the compound of formula III in the present invention has the following reaction formula:

[0058]

[0059] The method comprises the following steps:

[0060] (1) The compound of formula III is reacted in an acidic solution. After the reaction is completed, the pH of the reaction solution is adjusted to 8-10 with a base, and the reaction solution is treated to obtain the compound of formula IV.

[0061] In this step, the acidic solution used in the reaction includes but is not limited to aqueous hydrochloric acid solution, aqueous sulfuric acid solution, and aqueous phosphoric acid solution, preferably 4-8N aqueous hydrochloric acid solution, for example, 5N, 6N, 7N aqueous hydrochloric acid solution. The reaction temperature is 60-100°C, more preferably 85-95°C. The base used includes but is not limited to potassium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, and more preferably potassium carbonate. The process of treating the reaction is to extract the reaction solution, separate the organic phase and concentrate it, and the solvent used for extraction includes but is not limited to toluene, ethyl acetate, 1,2-dichloroethane, chloroform, and more preferably 1,2-dichloroethane.

[0062] (2) using ketoreductase to catalyze the reduction of the compound represented by formula IV to the compound represented by formula V. After the reaction is completed, treating the reaction solution to obtain the compound represented by formula V.

[0063] In this step, the amount of ketoreductase used is the amount commonly used in the art, and can also be determined according to actual experimental results. The reaction system also contains a coenzyme selected from NADP+, NADP salt and / or NADH, glucose and glucose dehydrogenase. The catalytic reduction reaction is carried out in a buffer with a pH value of 6.0 to 9.0, more preferably a pH value of 6.5 to 8.5, and most preferably a pH value of 7.5. The buffer includes but is not limited to PBS buffer, Tris-hydrochloric acid buffer, sodium acetate buffer, and more preferably Tris-hydrochloric acid buffer. The reaction temperature is 4 to 40°C, more preferably 20 to 30°C. The process of treating the reaction solution includes concentrating the reaction solution, adding a first solvent, adding a second solvent after concentrating, filtering, and concentrating the filtrate to obtain a compound shown in formula V; the first solvent is selected from methanol, ethanol, isopropanol, butanol, and more preferably ethanol. The second solvent is selected from methanol, ethanol, isopropanol, butanol, ethyl acetate, toluene, dichloromethane, and more preferably ethanol.

[0064] (3) The compound represented by formula V is subjected to hydroxyl protection using a silicon reagent in the presence of a base. After the reaction is completed, the reaction solution is treated to obtain the compound represented by formula VI.

[0065] In this step, the solvent used in the reaction includes but is not limited to DMF, DMSO, DMAc, THF, 1,4-dioxane, acetonitrile and toluene, preferably acetonitrile. The silicon reagent used is selected from TIPSCl or TIPSOTf, more preferably TIPSCl. The base used includes but is not limited to DMAP, pyridine, imidazole, DIPEA, DBU, preferably DBU. The reaction temperature is 40-80°C, more preferably 60-70°C. The process of treating the reaction solution includes: adding water and an extraction solvent to the reaction solution, separating the organic phase, and concentrating to obtain a compound shown in formula VI. The extraction solvent is a commonly used solvent in the art, including but not limited to toluene, ethyl acetate, dichloromethane, n-heptane, methyl tert-butyl ether, preferably ethyl acetate.

[0066] In the above-mentioned synthesis process, in the process of obtaining the compound of formula V from the compound of formula III as a raw material (the synthesis of the compound of formula III is referred to: Organic Letters, 2012, 14, 4938-4941), the compound of formula IV is not purified and is directly used for ketoreductase catalytic reduction reaction, and then the crude product of the unpurified compound of formula V is used as a raw material for hydroxyl protection to obtain the compound of formula VI, and the compound of formula VI is freed by using L-camphorsulfonic acid or D-camphorsulfonic acid as a salt-forming purification reagent to obtain a high-purity compound VI, and the three-step yield can reach 90.1%. The synthesis process of the compound of formula VI of the present invention can effectively remove impurities, and the product HPLC purity is greater than 99.9%, and there is no unknown impurity greater than 0.10%.

[0067] The inventors have also studied the impurities of the synthesis process of the present invention. The main impurities in the preparation process of the compound shown in formula V are the compound shown in formula VII and its enantiomer compound shown in formula V', and the derived impurities are the impurities shown in formula VIII and formula VI'. They can be well controlled by the synthesis process of the present invention. In the final product (compound shown in VI), the content of the compound shown in formula VIII is less than 0.10%, and the content of chiral impurities (VI') is also controlled within 0.15%. The ee of the final product can reach 99.8%. The synthesis process of the compound shown in formula VI of the present invention has a very good removal effect on chiral impurities. Even if the system contains 2% chiral impurities, it can still be removed to less than 0.15%. Unreacted raw materials, such as the compound shown in formula V and D-camphorsulfonic acid, are also put into the quality standard of the compound shown in formula VI as impurities, and none of them are detected. The quality of the product meets the requirements of FDA ICH Q3A for known impurities and unknown impurities.

[0068]

[0069] The main advantages of the present invention include:

[0070] 1. The synthetic process for preparing the compound of formula VI of the present invention is simple to operate. Two of the three-step process steps are telescope reactions. The chiral hydroxyl group is introduced by an enzyme-catalyzed method. No intermediate is purified, thereby reducing the production cost. The three-step yield can reach up to 90.1%, which is very suitable for industrialization.

[0071] 2. The chiral hydroxyl group of the present invention is introduced by the novel ketoreductase-catalyzed reduction of cycloheptane [b] pyridine-5,9-dione. The chiral hydroxyl compound has a small impurity content and high chiral purity. No purification is required. The reaction solution is filtered and the filtrate is concentrated to obtain a crude product which is directly used in the preparation of the compound shown in Formula VI.

[0072] 3. The present invention studies and controls the impurities of the compound represented by Formula VI, and the obtained product has high purity, with a normal phase HPLC purity of 99.8%, no unknown impurities greater than 0.10%, and chiral impurities controlled within 0.15%, which meets the requirements of registration regulations for starting materials.

[0073] The present invention will be further described below in conjunction with specific implementation. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0074] The synthesis of the compound of formula III can be found in: Organic Letters, 2012, 14, 4938-4941.

[0075] General method:

[0076] 1. Normal phase HPLC detection method:

[0077] Instrument: Agilent 1260 series HPLC.

[0078] Chromatographic column: Chiralpak IG, 4.6×250mm, 5μm (DAICEL CHIRAL TECHNOLOGIES P / N.:87325)

[0079] Column temperature: 30°C

[0080] Sample chamber temperature: 25°C

[0081] Mobile phase A: n-hexane: ethanol = 98:2

[0082] Mobile phase B: Chromatographic grade ethanol

[0083] Table 1

[0084] Time (min) % Mobile phase A % Mobile phase B Flow rate (min / mL) 0 100 0 0.5 15 100 0 0.5 17 50 50 0.8 48 50 50 0.8 50 100 0 0.5 90 100 0 0.5

[0085] Measurement time: 90 minutes

[0086] Detection wavelength: 262 nm.

[0087] 2. Reverse phase HPLC detection method:

[0088] Instrument: Agilent 1260 series HPLC.

[0089] Chromatographic column: Welch Ghost-Buster Column II 3.0×50mm (P / N.:06000-31016)

[0090] Column temperature: 40°C

[0091] Sample chamber temperature: 25°C

[0092] Mobile phase A: 1.0 g / L ammonium acetate aqueous solution, pH = 8 (± 0.05)

[0093] Mobile phase B: chromatographic grade acetonitrile

[0094] Table 2

[0095] Time (min) % Mobile phase A % Mobile phase B Flow rate (min / mL) 0 90 10 1.0 10 75 25 1.0 15 10 90 1.0 27 0 100 1.2 50 0 100 1.2 50.1 90 10 1.0 60 90 10 1.0

[0096] Measurement time: 60 minutes

[0097] Detection wavelength: 230 nm.

[0098] Example 1 Preparation of Compound of Formula III

[0099]

[0100] In an environment of 20-30°C, toluene (12L), 1.5kg (7.68mol) of the compound shown in Formula II and 1.8kg (11.68mol) of the compound shown in Formula I were added to the reactor, stirred, the temperature was controlled to be less than 30°C, 1M potassium tert-butoxide tetrahydrofuran solution (19.2L, 19.2mol) was added dropwise, heated to 50-60°C, and reacted for 2-3 hours. HPLC monitored the complete conversion of the compound shown in Formula II, reduced the temperature to 20-30°C, concentrated under reduced pressure to 13-14L, cooled the system to 0-10°C, controlled the temperature to 0-10°C, added n-heptane (23L), 22L of ice water, adjusted the pH of the system to 6-7 with acetic acid, solid precipitated, continued stirring for 1-2 hours, filtered, washed the filter cake with 4L of water, drained, and vacuum dried at 50-60°C for 10-15 hours to obtain 1.58kg of the compound of Formula III with a yield of 70.1%.

[0101] Example 2 Preparation of the compound represented by formula V

[0102] Add 1.5 kg (5.14 mol) of compound III and 7N aqueous hydrochloric acid solution (3.7 L, 25.7 mol) into the reactor, stir, heat to 85-95 ° C, react for 8-10 hours, monitor the reaction completion by HPLC, cool to 20-30 ° C, adjust pH to 9-10 with saturated potassium carbonate aqueous solution, extract three times with 1,2-dichloroethane (6 L * 3), combine the organic phases, and concentrate to obtain compound IV.

[0103] At 20-30°C, add the compound of formula IV and Tris-HCl buffer solution (7.2L, pH=8.5) to the reaction kettle, stir for 10-20 minutes, and the system becomes clear. Add isopropanol (1L), sodium NADP (Bidder Pharmaceuticals, BD116591, 1.5g), ketoreductase (0.75kg), glucose dehydrogenase (2g, 100kU, Shangke Biopharmaceuticals (Shanghai) Co., Ltd., GDH, 40U / mg), and glucose (24g). Raise the temperature to 45-55°C, react for 4-5 hours, and detect by HPLC. When the reaction is complete, concentrate the system to dryness, add ethanol (5L), concentrate to dryness, add ethanol (5L), stir for 1-2 hours, filter, and concentrate the filtrate to dryness to obtain an oily compound of formula V.

[0104] Example 3 Preparation of the compound represented by formula VI

[0105] The compound of formula V obtained in Example 2 and acetonitrile (9 L), DBU (1.56 kg), and TIPSCl (1.28 kg) were added to the reaction kettle, heated to 60-70 ° C, reacted for 19-20 hours, and monitored by HPLC. After the reaction was completed, the temperature was lowered to 20-30 ° C, water (2.3 L) and ethyl acetate (5 L) were added to the system, allowed to stand, and the liquids were separated. The aqueous phase was extracted once with ethyl acetate (2 L), the organic phases were combined, dried, and dichloromethane (6 L) and D-camphorsulfonic acid (1.2 kg) were added. The mixture was stirred for 2-3 hours, filtered, and vacuum dried at 40-50 ° C for 5-6 hours to obtain the camphorsulfonate of the compound of formula VI.

[0106] The camphorsulfonate salt of the compound of formula VI and methanol (3.75 L) were added to the reaction kettle, and the pH was adjusted to 9-10 with a 10% aqueous sodium hydroxide solution. Water (7.5 L) was added, cooled to 0-10° C., stirred for 2-3 hours, filtered, and dried in vacuo at 40-45° C. to obtain the compound of formula VI as a pale yellow solid, 1.55 kg, with a three-step yield of 90.1%, a normal phase HPLC purity of 99.9%, 0.084% of chiral impurity formula VI', no impurity VIII was detected, no raw material formula V compound was detected, no D-camphorsulfonic acid was detected, and no unknown impurities greater than 0.10% were detected. The structures of these impurities are shown in the following reaction formula 2. The results are shown in Tables 3 and 4 below.

[0107] The above-mentioned embodiments 1 to 3 may involve the following impurities:

[0108]

[0109] Table 3: Normal phase impurity distribution of the compound represented by formula VI

[0110] name Compound represented by formula VI Chiral impurity, compound represented by formula VI' content 99.92％ 0.084％

[0111] Table 4: Reverse phase impurity distribution of the compound represented by formula VI

[0112]

[0113] Example 4 Preparation of the compound represented by formula V

[0114] Add 50 g (0.17 mol, from Example 1) of compound III and 6.8 N aqueous hydrochloric acid solution (0.125 L, 0.8 mol) into the reaction kettle, stir, heat to 75-85 ° C, react for 12-14 hours, monitor the completion of the reaction by HPLC, cool to 20-30 ° C, adjust pH to 9-10 with saturated potassium carbonate aqueous solution, extract three times with chloroform (0.2 L * 3), combine the organic phases, and concentrate to dryness to obtain a compound of formula IV.

[0115] At 20-30°C, add the compound of formula IV and PBS buffer solution (0.24 L, pH = 8.0) to the reaction kettle until the system becomes clear, add isopropanol (0.33 L), sodium NADP (Bide Pharmaceuticals, BD116591, 0.04 g), ketoreductase (0.03 kg), glucose dehydrogenase (0.07 g, 100 kU, Shangke Biopharmaceuticals (Shanghai) Co., Ltd., GDH, 40 U / mg), glucose (1 g), raise the temperature to 50-60°C, react for 2-3 hours, and after the reaction is complete, concentrate the system to dryness, add methanol (0.36 L), concentrate to dryness, add methanol (0.17 L), stir for 1-2 hours, filter, and concentrate the filtrate to dryness to obtain an oily compound of formula V.

[0116] Example 5 Preparation of the compound represented by formula VI

[0117] The compound of formula V obtained in Example 4 and toluene (0.5 L), imidazole (0.05 kg), and TIPSCl (0.044 kg) were added to the reaction kettle, heated to 65-70 ° C, and reacted for 19-20 hours. After the reaction was completed, the temperature was reduced to 20-30 ° C, water (0.08 L) and MTBE (0.2 L) were added to the system, and the mixture was allowed to stand for separation. The aqueous phase was extracted once with MTBE (0.1 L), the organic phases were combined, dried, and n-heptane (0.2 L) and D-camphorsulfonic acid (0.04 kg) were added. The mixture was stirred for 2-3 hours, filtered, and dried in vacuo at 40-50 ° C for 5-6 hours to obtain the camphorsulfonate of the compound of formula VI.

[0118] Add camphorsulfonate of compound VI and ethanol (0.2 L) to the reaction kettle, adjust pH to 9-10 with 10% aqueous lithium hydroxide solution, add water (0.2 L), cool to 0-10° C., stir for 2-3 hours, filter, and dry in vacuo at 40-45° C. to obtain compound VI as a pale yellow solid, 0.05 kg, with a three-step yield of 87.3%, a normal phase HPLC purity of 99.8%, a chiral impurity of formula VI' of 0.10%, and no unknown impurities greater than 0.10%.

[0119] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for synthesizing a compound represented by formula VI, characterized in that: The synthesis method comprises the following steps: (1) The compound represented by formula III reacts in an acidic solution to form a compound represented by formula IV; (2) using ketoreductase to catalyze the reduction of the compound represented by formula IV to the compound represented by formula V, The amino acid sequence of the ketoreductase is shown in SEQ ID No. 1; (3) the compound represented by formula V is subjected to hydroxyl protection to generate the compound represented by formula VI, The reaction formula is as follows: The compound represented by Formula IV and the compound represented by Formula V were both crude products without purification and were directly used in the next reaction.

2. The method for synthesizing the compound of formula VI according to claim 1, characterized in that: The compound represented by formula VI uses L-camphorsulfonic acid or D-camphorsulfonic acid as a salt-forming and purification reagent, and a high-purity compound VI is obtained after being freed.

3. The method for synthesizing the compound of formula VI according to claim 1 or 2, characterized in that: The ketoreductase-catalyzed reduction in step (2) is carried out in the presence of a coenzyme selected from NADP+, NADP salt or NADPH.

4. The method for synthesizing the compound of formula VI according to claim 3, characterized in that: The coenzyme is selected from NADP salts.

5. The method for synthesizing the compound of formula VI according to claim 3, characterized in that: The ketoreductase catalyzed reduction system also includes glucose and glucose dehydrogenase.

6. The method for synthesizing the compound of formula VI according to claim 5, characterized in that: The reaction temperature of the ketoreductase-catalyzed reduction is 4 to 40°C, and / or The ketoreductase-catalyzed reduction reaction is carried out in a buffer system at pH = 6.0 to 8.

0.

7. The method for synthesizing the compound of formula VI according to claim 6, characterized in that: The reaction temperature of the ketoreductase-catalyzed reduction is 20 to 30°C, and / or The buffer is selected from PBS buffer, Tris-HCl buffer or sodium acetate buffer.

8. The method for synthesizing the compound of formula VI according to claim 1 or 2, characterized in that: In step (3), the hydroxyl protection reaction comprises the following steps: In the presence of a base, the compound represented by formula V is reacted with TIPSCl or TIPSOTf in a solvent to obtain (R)-9-triisopropylsilyloxy-6,7,8,9-tetrahydro-5H-cycloheptyl[b]pyridine-5-one.

9. The synthesis method according to claim 8, characterized in that The silicon reagent providing a triisopropylsilyl group is selected from TIPSCl, and / or The solvent is selected from DMF, DMSO, DMAc, THF, 1,4-dioxane, acetonitrile, toluene, or a combination thereof, and / or The base is selected from DMAP, pyridine, imidazole, DIPEA, DBU, or a combination thereof, and / or The temperature of the hydroxyl protection reaction is 40-80°C.

10. The synthesis method according to claim 9, characterized in that The solvent is selected from acetonitrile, and / or The base is selected from DBU, and / or The temperature of the hydroxyl protection reaction is 60-70°C.

11. The synthesis method according to claim 1 or 2, characterized in that: The three-step total yield of the synthesis method is as high as 90.1%, the purity of the compound represented by formula IV is 99.9%, there is no unknown impurity greater than 0.10%, and the chiral impurity is less than 0.15%.

12. A method for synthesizing a compound represented by formula V, characterized in that: The synthesis method comprises the following steps: The compound represented by Formula IV is reduced by ketoreductase to obtain the compound represented by Formula V. The reaction formula is as follows: Wherein, the amino acid sequence of the ketoreductase is shown as SEQ ID No.

1.

13. The method for synthesizing the compound of formula V according to claim 12, characterized in that: The ketoreductase-catalyzed reduction is carried out in the presence of a coenzyme selected from NADP+, NADP salt or NADPH, and / or The ketoreductase catalyzed reduction reaction system also includes glucose and glucose dehydrogenase, and / or The reaction temperature of the ketoreductase-catalyzed reduction reaction is 4 to 40°C, and / or The ketoreductase-catalyzed reduction reaction is carried out in a buffer system at pH = 6.0 to 8.

0.

14. The method for synthesizing the compound of formula V according to claim 13, characterized in that: The coenzyme is selected from NADP salts, and / or The reaction temperature of the ketoreductase-catalyzed reduction reaction is 20 to 30°C, and / or The buffer is selected from PBS buffer, Tris-HCl buffer or sodium acetate buffer.

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