A method for preparing a key intermediate of lorlatinib

Abstract

The present invention provides a method for preparing a key intermediate of lorlatinib (Formula IV). Specifically, the preparation method provided by the present invention comprises the steps of: (1) subjecting a compound of Formula I to a reduction reaction in a bioenzyme catalytic reduction system containing a bioenzyme, thereby forming a compound of Formula II; (2) subjecting the compound of Formula II obtained in Step (1) to a reaction in the presence of n-butyl lithium and carbon dioxide in a first inert solvent, thereby obtaining a compound of Formula III; and (3) subjecting the compound of Formula III obtained in Step (2) to an esterification reaction in a second inert solvent, thereby obtaining a compound of Formula IV. The preparation method of the present invention has a short synthetic route, low cost, and simple processing.

Description

Technical Field

[0001] The present invention belongs to the field of pharmaceutical chemistry, and specifically relates to a method for preparing 5-fluoro-3-methylisobenzofuran-1(3H)-one, a key intermediate of lorlatinib. Background Art

[0002] Lorlatinib is a potent dual ALK / ROSI inhibitor that plays an extremely important role in the treatment of cancer.

[0003] Lorlatinib was developed by Pfizer, an American company. It is an ALK inhibitor modified from crizotinib. It entered the clinical stage in 2014 and has a significant therapeutic effect on the treatment of lung cancer.

[0004] 5-Fluoro-3-methylisobenzofuran-1(3H)-one is an important intermediate in the synthesis of lorlatinib. In existing reports, its synthesis route is long, the cost is high, the yield is low, and the treatment is complicated.

[0005] In summary, there is an urgent need in the art to develop a new synthetic route for 5-fluoro-3-methylisobenzofuran-1(3H)-one with a short route, simple operation, high yield, high chiral purity and extremely low cost. Summary of the invention

[0006] The purpose of the present invention is to provide a new synthetic route of 5-fluoro-3-methylisobenzofuran-1(3H)-one which has short route, simple operation, high yield, high chiral purity and extremely low cost.

[0007] In the first aspect of the present invention, there is provided a method for preparing a compound of formula IV, the method comprising the steps of:

[0008]

[0009] (1) subjecting the compound of formula I to a reduction reaction in a bio-enzyme catalytic reduction system containing a bio-enzyme, thereby forming a compound of formula II;

[0010] (2) reacting the compound of formula II obtained in step (1) in a first inert solvent in the presence of n-butyl lithium and carbon dioxide to obtain a compound of formula III; and

[0011] (3) In a second inert solvent, subjecting the compound of formula III obtained in step (2) to an esterification reaction to obtain a compound of formula IV.

[0012] In another preferred embodiment, in step (1), the chiral purity of the compound of formula II is greater than 99.9%.

[0013] In another preferred embodiment, in step (3), the chiral purity of the compound of formula IV is greater than 99.9%.

[0014] In another preferred embodiment, the reaction temperature of step (2) is: -80 to -30°C; preferably, -60 to -30°C; more preferably, -40 to -30°C.

[0015] In another preferred embodiment, the molar ratio of n-butyl lithium to formula II in step (2) is (0.8-1.2):1; more preferably, (1±0.1):1.

[0016] In another preferred embodiment, the molar ratio of n-butyl lithium to formula II in step (2) is (0.9-1.0):1.

[0017] In another preferred embodiment, in step (2), the first inert solvent is an ether solvent; preferably, a C2-C6 ether solvent; more preferably, diethyl ether.

[0018] In another preferred embodiment, in step (2), the reaction time is 10 to 180 min; preferably, 10 to 60 min; most preferably, 45 to 50 min.

[0019] In another preferred embodiment, step (2) comprises the steps of:

[0020] (2.1) reacting the compound of formula II obtained in step (1) in the presence of n-butyllithium in a first inert solvent to obtain a reaction system containing the compound of formula II substituted with n-butyllithium;

[0021] (2.2) CO2 is introduced into the reaction system containing the compound of formula II substituted with n-butyl lithium in step (2.1) to react the compound of formula II substituted with n-butyl lithium, thereby obtaining a compound of formula III.

[0022] In another preferred embodiment, in step (2.2), the flow rate of CO2 is 3 to 8 L / h per 100 ml of the first inert solvent.

[0023] In another preferred embodiment, the reaction time of step (2.1) is 5 to 60 min; preferably, 20 to 40 min.

[0024] In another preferred embodiment, the reaction time of step (2.2) is 5 to 50 min; preferably, 10 to 30 min; more preferably, 15 to 20 min.

[0025] In another preferred embodiment, step (2) further comprises a second post-treatment step, wherein the second post-treatment step is used to separate and / or purify the compound of formula III.

[0026] In another preferred embodiment, the second post-treatment step includes: liquid separation, solvent removal (preferably, solvent removal by reduced pressure distillation) and / or drying (preferably, forced air drying).

[0027] In another preferred embodiment, the second post-treatment step does not include chiral resolution and / or chromatographic separation.

[0028] In another preferred embodiment, in step (1), the biological enzyme is a combination of perakine reductase and coenzyme NADPH.

[0029] In another preferred embodiment, in step (1), the concentration of the perakine reductase is 0.38-1.0 mg / ml (preferably, 0.62-0.85 mg / ml; more preferably, 0.69-0.77 mg / ml), based on the total volume of the bio-enzyme catalytic system.

[0030] In another preferred embodiment, in step (1), in the bio-enzyme catalytic reduction system, the final concentration of the perakine reductase is 0.38-1.0 mg / ml (preferably, 0.62-0.85 mg / ml; more preferably, 0.69-0.77 mg / ml).

[0031] In another preferred embodiment, in step (1), the concentration of the coenzyme NADPH is 0.002-0.15 mmol / L (preferably, 0.005-0.05 mmol / L; more preferably, 0.01-0.03 mmol / L; most preferably, 0.01-0.02 mmol / L), based on the total volume of the bio-enzyme catalytic system.

[0032] In another preferred embodiment, in step (1), in the bio-enzyme catalytic reduction system, the final concentration of the coenzyme NADPH is 0.002-0.15 mmol / L (preferably, 0.005-0.05 mmol / L; more preferably, 0.01-0.03 mmol / L; most preferably, 0.01-0.02 mmol / L).

[0033] In another preferred embodiment, in step (1), in the bio-enzyme catalysis system, the mass ratio of glucose dehydrogenase to perakine reductase is (0.5-2):1; preferably, (1±0.2):1; more preferably, (1±0.1):1.

[0034] In another preferred embodiment, in step (1), the pH of the bio-enzyme catalysis system is 7±1 (preferably, 7±0.5; more preferably, 7±0.1).

[0035] In another preferred embodiment, in step (1), the concentration of the compound of formula I is 0.1-2 mM (mmol / L) (preferably 0.3-1.0; more preferably 0.5-0.7 mM), based on the total volume of the bio-enzyme catalysis system.

[0036] In another preferred embodiment, in step (1), in the bioenzyme catalytic reduction system, the final concentration of the compound of formula I is 0.1-2 mM (preferably 0.3-1.0; more preferably 0.5-0.7 mM). In another preferred embodiment, in step (1), the bioenzyme catalytic system further comprises glucose and glucose dehydrogenase.

[0037] In another preferred embodiment, in step (1), the concentration of glucose is 0.1-10 mM (i.e., 0.0001-0.01 mmol / mL) (preferably, 0.5-2 mM (i.e., 0.0005-0.002 mmol / mL); more preferably, 1±0.1 mM (0.001±0.0001 mmol / mL)), based on the total volume of the bio-enzyme catalytic system.

[0038] In another preferred embodiment, in step (1), the concentration of glucose dehydrogenase is 0.38-1.0 mg / ml (preferably, 0.62-0.85 mg / ml; more preferably, 0.69-0.77 mg / ml), based on the total volume of the bio-enzyme catalysis system.

[0039] In another preferred embodiment, in step (1), in the bio-enzyme catalytic reduction system, the final concentration of glucose dehydrogenase is 0.38-1.0 mg / ml (preferably, 0.62-0.85 mg / ml; more preferably, 0.69-0.77 mg / ml).

[0040] In another preferred embodiment, the solvent of the bio-enzyme catalysis system in step (1) is water.

[0041] In another preferred embodiment, the bio-enzyme catalysis system also includes a pH buffer system.

[0042] In another preferred embodiment, the pH buffer system is a kpi buffer system.

[0043] In another preferred embodiment, the bio-enzyme catalysis system is mainly composed of the compound of formula I, perakine reductase, glucose dehydrogenase, glucose, NADPH, water and a pH buffer system (preferably, a kpi buffer system).

[0044] In another preferred embodiment, step (1) further comprises a first post-treatment step, wherein the first post-treatment step is used to separate and / or purify the compound of formula II.

[0045] In another preferred embodiment, in step (1), the first post-treatment step includes: extraction and separation, and / or removal of the solvent (preferably, removal of the solvent by concentration under reduced pressure).

[0046] In another preferred embodiment, in step (1), the first post-treatment step does not include chiral resolution and / or chromatographic separation.

[0047] In another preferred embodiment, in step (3), the esterification reaction is carried out in the presence of an acid.

[0048] In another preferred embodiment, in step (3), the acid is selected from the group consisting of sulfuric acid, acetic acid, oxalic acid, phosphoric acid, or a combination thereof; preferably, the acid is selected from the group consisting of phosphoric acid, sulfuric acid, or a combination thereof; more preferably, the acid is sulfuric acid.

[0049] In another preferred embodiment, in step (3), the second inert solvent is selected from the following group: alcohol solvents, water, or a combination thereof.

[0050] In another preferred embodiment, in step (3), the second inert solvent is a mixed solvent consisting of an alcohol solvent and water;

[0051] In another preferred embodiment, in step (3), the alcohol solvent is selected from the following group: methanol, ethanol, or a combination thereof; preferably, the alcohol solvent is ethanol (anhydrous ethanol).

[0052] In another preferred embodiment, in step (3), the second inert solvent is a mixed solvent consisting of an alcohol solvent selected from methanol, ethanol, or a combination thereof and water; most preferably, it is a mixed solvent consisting of ethanol and water.

[0053] In another preferred embodiment, in step (3), in the second inert solvent, the volume ratio of the alcohol solvent to water is (5-20):1; more preferably, (9±1):1.

[0054] In another preferred embodiment, in step (3), in the second inert solvent, the volume ratio of ethanol (anhydrous ethanol) to water is (5-20):1; more preferably, (9±1):1.

[0055] In another preferred embodiment, in step (3), the volume mass ratio (ml:g) of the second inert solvent to the compound of formula III is (5-20):1; more preferably, (10±2):1; most preferably, (10±1):1.

[0056] In another preferred embodiment, in step (3), the molar ratio of the acid to the compound of formula III is (5-20):1; preferably, (10±1):1;

[0057] In another preferred embodiment, in step (3), the reaction temperature of the esterification reaction is 0-50°C; preferably, 20-30°C.

[0058] In another preferred embodiment, in step (3), the reaction time of the esterification reaction is 1 to 10 hours; preferably, 2 to 3 hours.

[0059] In another preferred embodiment, step (3) further comprises a third post-treatment step, wherein the third post-treatment step is used to separate and / or purify the compound of formula IV.

[0060] In another preferred embodiment, the third post-treatment includes extraction and / or solvent removal (preferably, solvent removal by pressure distillation).

[0061] In another preferred embodiment, the third post-treatment step does not include chiral resolution and / or chromatographic separation.

[0062] In another preferred embodiment, the preparation method does not include a chiral separation treatment step.

[0063] In another preferred embodiment, the preparation method does not include chromatographic separation.

[0064] In another preferred embodiment, the preparation method only includes a simple post-processing step.

[0065] In another preferred embodiment, the total yield of the preparation method is ≥70%; more preferably, ≥75%.

[0066] In another preferred embodiment, the purity of the compound of formula IV obtained by the preparation method is ≥98%; preferably, ≥99.5%.

[0067] In the second aspect of the present invention, an intermediate as shown in formula IV is provided,

[0068]

[0069] The intermediate is prepared by the preparation method described in the first aspect.

[0070] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 is a chromatogram showing the chiral purity of the product of Example 1.

[0072] Figure 2 is a chromatogram showing the chiral purity of the product of Example 2.

[0073] Figure 3 is a chromatogram showing the chiral purity of the product of Example 3.

[0074] Figure 4 is a chromatogram showing the purity of the product of Example 7.

[0075] Figure 5 is a chromatogram showing the purity of the product of Example 8. DETAILED DESCRIPTION

[0076] After extensive and in-depth research, the inventor unexpectedly found that bioenzyme catalysis is very suitable for the chiral reduction of the compound of formula I. In addition, the inventor also unexpectedly found that compared with other conventional carboxylation systems (such as palladium acetate and carbon monoxide systems), n-butyl lithium and carbon dioxide are particularly suitable for carboxylation of the compound of formula II, thereby obtaining the compound of formula III with a high yield of more than 80% and a reaction time of less than 1 hour. The inventor first provides a new preparation method (or synthetic route) for directly preparing 5-fluoro-3-methylisobenzofuran-1 (3H)-one (formula IV) with high purity and chiral purity by only three steps of reaction using 2-bromo-5-fluoroacetophenone (formula I) as a raw material. Based on this, the inventor has completed the present invention.

[0077] the term

[0078] Unless otherwise specified, "post-treatment" refers to the steps used to separate and / or purify (purify) the target compound from the reaction system containing the target compound. As used herein, "simple post-treatment" refers to the steps of separating and / or purifying (purifying) the target compound from the reaction system containing the target compound by common and industrially suitable post-treatment means (methods or processes), for example, separation and / or purification by one or more of the following methods: separation, extraction, drying, distillation, concentration, filtration, drying, crystallization, etc.; generally, simple post-treatment does not include chiral resolution, chromatographic separation, etc.

[0079] As used herein, perakine reductase, also known as snakewood root perakine reductase, is derived from the medicinal plant snakewood of the genus Rauwolfia in the family Apocynaceae.

[0080] Preparation method of lorlatinib key intermediate (Formula IV)

[0081] The present invention provides a novel synthetic route of an intermediate as shown in Formula IV, which greatly shortens the synthetic method provided in the original report, simplifies the operation, improves the yield, and greatly reduces the cost. More importantly, the chemical method racemic resolution used in the past is changed to a method using a biological enzyme as a catalyst, which is environmentally friendly, simple, high in yield, and has no side reaction, thereby greatly improving the product quality.

[0082] Typically, the present invention provides a method for preparing a compound of formula IV, the method comprising the steps of:

[0083] (1) Chiral reduction of formula I under the catalysis of biological enzymes to obtain chiral formula II

[0084]

[0085] Preferably, the biological enzyme is perakine reductase and coenzyme NADPH.

[0086] In a specific embodiment, step (1) includes the steps of: providing a mixture of a compound of formula I, a biological enzyme (perakine reductase and glucose dehydrogenase) in a solvent (preferably, the solvent is water), adding a buffer, and optionally glucose and NADPH to the mixture to obtain a biological enzyme catalytic reduction system; and allowing the compound of formula I to form a compound of formula II in the biological enzyme catalytic reduction system.

[0087] Preferably, in the mixture, the concentration of the biological enzyme perakine is: 0.5-1.3 mg / ml, preferably: 0.8-1.1 mg / ml, and most preferably: 0.9-1.0 mg / ml.

[0088] Preferably, in the mixture, the concentration of the compound of formula I is 0.13-2.6; preferably, 0.4-1.3 mM; more preferably, 0.65-0.9 mM.

[0089] Preferably, the buffer is a Kpi buffer with a Ph of 7±0.5.

[0090] Preferably, the buffer is 50±10 nM Kpi buffer.

[0091] Preferably, the volume ratio of the buffer solution to the mixture is (0.1-0.5):1; preferably 0.3±0.1:1.

[0092] In another preferred embodiment, step (1) further comprises the step (i.e., the first post-treatment step): adding an organic solvent such as ethyl acetate to the system containing the compound of formula II to extract the liquid, and concentrating under reduced pressure to remove the organic solvent, thereby obtaining the separated compound of formula II.

[0093] In another preferred embodiment, in step (1), the solvent is: water.

[0094] In a specific embodiment, the preparation method of the compound of formula IV further comprises the steps of:

[0095] (2) reacting the compound of formula II obtained in step (1) in the presence of n-butyl lithium and carbon dioxide in a first inert solvent to obtain a compound of formula III; preferably, the compound of formula II is electrophilically substituted with n-butyl lithium and then reacted with carbon dioxide to produce the compound of formula III;

[0096]

[0097] In another preferred embodiment, in step (2), the reaction temperature is: -80 to -30°C, preferably: -60 to -30°C, and most preferably: -40 to -30°C.

[0098] In another preferred embodiment, in the step (2), the molar ratio of n-butyl lithium to the compound of formula II is (0.8-1.2):1, and the optimal ratio is: (1±0.1):1.

[0099] In another preferred embodiment, step (2) comprises the steps of: (2.1) providing a solution of the compound of formula II in a first inert solvent, cooling the temperature to -40 to -38°C, adding (preferably, dropwise adding) n-butyl lithium (preferably, n-butyl lithium is added in the form of its n-hexane solution); and (2.2) introducing CO2 to bubble the reaction for 15 to 20 minutes, thereby obtaining a reaction solution containing the compound of formula III.

[0100] Preferably, the flow rate of the introduced CO2 is 3 to 8 L / h per 100 ml of the first inert solvent.

[0101] In another preferred embodiment, the reaction of step (2) is carried out at ≤5 standard atmospheric pressure; preferably, the reaction of step (2) is carried out at normal pressure (0.9 to 1.1 standard atmospheric pressure).

[0102] In another preferred embodiment, step (2) further includes the step (i.e., the second post-treatment step): adding the reaction solution containing the compound of formula III to a dilute hydrochloric acid solution (e.g., a 1.2 M dilute hydrochloric acid solution) and stirring (e.g., stirring for 30 minutes), taking the organic layer, removing the solvent and / or drying, thereby obtaining the compound of formula III.

[0103] In a specific embodiment, the preparation method of the compound of formula IV further comprises the steps of:

[0104] (3) subjecting the compound of formula III to an esterification reaction to obtain the compound of formula IV.

[0105]

[0106] In another preferred embodiment, in the step (3), the esterification reaction is carried out in the presence of an acid.

[0107] In another preferred embodiment, in the step (3), the esterification reaction is carried out in the presence of one or a mixture of sulfuric acid, acetic acid, oxalic acid, phosphoric acid (preferably, phosphoric acid, sulfuric acid or a combination thereof; most preferably, sulfuric acid).

[0108] In another preferred embodiment, in step (3), the solvent for the esterification reaction (i.e., the second inert solvent) is methanol, ethanol, or a mixed solvent formed by one or a combination of other polyols and water, preferably, a mixed solvent formed by methanol, ethanol or a combination thereof and water; most preferably, a mixed solvent formed by ethanol and water.

[0109] In another preferred embodiment, step (3) comprises the steps of: providing a solution of the compound of formula III in a second inert solvent, adding phosphoric acid and reacting (preferably, reacting at 20-30° C.), reacting for 2-3 hours, thereby obtaining a compound of formula IV.

[0110] In another preferred embodiment, step (3) further includes the step (i.e., the third treatment step): adding the reaction solution dropwise into water, extracting the solution with an organic solvent (such as dichloromethane), taking the organic layer, and removing the organic solvent (preferably, removing the solvent by pressure distillation), thereby obtaining a separated and / or purified compound of formula IV.

[0111] The main advantages of the present invention include:

[0112] (a) The synthesis method provided by the original report is greatly shortened, and only three steps are required to prepare the key intermediate 5-fluoro-3-methylisobenzofuran-1(3H)-one (Formula IV) from 2-bromo-5-fluoroacetophenone (Formula I) as a raw material.

[0113] (b) The preparation method of the present invention is simple to operate. No complicated operations such as chromatographic separation and chiral separation are required in each step.

[0114] (c) The compound of formula IV obtained by the preparation method of the present invention has high purity (>98%) and high chiral purity (even up to 100%).

[0115] (d) The total yield of the preparation method of the present invention is as high as 77.1%.

[0116] (e) It avoids the chemical method of racemic resolution used in traditional chiral resolution and adopts biological enzyme as catalyst.

[0117] (f) Greatly reduces costs and avoids the use of expensive chromatographic separation, chiral separation and other operations.

[0118] (g) Environmentally friendly, simple / no side reaction, greatly improving product quality.

[0119] (h) The preparation method of the present invention does not require high pressure conditions.

[0120] In particular, when a mixed solvent of anhydrous ethanol and water is used as the inert solvent for the reaction in step (3) and in the presence of sulfuric acid, the purity of the key intermediate of lorlatinib prepared by the method of the present invention can even reach 99.8%.

[0121] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods for the unrecorded specific conditions in the following examples are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are weight percentages and weight parts.

[0122] Unless otherwise specified, the reagents, raw materials, catalysts, enzymes, etc. used in the examples can be obtained commercially or prepared according to conventional methods. For example, the perakine reductase used in the examples was purchased from Shanghai Runtai Pharmaceutical Technology Co., Ltd., and the compound of formula I can be obtained commercially.

[0123] Example 1 Preparation of Compound of Formula II

[0124] The compound of formula I (18.0 mg, 0.083 mmol, commercially available) was added to water (100 mL), perakine reductase (100 mg), glucose dehydrogenase (100 mg), 50 mM Kpi buffer (30 ml) with a pH of 7, glucose (0.03 g 0.13 mmol), NADPH (1.48 mg 0.002 mmol) were added, stirred at 20-30°C for about 10 h, ethyl acetate (50 ml) was added to extract the liquid, and ethyl acetate (30 ml) was added to extract the liquid, the ethyl acetate was combined, and the solvent was removed by concentration under reduced pressure to obtain 16.53 mg of a light yellow solid, yield: 91.0% (relative to formula I). ​​MS (ESI): [M+1] + =220.20. After testing, the chiral purity is 100.0% (see Figure 1 ).

[0125] Example 2 Preparation of Compound of Formula II

[0126] The compound of formula I (18.0 mg, 0.083 mmol, commercially available) was added to water (100 mL), perakine reductase (110 mg), glucose dehydrogenase (100 mg), 50 mM Kpi buffer (30 ml) with a pH of 7, glucose (0.03 g 0.13 mmol), NADPH (1.48 mg 0.002 mmol) were added, stirred at 20-30°C for about 10 h, ethyl acetate (50 ml) was added to extract the liquid, and ethyl acetate (30 ml) was added to extract the liquid, the ethyl acetate was combined, and the solvent was removed by concentration under reduced pressure to obtain 15.63 mg of a light yellow solid, yield: 86.1% (relative to formula I). ​​MS (ESI): [M+1] + =220.20. After testing, the chiral purity is 99.7% (see Figure 2 ).

[0127] Example 3 Preparation of Compound of Formula II

[0128] The compound of formula I (18.0 mg, 0.083 mmol, commercially available) was added to water (100 mL), perakine reductase (70 mg), glucose dehydrogenase (100 mg), 50 mM Kpi buffer (30 ml) with a pH of 7, glucose (0.03 g 0.13 mmol), NADPH (1.48 mg 0.002 mmol) were added, stirred at 20-30°C for about 10 h, ethyl acetate (50 ml) was added to extract the liquid, and ethyl acetate (30 ml) was added to extract the liquid, the ethyl acetate was combined, and the solvent was removed by concentration under reduced pressure to obtain 14.91 mg of a light yellow solid, yield: 82.0% (relative to formula I). ​​MS (ESI): [M+1] + =220.2. After testing, the chiral purity is 97.3% (see Figure 3 ).

[0129] Example 4 Preparation of Compound of Formula III

[0130] The compound of formula II (10 g, 45.6 mmol, prepared according to the method of Example 1) was added to ether (100 ml), the ethanol was cooled to -40--38°C with dry ice, and a 1.6 M n-butyl lithium n-hexane solution (28 ml 45 mmol) was added dropwise. The temperature of the addition process was controlled not to exceed -30°C. After the addition was completed, the mixture was kept warm and stirred for 30 min. CO2 was bubbled into the mixture at -30°C for 15-20 min. The mixture was cooled and slowly heated to about 20°C. The reaction solution was added dropwise to a 1.2 M dilute hydrochloric acid solution (100 ml), stirred for 30 min, allowed to stand to separate the organic layer, dried over anhydrous sodium sulfate, filtered to remove anhydrous sodium sulfate, and distilled under reduced pressure at 30°C to obtain a light yellow solid. The mixture was dried at 50°C to obtain a light yellow solid (7.99 g). The yield was 95.1% (relative to formula II). MS (ESI): [M+1] + =185.16.

[0131] Example 5 Preparation of Compound of Formula III

[0132] The compound of formula II (10 g, 45.6 mmol, prepared according to the method of Example 1) was added to ether (100 ml), the ethanol was cooled to -40--38°C with dry ice, and a 1.6 M n-butyl lithium n-hexane solution (22.5 ml 36 mmol) was added dropwise. The temperature of the addition process did not exceed -30°C. After the addition was completed, the mixture was kept warm and stirred for 30 min. CO2 was bubbled into the mixture at -30°C for 15-20 min. The mixture was cooled and slowly heated to about 20°C. The reaction solution was added dropwise to a 1.2 M dilute hydrochloric acid solution (100 ml), stirred for 30 min, allowed to stand to separate the organic layer, dried over anhydrous sodium sulfate, filtered to remove anhydrous sodium sulfate, and distilled under reduced pressure at 30°C to obtain a light yellow solid. The mixture was dried at 50°C to obtain a light yellow solid (6.93 g). Yield: 82.5% (relative to formula II) MS (ESI): [M+1] + =185.16.

[0133] Example 6 Preparation of Compound of Formula III

[0134] The compound of formula II (10 g, 45.6 mmol, prepared according to the method of Example 1) was added to ether (100 ml), the ethanol was cooled to -40--38°C with dry ice, and a 1.6 M n-butyl lithium n-hexane solution (33.8 ml 54 mmol) was added dropwise. The temperature of the addition process was controlled not to exceed -30°C. After the addition was completed, the mixture was kept warm and stirred for 30 min. CO2 was bubbled into the mixture at -30°C for 15-20 min. The mixture was cooled and slowly heated to about 20°C. The reaction solution was added dropwise to a 1.2 M dilute hydrochloric acid solution (100 ml), stirred for 30 min, allowed to stand to separate the organic layer, dried over anhydrous sodium sulfate, filtered to remove anhydrous sodium sulfate, and distilled under reduced pressure at 30°C to obtain a light yellow solid. The mixture was dried at 50°C to obtain a light yellow solid (7.11 g). Yield: 84.6% (relative to formula II) MS (ESI): [M+1] + =185.16.

[0135] Example 7 Preparation of Compound of Formula IV

[0136] The compound of formula III (50 g, 0.27 mol, prepared according to the method of Example 4) was added to a mixed solution of anhydrous ethanol (450 ml) and water (50 ml), and concentrated sulfuric acid (264.6 g 2.7 mol) was added dropwise. The temperature was controlled at 20-30°C and the reaction was completed. The reaction solution was added dropwise into water (600 ml) and stirred. Dichloromethane (400 ml) was added for extraction, and then dichloromethane (200 ml) was added for extraction and separation. The dichloromethane was combined and the product (40.14 g) was obtained by pressure distillation. The yield was 89.1% (relative to formula III). MS (ESI): [M+1] + =167.17. After testing, the purity is 99.8% (see Figure 4 ).

[0137] Example 8 Preparation of Compound of Formula IV

[0138] The compound of formula III (50 g, 0.27 mol, prepared according to the method of Example 4) was added to a mixed solution of methanol (450 ml) and water (50 ml), and phosphoric acid (264.6 g 2.7 mol) was added dropwise. The temperature was controlled at 20-30°C and the reaction was completed. The reaction solution was added dropwise into water (600 ml) and stirred. Dichloromethane (400 ml) was added for extraction, and then dichloromethane (200 ml) was added for extraction and separation. The dichloromethane was combined and the product (39.3 g) was obtained by pressure distillation. The yield was 87.2% (relative to formula III). MS (ESI): [M+1] + =167.17. After testing, the purity is 98.9% (see Figure 5 ).

[0139] Comparative Example 1 Preparation of Compound of Formula III

[0140] The compound of formula II (10 g, 45.6 mmol, prepared according to the method of Example 1) was added to ethanol (600 ml), added to a high-pressure reactor, and palladium acetate (8.0 g) was added. After carbon monoxide replaced the air in the reactor, carbon monoxide was kept flowing in. The pressure in the reactor was maintained at 12 atm. The temperature was raised to 110° C., reacted for 6 h, cooled to room temperature, filtered to remove the solid catalyst, and the filtrate was concentrated under reduced pressure to obtain a brown solid compound, which was dried with air at 50° C. to obtain a khaki solid (4.12 g, yield: 49.0%) (relative to formula II) MS (ESI): [M+1]+=185.16.

[0141] 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 preparing a compound of formula IV, characterized in that: The preparation method comprises the steps of: (1) subjecting the compound of formula I to a reduction reaction in a bioenzyme catalytic reduction system containing bioenzyme, glucose and glucose dehydrogenase to form a compound of formula II; in, The biological enzyme is a combination of perakine reductase and coenzyme NADPH; The solvent of the bio-enzyme catalysis system is: water; The pH of the bio-enzyme catalysis system is 7±1; The concentration of the perakine reductase is 0.69-0.77 mg / ml, and the concentration of the coenzyme NADPH is 0.01-0.02 mmol / L, based on the total volume of the bio-enzyme catalytic system; The concentration of the compound of formula I is 0.5 to 0.7 mM, based on the total volume of the bioenzyme catalysis system; The concentration of glucose is 1±0.1 mmol / L, based on the total volume of the bio-enzyme catalysis system; The concentration of glucose dehydrogenase is 0.69-0.77 mg / ml, based on the total volume of the bio-enzyme catalysis system; and In the bio-enzyme catalysis system, the mass ratio of glucose dehydrogenase to perakine reductase is 1:1; and the chiral purity of the compound of formula II is greater than 99.9%; (2) reacting the compound of formula II obtained in step (1) in the presence of n-butyl lithium and carbon dioxide in a first inert solvent to obtain a compound of formula III; wherein the reaction temperature is: -40 to -30°C, the reaction time is 45 to 50 min, the molar ratio of n-butyl lithium to formula II is (1±0.1):1, and the first inert solvent is diethyl ether; and (3) in a second inert solvent, subjecting the compound of formula III obtained in step (2) to an esterification reaction to obtain a compound of formula IV; wherein the esterification reaction is carried out in the presence of an acid, and the acid is sulfuric acid; wherein the second inert solvent is selected from the group consisting of an alcohol solvent, water, or a combination thereof, the alcohol solvent is ethanol, the volume ratio of the alcohol solvent to water is (9±1):1, the molar ratio of the acid to the compound of formula III is (10±1):1, the reaction temperature of the esterification reaction is 20-30° C., and the reaction time of the esterification reaction is 2-3 h.

2. The preparation method according to claim 1, characterized in that In step (3), the chiral purity of the compound of formula IV is greater than 99.9%.

3. The method according to claim 1, characterized in that In step (3), the volume mass ratio (ml:g) of the second inert solvent to the compound of formula III is (5-20):

1.

4. The method according to claim 1, characterized in that Step (3) has one or more of the following characteristics: (i) In step (3), the volume ratio of the alcohol solvent to water in the second inert solvent is: (ii) In step (3), the volume mass ratio (ml:g) of the second inert solvent to the compound of formula III is (10±1):

1.

5. The preparation method according to claim 1, characterized in that: The preparation method does not include a chiral resolution step and the preparation method does not include chromatographic separation.

6. The preparation method according to claim 1, characterized in that: The total yield of the preparation method is ≥75%.

7. The preparation method according to claim 1, characterized in that: The purity of the compound of formula IV prepared by the preparation method is ≥99.5%.

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