A method for preparing deoxycholic acid intermediate

Abstract

The present invention provides a method for preparing compound B, wherein compound A is subjected to an oxidation reaction to generate compound B. The oxidation is carried out under the action of an oxidant and a co-oxidant, the oxidant tert-butyl hydroperoxide is slowly added, the molar ratio of the oxidant to compound A is (5-15):1; the co-oxidant is a copper-containing oxidant, and the molar ratio of the co-oxidant to compound A is (0.5-1):1; the reaction temperature is 75°C-85°C. The method is suitable for preparing a key intermediate of deoxycholic acid, is simple to operate, is environmentally friendly, has low cost, high yield, and is suitable for industrial production applications.

Description

Technical Field

[0001] The invention belongs to the field of pharmaceutical chemistry, and particularly relates to a method for preparing a deoxycholic acid intermediate. Background Art

[0002] Steroid compounds are one of the most widely occurring components in natural products, and almost all organisms can biosynthesize steroid compounds. As a large type of steroid compounds, bile acids and their derivatives have a wide range of biological activities. Since bile acids have high stereochemical purity and amphiphilic structural characteristics, and are endogenous natural products, the study of the biological activities of bile acids and their derivatives has always been one of the research hotspots in the field of pharmacology and drug discovery. There is a literature (New Progress in the Study of the Biological Activity of Bile Acid Derivatives, "Life Science", Vol. 29, No. 1, January 2017) reporting that bile acid compounds have biological activities such as anti-tumor, treatment of metabolic syndrome, antibacterial, anti-tuberculosis, anti-malarial and anti-trypanosoma.

[0003] Deoxycholic acid (DCA, Formula I), also known as deoxycholic acid, is a secondary bile acid metabolized in the human body, which helps the absorption and transport of fat and fat-soluble vitamins in the body. In 2015, the deoxycholic acid injection developed by Kythera was approved by the U.S. Food and Drug Administration as a drug that can be used for injectable lipolysis. The trade name is Kybella, which is used to improve the bulge or fullness of moderate to severe submental fat in adults (double chin). Deoxycholic acid has also become the first drug used for non-surgical treatment to eliminate excess submental fat. At present, deoxycholic acid is mainly derived from animal bodies. Although the cost is low, there is a risk that it may contain animal pathogens and other harmful factors.

[0004] (I)

[0005] The prior art has disclosed a chemical synthesis method for deoxycholic acid, wherein compound D is a key intermediate for synthesizing deoxycholic acid, and its structural formula is shown below, wherein P represents a hydroxyl protecting group, such as acetyl (Ac) or benzoyl (Bz).

[0006] (D)

[0007] For example, CN106083969A discloses a method for the total synthesis of deoxycholic acid, as shown in Scheme 1 below. This method uses chromium trioxide as an oxidant in the process of synthesizing intermediate 1.10. Chromium (VI) is one of the most toxic pollutants and has been listed in the Level 3 carcinogen list by the International Agency for Research on Cancer of the World Health Organization. Chromium trioxide is highly toxic, highly polluting and carcinogenic, and is harmful to both the human body and the environment.

[0008]

[0009] Solution 1

[0010] CN107011401A discloses a method for preparing deoxycholic acid, and the synthesis route is shown in Scheme 2. The method includes two steps in synthesizing the intermediate 2.24. The first step is to oxidize 2.32 using tert-butyl peroxide (TBHP) and hypochlorite, and the second step is to further oxidize using pyridinium chlorochromate (PCC) to obtain the intermediate 2.24.

[0011]

[0012] Solution 2

[0013] CN106146593A discloses a method for preparing deoxycholic acid, wherein the synthesis route of the deoxycholic acid intermediate 3.4 is shown in Scheme 3. In the process of preparing the intermediate 3.4, a TBHP / CuI oxidation system is used, and the reaction product contains a large amount of byproduct 3.4a, which needs to be further oxidized under the action of pyridinium chlorochromate (PCC) to generate 3.4.

[0014]

[0015] Solution 3

[0016] CN103906517A discloses a method for synthesizing deoxycholic acid, and the synthesis route of deoxycholic acid intermediate 129 is shown in Scheme 4. Compound 128 undergoes oxidation reaction at 50°C under the action of TBHP (2.5eq) and CuI to generate compound 129. HPLC detection shows that the conversion rate of the target product 129 generated by the reaction is very low (29.8%), and a large amount of byproduct 128a (61.7%) is generated. The byproduct 128 needs to be further oxidized with pyridinium chlorochromate (PCC) to obtain compound 129.

[0017]

[0018] Solution 4

[0019] In the process of synthesizing intermediate D, TBHP / co-oxidant (such as sodium hypochlorite, CuI, etc.) is used as an improved oxidation system to replace the chromium (VI) oxidant, which can reduce environmental pollution. However, the reaction has the problems of low conversion rate and many by-products. It is necessary to use pyridinium chlorochromate (PCC) to perform secondary oxidation on the by-products to convert them into intermediate D to improve the yield. This not only makes the reaction process complicated, but also pyridinium chlorochromate is also a metal chromium (VI) oxidant, which has the problems of high waste liquid treatment cost and environmental pollution.

[0020] Therefore, it is of great significance to develop a method for preparing deoxycholic acid intermediate D with high yield and being environmentally friendly. Summary of the invention

[0021] The purpose of the present invention is to overcome the above problems and provide a method for preparing compound B, which is particularly suitable for preparing deoxycholic acid intermediate D. The method uses TBHP / co-oxidant (such as CuI) as an oxidation system, optimizes process conditions, improves the selectivity and conversion rate of the oxidation reaction, not only improves the yield of compound B, but also avoids the use of PCC for secondary oxidation, simplifies the reaction process, reduces environmental pollution, reduces production costs, and is more suitable for industrial production applications.

[0022] Specifically, the present invention provides the following technical solutions:

[0023] A method for preparing compound B, comprising: subjecting compound A to oxidation reaction to obtain compound B, the reaction formula is as follows:

[0024]

[0025] in:

[0026] P is a hydroxyl protecting group, which may be selected from benzyl, p-methoxybenzyl, benzoyl, acetyl, formyl and benzyloxycarbonyl; preferably, P is benzoyl or acetyl;

[0027] R is an alkyl group, preferably a C1-C4 alkyl group, such as methyl, ethyl, propyl, butyl, etc., more preferably a methyl group;

[0028] The oxidation reaction is carried out under the action of an oxidant and a co-oxidant.

[0029] The oxidant is tert-butyl hydroperoxide (TBHP), for example, in a 70 wt % water-soluble form.

[0030] The oxidant is added in a slow addition manner. The preferred TBHP addition rate is ≤30 g / L / h, i.e., less than 30 g TBHP is added to each liter of the reaction system per hour. The more preferred TBHP addition rate is 5-25 g / L / h, such as 10 g / L / h, 15 g / L / h, 20 g / L / h, etc.

[0031] The co-oxidant is a copper-containing oxidant, for example, at least one selected from CuI, CuBr, CuCl, CuOAc and Cu powder; preferably, the co-oxidant is CuI. The molar ratio of the co-oxidant to compound A is (0.5-1.0):1, preferably 0.7:1.

[0032] The molar ratio of the oxidant to compound A is (5-15):1, preferably (5-10):1, such as 5:1, 8:1, 10:1.

[0033] The temperature of the oxidation reaction is 65°C to 100°C, preferably 75°C to 85°C.

[0034] The weight-to-volume ratio of the compound A to the reaction solvent is 1 g: (5-10) mL, for example 1 g: (5-8) mL.

[0035] In an exemplary embodiment, a method for preparing a deoxycholic acid intermediate compound D is provided, comprising subjecting compound C to an oxidation reaction to obtain compound D; the reaction formula is as follows:

[0036]

[0037] Wherein, P is a hydroxyl protecting group, preferably, P is a benzoyl group or an acetyl group;

[0038] The oxidation reaction is carried out under the action of an oxidant and a co-oxidant.

[0039] The oxidant is tert-butyl hydroperoxide. The molar ratio of the oxidant to compound C is (5-15):1, preferably (5-10):1, and more preferably 5:1.

[0040] The oxidant is added in a continuous and slow manner. The addition rate of TBHP is preferably ≤30 g / L / h, i.e., no more than 30 g TBHP is added to each liter of the reaction system per hour. A more preferred addition rate of TBHP is 5-25 g / L / h, and further preferably 5-20 g / L / h.

[0041] The co-oxidant is a copper-containing oxidant, which can be selected from at least one of CuI, CuBr, CuCl, CuOAc and Cu powder; preferably, the co-oxidant is CuI. The molar ratio of the co-oxidant to compound C is (0.5-1.0):1, preferably 0.7:1.

[0042] The temperature of the oxidation reaction is 65°C to 100°C, preferably 75°C to 85°C.

[0043] The reaction solvent of the reaction is preferably acetonitrile.

[0044] The weight-to-volume ratio of the compound C to the reaction solvent is 1 g: (5-10) mL, for example 1 g: (5-8) mL.

[0045] In a particularly preferred embodiment, the method comprises the following features:

[0046] The oxidation reaction is carried out under the action of tert-butyl hydroperoxide and CuI; the molar ratio of tert-butyl hydroperoxide to compound C is 5:1; the molar ratio of CuI to compound C is 0.7:1; the reaction temperature is 75-85°C; the weight volume ratio of compound C to the reaction solvent is 1g: (5-10)mL; the reaction solvent is acetonitrile; TBHP is preferably in the form of a 70wt% aqueous solution. The TBHP is added slowly and continuously; the TBHP addition rate is 5-20 g / L / h.

[0047] The method of the present invention improves the reaction conversion rate and the yield of the target product by improving various reaction conditions, including the oxidation system, feed ratio, addition method, reaction temperature, etc., and avoids the use of a chromium-containing oxidant (PCC) for secondary oxidation reaction, which not only simplifies the process and reduces the harm to the environment and people, but also does not require a large amount of cost to treat chromium-containing waste liquid, significantly reducing the production cost. The method is particularly suitable for preparing deoxycholic acid intermediate compound B, is environmentally friendly, convenient for post-treatment, low in cost, high in yield, and suitable for industrial production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is the liquid chromatogram of Example 5;

[0049] Figure 2 It is the liquid chromatogram of Example 7;

[0050] Figure 3 It is the liquid chromatogram of comparative example 1;

[0051] Figure 4 It is the liquid chromatogram of comparative example 2. DETAILED DESCRIPTION

[0052] The present invention is described in detail below by way of examples. It should be understood that the methods in the examples are for illustrative purposes only and do not constitute any limitation to the present invention. Unless otherwise specified, the materials used in the examples are commercially available (TBHP is purchased from Anhui Zesheng Technology Co., Ltd., with specifications of 70%wt solution in water, 5.0-6.0mol / L in decane). Unless otherwise specified, the experimental methods used are all conventional methods. In the examples, the completion of the reaction is monitored by HPLC, and the mass percentage of the compound is obtained by area normalization. Unless otherwise specified, the percentages of the solutions used in the examples are the mass percentages of the solutes contained; the reaction temperature refers to the external temperature, which may be the reactor jacket or oil bath temperature.

[0053] The steroid structure skeleton numbering in the present invention follows the general rules:

[0054]

[0055] Unless otherwise indicated, the backbone only indicates the position of carbon atoms. If not specifically indicated, the substituent groups on the backbone structure of the support may include R configuration, S configuration, or a mixture thereof.

[0056] In the present invention, "hydroxyl protecting group P" refers to a protecting group suitable for preventing hydroxyl side reactions well known in the field of organic synthesis. For example, many protecting groups are described in TW Greene and GM Wuts, Protecting Groups in Organic Synthesis, 3rd edition, Wiley, New York, 1999 and references cited therein. Representative hydroxyl protecting groups include, but are not limited to: alkyl (such as methyl, ethyl and tert-butyl); acyl (such as formyl, acetyl, benzoyl); arylmethyl (such as benzyl Bn, p-methoxybenzyl PMB, 9-fluorenylmethyl Fm, diphenylmethyl DPM; silyl (such as trimethylsilyl TMS, tert-butyldimethylsilyl TBS), etc. Preferably, the hydroxyl protecting group is acetyl or benzoyl.

[0057] The "alkyl" of the present invention refers to a saturated monovalent hydrocarbon group, preferably a C1-C4 alkyl group, such as methyl, ethyl, propyl, isopropyl, butyl and the like.

[0058] When the hydroxyl substituent at the 3-position of the steroid ring of the key intermediate D of deoxycholic acid in the embodiment is Bz, the compound is represented by D-1; when the hydroxyl substituent is Ac, the compound is represented by D-2; the synthetic route is as follows:

[0059]

[0060] Compound C is a raw material for preparing intermediate D and is also an intermediate of deoxycholic acid. It can be prepared by referring to a public method, such as the literature method mentioned in the background technology. Compound C-1 in the following examples is prepared by referring to the method of CN106146593A (the difference is that the acetonitrile solution containing the target product C-1 is prepared in Example 8 of the patent and is directly used in the next reaction without purification; while in the present invention, the acetonitrile solution is cooled and crystallized, filtered, and compound C-1 solid is obtained, with a yield of about 90~95%).

[0061] Example 1. Preparation of deoxycholic acid intermediate D-1

[0062] Compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) were added to a three-necked flask, stirred evenly at 75°C, CuI (26.65 g, 0.14 mol) was added at once, and 70% TBHP aqueous solution (260 g, containing 182 g TBHP, 2.02 mol, 10.0 eq) was slowly added. The addition was completed in about 10 hours (based on TBHP, the addition rate was about 28 g / L / h, the same below), and then reacted at 75°C for 24 hours. HPLC monitoring showed that the reaction was complete (the ratio of the compounds was C-1: 0.11%, D-1: 84.30%, E-1: 11.87%; peak area ratio, area normalization method, the same below). 20%wt sodium sulfite solution (1 kg) was added to the reaction solution and stirred at room temperature for 0.5 hours. EtOAc (1 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20% wt sodium chloride solution (750 g). The organic phase was concentrated to remove the solvent. Methanol (1 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (100 mL, 1 V). The product was dried under vacuum at 40 °C to obtain 71.13 g of a white solid product with a yield of 69.2%.

[0063] 1 H NMR (400 MHz, DMSO-d6) δ 7.93-7.95(d, 2H), 7.62-7.64(t,J = 7.4 Hz,1H), 7.48-7.52(t,J = 2H), 5.64(s, 1H), 4.93(s, 1H), 3.58(s,3H), 2.41-2.49 (m,1H), 2.34-2.36(m, 1H), 2.22-2.26(m, 1H), 2.10-2.13(m, 2H), 1.86-1.88(m, 2H),1.64-1.75(m, 6H), 1.32-1.55(m, 7H), 1.20(s, 3H), 1.24-1.26(m, 2H), 0.91-0.93(d, 3H), 0.86(s, 3H). m / z(ESI + ):506 [M+H] + .

[0064] Example 2. Preparation of deoxycholic acid intermediate D-1

[0065] Add compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) to a three-necked flask, stir evenly at 75°C, add CuI (26.65 g, 0.14 mol) at one time, slowly add 70% TBHP aqueous solution (390 g, containing 273 g TBHP, 3.03 mol, 15.0 eq), and add it in about 15 hours (about 28 g / L / h). Then react at 75°C for 24 hours. HPLC monitoring shows that the reaction is complete (C-1: 0.3%, D-1: 82.81%, E-1: 16.90%). Add 20%wt sodium sulfite solution (1 kg) to the reaction solution and stir at room temperature for 0.5 hours. EtOAc (1 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20%wt sodium chloride solution (750 g). The organic phase was concentrated to remove the solvent. Methanol (1 L, 10V) was added and heated to 60°C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (100 mL, 1V). The product was dried under vacuum at 40°C to obtain 70.31 g of a white solid product with a yield of 68.4%.

[0066] Example 3. Preparation of deoxycholic acid intermediate D-1

[0067] Add compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) into a three-necked flask and stir evenly at 75°C. Add CuI (26.65 g, 0.14 mol) at one time, and slowly add 70% TBHP aqueous solution (130 g, containing 91g TBHP, 1.01 mol, 5.0 eq). The addition is completed in about 10 hours (about 14 g / L / h). Then react at 75°C for 24 hours. HPLC monitoring shows that the reaction is complete (the ratio of the compounds is C-1: 0.07%, D-1: 89.11%, E-1: 3.97%). Add 20%wt sodium sulfite solution (3 kg) and stir at room temperature for 0.5 hours. EtOAc (3 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20%wt sodium chloride solution (2.25 kg). The organic phase was concentrated to remove the solvent. Methanol (3 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (300 mL, 1 V). The product was dried in vacuo at 40 °C to obtain 74.63 g of a white solid product with a yield of 72.6%.

[0068] Example 4. Preparation of deoxycholic acid intermediate D-1

[0069] Compound C-1 (500 g, 1.01 mol, 1.0 eq) and acetonitrile (3 L) were added to the reactor and stirred at 75°C. CuI (135.22 g, 0.71 mol) was added at once, and 70% TBHP aqueous solution (1300 g, containing TBHP910 g, 10.10 mol, 10.0 eq) was slowly added. The addition was completed in about 15 hours (about 20.2 g / L / h). Then the reaction was carried out at 75°C for 24 hours. HPLC monitoring showed that the reaction was complete (the ratio of the compounds was C-1: 0%, D-1: 87.81%, E-1: 11.15%). 20%wt sodium sulfite solution (5 kg) was added and stirred at room temperature for 0.5 hours. EtOAc (5 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20%wt sodium chloride solution (3.75 kg). The organic phase was concentrated to remove the solvent. Methanol (5 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (500 mL, 1 V). The product was dried in vacuo at 40 °C to obtain 364.05 g of a white solid product with a yield of 70.8%.

[0070] Example 5. Preparation of deoxycholic acid intermediate D-1

[0071] Add compound C-1 (500 g, 1.01 mol, 1.0 eq) and acetonitrile (3 L) into the reactor and stir evenly at 75°C. Add CuI (135.22 g, 0.71 mol) at one time, and slowly add 70% TBHP aqueous solution (650 g, containing 455 g TBHP, 5.07 mol, 5.0 eq) for about 10 hours (about 15.1 g / L / h). Then react at 75°C for 24 hours. HPLC monitoring shows that the reaction is complete (the ratio of the compounds is C-1: 0.03%, D-1: 88.66%, E-1: 0.68%). Add 20%wt sodium sulfite solution (5 kg) and stir at room temperature for 0.5 hours. EtOAc (5 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20%wt sodium chloride solution (3.75 kg). The organic phase was concentrated to remove the solvent. Methanol (5 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (500 mL, 1 V). The product was dried in vacuo at 40 °C to obtain 375.8 g of a white solid product with a yield of 73.1%.

[0072] Example 6. Preparation of deoxycholic acid intermediate D-1

[0073] Compound C-1 (500 g, 1.01 mol, 1.0 eq) and acetonitrile (3 L) were added to the reactor and stirred at 75°C. CuI (135.22 g, 0.71 mol) was added at once, and 70% TBHP aqueous solution (650 g, containing 455 g TBHP, 5.05 mol, 5.0 eq) was slowly added. The addition was completed in about 8 hours (about 18.9 g / L / h). Then the reaction was carried out at 75°C for 24 hours. HPLC monitoring showed that the reaction was complete (the ratio of the compounds was C-1: 0.07%, D-1: 88.82%, E-1: 3.00%). 20%wt sodium sulfite solution (5 kg) was added and stirred at room temperature for 0.5 hours. EtOAc (5 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20%wt sodium chloride solution (3.75 kg). The organic phase was concentrated to remove the solvent. Methanol (5 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (500 mL, 1 V). The product was dried in vacuo at 40 °C to obtain 373.7 g of a white solid product with a yield of 72.7%.

[0074] Example 7: Preparation of deoxycholic acid intermediate D-1

[0075] Compound C-1 (500 g, 1.01 mol, 1.0 eq) and acetonitrile (3 L) were added to the reactor and stirred at 85°C. CuI (135.22 g, 0.71 mol) was added at once, and 70% TBHP aqueous solution (650 g, containing 455 g TBHP, 5.05 mol, 5.0 eq) was slowly added. The addition was completed in about 12 hours (about 12.6 g / L / h), and then reacted at 85°C for 24 hours. HPLC monitoring showed that the reaction was complete (the ratio of the compounds was C-1: 0.07%, D-1: 90.81%, E-1: 1.18%). 20%wt sodium sulfite solution (5 kg) was added and stirred at room temperature for 0.5 hours. EtOAc (5 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20%wt sodium chloride solution (3.75 kg). The organic phase was concentrated to remove the solvent. Methanol (5 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (500 mL, 1 V). The product was dried in vacuo at 40 °C to obtain 381.53 g of a white solid product with a yield of 74.2%.

[0076] Example 8. Preparation of deoxycholic acid intermediate D-1

[0077] Add compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) to a three-necked flask and stir evenly at 100°C. Add CuI (26.65 g, 0.14 mol) at one time, and slowly add 70% TBHP aqueous solution (130.0 g, containing TBHP 91.0 g, 1.01 mol, 5.0 eq) for about 6 hours (about 23.3 g / L / h). Then react at 100°C for 24 hours, and HPLC monitoring shows that the reaction is complete. Add 20%wt sodium sulfite solution (1 kg) to the reaction solution and stir at room temperature for 0.5 hours. EtOAc (1 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20% wt sodium chloride solution (750 g). The organic phase was concentrated to remove the solvent. Methanol (1 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (100 mL, 1 V). The product was dried under vacuum at 40 °C to obtain 60.89 g of a white solid product with a yield of 68.6%.

[0078] Example 9. Preparation of deoxycholic acid intermediate D-1

[0079] Add compound C-1 (1 kg, 2.02 mol, 1.0 eq) and acetonitrile (6.5 L) to the reactor and stir evenly at 75°C. Add CuI (266.6 g, 1.40 mol) at one time, and slowly add 70% TBHP aqueous solution (2.06 kg, containing 1.44 kg TBHP, 16.0 mol, 8.0 eq). The addition is completed in about 20 hours (about 11 g / L / h), and then react at 75°C for 24 hours until the reaction is complete. Add 20%wt sodium sulfite solution (10.0 kg) and stir at room temperature for 0.5 hours. EtOAc (10 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20% wt sodium chloride solution (7.5 kg). The organic phase was concentrated to remove the solvent. Methanol (10 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (1 L, 1 V). The product was dried in vacuo at 40 °C to obtain 760.76 g of a white solid product with a yield of 73.0%.

[0080] Example 10. Preparation of deoxycholic acid intermediate D-1

[0081] Add compound C-1 (1 kg, 2.02 mol, 1.0 eq) and acetonitrile (6.5 L) to the reactor and stir evenly at 85°C. Add CuI (266.6 g, 1.40 mol) at one time, and slowly add 70% TBHP aqueous solution (1287.4 g, containing TBHP901.2 g, 10.0 mol, 5.0 eq). The addition is completed in about 15 hours (about 9.24 g / L / h), and then react at 85°C for 24 hours. Add 20%wt sodium sulfite solution (10.0 kg) and stir at room temperature for 0.5 hours. EtOAc (10 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20% wt sodium chloride solution (7.5 kg). The organic phase was concentrated to remove the solvent. Methanol (10 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (1 L, 1 V). The product was dried in vacuo at 40 °C to obtain 751.9 g of a white solid product with a yield of 74.2%.

[0082] Example 11. Preparation of deoxycholic acid intermediate D-1

[0083] Add compound C-1 (2 kg, 4.06 mol, 1.0 eq) and acetonitrile (13 L) to the reactor and stir evenly at 75°C. Add CuI (540 g, 2.84 mol) at one time, and slowly add 70% TBHP aqueous solution (2.61 kg, containing 1.82 kg TBHP, 20.2 mol, about 5.0 eq). The addition is completed in about 15 hours (about 9.33 g / L / h), and then react at 75°C for 24 hours. Add 20%wt sodium sulfite solution (15.0 kg) and stir at room temperature for 0.5 hours. EtOAc (15 kg) was added for extraction. The mixture was filtered and separated. The organic phase was washed with 20% wt sodium chloride solution (11.25 kg). The organic phase was concentrated to remove the solvent. Methanol (15 L, 10 V) was added and heated to 60 °C and stirred for 0.5 hour. The mixture was cooled to room temperature and stirred for 2 hours. The mixture was filtered and the filter cake was washed with methanol (1.5 L, 1 V). The mixture was dried in vacuo at 40 °C to obtain 1532.3 g of a white solid product with a yield of 74.5%.

[0084] Comparative Example 1. Preparation of deoxycholic acid intermediate D-1

[0085] Compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) were added to a three-necked flask, stirred evenly at 55°C, and CuI (26.65 g, 0.14 mol) was added at once. A 70% TBHP aqueous solution (105 g, containing 73.5 g TBHP, 0.81 mol, 4.0 eq) was added, and the addition was completed in about 1 hour (about 113 g / L / h), and then reacted at 55°C for 24 hours. HPLC monitoring showed that the ratio of the compounds was C-1: 7.54%, D-1: 44.41%, and E-1: 44.72%.

[0086] Under the reaction conditions, the substrate C-1 has not been completely reacted, and the conversion rate of the target product is low, the content of D-1 is only 44.41%, and the content of the byproduct E-1 reaches 44.72%, so the post-treatment step described in the embodiment is not performed. In order to improve the yield, a secondary oxidation reaction is required using an oxidant such as PCC.

[0087] Comparative Example 2. Preparation of deoxycholic acid intermediate D-1

[0088] Compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) were added to a three-necked flask, stirred evenly at 65°C, and CuI (26.65 g, 0.14 mol) was added at once. A 70% TBHP aqueous solution (130 g, containing TBHP 91 g, 1.01 mol, 5.0 eq) was added, and the addition was completed in about 1.5 hours (about 93.3 g / L / h), and then reacted at 65°C for 24 hours. HPLC monitoring showed that the ratio of the compounds was C-1: 1.90%, D-1: 64.10%, and E-1: 31.05%.

[0089] Under the reaction conditions, the conversion rate of substrate C-1 to target product D-1 increased to about 64.10%, but the content of by-product E-1 still reached 31.05%, requiring a secondary oxidation step using the oxidant PCC.

[0090] Comparative Example 3. Preparation of deoxycholic acid intermediate D-1

[0091] Compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) were added to a three-necked flask, stirred evenly at 75°C, CuI (26.65 g, 0.14 mol) was added at once, and then 70% TBHP aqueous solution (130 g, containing 91 g TBHP, 1.01 mol, 5.0 eq) was added. The addition was completed in about 3 hours (about 46.6 g / L / h), and then reacted at 75°C for 24 hours. HPLC monitoring showed that the ratio of the compounds was C-1: 4.63%, D-1: 74.37%, and E-1: 18.18%. EtOAC (500 mL) and saturated Na2SO4 aqueous solution (500 mL) were added to the reaction solution, stirred at 55°C, and filtered. The filtrate was washed with saturated aqueous NaCl solution (500 mL×3), and the organic phases were combined, dried over anhydrous Na2SO4, filtered, and concentrated to obtain a crude product. Column chromatography (PE:EA=30:1-10:1) gave 52.43 g of a white solid product with a yield of 51.0%.

[0092] Under the reaction conditions, due to the influence of by-products, the post-treatment method of solvent stirring could not precipitate a pure target solid product, so a column chromatography purification method was used for preparation.

[0093] Comparative Example 4. Preparation of deoxycholic acid intermediate D-1

[0094] Compound C-1 (100 g, 0.20 mol, 1.0 eq) and acetonitrile (650 mL) were added to the reaction flask, stirred evenly at 75°C, CuI (26.65 g, 0.14 mol) was added at once, and then 70% TBHP aqueous solution (130 g, containing 91 g TBHP, 1.01 mol, 5.0 eq) was divided into 3 equal parts and added to the reaction system in batches, with an interval of 1.5 hours between each batch. After the addition was completed, the reaction was continued at 75°C for 24 hours. EtOAC (50 mL) and saturated Na2SO4 aqueous solution (50 mL) were added to the reaction solution, stirred at 55°C, and filtered. The filtrate was washed with saturated NaCl aqueous solution (50 mL×3), the organic phases were combined, dried over anhydrous Na2SO4, filtered, and concentrated to obtain the crude product, which was purified by column chromatography (PE:EA=30:1-10:1) to obtain 6.44 g of a white solid product with a yield of 62.6%.

[0095] Comparative Example 5. Preparation of deoxycholic acid intermediate D-1

[0096] Compound C-1 (500 g, 1.01 mol, 1.0 eq) and acetonitrile (3 L) were added to the reactor and stirred at 75°C. CuI (135.22 g, 0.71 mol) was added at once, and 70% TBHP aqueous solution (650 g, containing 455 g TBHP, 5.05 mol, 5.0 eq) was slowly added. The addition was completed in about 4.5 hours (about 33.7 g / L / h), and then reacted at 75°C for 24 hours. HPLC monitoring showed that the ratio of the compounds was C-1: 4.63%, D-1: 54.37%, and E-1: 28.18%.

[0097] Under the reaction conditions, the reaction was nearly complete after 24 hours, but the conversion rate of substrate C-1 to target product D-1 was about 54.37%, and the content of by-product E-1 was high, requiring a secondary oxidation step using the oxidant PCC.

[0098] Comparative Example 6.

[0099] Compound C-1 (10 g, 20.3 mmol, 1.0 eq) and acetonitrile (65 mL) were added to a 2 L three-necked flask, stirred evenly at 75 °C, and manganese (III) acetate dihydrate (Mn) was added at once. (OAc)3·2H2O (134 mg, 0.5 mmol), slowly add 70% TBHP aqueous solution (13 g, containing 9.10 g TBHP, 5.0 eq), add for about 3 hours, and then react at 75°C for 24 hours. HPLC monitoring shows: compound C-1: 5.31%, D-1: 50.51%, E-1: 31.21%; when the reaction is continued for 44 hours, HPLC monitoring shows: compound C-1: 0.55%, D-1: 61.39%, E-1: 19.50%. Under this reaction condition, the conversion rate of the target product is low, and this reaction condition is not applicable, and no post-treatment is performed.

[0100] Comparative Example 7:

[0101] Compound C-1 (10 g, 20.3 mmol, 1.0 eq) and acetonitrile (65 mL) were added to a 3 L three-necked flask, stirred evenly at 75°C, dirhodium (II) tetracaprolactam (32.7 mg, 0.05 mmol) was added at once, and 70% TBHP aqueous solution (13 g, containing TBHP 9.10 g, 5.0 eq) was slowly added. The addition was completed in about 3 hours, and then the reaction was continued at 75°C for 24 hours. HPLC monitoring showed: Compound C-1: 7.66%, D-1 35.76%, E-1: 18.15%. This indicates that under this condition, the reaction is incomplete and the conversion rate of the target product is very low. The reaction conditions are not applicable and no post-treatment is performed.

[0102] Comparative Example 8:

[0103] Compound C-1 (10 g, 20.3 mmol, 1.0 eq) and acetonitrile (65 mL) were added to a 3 L three-necked flask, stirred evenly at 75°C, BiCl3 (bismuth trichloride, 1.63 g, 0.5 mmol) was added at once, and 5.0 mol / L TBHP decane solution (20.3 ml, containing TBHP 101.5 mmol, about 9.15 g) diluted with 9 mL acetonitrile was slowly added. The addition was completed in about 3 hours. Then the reaction was continued at 75°C for 24 hours. HPLC monitoring showed: Compound C-1: 20.81%, D-1: 15.88%, E-1: 15.01%. This indicates that under this condition, the reaction was incomplete and the conversion rate of the target product was very low. The reaction conditions were not applicable and no post-treatment was performed.

[0104] The inventors have thoroughly studied the preparation of the intermediate of deoxycholic acid and screened and optimized the various process conditions of the reaction. According to the above examples and comparative tests of the present invention, it can be seen that the amount and addition method of the oxidant TBHP, the type of the co-oxidant, and the reaction temperature all have an impact on the yield of the reaction.

[0105] First, according to the experimental results of the present invention, as the amount of oxidant TBHP increases, it gradually increases from 4eq to 15eq, the conversion rate of the target product increases, and the yield increases accordingly. Preferably, the molar equivalent of the oxidant TBHP of the present invention can be 5 to 15 times that of the reaction substrate (compound C); considering the production cost, reaction yield, post-treatment, etc., the molar equivalent of TBHP is preferably 5 to 10 times that of the reaction substrate, and more preferably 5 to 8 times. In addition, the present invention studies the effects of different co-oxidants on the reaction, and finds that other metal catalysts such as rhodium-containing catalysts and bismuth-containing catalysts are not suitable for the reaction of the present invention. The preferred co-oxidant is a copper-containing catalyst, preferably CuI.

[0106] Secondly, the addition of the oxidant TBHP has a significant effect on the conversion rate and yield of the reaction. When TBHP is added in a conventional rapid addition or in batches, the conversion rate and yield of the target product are both low. The inventor unexpectedly found that when TBHP is added slowly, the conversion rate and yield of the target product can be significantly improved. For the same reaction system, the slower the TBHP addition rate, the more conducive to the improvement of the conversion rate and yield. We found through small-scale experiments and scaled-up production experiments that as the volume of the reaction system increases, the addition rate of TBHP can be accelerated accordingly, and the same good yield of the target product can be obtained. It is speculated that this may be related to the concentration of TBHP in the reaction solution and the degree of reaction. After conversion, the addition rate of TBHP is preferably no more than 30g / L / h, that is, no more than 30gTBHP is added to each liter of the reaction system per hour. The more preferred addition rate of TBHP is 5~25 g / L / h, and more preferably 10~20 g / L / h. In the present invention, the volume of the reaction system is substantially the same as the volume of the reaction solvent. "g / L / h" refers to the amount of TBHP added to each liter of the reaction system (reaction solvent) per hour. Preferably, the weight-to-volume ratio of substrate to reaction solvent is 1 g: (5-10) mL, for example 1 g: (5-8) mL.

[0107] Again, the inventors investigated the effect of different reaction temperatures on the reaction yield. The reaction can be carried out at 65-100°C, but the preferred reaction temperature is 75-85°C, more preferably 75°C.

[0108] Taking into account various aspects such as time cost and economic cost, the most preferred conditions recommended by the present invention are that the molar equivalent of the oxidant TBHP is 5 times that of the reaction substrate, the reaction temperature is 75-85°C; the addition rate of TBHP is 5-25 g / L / h, more preferably 10-20 g / L / h.

[0109] The method of the present invention only requires one step of oxidation reaction to achieve a relatively high yield for preparing the deoxycholic acid intermediate, and does not require the use of a chromium-containing oxidant (such as PCC) for secondary oxidation of the reaction byproducts, which not only simplifies the reaction operation, but also avoids the increase in production costs and environmental pollution caused by the waste liquid treatment of toxic chromium reagents, and has the significant advantages of being environmentally friendly and low in cost. The above embodiments are only examples of the technical solutions of the present invention. Those skilled in the art can make further combinations and improvements based on the present invention, which are within the scope of protection of the present invention as long as they do not violate the ideas of the present invention.

Claims

1. A method for preparing compound B, comprising: Compound A is oxidized to obtain compound B, and the reaction formula is as follows: ； Wherein: P is a hydroxyl protecting group selected from benzyl, p-methoxybenzyl, benzoyl, acetyl, formyl and benzyloxycarbonyl; R is an alkyl selected from C1-C4 alkyl; The oxidation reaction is carried out under the action of an oxidant and a co-oxidant; the oxidant is tert-butyl hydroperoxide, and the co-oxidant is CuI; the molar ratio of the tert-butyl hydroperoxide to compound A is (5-15):1, and the molar ratio of the co-oxidant to compound A is (0.5-1.0):1; the tert-butyl hydroperoxide is added by slow addition, wherein the addition rate is less than 30 g of tert-butyl hydroperoxide per liter of reaction system per hour based on the tert-butyl hydroperoxide; the reaction temperature of the oxidation reaction is 75-85°C.

2. The method according to claim 1, wherein the molar ratio of the oxidant to compound A is (5-10):1; the molar ratio of the co-oxidant to compound A is 0.7:

1.

3. A method for preparing a deoxycholic acid intermediate compound D, comprising subjecting compound C to an oxidation reaction to obtain compound D, the reaction formula being as follows: ； P is a hydroxyl protecting group selected from benzoyl or acetyl; The oxidation reaction is carried out under the action of tert-butyl hydroperoxide and CuI; The molar ratio of the tert-butyl hydroperoxide to the compound C is (5-15):1; the tert-butyl hydroperoxide is added in a continuous and slow manner, and the addition rate is less than 30 g of tert-butyl hydroperoxide per liter of the reaction system per hour; the molar ratio of CuI to the compound C is (0.5-1.0):1; the reaction temperature is 75°C-85°C.

4. The method according to claim 3, wherein the molar ratio of tert-butyl hydroperoxide to compound C is (5-10):1; and the molar ratio of CuI to compound C is 0.7:

1.

5. The method of claim 3, wherein the tert-butyl hydroperoxide addition rate is 5 to 25 g of tert-butyl hydroperoxide per liter of reaction system per hour.

6. The method of claim 3, wherein the tert-butyl hydroperoxide addition rate is 5 to 20 g of tert-butyl hydroperoxide per liter of reaction system per hour.

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