A preparation method of chenodeoxycholic acid

Abstract

The present invention belongs to the field of organic synthesis and provides a method for preparing chenodeoxycholic acid. Using phocholic acid, a major component of waste products from the extraction of chenodeoxycholic acid from duck bile paste, as a raw material, chenodeoxycholic acid is obtained through propylidene protection, acetylation, depropylidene, methylation, reaction with p-toluenesulfonyl chloride, bromine substitution, debromination, and deprotection. The method for preparing chenodeoxycholic acid is simple, has abundant raw material sources, high product yield, and is easily industrializable.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and in particular to a method for preparing chenodeoxycholic acid. Background Art

[0002] Ursodeoxycholic acid represented by formula (A) is an effective component in bear bile and an endogenous bile acid. It is used to treat diseases such as reflux gastritis, cholecystopancreatitis, alcoholic liver disease, primary biliary cirrhosis and drug-induced hepatitis, and has high medicinal value.

[0003]

[0004] Before the advent of chemical production methods, ursodeoxycholic acid was primarily obtained by extracting bear bile directly from animals. This practice caused great suffering and suffering to the animals, leading to a significant decline in bear populations and numbers. In the 21st century, people advocate for animal and environmental protection. Scientists have developed various methods to artificially produce ursodeoxycholic acid to reduce the burden on nature.

[0005] Chemical synthesis is by far the most effective way to achieve mass production while minimizing costs. Existing literature reports on chemical synthesis methods for preparing ursodeoxycholic acid primarily use chenodeoxycholic acid as a raw material, oxidizing the 7-hydroxyl group to a ketone, and then selectively reducing the ketone to β-OH to obtain ursodeoxycholic acid. As a key compound in the preparation of ursodeoxycholic acid, chenodeoxycholic acid has therefore attracted widespread attention.

[0006] At present, chenodeoxycholic acid is mainly directly extracted from the bile paste of poultry animals, and its source is relatively wide. However, the output is still limited, which further limits the production capacity of ursodeoxycholic acid. There have been reports of preparing chenodeoxycholic acid by chemical synthesis, such as patent documents CN201710328547.8, CN200610046854.9, CN201110023467.4, etc., as well as non-patent literature "Study on the Synthesis Process of Chenodeoxycholic Acid and Ursodeoxycholic Acid", etc. However, the starting materials used in these existing technologies are all bile acid and its derivatives, but their sources are also extracted from animals, which also limits production capacity to a certain extent.

[0007] Therefore, it is of great research value to explore a preparation method of chenodeoxycholic acid with abundant raw material sources and simple preparation method. Summary of the Invention

[0008] The object of the present invention is to provide a method for preparing chenodeoxycholic acid with abundant raw material sources and simple preparation method.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A preparation method of chenodeoxycholic acid, the preparation process route is:

[0011]

[0012] Specifically, the specific reactions of each step of the above process route are:

[0013] a. Propylidene Protection Reaction: PhCA Synthesis of PhCA-1

[0014] PhCA, acetone, and concentrated sulfuric acid were weighed in proportion and added to a reactor in sequence. The mixture was reacted at 23°C to 28°C for 8 to 10 hours. Anhydrous magnesium sulfate was then added to react overnight for 14 to 18 hours, and the reaction was continued for 22 to 26 hours. After the reaction, the mixture was filtered through diatomaceous earth and washed with a small amount of acetone. The filtrate was added with saturated sodium carbonate solution to adjust the pH to ≈ 8, and filtered again with absorbent cotton. The filtrate was decompressed to remove most of the acetone, saturated brine was added, and the mixture was extracted with ethyl acetate. The layers were separated, the organic phase was dried, and concentrated to obtain PhCA-1.

[0015] b. Acetylation reaction: PhCA-1 synthesizes PhCA-2

[0016] PhCA-1, pyridine, and acetic anhydride were weighed in proportion and added to a reactor in sequence. The reaction was carried out at 23°C to 28°C for 22 to 26 hours. After the reaction, water was slowly added dropwise in an ice bath until solid precipitated. After the addition was complete, the mixture was stirred for 30 minutes. The mixture was filtered, and the filter cake was washed with water and then with petroleum ether to obtain a gray-yellow solid with good dispersion, thereby obtaining PhCA-2.

[0017] c. Depropylation reaction: synthesis of PhCA-OAc from PhCA-2

[0018] PhCA-2 was weighed and dissolved in a solvent (preferably THF). When the temperature reached 25°C, concentrated HCl was slowly added dropwise, and the reaction temperature was controlled to be below 40°C during the addition. After the addition was completed, the reaction was carried out at 33-38°C for 20-30 minutes. After the reaction was completed, saturated brine was added, and then ethyl acetate was added for extraction. The organic phase was dried and concentrated to obtain PhCA-OAc.

[0019] d. Methylation reaction: PhCA-OAc to PhCA-OAc-OMe

[0020] The methyl esterification reaction can be carried out by any of the following methods:

[0021] Method 1: PhCA-OAc, methanol, and a catalyst (preferably concentrated sulfuric acid) are weighed in proportion and added to a reactor. The mixture is reacted at room temperature for 3.5 to 4.5 hours. After the reaction is completed, saturated brine is added, followed by extraction with ethyl acetate. The organic phase is dried, concentrated, and subjected to column chromatography to obtain a yellow solid to obtain PhCA-OAc-OMe.

[0022] Method 2: PhCA-OAc is weighed in proportion and dissolved in methanol, and the mixture is stirred and dissolved in an ice-water bath to form solution 1. Dichlorothionyl is weighed and dissolved in solvent 2 (preferably dichloromethane) to form solution 2. Solution 2 is slowly dripped into solution 1. After the dripping is completed, the temperature is gradually restored to room temperature (15°C) and the reaction is carried out for 4-6 hours. After the reaction is completed, dichloromethane and water are added, the layers are separated, and the dichloromethane is extracted multiple times. The organic phases are combined, washed with saturated brine, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain solid PhCA-OAc-OMe.

[0023] e. Reaction with p-toluenesulfonyl chloride: PhCA-OAc-OMe to synthesize PhCA-OAc-OMe-Tos

[0024] Weigh PhCA-OAc-OMe and dissolve it in a solvent (preferably dichloromethane). Add a catalyst (preferably DMAP) and p-toluenesulfonyl chloride in proportion, and stir at room temperature for 1 to 1.2 hours. After the reaction, add water and adjust the pH to ≈ 7 with 1M / L HCl. The layers are separated, and the aqueous phase is extracted once with DCM. The organic phases are combined, dried, and concentrated to obtain a yellow viscous product, PhCA-OAc-OMe-Tos.

[0025] f. Bromine substitution reaction: PhCA-OAc-OMe-Tos synthesizes PhCA-OAc-OMe-Br

[0026] PhCA-OAc-OMe-Tos and lithium bromide were weighed in proportion, a solvent (preferably tetrahydrofuran) was added, and the mixture was reacted at 50°C to 60°C for 9 to 11 hours. After the reaction, the solvent was evaporated, ethyl acetate and water were added and stirred, the layers were separated, and the aqueous phase was extracted with ethyl acetate three times. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and evaporated to obtain solid PhCA-OAc-OMe-Br.

[0027] g. Debromination reaction: PhCA-OAc-OMe-Br to CDCA-OAc-OMe

[0028] PhCA-OAc-OMe-Br and sodium borohydride were weighed in proportion, added to a solvent (preferably dimethyl sulfoxide), and reacted in a water bath at 15-25°C for 25-35 minutes. After the reaction, water was added, treated with saturated ammonium chloride solution, and extracted three times with ethyl acetate. The organic phases were combined, washed with water and saturated brine, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain solid CDCA-OAc-OMe.

[0029] h. Deprotection reaction: CDCA-OAc-OMe synthesis of CDCA

[0030] CDCA-OAc-OMe was weighed in proportion and added to anhydrous ethanol. A 28% aqueous sodium hydroxide solution was added under stirring and reacted at 45-55°C for 2.8-3.2 hours. After the reaction, water was added and the pH was adjusted to 1-2 with a 2 mol / L aqueous hydrochloric acid solution. The precipitated solid was filtered, washed with water, and dried to obtain the target product CDCA.

[0031] The beneficial effects of the present invention are:

[0032] 1. The method of the present invention uses phocholic acid, one of the main components of the waste after extracting chenodeoxycholic acid from duck bile paste, as the starting material. The raw material source is abundant, and the method plays a role in waste utilization, thus having good economic value.

[0033] 2. The method of the present invention designs a reaction route based on the starting materials, and obtains chenodeoxycholic acid through reactions such as propylidene protection, acetylation, depropylidene, methylation, reaction with p-toluenesulfonyl chloride, bromination, debromination, and deprotection. The preparation method of each step in the entire reaction route is relatively simple, the raw materials used are readily available, and the entire process is easy to industrialize.

[0034] 3. The method of the present invention has a total yield of more than 50% in the entire preparation process, which is relatively high.

[0035] In summary, the preparation method of the present invention has abundant raw material sources, a simple preparation method, a high yield, and good industrial application value. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the present invention is further described below in conjunction with specific embodiments.

[0037] Example 1 Preparation of chenodeoxycholic acid

[0038] a. Propylidene Protection Reaction: PhCA Synthesis of PhCA-1

[0039] 80 g of PhCA (70% content) was added to a 3 L three-necked flask, followed by 1.6 L of acetone and 8 mL of sulfuric acid. The mixture was reacted at 23° C. for 9 h. 52 g of anhydrous magnesium sulfate was added and the reaction was continued overnight for 16 h. The reaction was continued for 24 h. The mixture was filtered through celite and washed with a small amount of acetone. The filtrate was adjusted to pH ≈ 8 by adding saturated sodium carbonate solution and filtered again (with cotton wool). Most of the acetone was removed from the filtrate under reduced pressure. Saturated brine was added and the mixture was extracted with ethyl acetate. The layers were separated, the organic phase was dried, and concentrated to obtain 40 g of PhCA-1 with a content of approximately 85%.

[0040] 1H NMR (300MHz, CDCl3) δ5.30 (s, 1H), 4.47-4.43 (d, 1H), 3.86-3.85 (d, 1H), 3.66-3.42 (m, 1H), 2.17 (s, 3H), 2.10-1.0 (m, 49H), 0.69 (s, 4H).

[0041] b. Acetylation reaction: PhCA-1 synthesizes PhCA-2

[0042] 40 g of PhCA-1 obtained in step a was added to a 3 L single-necked flask, 400 mL of pyridine and 400 mL of acetic anhydride were added, and the mixture was reacted at 25 ° C for 24 h. 2.2 L of water was slowly added dropwise under an ice bath until solid precipitated. After the addition was completed, the mixture was stirred for 30 min; filtered, and the filter cake was washed with 2 L of water and then with 200 mL of petroleum ether to obtain a gray-yellow solid with good dispersion, with a yield of 96%.

[0043] 1H NMR (300MHz, CDCl3) δ5.30 (s, 1H), 4.88-4.87 (d, 1H), 4.58-4.46 (m, 1H), 4.46-4.42 (d, 1H), 2.05-0.93 (m, 46H), 0.68 (s, 3H).

[0044] c. Depropylation reaction: synthesis of PhCA-OAc from PhCA-2

[0045] 10 g of PhCA-2 obtained in step b was added to a 100 mL three-necked flask, 50 mL of THF was added, and 10 mL of concentrated HCl was added dropwise at 25 ° C. The reaction temperature was controlled below 40 ° C during the addition. After the addition was completed, the mixture was reacted at 35 ° C for 25 min; 20 mL of saturated brine was added, and then ethyl acetate was added for extraction. The organic phase was dried and concentrated to obtain 10 g of crude PhCA-OAc with a product content of 95%. The crude product was directly used in the next step.

[0046] 1H NMR (300MHz, CDCl3) δ10.62 (s, 1H), 7.00-6.93 (m, 2H), 6.88-6.85 (m, 1H), 4.75 (s, 1H), 1.99-0.82 (m, 26H).

[0047] d. Methylation reaction: PhCA-OAc to PhCA-OAc-OMe

[0048] Method 1: Take 10 g of the crude PhCA-OAc obtained in step c and add it to a 250 mL single-necked bottle. Add 100 mL of methanol and 0.1 mL of concentrated sulfuric acid, and react at room temperature for 4 h. Add 60 mL of saturated brine, then add ethyl acetate for extraction. The organic phase is dried, concentrated, and purified by column chromatography to obtain 6.9 g of a yellow solid (yield 70%).

[0049] 1H NMR (300MHz, CDCl3) δ4.88-4.87 (d, 1H), 4.62-4.57 (m, 1H), 4.25-4.21 (m, 1 H), 3.78 (s, 3H), 2.58 (s, 1H), 2.04-0.93 (m, 40H), 0.93 (s, 3H), 0.68 (s, 3H).

[0050] Method 2: 4.227 g of the crude PhCA-OAc obtained in step c was added to a 250 mL three-necked flask, 170 mL of methanol was added, and the mixture was stirred in an ice-water bath to dissolve to obtain a methanol solution of PhCA-OAc; 0.16 mL of thionyl chloride was weighed and dissolved in 5 mL of dichloromethane, and the mixture was slowly added dropwise to the methanol solution of PhCA-OAc. After the addition was completed, the temperature was gradually restored to room temperature (15°C) and the reaction was carried out for 4-6 hours; dichloromethane and water were added, the layers were separated, and the mixture was extracted with dichloromethane three times. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain 4.8 g of solid PhCA-OAc-OMe with a yield of 92%.

[0051] 1H NMR (300MHz, CDCl3) δ4.87-4.86 (d, 1H), 4.57-4.56 (m, 1H), 4.24-4.19 (m, 1H), 3.76 (s, 3H), 2.64-2.62 (d, 1H), 2.03-0.99 (m, 34H), 0.92 (s, 3H), 0.67 (s, 3H).

[0052] e. Reaction with p-toluenesulfonyl chloride: PhCA-OAc-OMe to synthesize PhCA-OAc-OMe-Tos

[0053] Take 10 g of the pure PhCA-OAc-OMe prepared in method 1 and add it to a 250 mL single-necked bottle. Add 100 mL of dichloromethane, 4.3 g of DMAP, and 5.4 g of p-toluenesulfonyl chloride, and stir at room temperature for 1 h. Add 30 mL of water, and then adjust the pH to ≈ 7 with 1N HCl. The layers are separated, and the aqueous phase is extracted once with DCM. The organic phases are combined, dried, and concentrated to obtain 13.85 g of a yellow viscous product, PhCA-OAc-OMe-Tos, which can be directly used for the next step without purification.

[0054] 1H NMR (300MHz, CDCl3) δ7.82-7.80 (d, 2H), 7.35-7.32 (d, 2H), 4.88-4.85 (d, 2H), 4.61-4.54 (m, 1H), 3.66-3.62 (m, 3H), 2.45 (s, 3H), 2.03-1.05 (m, 36H), 0.92 (s, 3H), 0.79-0.78 (d, 5H), 0.55 (s, 3H).

[0055] f. Bromine substitution reaction: PhCA-OAc-OMe-Tos synthesizes PhCA-OAc-OMe-Br

[0056] 8.8 g of PhCA-OAc-OMe-Tos obtained in step e was added to a 250 mL single-necked bottle, 8.1 g of lithium bromide was added, 80 mL of tetrahydrofuran (10 mL / 1 g) was added, and the mixture was reacted at 50-60° C. for 10 hours; the tetrahydrofuran was evaporated to dryness, ethyl acetate and water were added and stirred, the layers were separated, the aqueous phase was extracted three times with ethyl acetate, the organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain 7.7 g of solid PhCA-OAc-OMe-Br, which was separated by column chromatography with a yield of 86%.

[0057] 1H NMR (300MHz, CDCl3) δ4.84 (s, 1H), 4.55-4.32 (m, 1H), 4.29-4.25 (m, 1H), 3.75-3.74 (d, 3H), 2.97 (s, 1H), 2.02-0.59 (m, 50H).

[0058] g. Debromination reaction: PhCA-OAc-OMe-Br to CDCA-OAc-OMe

[0059] 359 mg of PhCA-OAc-OMe-Br obtained in step f was added to a 50 mL single-necked bottle, 23.90 mg of sodium borohydride was added, 6.5 mL of fresh (dried over anhydrous sodium sulfate) dimethyl sulfoxide (18 mL / 1 g) was added, and the mixture was reacted in a water bath at 15-25° C. for 30 minutes; water was added, the mixture was treated with saturated ammonium chloride solution, and the mixture was extracted three times with ethyl acetate. The organic phases were combined, washed with water, washed with saturated brine, dried over anhydrous sodium sulfate, evaporated to dryness, and separated by column chromatography to obtain 280 mg of solid CDCA-OAc-OMe in a yield of 91%.

[0060] 1H NMR (300MHz, CDCl3) δ 4.88-4.87 (d, 1H), 4.62-4.53 (m, 1H), 3.66 (s, 3H), 2.37-1.12 (m, 40H), 0.92-0.90 (d, 6H), 0.64 (s, 3H).

[0061] h. Deprotection reaction: CDCA-OAc-OMe synthesis of CDCA

[0062] 70 mg of CDCA-OAc-OMe obtained in step h was added to a 50 mL single-necked bottle, 1 mL of anhydrous ethanol was added, and 0.1 mL of 28% aqueous sodium hydroxide solution was added with stirring. The reaction was carried out at 50° C. for 3 hours. Water was added and the pH was adjusted to 1-2 with 2 mol / L aqueous hydrochloric acid solution. The precipitated solid was filtered, washed with water, and dried to obtain 45 mg of the target product CDCA with a yield of 80% and a content of 90-95%.

[0063] 1H NMR (300MHz, CDCl3) δ3.85 (s, 1H), 3.51-3.43 (m, 1H), 0.94 (d, 3H), 0.90 (s, 3H), 0.66 (s, 3H).

[0064] The above examples show that the preparation method of the present invention can use starting materials with abundant sources to obtain the target product in a simple preparation method with high yield, which solves the main problems existing in the preparation of chenodeoxycholic acid in the prior art and has good industrial application value.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing chenodeoxycholic acid, characterized in that: The preparation process route is: 。 2. The method for preparing chenodeoxycholic acid according to claim 1, wherein The step a is a propylidene protection reaction, in which PhCA reacts with acetone under the catalysis of concentrated sulfuric acid to carry out propylidene protection on the hydroxyl groups at the 23rd and 24th carboxyl groups to obtain PhCA-1.

3. The method for preparing chenodeoxycholic acid according to claim 1, wherein The step b is an acetylation reaction, in which PhCA-1 and acetic anhydride react in pyridine to obtain PhCA-2.

4. The method for preparing chenodeoxycholic acid according to claim 1, wherein The step c is a depropylidene reaction, wherein PhCA-2 is dissolved in a solvent and concentrated HCl is slowly added dropwise to react to obtain PhCA-OAc.

5. The method for preparing chenodeoxycholic acid according to claim 1, wherein The step d is a methyl esterification reaction, in which PhCA-OAc and methanol react in the presence of a catalyst to obtain PhCA-OAc-OMe.

6. The method for preparing chenodeoxycholic acid according to claim 1, characterized in that: The step d is a methyl esterification reaction, wherein PhCA-OAc and methanol form solution 1, thionyl chloride is dissolved in solvent 2 to form solution 2, and solution 2 is slowly dripped into solution 1 to react to obtain PhCA-OAc-OMe.

7. The method for preparing chenodeoxycholic acid according to claim 1, characterized in that: The step e is a reaction of PhCA-OAc-OMe with p-toluenesulfonyl chloride. PhCA-OAc-OMe and p-toluenesulfonyl chloride react in a solvent in the presence of a catalyst to obtain PhCA-OAc-OMe-Tos.

8. The method for preparing chenodeoxycholic acid according to claim 1, characterized in that: The step f is a bromine substitution reaction, in which PhCA-OAc-OMe-Tos and lithium bromide react in a solvent to obtain PhCA-OAc-OMe-Br.

9. The method for preparing chenodeoxycholic acid according to claim 1, wherein The step g is a debromination reaction, in which PhCA-OAc-OMe-Br reacts with sodium borohydride in a solvent to obtain CDCA-OAc-OMe.

10. The method for preparing chenodeoxycholic acid according to claim 1, characterized in that: The step h is a deprotection reaction, wherein CDCA-OAc-OMe is dissolved in anhydrous ethanol and reacts with a sodium hydroxide aqueous solution to obtain the target product CDCA.

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