A synthetic method of chenodeoxycholic acid

Abstract

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

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and in particular to a method for synthesizing 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 the source is also extracted from animals, and its production capacity is strictly limited.

[0007] Therefore, it is of great research value to explore a synthetic method for 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 synthesizing 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 method for synthesizing chenodeoxycholic acid, the preparation process route is:

[0011]

[0012] Specifically, the synthesis method of chenodeoxycholic acid of the present application comprises the following steps:

[0013] a. Methylation reaction: PhCA to synthesize PhCA-OMe

[0014] PhCA, methanol, and a catalyst (preferably concentrated sulfuric acid) were weighed in proportion and reacted at room temperature overnight. After the reaction, the mixture was filtered through celite and the methanol was evaporated under reduced pressure at 40°C. The residue was added with water and extracted with EA. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain PhCA-OMe.

[0015] b. Reaction with p-toluenesulfonyl chloride: PhCA-OMe synthesizes PhCA-OMe-Tos

[0016] PhCA-OMe was weighed and dissolved in a solvent (preferably DCM). A catalyst (preferably DMAP) was added in proportion. P-toluenesulfonyl chloride was slowly added while stirring in an ice-water bath. The mixture was slowly returned to room temperature and stirred overnight. After the reaction, 1 M / L HCl (aq) was added to adjust the pH to 5. The layers were separated, and the aqueous phase was extracted with DCM. The organic phases were combined, washed with water, and dried. The solvent was removed under reduced pressure to obtain a foamy solid PhCA-OMe-Tos.

[0017] In the above step b, the molar ratio of PhCA-OMe to p-toluenesulfonyl chloride is strictly controlled to meet the following conditions: 1:0.8-1.2.

[0018] In the above step b, the molar ratio of DMAP to PhCA-OMe satisfies: 0.5-2:1.

[0019] c. Bromine substitution reaction: PhCA-OMe-Tos to PhCA-OMe-Br

[0020] PhCA-OMe-Tos was weighed in proportion and added to a solvent (preferably THF). LiBr was added under stirring, and the temperature was raised to 65-75°C and refluxed for 9-11 hours. After the reaction, the mixture was cooled to room temperature, most of the solvent was removed under reduced pressure, water was added, and EA was used for extraction. The organic phases were combined and concentrated under reduced pressure to obtain a foamy solid PhCA-OMe-Br.

[0021] d. Debromination reaction: PhCA-OMe-Br to CDCA-OMe

[0022] Weigh PhCA-OMe-Br, add a solvent (preferably DMSO), add sodium borohydride in batches under ice-water bath conditions, and react for about 2 hours after the addition. After the reaction is complete, slowly add ammonium chloride aqueous solution dropwise, then add 1M / L hydrochloric acid to adjust the pH to 3, extract with EA, wash with saturated brine, combine the organic phases, dry and concentrate to obtain CDCA-OMe.

[0023] e. Deprotection reaction: CDCA-OMe synthesis of CDCA

[0024] CDCA-OMe was weighed in proportion and added to anhydrous ethanol, and a 28% aqueous sodium hydroxide solution was added, and the reaction was carried out at 20-25°C for 2.8 to 3.2 hours. After the reaction, the pH was adjusted to 6, the ethanol was removed under reduced pressure, 1M NaOH (aq) was added, and the mixture was extracted with ethyl acetate. The aqueous phase was adjusted to pH 4, extracted with EA, and crystallized by beating with acetonitrile to obtain the target product CDCA.

[0025] The beneficial effects of the present invention are:

[0026] The method of the present invention uses seal cholic acid, one of the main components in the waste after chenodeoxycholic acid is extracted from duck bile paste, as a starting material. The raw material source is abundant, the waste is utilized, and the method has good economic value. According to the selection of the starting material, a reaction route is reasonably designed to obtain chenodeoxycholic acid through methyl esterification, reaction with p-toluenesulfonyl chloride, bromine substitution, debromination, deprotection and other reactions. The preparation method of each step adopted in the entire reaction route is relatively simple, the raw materials involved in the process are widely available, and the entire process is easy to industrialize. The total yield of the entire preparation process can reach more than 50%, which is a high yield. 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

[0027] 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.

[0028] Example 1 Preparation of chenodeoxycholic acid

[0029] a. Methylation reaction: PhCA to synthesize PhCA-OMe

[0030] 100 g of PhCA was added to a 2 L round-bottom flask, along with 1 L of methanol. 5 mL of concentrated sulfuric acid was slowly added dropwise with stirring. The mixture was allowed to react at room temperature overnight. The mixture was filtered through Celite, and the methanol was evaporated under reduced pressure at 40°C. The residue was added with 300 mL of water and extracted with EA. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to yield 90 g of PhCA-OMe (87% yield).

[0031] 1H NMR (300MHz, CDCl3) δ4.24-4.20 (d, 1H), 3.84 (s, 1H), 3.78 (s, 3H), 3.72-3.70 ( d, 1H), 3.66 (s, 1H), 3.47 (s, 1H), 2.18-0.69 (m, 55H), 0.69 (s, 3H), 0.65 (s, 1H).

[0032] b. Reaction with p-toluenesulfonic acid: PhCA-OMe synthesizes PhCA-OMe-Tos

[0033] 10 g of PhCA-OMe was added to a 100 mL round-bottom flask, along with 80 mL of DCM and 4.33 g of DMAP catalyst. 4.51 g of p-toluenesulfonyl chloride was slowly added while stirring in an ice-water bath. The mixture was slowly returned to room temperature and stirred overnight. 1 M / L HCl (aq) was added to adjust the pH to 5. The layers were separated, and the aqueous phase was extracted with 30 mL of DCM. The combined organic phases were washed with water, dried, and the solvent removed under reduced pressure to yield 12.6 g of a foamy solid (92% yield).

[0034] 1H NMR (300MHz, CDCl3) δ7.83-7.76 (m, 3H), 7.35-7.26 (m, 3H), 4.86-4.83 (d, 1H), 4.13-4.10 (m, 1H), 3.83-3.78 (d, 3H), 3.66- 3.65 (d, 5H), 3.67-3.45 (m, 2H), 2.45-2.43 (d, 4H), 2.16-0.86 (m, 61H), 0.78-0.76 (d, 3H), 0.69-0.56 (m, 3H), 0.56 (s, 3H).

[0035] c. Bromine substitution reaction: PhCA-OMe-Tos to PhCA-OMe-Br

[0036] 10 g of PhCA-OMe-Tos was added to a 250 mL round-bottom flask, along with 100 mL of THF. 10.9 g of LiBr was added with stirring, and the temperature was raised to 70°C and refluxed for about 10 h. The mixture was cooled to room temperature, and most of the THF was removed under reduced pressure. 30 mL of water was added, and the mixture was extracted with EA. The organic phases were combined and concentrated under reduced pressure to obtain 7.6 g of a foamy solid with a yield of 90%.

[0037] 1H NMR (300MHz, CDCl3) δ 4.30-4.29 (m, 1H), 4.10-4.07 (m, 1H), 3.81 (s, 1H), 3.75 (s, 3H), 3.63 (s, 1H), 3.43-3.41 (m, 1H), 2.16-0.60 (m, 52H).

[0038] d. Debromination reaction: PhCA-OMe-Br to CDCA-OMe

[0039] 84 g of PhCA-OMe-Br was added to a 2 L round-bottom flask, along with 840 mL of DMSO. The mixture was placed in an ice-water bath and 6.3 g of sodium borohydride was added portionwise. After addition, the mixture was allowed to react for another 2 h. An aqueous ammonium chloride solution was slowly added dropwise, and the pH was adjusted to 3 with 1 M hydrochloric acid. The mixture was extracted with EA and washed with saturated brine. The organic phases were combined, dried, and concentrated to give 69 g of a solid (98% yield).

[0040] 1H NMR (300MHz, CDCl3) δ4.13-4.06 (m, 1H), 3.83 (s, 1H), 3.64 (s, 2H), 3.45-3. 44 (m, 1H), 2.60 (s, 6H), 2.17-1.21 (m, 28H), 0.97-0.88 (m, 6H), 0.64 (s, 3H).

[0041] e. Deprotection reaction: CDCA-OMe synthesis of CDCA

[0042] 70 g of CDCA-OMe was added to a 2 L round-bottom flask, followed by 1 L of anhydrous ethanol and 37 mL of a 28% aqueous sodium hydroxide solution. The mixture was reacted at 20-25° C. for 3 h. The pH was adjusted to 6, the ethanol was removed under reduced pressure, 1 M NaOH (aq) was added, and the mixture was extracted with ethyl acetate. The aqueous phase was adjusted to pH 4, extracted with EA, and 58 g of the product was crystallized by acetonitrile beating. The yield was 85% and the content was 92-95%.

[0043] 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).

[0044] 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.

[0045] 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 synthesizing chenodeoxycholic acid, characterized in that: The preparation process route is:

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

3. The method for synthesizing chenodeoxycholic acid according to claim 1, wherein: The step b is a reaction of PhCA-OMe with p-toluenesulfonyl chloride, wherein PhCA-OMe and p-toluenesulfonyl chloride react in a solvent under the action of a catalyst to obtain PhCA-OMe-Tos.

4. The method for synthesizing chenodeoxycholic acid according to claim 3, wherein: In the step b, the molar ratio of PhCA-OMe to p-toluenesulfonyl chloride should be controlled between 1:0.8-1.

2.

5. The method for synthesizing chenodeoxycholic acid according to claim 3, wherein: In the step b, the catalyst is DMAP.

6. The method for synthesizing chenodeoxycholic acid according to claim 5, characterized in that: In the step b, the molar ratio of DMAP to PhCA-OMe satisfies: 0.5 to 2:

1.

7. The method for synthesizing chenodeoxycholic acid according to claim 1, wherein: The step c is a bromine substitution reaction, in which PhCA-OMe-Tos and lithium bromide react in a solvent to obtain PhCA-OMe-Br.

8. The method for synthesizing chenodeoxycholic acid according to claim 1, wherein: The step d is a debromination reaction, in which PhCA-OMe-Br and sodium borohydride react in a solvent to obtain CDCA-OMe.

9. The method for synthesizing chenodeoxycholic acid according to claim 1, wherein: The step e is a deprotection reaction, in which CDCA-OMe is dissolved in anhydrous ethanol and reacted with a sodium hydroxide aqueous solution to obtain the target product CDCA.

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