A preparation method of chenodeoxycholic acid

Abstract

The application discloses a preparation method of chenodeoxycholic acid. The method uses 22E-3alpha-acyloxy-7-ketone-cholest-5,22-diene-24-carboxylic acid methyl ester as raw material, and one-pot three-site hydrogenation reduction of an olefinic bond and a carbonyl group is simultaneously carried out under the reduction condition of a metal catalyst to obtain a 5beta-hydrogen-7alpha-hydroxyl intermediate with high selectivity, and then chenodeoxycholic acid is obtained through hydrolysis. The method for preparing chenodeoxycholic acid directly constructs two chiral centers (5beta and 7alpha) through one-step hydrogenation. The reaction has the characteristics of simplicity, high efficiency, safe operation, high stereoselectivity and convenient product purification, can effectively prepare chenodeoxycholic acid, and is suitable for industrialization. The application has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of organic synthetic chemistry technology, specifically relating to a method for preparing chenodeoxycholic acid. Background Technology

[0002] Chenodeoxycholic acid, abbreviated as CDCA, also known as 3α,7α-dihydroxy-5β-cholanic acid, exists as colorless needle-like crystals, and its structural formula is shown in Formula I:

[0003]

[0004] Currently, chenodeoxycholic acid is a cholanic acid with strong pharmacological effects extracted from the bile of pigs, geese, ducks, and chickens. Chenodeoxycholic acid has effects such as lowering cholesterol, protecting the liver, improving liver function, promoting hepatocyte recovery, and preventing cardiovascular and cerebrovascular diseases. Clinically, it has good therapeutic effects on various biliary and digestive tract diseases and is currently one of the most widely used drugs for treating gallstones in the world.

[0005] The direct preparation of chenodeoxycholic acid using chemical methods mainly starts from animal-derived raw materials. For example, patent document CN112341512A reports a method for preparing chenodeoxycholic acid using seal urchin (PCA) as raw material, as shown in reaction formula (a).

[0006]

[0007] Patent document CN112209982B reports a method for preparing chenodeoxycholic acid from porcine deoxycholic acid as a raw material, as shown in reaction formula (b).

[0008]

[0009] Furthermore, chenodeoxycholic acid can be synthesized using 7-ketolithocholic acid as an intermediate (Tetrahedron Letters Volume 24, Issue 24, 1983, Pages 2487-2490), as shown in reaction formula (c).

[0010]

[0011] However, the preparation of 7-ketolithocholic acid is mainly carried out through the synthesis of steroidal raw materials from animal sources. For example, PCT international patent application WO2014020024A1 reports the preparation of 7-ketolithocholic acid using cholic acid as a raw material (as shown in reaction formula (d)). The entire process uses the Huangminglong reaction at a very high temperature. This step of the reaction has a relatively high temperature, and hydrazine hydrate is highly toxic and explosive, which places high demands on the equipment.

[0012]

[0013] Patent document CN110423261B reports the preparation of 7-ketolithocholic acid from porcine cholic acid (as shown in reaction formula (e)). The disadvantages of this method are high pollution levels, significant environmental impact, and high overall cost.

[0014]

[0015] A 2004 paper (Biosci. Biotechnol. Biochem., 68(6), 1332–1337, 2004) reported a synthetic route for preparing chenodeoxycholic acid from stigmasterol as a raw material. As shown in reaction formula (f), compound 5 needs to be selectively reduced at -78°C to generate 7α-hydroxyl, and the ratio of 7α:7β is 2:1. The reaction conditions are harsh and the stereoselectivity is poor.

[0016]

[0017] A 2017 PCT international patent application, WO 2017 / 019524 A1, reported a method for preparing chenodeoxycholic acid, as shown in reaction formula (g). This patent's synthetic strategy uses diosgenin as a starting material and proceeds through a 12-step reaction to obtain compound 15. First, the 7-ketone is selectively reduced to a 7α-hydroxyl group, then the double bond is hydrogenated using Pd / C, followed by the removal of two protecting groups to obtain chenodeoxycholic acid. However, in reality, Pd / C-catalyzed hydrogenation cannot yield a highly selective 5β-hydrogen product, and the reaction steps are lengthy, which is detrimental to industrialization.

[0018]

[0019] The reported synthetic routes for chenodeoxycholic acid currently have problems such as overly complicated steps, low yield, high pollution, and expensive raw materials. Therefore, developing an efficient synthetic method for chenodeoxycholic acid is of great significance and industrial value. Summary of the Invention

[0020] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing chenodeoxycholic acid. The method utilizes methyl 22E-3α-acyloxy-7-keto-cholest-5,22-diene-24-carboxylic acid as a raw material (which can be prepared using the method described in the literature (Biosci. Biotechnol. Biochem., 68(6), 1332–1337, 2004)). Under metal catalyst reduction conditions, a one-pot, three-site simultaneous hydrogenation reduction of the olefin bond and carbonyl group is performed to selectively obtain a 5β-hydrogen-7α-hydroxy intermediate, which is then hydrolyzed to obtain chenodeoxycholic acid. This method directly constructs two chiral centers (5β and 7α) through a one-step hydrogenation process. The reaction is simple, efficient, safe, highly stereoselective, and easy to purify, effectively preparing chenodeoxycholic acid and suitable for industrial application.

[0021] This invention provides a method for preparing chenodeoxycholic acid. The method uses methyl 22E-3α-acyloxy-7-keto-cholest-5,22-diene-24-carboxylic acid as a raw material. Under the condition of metal catalyst reduction, the olefin bond and carbonyl group are simultaneously hydrogenated and reduced in one pot at three sites, and the 5β-hydro-7α-hydroxy intermediate is obtained with high selectivity. Then, chenodeoxycholic acid is prepared by hydrolysis.

[0022] The reaction process of the preparation method described in this invention is shown in reaction formula (I):

[0023]

[0024] In the above reaction formula (I), R is a C2-C6 alkane acyl group; preferably, it is an acetyl group, isopropionyl group, or pivaloyl group; more preferably, it is a pivaloyl group.

[0025] The method for preparing chenodeoxycholic acid using methyl 22E-3α-acyloxy-7-keto-cholest-5,22-diene-24-carboxylic acid as described in this invention specifically includes the following steps:

[0026] Step (1) Hydrogenation reaction: The compound of formula (1) is dissolved in the first solvent, a metal reduction catalyst is added, and a hydrogenation reaction is carried out in the presence of hydrogen to prepare the compound of formula (2); the reaction process is shown in reaction formula (A):

[0027]

[0028] Wherein, R is a C2-C6 alkane acyl group; preferably, it is an acetyl group, isopropionyl group, or pivaloyl group; more preferably, it is a pivaloyl group.

[0029] Step (2) Hydrolysis reaction: The compound of formula (2) is dissolved in a second solvent and hydrolyzed under alkaline conditions to prepare chenodeoxycholic acid; the reaction process is shown in reaction formula (B):

[0030]

[0031] Wherein, R is a C2-C6 alkane acyl group; preferably, it is an acetyl group, isopropionyl group, or pivaloyl group; more preferably, it is a pivaloyl group.

[0032] In step (1) of the present invention, the hydrogenation reaction specifically involves dissolving the compound of formula (1) in a first solvent, adding a reducing metal catalyst, and carrying out a hydrogenation reaction under hydrogen conditions to prepare the compound of formula (2).

[0033] The metal catalyst is one or more of palladium on carbon, palladium carbonate, palladium hydroxide, and platinum oxide; preferably, it is platinum oxide.

[0034] The first solvent is one or more of methanol, ethanol, isopropanol, ethyl acetate, isopropyl acetate, tetrahydrofuran, methyltetrahydrofuran, etc.; preferably, it is isopropanol.

[0035] Wherein, the weight ratio of the compound of formula (1), the first solvent and the metal catalyst is 1:(5-20):(0.01-0.5); preferably, it is 1:(5-10):(0.01-0.1); more preferably, it is 1:10:0.1.

[0036] The hydrogenation reaction is carried out at a temperature of 25–75°C; preferably, at 50°C.

[0037] The hydrogenation reaction takes 6 to 48 hours; preferably, it takes 24 hours.

[0038] In step (2) of this invention, the hydrolysis reaction specifically involves dissolving the compound of formula (2) in a second solvent, adding an alkali, and performing a hydrolysis reaction to prepare chenodeoxycholic acid.

[0039] The alkali is selected from one or more of LiOH (lithium hydroxide), KOH (potassium hydroxide), NaOH (sodium hydroxide), and K2CO3 (potassium carbonate); preferably, it is potassium hydroxide.

[0040] The second solvent is selected from one or more of methanol, ethanol, isopropanol, etc.; preferably, it is ethanol.

[0041] Wherein, the molar ratio of the compound of formula (2), the second solvent, and the base is 1:(5-20):(1-4); preferably, it is 1:10:4.

[0042] The hydrolysis reaction is carried out at a temperature of 10–75°C; preferably, at 50°C.

[0043] The hydrolysis reaction takes 0.3 to 12 hours; preferably, it takes 12 hours.

[0044] Generally, chenodeoxycholic acid is prepared by chemical methods in two main ways. One way is to first reduce the 7-keto group of compound (1) to generate a 7α-hydroxy group, then hydrogenate the 5,6-ene, and finally hydrolyze it to obtain the product. The other way is to first reduce the 5,6-ene of compound (1), then reduce the 7-keto group, and finally hydrolyze it to obtain the product. The method provided by this invention can directly reduce the double bond and keto group simultaneously through one-step hydrogenation to construct 5β-hydrogen and 7α-hydroxy group. This method has not been reported in the literature and has the characteristics of high efficiency, simple operation, and good stereoselectivity.

[0045] The beneficial effects of the present invention include: the method for preparing chenodeoxycholic acid provided by the present invention directly constructs two chiral centers through one-step hydrogenation, which has the characteristics of high efficiency and simplicity of reaction, safe operation, high stereoselectivity and convenient product purification, and can effectively prepare chenodeoxycholic acid, which is suitable for industrialization. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to specific embodiments. The processes, conditions, and experimental methods for implementing the present invention, except as specifically mentioned below, are all common knowledge and general knowledge in the art, and the present invention does not have any particular limitations. Where specific experimental steps or conditions are not described in the embodiments, they can be performed according to the conventional experimental methods described in publicly available texts in the art. Reagents or equipment whose manufacturers are not specified are all commercially available conventional products.

[0047] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0048] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0049] This invention discloses a method for preparing chenodeoxycholic acid. The method utilizes methyl 22E-3α-acyloxy-7-keto-cholest-5,22-diene-24-carboxylic acid as a raw material, and performs a one-pot, three-site simultaneous hydrogenation reduction of the olefin and carbonyl groups under metal catalyst conditions, yielding a highly selective 5β-hydrogen-7α-hydroxy intermediate, which is then hydrolyzed to obtain chenodeoxycholic acid. This method for preparing chenodeoxycholic acid directly constructs two chiral centers (5β and 7α) through a one-step hydrogenation process. The reaction is simple, efficient, safe, highly stereoselective, and facilitates product purification, effectively preparing chenodeoxycholic acid and is suitable for industrial application. This invention has broad application prospects.

[0050] Unless otherwise specified, the experimental materials used in the embodiments of this invention are all conventional biochemical reagents.

[0051] Example 1: Hydrogenation and hydrolysis reaction (palladium on carbon, ethanol, 3-acetyl base compound, i.e., R is an acetyl group in compound (1))

[0052] The compound of formula (1) (1.0 g, 2.26 mmol) was dissolved in 10 g of ethanol, and 0.1 g of palladium on carbon was added. The temperature was raised to 50 °C, and the reaction was maintained under hydrogen protection for 24 h. Samples were taken and analyzed by liquid chromatography. After the reaction was completed, the mixture was cooled to 20 °C, filtered, and concentrated to obtain the crude product of compound (2). 1.0 g of the crude product was dissolved in 10 g of ethanol, and 1.0 g of potassium hydroxide solid (1.0 g, 17.86 mmol) was added. The mixture was stirred at 50 °C for 12 h. After the reaction was completed, the mixture was cooled to 20-25 °C. 100 g of water was added, and hydrochloric acid was added to adjust the pH of the system to acidic. A white solid precipitated out. The solid was filtered, dried, and crude chenodeoxycholic acid was obtained. 5 g of methanol was added for recrystallization to obtain 0.39 g of refined chenodeoxycholic acid, with a molar yield of 44%.

[0053] Example 2: Hydrogenation and hydrolysis reaction (palladium on carbon, ethanol, 3-pivaloyl base compound, i.e., R in compound (1) is pivaloyl group)

[0054] The aforementioned compound (1.0 g, 2.06 mmol) was dissolved in 10 g of ethanol, and 0.1 g of palladium on carbon was added. The temperature was raised to 50 °C, and the reaction was maintained under hydrogen protection for 24 h. Samples were taken and analyzed by liquid chromatography. After the reaction was complete, the mixture was cooled to 20 °C, filtered, and concentrated to obtain the crude product of compound (2). 1.0 g of the crude product was dissolved in 10 g of ethanol, and 1.0 g of potassium hydroxide solid (1.0 g, 17.86 mmol) was added. The mixture was stirred at 50 °C for 12 h. After the reaction was complete, the mixture was cooled to 20-25 °C. 100 g of water was added, and hydrochloric acid was added to adjust the pH of the system to acidic. A white solid precipitated out. The solid was filtered, dried, and crude chenodeoxycholic acid was obtained. 5 g of methanol was added for recrystallization to obtain 0.36 g of refined chenodeoxycholic acid, with a molar yield of 53%.

[0055] Example 3: Hydrogenation and hydrolysis reaction (palladium hydroxide, ethanol, 3-pivaloyl base compound, i.e., R in compound (1) is pivaloyl group)

[0056] The aforementioned compound (1.0 g, 2.06 mmol) was dissolved in 10 g of ethanol, and 0.1 g of palladium hydroxide was added. The mixture was heated to 50 °C and kept at this temperature under hydrogen protection for 24 h. Samples were taken and analyzed by liquid chromatography. After the reaction was complete, the mixture was cooled to 20 °C, filtered, and concentrated to obtain the crude product of compound (2). 1.0 g of the crude product was dissolved in 10 g of ethanol, and 1.0 g of potassium hydroxide solid (1.0 g, 17.86 mmol) was added. The mixture was stirred at 50 °C for 12 h. After the reaction was complete, the mixture was cooled to 20-25 °C. 100 g of water was added, and hydrochloric acid was added to adjust the pH of the system to acidic. A white solid precipitated out. The solid was filtered, dried, and crude chenodeoxycholic acid was obtained. 5 g of methanol was added for recrystallization to obtain 0.16 g of refined chenodeoxycholic acid, with a molar yield of 20%.

[0057] Example 4: Hydrogenation and hydrolysis reaction (platinum oxide, ethanol, 3-pivaloyl base compound, i.e., R in compound (1) is pivaloyl group)

[0058] The aforementioned compound (1.0 g, 2.06 mmol) was dissolved in 10 g of ethanol, and 0.1 g of platinum oxide was added. The mixture was heated to 50 °C and kept at this temperature under hydrogen protection for 24 h. Samples were taken and analyzed by liquid chromatography. After the reaction was complete, the mixture was cooled to 20 °C, filtered, and concentrated to obtain the crude product of compound (2). 1.0 g of the crude product was dissolved in 10 g of ethanol, and 1.0 g of potassium hydroxide solid (1.0 g, 17.86 mmol) was added. The mixture was stirred at 50 °C for 12 h. After the reaction was complete, the mixture was cooled to 20-25 °C. 100 g of water was added, and hydrochloric acid was added to adjust the pH of the system to acidic. A white solid precipitated out. The solid was filtered, dried, and crude chenodeoxycholic acid was obtained. 5 g of methanol was added for recrystallization to obtain 0.59 g of refined chenodeoxycholic acid, with a molar yield of 75%.

[0059] Example 5: Hydrogenation and hydrolysis reaction (platinum oxide, tetrahydrofuran, 3-pivaloyl base compound, i.e., R in compound (1) is pivaloyl group)

[0060] The aforementioned compound (1.0 g, 2.06 mmol) was dissolved in 10 g of tetrahydrofuran, and 0.1 g of platinum oxide was added. The mixture was heated to 50 °C and kept at this temperature under hydrogen protection for 48 h. Samples were taken and analyzed by liquid chromatography. After the reaction was complete, the mixture was cooled to 20 °C, filtered, and concentrated to obtain the crude compound (2). 1.0 g of the crude compound was dissolved in 10 g of ethanol, and 1.0 g of potassium hydroxide solid (1.0 g, 17.86 mmol) was added. The mixture was stirred at 50 °C for 12 h. After the reaction was complete, the mixture was cooled to 20-25 °C. 100 g of water was added, and hydrochloric acid was added to adjust the pH of the system to acidic. A white solid precipitated out. The solid was filtered, dried, and crude chenodeoxycholic acid was obtained. 5 g of methanol was added for recrystallization to obtain 0.33 g of refined chenodeoxycholic acid, with a molar yield of 41%.

[0061] Example 6: Hydrogenation reaction (platinum oxide, isopropanol, 3-pivaloyl base, i.e., R in compound (1) is pivaloyl group) The compound (1.0 g, 2.06 mmol) of formula (1) was dissolved in 10 g of isopropanol, 0.1 g of platinum oxide was added, the temperature was raised to 50 °C, and the reaction was carried out under the protection of hydrogen for 24 h. The sample was taken and the liquid phase was detected. After the reaction of the raw materials was completed, the mixture was cooled to 20 °C, filtered, and concentrated to obtain the crude product of compound (2). 1.0 g of the crude product was dissolved in 10 g of ethanol, and potassium hydroxide solid (1.0 g, 17.86 mmol) was added. The mixture was stirred at 50 °C for 12 h. After the reaction of the raw materials was completed, the mixture was cooled to 20-25 °C. Add 100g of water and hydrochloric acid to adjust the pH of the system to acidic. A white solid precipitates out. Filter and dry to obtain crude chenodeoxycholic acid. Add 5g of methanol for recrystallization to obtain 0.67g of refined chenodeoxycholic acid, with a molar yield of 83%. 1 HNMR (CD3OD, 400MHz): δ0.70 (s, 3H); 0.93 (s, 3H); 0.96 (d, J = 6.6Hz, 3H); 3.35-3.38 (m, 1H); 3.80 (s, 1H). 13 C-NMR (CDCl3, 400MHz): 11.9, 18.4, 20.7, 22.9, 23.8, 28.3, 30.6, 31.0, 31.3, 32. 9,34.6,35.1,35.4,35.6,39.5,39.7,41.6,42.8,50.4,55.9,68.6,72.0,178.6.

[0062] The scope of protection of this invention is not limited to the above embodiments. Any variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in this invention and are protected by the appended claims.

[0063] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0064] As used in this invention, the term "comprising" is an open-ended expression, meaning it includes the contents specified in this invention but does not exclude other aspects.

[0065] As used in this invention, the term "and / or" includes any one or more of the associated listed items and all combinations thereof. Although embodiments of this description have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this description, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing chenodeoxycholic acid, characterized in that, The preparation method uses methyl 22E-3α-acyloxy-7-keto-cholest-5,22-diene-24-carboxylate as a raw material, and performs a one-pot, three-site simultaneous hydrogenation reduction of the olefin and carbonyl groups under metal catalyst reduction conditions, yielding 5... The -hydro-7α-hydroxy intermediate is then hydrolyzed to prepare chenodeoxycholic acid; the reaction process of the preparation method is shown in reaction formula (I): Reaction formula (I); Wherein, R is a C2-C6 alkane acyl group; The method includes the following steps: Step (1) Hydrogenation reaction: The compound of formula (1) is dissolved in a first solvent, a metal catalyst is added, and a hydrogenation reaction is carried out in the presence of hydrogen to prepare the compound of formula (2); the metal catalyst is one or more of palladium on carbon, palladium carbonate, palladium hydroxide, and platinum oxide; the first solvent is one or more of methanol, ethanol, isopropanol, tetrahydrofuran, and methyltetrahydrofuran; the reaction process is shown in reaction formula (A): Reaction formula (A); Step (2) Hydrolysis reaction: The compound of formula (2) is dissolved in a second solvent and hydrolyzed under alkaline conditions to prepare chenodeoxycholic acid; the reaction process is shown in reaction formula (B): Reaction formula (B).

2. The preparation method according to claim 1, characterized in that, R is acetyl, isopropionyl, or pivaloyl.

3. The preparation method according to claim 1, characterized in that, In step (1), the weight ratio of the compound of formula (1), the first solvent, and the metal catalyst is 1:(5-20):(0.01-0.5).

4. The preparation method according to claim 1, characterized in that, In step (1), the temperature of the hydrogenation reaction is 25–75°C; and / or the time of the hydrogenation reaction is 6–48 h.

5. The preparation method according to claim 1, characterized in that, In step (2), the alkali is selected from one or more of LiOH, KOH, NaOH, and K2CO3; and / or, the second solvent is selected from one or more of methanol, ethanol, and isopropanol.

6. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of the compound of formula (2), the second solvent, and the base is 1:(5-20):(1-4).

7. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the hydrolysis reaction is 10 to 75°C.

8. The preparation method according to claim 1, characterized in that, In step (2), the hydrolysis reaction takes 0.3 to 12 hours.

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