Synthetic methods and applications of 7-ketolithocholic acid intermediates

Abstract

The present invention provides a method for synthesizing 7-ketolithocholic acid intermediate, which comprises the step of obtaining 7-ketolithocholic acid intermediate OB from compound OB-1 in an amide solvent. The method of the present invention has easy availability of raw materials, high yield, simple and mild reaction conditions, and is suitable for industrial production.

Description

[Technical Field]

[0001] The present invention claims priority from a Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on March 25, 2022, bearing patent application number 202210321879.4 and entitled "Synthetic method and application of 7-ketolithocholic acid intermediate," the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the field of pharmaceutical synthesis, and in particular to the synthesis and application of 7-ketolithocholic acid intermediates. [Background technology]

[0003] 7-ketolithocholic acid has a CAS number of 4651-67-6 and a molecular formula of C 24 H 38 O4, has a molecular weight of 390.56, and has the following structural formula: [ka]

[0004] 7-Ketotricholic acid is an important pharmaceutical intermediate. Chenodeoxycholic acid (Tetrahedron Letters Volume 24, Issue 24, 1983, Pages 2487-2490), ursodeoxycholic acid (J. Org. Chem. 1993, 58, Pages 499-501), and obeticholic acid (J. Med. Chem. 2002, 45, 17, Pages 3569-3572) can be synthesized using 7-ketotricholic acid as an intermediate, as shown below. [ka]

[0005] Currently, most of the manufacturing processes for ursodeoxycholic acid and obeticholic acid are based on methods that use 7-ketolithocholic acid as a raw material, so it is extremely important to efficiently obtain 7-ketolithocholic acid.

[0006] Currently, the synthesis of 7-ketolithocholic acid can be mainly classified into the following methods:

[0007] 1. Method using cholic acid as raw material WO2014020024A1 reports that cholic acid is used as a starting material, the acid in the side chain is esterified with a methanolic solution of hydrochloric acid, the hydroxyl groups at positions 3 and 7 are doubly protected with acetic anhydride, the hydroxyl group at position 12 is oxidized to a ketone with sodium hypochlorite, and the ketone at position 12 is reduced by a Huang-Minglong reduction reaction. Finally, the hydroxyl group at position 7 is selectively oxidized with sodium hypobromite to form a ketone, thereby obtaining the target compound, 7-ketolithocholic acid. The entire process involves the use of a high-temperature Huang-Minglong reduction reaction. This reaction requires high equipment requirements due to the relatively high temperature and the high toxicity and high explosiveness of hydrazine hydrate. [ka]

[0008] 2. Method using chenodeoxycholic acid as raw material CN106046095 reports the oxidation of chenodeoxycholic acid with N-bromosuccinimide (NBS) in acetone and water to give 7-ketolithocholic acid. Chenodeoxycholic acid has limited applications due to its relatively high price. [ka]

[0009] 3. Method using hyocholic acid as raw material Patent document CN110423261A reports a manufacturing method using hyocholic acid as a raw material. The drawbacks of this solution are: 1) the use of chromium-based reagents such as Jones reagent causes heavy pollution and environmental protection pressure; 2) some reagents, such as lithium iodide and TBSCl, are expensive, making the overall route cost high; 3) pyridine is used as a solvent in the third step, which causes a strong odor and is relatively toxic. [ka]

[0010] In addition to the various drawbacks of the three methods mentioned above, another major reason is that all of these methods use animal-derived cholic acid. Animals generally contain various animal viruses, such as hog cholera, avian influenza, and prions, as well as various other physiologically active substances. These substances have some degree of toxicity to the human body. Therefore, it is necessary to find a new, safe, and effective method for synthesizing 7-ketolithocholic acid intermediates. Summary of the Invention

[0011] In order to solve the above problems, the present invention provides: The present invention provides a method for synthesizing a 7-ketolithocholic acid intermediate OB, which comprises a step of hydrogenating a compound OB-1 in an amide solvent to obtain the 7-ketolithocholic acid intermediate OB. [ka] However, R1 is, for example, C such as methyl, ethyl, propyl, tert-butyl, etc. 1~6 alkyl groups such as alkyl groups.

[0012] In one embodiment of the present invention, the reaction is carried out in the presence of a catalyst, for example, selected from the group consisting of Raney-Ni (Raney nickel) catalyst, Pd / C catalyst, Pt / C catalyst, and Ru / C catalyst;

[0013] In one embodiment of the present invention, the mass ratio of the compound OB1 to the catalyst is (2-20):1, for example, (5-15):1, and one example is 10:1.

[0014] In one embodiment of the present invention, the amide solvent in the reaction is, for example, at least one selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, formamide, N-methylpyrrolidone, N-methylformamide, N-methylacetamide, and N,N-dimethylpropyleneurea;

[0015] In one embodiment of the present invention, the ratio (g:mL) of the mass of the compound OB1 to the volume of the solvent is 1:(1 to 20), for example, 1:(1 to 10), and as an example, 1:6.

[0016] As a result of investigation, the present inventors have found that OB1 has the following tautomer 1. [ka]

[0017] The amide solvent used in the present invention has weak alkaline properties, and therefore, in the presence of the amide solvent, the conversion of the tautomer to OB1 is favorably promoted, and under the conditions of the present invention, the product OB is mainly obtained.

[0018] In one embodiment of the present invention, a method for preparing compound OB-1 comprises the steps of: [ka] Includes: wherein R1 has the definition above. a) subjecting compound BA to an oxidation reaction to obtain compound OB-5; b) Compound OB-5 with, for example, triethyl phosphonoacetate ( [ka] ) etc. [ka] (However, R2 and R3 are, for example, C such as ethyl. 1~6 a Wittig reaction of compound OB-5 with a compound: [ka] and subjecting the compound to a Knoevenagel condensation reaction to obtain compound OB-4; c) performing a protection reaction of compound OB-4 with ethylene glycol to obtain compound OB-3; d) subjecting compound OB-3 to an oxidation reaction to obtain compound OB-2; e) A step of subjecting compound OB-2 to a deprotection reaction with ethylene glycol to obtain compound OB-1.

[0019] The present invention also provides a method for producing 7-ketolithocholic acid (7-KLCA), which comprises producing compound OB by the above-mentioned steps and then hydrolyzing compound OB to obtain 7-ketolithocholic acid (7-KLCA). [ka] wherein R1 has the definition above. [Effects of the Invention]

[0020] The present invention provides a novel method for synthesizing 7-ketolithocholic acid intermediate OB, which uses a specific amide solvent to stabilize the structure of raw material OB-1 and produce intermediate OB.

[0021] The present invention uses bisnoralcohol (BA), a biodegradable phytosterol, as the starting material. Bisnoralcohol is widely available, inexpensive, and does not pose any risk factors for animal viruses. The starting material undergoes oxidation, Wittig reaction, ketal protection, allylic oxidation, ketal deprotection, and hydrogenation to obtain the 7-ketolithocholic acid intermediate OB. The method of the present invention offers easy access to raw materials, high yields, and simple and mild reaction conditions, making it suitable for industrial production.

[0022] <Terminology definitions and explanations> Unless otherwise specified, the definitions of groups and terms described in the specification and claims of this application can be combined in any combination with each other, including exemplary definitions, exemplary definitions, preferred definitions, definitions set forth in tables, definitions of specific compounds in the examples, etc. Such combined and combined group definitions and compound structures should be understood to be within the scope described in the specification and / or claims of this application.

[0023] The term “C 1~6"Alkyl" refers to a saturated monovalent hydrocarbon radical of a straight or branched alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl, 1,2-dimethylbutyl, and the like, and isomers thereof. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will be described in more detail below with reference to specific examples. However, it should be understood that the following examples are merely illustrative and specific explanations of the present invention and should not be considered as limiting the scope of the claims of the present invention. Any technology realized based on the above content of the present invention is included in the intended scope of the claims of the present invention.

[0025] Unless otherwise specified, all raw materials and reagents used in the following examples are commercially available products or can be produced by known methods.

[0026] Patent document CN1137800A is referred to in which BA is oxidized with sodium hypochlorite to produce compound 5; and reference is made to Heletica Chimica Acta, 2002 vol. 85, 4, pp. 1096-1101 in which compound 5 is subjected to a Wittig reaction to produce compound 4.

[0027] Example 1: Synthesis of Compound 3 [ka] Under nitrogen gas (N2) protection, compound 4 (50 g, 126 mmol), ethylene glycol (50 g, 806 mmol), DCM (600 mL), triethyl orthoformate (28 g, 189 mmol), and p-methylbenzenesulfonic acid (0.5 g, 2.6 mmol) were added to a 1 L three-neck flask and stirred at 25 °C for 10 h. After TLC showed the reaction was complete, 1 mL of triethylamine was added and the mixture was stirred for 30 min. 100 mL of water was added and washed with water. After drying over anhydrous sodium sulfate, the mixture was concentrated to remove the solvent, yielding the crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 10:1) to give 51.1 g of compound 3 (yield: 92%, HPLC purity: 95%). ESI-MS: [M+H] + :443.35.

[0028] Example 2: Synthesis of Compound 2 [ka] Compound 3 (44.2 g, 100 mmol), TBHP (120 mL, 600 mmol, 5.0 M n-decane solution), copper(I) iodide (0.19 g, 1 mmol), and acetonitrile (300 mL) were added to a reaction flask. The mixture was reacted at 50 °C for 20 hours, then cooled to 25 °C and quenched by adding saturated aqueous sodium sulfite solution (300 mL). The mixture was filtered through Celite. The filtrate was extracted with ethyl acetate (200 mL × 2). The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure. The product was purified by column chromatography (n-hexane: EtOAc = 6:1) to give 36.9 g of product (yield: 81%, HPLC purity: 97%). ESI-MS: [M+H] + :457.29.

[0029] Example 3: Synthesis of Compound 1 [ka] A 1-L single-neck flask was charged with water (40 mL) and THF (100 mL), followed by the addition of concentrated sulfuric acid (4 g, 40.8 mmol) at 0 °C with stirring. The mixture was stirred for 10 minutes, followed by the addition of compound 2 (12 g, 26.2 mmol). The cooling bath was removed and the mixture was stirred at 25 °C for 6 hours. Water (100 mL) was added, followed by the addition of NaHCO3 (10 g, 119 mmol) in batches to adjust the pH to 7-8. Extraction was then performed with EtOAc (100 mL x 2). The combined organic phases were dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain a yellow oily crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 3:1) to obtain 9.4 g of solid compound 1 (yield: 87%, HPLC purity: 94%). ESI-MS: [M+H] + :413.37.

[0030] Example 4: Synthesis of Compound A [ka] To a solution of compound 1 (5.0 g, 12.13 mmol) in N,N-dimethylformamide (DMF) (30 mL) was added 0.5 g of Raney-Ni catalyst. The reaction mixture was hydrogenated at 25°C under 0.1 MPa of hydrogen gas for 12 hours. After the hydrogenation reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain 5.10 g of crude compound A. The crude product was purified with acetone to obtain 4.57 g of white solid A (yield: 76%, HPLC purity: 92%). ESI-MS: [M+H] + :419.30. 1H-NMR(DMSO-d6, 400MHz)δ(ppm): 4.48(d, J=4.8Hz, 1H), 4.04(q, J=6.8Hz, 2H), 2.90(dd, J=6Hz, 12Hz, 1H), 2.47-2.41(m, 1H), 2.36-2.27(m, 1H), 2.22-2.15(m, 1H), 2.09-2.02(m,1H), 1.94-1.90(m, 1H), 1.85-1.76(m, 2H), 1.73-1.64(m, 4H), 1.50-1.45(m, 2H), 1.39-1.30(m, 4H), 1.27-1.21(m, 2H), 1.17(t, J=6.8Hz, 3H), 1.14(s, 3H), 1.11-1.01(m, 5H), 0.96-0.77(m, 2H), 0.88(d, J=6.4Hz, 3H), 0.61(s, 3H).

[0031] Example 5: Synthesis of Compound A To a solution of compound 1 (5.0 g, 12.13 mmol) in N,N-dimethylformamide (DMF) (30 mL), 0.5 g of 5% palladium-carbon catalyst was added. The reaction mixture was hydrogenated at 25°C under 0.1 MPa of hydrogen gas for 12 hours. After the hydrogenation reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 3:1) to obtain 3.8 g of a white solid A (yield: 65%, HPLC purity: 90%). ESI-MS: [M+H] + :419.30.

[0032] Example 6: Synthesis of Compound A To a solution of compound 1 (5.0 g, 12.13 mmol) in N,N-dimethylformamide (DMF) (30 mL), 0.5 g of 5% platinum-on-carbon catalyst was added. The reaction mixture was hydrogenated at 25°C under 0.1 MPa of hydrogen gas for 12 hours. After the hydrogenation reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 3:1) to obtain 3.19 g of a white solid A (yield: 68%, HPLC purity: 91%). ESI-MS: [M+H] +:419.30.

[0033] Example 7: Synthesis of Compound A To a solution of compound 1 (5.0 g, 12.13 mmol) in N,N-dimethylformamide (DMF) (30 mL), 0.5 g of 5% ruthenium-carbon catalyst was added. The reaction mixture was hydrogenated at 25°C under 0.1 MPa of hydrogen gas for 12 hours. After the hydrogenation reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 3:1) to obtain 3.45 g of a white solid A (yield: 58%, HPLC purity: 91%). ESI-MS: [M+H] + :419.30.

[0034] Example 8: Synthesis of Compound A To a solution of compound 1 (5.0 g, 12.13 mmol) in N,N-dimethylacetamide (30 mL) was added 0.5 g of Raney nickel catalyst. The reaction mixture was hydrogenated at 25°C under 0.1 MPa of hydrogen gas for 12 hours. After the hydrogenation reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 3:1) to obtain 4.46 g of a white solid A (yield: 71%, HPLC purity: 92%). ESI-MS: [M+H] + :419.30.

[0035] Example 9: Synthesis of Compound A To a solution of compound 1 (5.0 g, 12.13 mmol) in formamide (30 mL) was added 0.5 g of Raney nickel catalyst. The reaction mixture was hydrogenated at 25°C under 0.1 MPa of hydrogen gas for 12 hours. After the hydrogenation reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 3:1) to obtain 4.46 g of a white solid A (yield: 67%, HPLC purity: 92%). ESI-MS: [M+H] + :419.30.

[0036] Example 10: Synthesis of Compound A To a solution of compound 1 (5.0 g, 12.13 mmol) in N-methylpyrrolidone (30 mL) was added 0.5 g of Raney nickel catalyst. The reaction mixture was hydrogenated at 25°C under 0.1 MPa of hydrogen gas for 12 hours. After the hydrogenation reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (n-hexane: EtOAc = 3:1) to obtain 4.31 g of a white solid A (yield: 62%, HPLC purity: 91%). ESI-MS: [M+H] + :419.30.

[0037] The above is an illustrative description of the embodiments of the present invention. However, it should be understood that the scope of the claims of the present invention is not limited to the above embodiments. Any modifications, equivalent changes, improvements, etc. made without departing from the spirit and principles of the present disclosure should be included in the scope of the claims of this application.

Claims

1. A method for synthesizing a 7-ketolithocholic acid intermediate OB, comprising the step of hydrogenating a compound OB-1 in an amide solvent to obtain a 7-ketolithocholic acid intermediate OB. 【Chemistry 1】 However, R １ is an alkyl group.

2. R １ But C １～６ 2. The method of claim 1, wherein the alkyl group is an alkyl group.

3. The method of claim 1, wherein R 1 is methyl, ethyl, propyl, or tert-butyl.

4. 2. The method of claim 1, wherein the reaction is carried out in the presence of a catalyst, the catalyst being selected from the group consisting of a Raney-Ni catalyst, a Pd / C catalyst, a Pt / C catalyst, and a Ru / C catalyst.

5. 5. The method of claim 4, wherein the mass ratio of OB-1 to the catalyst is (2-20):

1.

6. 2. The method according to claim 1, wherein the amide solvent is at least one selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, formamide, N-methylpyrrolidone, N-methylformamide, N-methylacetamide, and N,N-dimethylpropyleneurea.

7. 7. The method according to claim 6, wherein the ratio (g:mL) of the mass of OB-1 to the volume of the solvent is 1:(1 to 20).

8. The method for producing the compound OB-1 comprises the following steps: a) a step of oxidizing compound BA to obtain compound OB-5; b) compound OB-5; and 【Chemistry 2】 or a step of subjecting compound OB-5 and compound 【Transformation 3】 and R 2 are C 1-6 alkyl groups by Knoevenagel condensation to obtain compound OB-4. c) performing a protection reaction of compound OB-4 with ethylene glycol to obtain compound OB-3; d) a step of oxidizing compound OB-3 to obtain compound OB-2; e) performing a deprotection reaction of compound OB-2 with ethylene glycol to obtain compound OB-1. 【Chemistry 4】 However, R １ has the definition set forth in claim 1. 【Request Item 9】 【Chemistry 5】 teeth, 【Transformation 6】 9. The method of claim 8, wherein:

10. A method for producing 7-ketolithocholic acid, comprising the steps of producing compound OB by the method according to any one of claims 1 to 9, and then hydrolyzing compound OB to obtain 7-ketolithocholic acid (7-KLCA). 【Transformation 7】 However, R １ has the definition set forth in claim 1.

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