7-ketolithocholic acid intermediates, methods of synthesis and use thereof

Abstract

This invention provides a method for synthesizing 7-ketolithocholic acid or its intermediates, which is prepared via a novel intermediate I-1. The method uses phytosterol degradation product dichlorol as a starting material and proceeds through oxidation, Knoevenagel reaction (or Wittig reaction), hydrogenation, esterification, ketal protection, allylic oxidation, deketal protection, and hydrogenation to obtain 7-ketolithocholic acid or its intermediates. The method of this invention uses readily available raw materials, has high yield, and employs simple and mild reaction conditions, making it suitable for industrial production.

Description

[0001] This invention claims priority to an earlier application filed on March 25, 2022, with China National Intellectual Property Administration, patent application number 2022103218915, entitled "A 7-ketolithocholic acid intermediate and its synthesis method and application". The entire contents of the earlier application are incorporated herein by reference. Technical Field

[0002] This invention belongs to the field of pharmaceutical synthesis, specifically relating to a 7-ketolithocholic acid intermediate, its synthesis method, and its application. Background Technology

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

[0004]

[0005] 7-Ketolithocholic acid is an important pharmaceutical intermediate. It can be used as an intermediate to synthesize chenodeoxycholic acid (Tetrahedron Letters Volume 24, Issue 24, 1983, Pages 2487-2490), ursodeoxycholic acid (J.Org.Chem.1993, 58, 499-501), obeticholic acid (J.Med.Chem.2002, 45, 17, 3569–3572), and other drugs.

[0006]

[0007] Currently, most production processes for ursodeoxycholic acid and obeticholic acid are based on 7-ketolithocholic acid as a raw material, making the effective acquisition of 7-ketolithocholic acid extremely important.

[0008] Based on current literature and patent research, the synthesis of 7-ketolithocholic acid mainly involves the following methods:

[0009] I. Using bile acids as raw materials

[0010] WO2014020024A1 reports a process using cholic acid as a raw material, involving esterification of the side chain acid with hydrochloric acid and methanol, double protection of the 3 and 7-hydroxyl groups with acetic anhydride, oxidation of the 12-hydroxyl group with sodium hypochlorite to form a ketone, reduction of the 12-hydroxyl group with Huangminglong, and finally selective oxidation of the 7-hydroxyl group with sodium hypobromite to form a ketone, yielding the target compound 7-ketolithocholic acid. The entire process utilizes a high-temperature Huangminglong reaction. This step involves a high-temperature reaction, and hydrazine hydrate is highly toxic and explosive, placing high demands on the equipment.

[0011]

[0012] II. Using chenodeoxycholic acid as a raw material

[0013] CN106046095 reports a method for oxidizing chenodeoxycholic acid with NBS to obtain 7-ketolithocholic acid in acetone and water. However, chenodeoxycholic acid is relatively expensive, which limits its application.

[0014]

[0015] III. Using porcine bile acid as a raw material

[0016] Patent CN110423261 A reports a preparation method using porcine cholic acid as a raw material. The disadvantages of this method are: 1) It uses chromium-based reagents such as Jones reagent, which causes a lot of pollution and puts great pressure on the environment; 2) Some reagents, such as lithium iodide and TBSCl, are expensive, resulting in a high overall cost of the route; 3) The third step uses pyridine as a solvent, which has a strong odor and is relatively toxic.

[0017]

[0018] Besides the various drawbacks of the three methods mentioned above, another major reason is that these methods all use animal-derived bile acids. Animals generally carry many animal viruses such as swine fever, avian influenza, prions, and other physiologically active substances, which pose certain biotoxicities to humans. Therefore, it is necessary to find new, safe, and effective intermediates for 7-ketolithocholic acid and their synthetic methods. Summary of the Invention

[0019] To address the aforementioned technical problems, the present invention aims to provide a method for preparing 7-ketolithocholic acid or its intermediates. This method utilizes a novel intermediate I-1, is simple, yield-efficient, and safe. Another objective of the present invention is to provide a novel intermediate I-1 and its preparation method.

[0020] The objective of this invention is achieved through the following technical solution:

[0021] A method for preparing a compound of formula I, the method comprising: hydrogenating compound I-1 under the action of a catalyst to obtain compound I;

[0022]

[0023] Wherein, R1 is H or an alkyl group; for example, C. 1-6 Alkyl; such as methyl, ethyl, propyl, or tert-butyl;

[0024] According to an embodiment of the present invention, in the above reaction, the catalyst is selected from Raney Ni catalyst, Pd / C catalyst, Pt / C catalyst or Ru / C catalyst.

[0025] According to an embodiment of the present invention, in the above reaction, the mass ratio of compound I-1 to catalyst is (2-20):1, for example (5-15):1, and exemplarily 10:1;

[0026] According to an embodiment of the present invention, in the above reaction, the reaction is carried out in the presence of a solvent, which is an amide solvent, for example, at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, formamide, N-methylpyrrolidone, N-methylformamide, N-methylacetamide and N,N-dimethylpropenylurea.

[0027] According to the present invention, when R1 in the compound of formula I is an alkyl group, the method further includes the following method: hydrolyzing the compound of formula I with R1 being an alkyl group to obtain the compound of formula I with R1 being H, namely 7-ketolithocholic acid.

[0028]

[0029] According to the present invention, the hydrolysis reaction is carried out under alkaline conditions; for example, it can be carried out in the presence of sodium hydroxide, potassium hydroxide, etc.

[0030] The present invention also provides intermediate compounds I-1 or I-2 as shown below:

[0031]

[0032] Wherein, R1 has the definition described above, and R2 is an alkyl group.

[0033] This invention also provides a method for preparing compound I-1: comprising,

[0034]

[0035] Wherein, R1 has the definition described above, and R2 is an alkyl group;

[0036] h) Compound I-3 was allylated to give compound I-2;

[0037] i) Deglycolize compound I-2 to obtain compound I-1 with R1 being an alkyl group; or deglycolize and hydrolyze compound I-2 to obtain compound I-1 with R1 being H.

[0038] According to an embodiment of the present invention, in step h), compound I-3 undergoes an allylic oxidation reaction in the presence of an oxidant and a catalyst to obtain compound I-2.

[0039] According to an embodiment of the present invention, step h) is carried out in the following reaction system h1 or h2:

[0040] h1: A reaction system in which the oxidant is oxygen or air, the catalyst is N-hydroxyphthalimide (NHPI) and cobalt acetate; a free radical initiator, such as benzoyl peroxide, may also be added to the above system; according to an embodiment of the present invention, the molar ratio of compound I-3, catalyst, initiator and cobalt acetate is (1-20):1:1:(0.01-0.5), for example (5-15):1:1:(0.02-0.1), and an exemplary 10:1:1:0.05;

[0041] h2: A reaction system in which the oxidant is tert-butanol peroxide (TBHP) and the catalyst is manganese(III) acetate, manganese(III) acetate dihydrate or cuprous iodide (CuI); according to an embodiment of the present invention, the molar ratio of compound I-3, oxidant and catalyst is 1:(1-20):(0.5-10), for example 1:(2-10):(1-5), and exemplary 1:5:2.74.

[0042] According to an embodiment of the present invention, in step i), the deglycolization protection reaction is carried out in the presence of an acid, such as at least one selected from concentrated sulfuric acid, p-toluenesulfonic acid, and hydrochloric acid. The hydrolysis reaction is carried out under alkaline conditions, for example, in the presence of sodium hydroxide or potassium hydroxide.

[0043] According to an embodiment of the present invention, the preparation method of compound I-3 includes either method one or method two:

[0044] Method 1:

[0045]

[0046] R2 has the definition described above;

[0047] b) Compound I-8 with monoalkyl malonate Knoevenagel condensation reaction yields compound I-7; or compound I-8 is reacted with... (R3 and R4 are C) 1-6 Alkyl groups (e.g., ethyl groups), such as triethyl phosphonoacetate. The Wittig reaction was carried out to give compound I-7;

[0048] d) Compound I-7 was protected with ethylene glycol to obtain compound I-5;

[0049] f) The reduction reaction of compound I-5 yields compound I-3;

[0050] According to an embodiment of the present invention, in step b), the molar ratio of compound I-8 and monoalkyl malonate is 1:(0.5-10), for example 1:(1-5), and exemplary 1:1.5;

[0051] According to an embodiment of the present invention, step b) is carried out in the presence of a catalyst, wherein the catalyst is DMAP;

[0052] According to an embodiment of the present invention, step d) is carried out under the action of a catalyst, wherein the catalyst is selected from catalyst A and / or catalyst B, wherein catalyst A is selected from p-toluenesulfonic acid or concentrated sulfuric acid, and catalyst B is selected from trimethyl orthoformate, triethyl orthoformate or trimethyl orthoacetate; in one embodiment, when the catalyst is selected from catalyst A and catalyst B, the mass ratio of catalyst A to catalyst B can be 1:(0-100), for example 1:(40-80), and exemplarily 1:56;

[0053] According to an embodiment of the present invention, in step d), the mass ratio of compound I-7, ethylene glycol and catalyst is 1:(0.2-5):(0.1-5), for example 1:(0.5-3):(0.2-2), and exemplary 1:1:0.57;

[0054] According to an embodiment of the present invention, step f) is carried out under the action of a catalyst, wherein the catalyst is Pd / C;

[0055] According to an embodiment of the present invention, in step f), the mass ratio of compound I-5 to the catalyst is (2-30):1, for example (10-25):1, and exemplarily 20:1;

[0056] Method 2:

[0057]

[0058] R2 has the definition described above;

[0059] c) Compound I-8 is reacted with Michaelis acid compounds ( Where R5 and R6 are C 1-6 Alkyl groups (e.g., methyl groups), or R5, R6, together with the attached carbon atom to form a C group. 3-8 The Knoevenagel condensation reaction of cycloalkyl groups yields compound I-6;

[0060] e) Reaction of compound I-6 with R2OH yields compound I-4;

[0061] g) Compound I-4 was protected with ethylene glycol to obtain compound I-3;

[0062] According to an embodiment of the present invention, in step c), the molar ratio of compound I-8 and Michaelis acid compound is 1:(0.1-10), for example 1:(0.5-5), and exemplarily 1:1.2;

[0063] According to an embodiment of the present invention, step e) is carried out in the presence of a catalyst, said catalyst being selected from at least one of concentrated sulfuric acid, p-toluenesulfonic acid, and hydrochloric acid;

[0064] According to an embodiment of the present invention, step g) is carried out under the action of a catalyst, wherein the catalyst is selected from catalyst A and / or catalyst B, wherein catalyst A is selected from p-toluenesulfonic acid or concentrated sulfuric acid, and catalyst B is selected from trimethyl orthoformate, triethyl orthoformate or trimethyl orthoacetate; in one embodiment, when the catalyst is selected from catalyst A and B, the molar ratio of catalyst A and catalyst B can be 1:(0-100), for example 1:(20-80), exemplarily 1:0, 1:29, 1:73;

[0065] According to an embodiment of the present invention, in step g), the molar ratio of compound I-4, ethylene glycol and catalyst is 1:(1-50):(1-20), for example 1:(5-25):(1-10), and exemplary ratios are 1:6.5:1.5 and 1:21.6:6.2;

[0066] According to an embodiment of the present invention, the preparation method of compound I-8 includes the following steps: compound BA is oxidized to obtain compound I-8;

[0067]

[0068] Beneficial effects

[0069] This invention provides a novel method for synthesizing 7-ketolithocholic acid or its intermediates, which is prepared via a novel intermediate I-1. Using the novel intermediate I-1 in the reaction favors the formation of compound I, reduces isomers, and increases the yield. Furthermore, the use of a weakly basic amide solvent in this reaction facilitates the conversion of tautomers towards compound I. The preparation method of this invention features mild and simple reaction conditions, high yield, and is suitable for industrial production.

[0070] This invention can also use phytosterol biodegradation product bis(BA) as a starting material to obtain 7-ketolithocholic acid through oxidation, Knoevenagel condensation (or Wittig reaction), hydrogenation, esterification, ketal protection, allylic oxidation, deketal protection, hydrogenation, and hydrolysis. This method uses readily available raw materials, has a high yield, and employs simple and mild reaction conditions, making it suitable for industrial production.

[0071] Terminology Definitions and Explanations

[0072] Unless otherwise stated, the definitions of groups and terms recorded in this application specification and claims, including definitions as examples, exemplary definitions, preferred definitions, definitions recorded in tables, and definitions of specific compounds in the examples, can be arbitrarily combined and combined with each other. Such combinations and combinations of group definitions and compound structures should be understood as being within the scope of this application specification and / or claims.

[0073] Term "C" 1-6 "Alkyl" refers to a straight-chain or branched alkyl saturated monovalent hydrocarbon group having 1, 2, 3, 4, 5, or 6 carbon atoms. The alkyl group is, for example, 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, or 1,2-dimethylbutyl, or their isomers.

[0074] Term "C" 3-8 "Cycloalkyl" should be understood as representing a saturated monovalent monocyclic cycloalkane ring having 3, 4, 5, 6, 7, or 8 carbon atoms. Examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Detailed Implementation

[0075] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0076] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0077] Example 1: Synthesis of A8

[0078]

[0079] To a mixture of DCM (600 mL) and water (100 mL) containing BA (100 g, 303 mmol), NaBr (3.2 g, 31.06 mmol), TEMPO (1 g, 6.4 mmol), and NaHCO3 (30.6 g, 364 mmol) were added. The mixture was cooled to 0–5 °C, and a 10% NaClO solution (115 g, 155 mmol) was added dropwise with stirring. After the addition was complete, stirring was continued for 30 min. The solution was then quenched with 5 g of Na2SO3 and stirred for another 30 min. The mixture was allowed to stand and separated. The lower layer was washed once with saturated NaHCO3, dried, and concentrated under reduced pressure to obtain 90 g of white solid A8, with a yield of 90.5% and an HPLC purity of 90%.

[0080] Example 2: Synthesis of A8

[0081]

[0082] BA (33 g, 100 mmol) and DCM (100 mL) were added to a reaction flask and stirred until dissolved. Hydrochloric acid (3.7%, 2 mmol, 2 g), TEMPO (0.31 g, 2 mmol), and sodium bromate (5 g, 35 mmol) were then added. The mixture was stirred at 25 °C for 16 hours, then the reaction was stopped. Water (100 mL) was added, and the mixture was separated. The organic phase was washed with saturated sodium bicarbonate aqueous solution (100 mL) and saturated brine (100 mL), dried over anhydrous sodium sulfate, filtered, concentrated to remove the solvent, and subjected to silica gel column chromatography (n-hexane:EtOAc = 10:1) to obtain 28.2 g of A8, yield 86%, HPLC purity 96%.

[0083] Example 3: Synthesis of A7

[0084]

[0085] Add A8 (65.6 g, 200.00 mmol) and monoethyl malonate (39.6 g, 300.00 mmol) prepared in Example 2 to a 1 L three-necked flask containing 500 mL DMF. Stir until homogeneous, then add DMAP (2.44 g, 20 mmol) at 25 °C and stir for 16 hours. After the reaction of A8 is complete, monitor the reaction by TLC. Add 500 mL of methyl ether. Wash the organic phase successively with saturated NaHCO3 aqueous solution (500 mL), saturated brine (500 mL), dry with anhydrous sodium sulfate, filter, and concentrate under reduced pressure to obtain 90 g of white solid A7, yield 90.5%, HPLC purity 98%.

[0086] Example 4: Synthesis of A7

[0087]

[0088] 40.9 g of triethyl phosphonoacetate and 400 mL of THF were added to a 1 L three-necked flask. The temperature was controlled at 0-5 °C, and 6.7 g of 60% NaH was added in batches with stirring, releasing a large amount of gas. After stirring for 1 h, a 300 mL THF solution containing 49.8 g of A8 prepared in Example 2 was added dropwise to the above system using a 500 mL constant pressure funnel. After the addition was complete, stirring continued for 2 h. The reaction was quenched by adding 200 mL of an aqueous solution of 20 g of ammonium chloride. After stirring for 1 h, the mixture was separated. The aqueous phase was extracted once with 200 mL of EA, the organic phases were combined, dried, and concentrated under reduced pressure to obtain 55 g of crude product. The crude product was pulped with 80 mL of petroleum ether and filtered to obtain 55 g of grayish-white solid A7, with a yield of 91% and an HPLC purity of 95%.

[0089] Example 5: Synthesis of A5

[0090]

[0091] Under nitrogen protection, 50g of A7 prepared in Example 3, 50g of ethylene glycol, 600mL of DCM, 28g of triethyl orthoformate, and 0.5g of p-toluenesulfonic acid were added to a 1L three-necked flask. The mixture was stirred at 25°C for 10 hours. TLC showed the reaction was complete. 1mL of triethylamine was added, and the mixture was stirred for 30 minutes. 100mL of water was added for washing and separation. After drying, the mixture was concentrated to obtain 55g of crude A5. The crude product was then refluxed with 150mL of petroleum ether and stirred to obtain 48.5g of A5, with a yield of 87.3% and an HPLC purity of 97%.

[0092] Example 6: Synthesis of A3

[0093]

[0094] 2.01 g of A5 prepared in Example 5 and 0.1 g of 5% palladium on carbon were added to 20 mL of ethyl acetate and stirred at 25 °C for 1 h under 0.2 MPa hydrogen pressure. After filtration and concentration under reduced pressure, 1.95 g of white solid A3 was obtained, with a yield of 97% and an HPLC purity of 97%.

[0095] Example 7: Synthesis of A6

[0096]

[0097] The A8 (258 g, 789 mmol, 1.0 eq) prepared in Example 2, Michaelis-Menten acid (136 g, 947 mmol, 1.2 eq), and a formic acid / triethylamine mixture (formic acid / triethylamine = 5:2, 1000 mL) were added to the reaction flask. The reaction mixture was heated at 110 °C for 16 hours. TLC monitoring showed that the A8 reaction was complete. The reactants were poured into ice water (1000 mL), adjusted to pH 10 with 1 N NaOH, and washed with ethyl acetate (200 mL × 2). The aqueous phase was adjusted to pH 2 with 1 N HCl, and then extracted with ethyl acetate (200 mL × 3). The combined organic phases yielded 288 g of crude product, which was purified with acetone to obtain 270 g, with a yield of 91.8% and an HPLC purity of 96%.

[0098] Example 8: Synthesis of A4

[0099]

[0100] The A6 (100 g, 270 mmol) prepared in Example 7, ethanol (300 mL), and hydrochloric acid (20 mL, 37.5%) were added to a reaction flask. The mixture was stirred at 25 °C for 16 hours. TLC monitoring showed that the A6 reaction was complete. The reactants were concentrated under reduced pressure to remove excess ethanol, and diluted with ethyl acetate (300 mL). The organic phase was washed successively with water (300 mL), saturated sodium bicarbonate aqueous solution (300 mL), and saturated sodium chloride aqueous solution (300 mL), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 100 g of A4, with a yield of 93% and an HPLC purity of 96%. ESI-MS [M+H] + 445.33.

[0101] Example 9: Synthesis of A4

[0102]

[0103] The A6 (74.4 g, 200 mmol) prepared in Example 7, ethanol (200 mL), and concentrated sulfuric acid (5 mL) were added to the reaction flask. The reaction was refluxed and stirred for 24 hours. TLC monitoring showed that the A6 reaction was complete. The reactants were concentrated under reduced pressure to remove excess ethanol, and then diluted with dichloromethane (200 mL). The organic phase was washed successively with water (200 mL), saturated sodium bicarbonate aqueous solution (200 mL), and saturated sodium chloride aqueous solution (200 mL), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 73.6 g of A4, with a yield of 92% and an HPLC purity of 97%. ESI-MS [M+H] + 445.33.

[0104] Example 10: Synthesis of A3

[0105]

[0106] Under nitrogen protection, A4 (50 g, 125 mmol), ethylene glycol (50 g, 806 mmol), DCM (600 mL), triethyl orthoformate (28 g, 189 mmol), and p-toluenesulfonic acid (0.5 g, 2.6 mmol) prepared in Example 9 were added to a 1 L three-necked flask and stirred at 25 °C for 10 h. TLC showed the reaction was complete. 1 mL of triethylamine was added and the mixture was stirred for 30 min. After washing with 100 mL of water, the mixture was separated, dried over anhydrous sodium sulfate, and concentrated to obtain 58 g of crude A3. The crude product was refluxed with 150 mL of petroleum ether and stirred to obtain 51.8 g of A3, with a yield of 95% and an HPLC purity of 95%. ESI-MS [M+H] + 444.35. 1 H-NMR (CDCl3, 400MHz) δ (ppm): 5.36-5.34 (m, 1H), 4.12 (q, J=7.2Hz, 2H), 3.98-3.91 (m, 4H), 2.58-2.54 (m, 1H), 2.38-2.30 (m, 1H), 2.13-2.09 (m, 1H),2.00-1.92(m,2H),1.89-1.73(m,4H),1.67-1.60(m,3H),1.49-1.40(m,4H), 1.36-1.30(m,2H),1.25(t,J=7.2Hz,3H),1.20-1.06(m,4H),1.02(s,3H),0.92(d, J = 6.4 Hz (3H), 0.68 s (3H).

[0107] Example 11: Synthesis of A3

[0108]

[0109] Under an inert gas atmosphere, A4 (50 g, 125 mmol), ethylene glycol (150 mL, 2702 mmol), 90 g of trimethyl orthoacetate (90 g, 750 mmol), and p-toluenesulfonic acid (5 g, 26 mmol) prepared in Example 9 were added to a reaction flask. The reaction was carried out at 25 °C for 2 hours, resulting in the precipitation of a large amount of solid. Methanol (100 mL) was added to disperse the solid, and the pH was adjusted to 7-8 with triethylamine. The mixture was filtered, dried, and 50.2 g of compound A3 was obtained, with a yield of 92% and an HPLC purity of 98%. ESI-MS [M+H] + 444.35.

[0110] Example 12: Synthesis of A3

[0111]

[0112] Under an inert gas atmosphere, A4 (50 g, 125 mmol), ethylene glycol (39, 625 mmol), p-toluenesulfonic acid (5 g, 26 mmol), and toluene (200 mL) prepared in Example 9 were added to a reaction flask. The reaction mixture was heated under reflux to remove water for 24 hours. The reaction mixture was cooled to 25°C and washed successively with water (200 mL), saturated sodium bicarbonate (200 mL), and saturated brine (200 mL). After drying with anhydrous sodium sulfate, the mixture was concentrated to obtain 57 g of crude A3. The crude product was then slurried under reflux with 150 mL of petroleum ether to obtain 46.3 g of A3, with a yield of 85% and an HPLC purity of 90%. ESI-MS [M+H] + 444.35.

[0113] Example 13: Synthesis of A2

[0114]

[0115] Compound A3 (44.4 g, 100 mmol) prepared in Example 11, N-hydroxyphthalimide (NHPI) (1.63 g, 10 mmol), benzoyl peroxide (2.4 g, 10 mmol), cobalt acetate (88 mg, 0.5 mmol), and cyclohexanone (200 mL) were added to a reaction flask. The reaction mixture was stirred at 25 °C for 10 min, heated to 60 °C, and air was bubbled into the mixture. After the reaction was complete, the mixture was concentrated to remove cyclohexanone. Dichloromethane was added, and the catalyst was removed by filtration. Triethylamine (10 g, 100 mmol) and acetic anhydride (10 g, 100 mmol) were added, and the mixture was reacted at 25 °C for 10 h. After the reaction was complete, ethanol was added to quench the reaction mixture, and the mixture was concentrated. Ethanol was added again to discharge the mixture, and the residue was dried to give 30 g of compound A2, with a yield of 65.8% and an HPLC purity of 95%. ESI-MS [M+H] + 459.35. 1 H-NMR (CDCl3, 400MHz) δ (ppm): 5.67 (s, 1H), 4.12 (brs, 2H), 3.97 (brs, 4H), 2.70-2.66 (m, 1H), 2.45-2.22 (m, 5H), 2.00-1.75 (m, 6H),1.59-1.11(m,17H),0.94(s,3H),0.69(s,3H).

[0116] Example 14: Synthesis of A2

[0117]

[0118] The reaction flask was filled with A3 (100 g, 270 mmol) prepared in Example 11, ethyl acetate (200 mL), TBHP (270 mL, 1350 mmol, 5.0 M n-decane solution), 3A molecular sieve (20 g), and manganese(III) acetate dihydrate (740 mg, 27 mmol). The reaction mixture was reacted at 25 °C for 48 hours. The system was diluted with methyl ether (200 mL) and filtered through diatomaceous earth. The filtrate was desolventized under reduced pressure and purified by column chromatography (n-hexane:EtOAc = 5:1) to obtain 110 g of product, yield 90%, HPLC purity 98%. ESI-MS [M+H] + 459.35.

[0119] Example 15: Synthesis of A2

[0120]

[0121] The reaction flask was filled with A3 (44 g, 100 mmol) prepared in Example 11, TBHP (120 mL, 600 mmol, 5.0 M n-decane solution), cuprous iodide (0.19 g, 1 mmol), and acetonitrile (200 mL). The reaction mixture was reacted at 50 °C for 20 hours. The system was filtered through diatomaceous earth. The filtrate was desolvated under reduced pressure, and purified by column chromatography (n-hexane:EtOAc = 5:1) to obtain 38 g of product, yield 83%, HPLC purity 96%. ESI-MS [M+H] + 459.35.

[0122] Example 16: Synthesis of A1

[0123]

[0124] Water (40 mL) and THF (100 mL) were added to a 1 L single-necked flask. Concentrated sulfuric acid (4 g, 40.8 mmol) was added with stirring at 0 °C for 10 minutes. Then, A2 (12 g, 26.2 mmol) prepared in Example 14 was added. The cold bath was removed, and the mixture was stirred overnight at 25 °C. After adding 100 mL of water, NaHCO3 (10 g, 119 mmol) was added in portions, maintaining the pH at 7-8. The mixture was then extracted twice with 200 mL of EtOAc. The organic phases were combined and concentrated under reduced pressure to obtain a crude yellow oily product. The crude product was subjected to column chromatography (n-hexane:EtOAc = 3:1) to give 9.97 g of solid A1, yield 92%, HPLC purity 95%. ESI-MS [M+H] + 415.30.

[0125] Example 17: Synthesis of A1

[0126]

[0127] Add 54 g (118 mmol) of A2 prepared in Example 14 and 5.2 g (27.4 mmol) of p-toluenesulfonic acid monohydrate to a 1 L reaction flask containing 200 mL toluene and 50 mL water. Stir at 50 °C for 1 h, then cool to 25 °C and add NaHCO3 (10 g, 119 mmol) to quench the reaction. Allow to stand and separate the phases; extract the aqueous phase once with toluene (100 mL). Combine the organic phases and concentrate under reduced pressure to obtain a crude yellow oily product. Column chromatography (n-hexane:EtOAc = 3:1) yielded 46.8 g of pale yellow solid A1, 96% yield, HPLC purity 98%. ESI-MS: [M+H] + 415.30

[0128] 1 H-NMR(DMSO-d6,400MHz)δ(ppm):10.25(brs,1H),5.29-5.28(m,2H),4.03(q, J=7.2Hz,2H),2.41-2.12(m,6H),1.98-1.66(m,4H),1.11-1.53(m,10H),1.17(t, J=7.2Hz,3H),1.05(s,3H),0.91(d,J=6Hz,3H),0.66(s,3H).

[0129] Example 18: Synthesis of A

[0130]

[0131] The A1 (3.2 g, 7.73 mmol) prepared in Example 17 was dissolved in N,N-dimethylformamide (DMF) (32 mL), and then 0.32 g of Raney nickel was added. The reaction mixture was hydrogenated at 25 °C and 0.1 MPa hydrogen for 12 h. After hydrogenation, the mixture was filtered and concentrated under reduced pressure to obtain 3.3 g of crude A. Purification with acetone yielded 2.84 g of white solid A, with a yield of 88% and an HPLC purity of 98%. ESI-MS [M+H] + 419.30.

[0132] 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).

[0133] Example 19: Synthesis of A

[0134]

[0135] The A1 (3.2 g, 7.73 mmol) prepared in Example 17 was dissolved in N,N-dimethylacetamide (32 mL), and then 0.32 g of Raney nickel was added. The reaction mixture was hydrogenated at 25 °C under 0.1 MPa hydrogen for 12 h. After hydrogenation, the mixture was filtered and concentrated under reduced pressure to obtain 3.4 g of crude A. Purification with acetone yielded 2.74 g of white solid A, with a yield of 85% and an HPLC purity of 98%. ESI-MS [M+H] + 419.30.

[0136] Example 20: Synthesis of A

[0137]

[0138] The A1 (3.2 g, 7.73 mmol) prepared in Example 17 was dissolved in N-methylpyrrolidone (32 mL), and then 0.32 g of Raney nickel was added. The reaction mixture was hydrogenated at 25 °C and 0.1 MPa hydrogen for 12 h. After hydrogenation, the mixture was filtered and concentrated under reduced pressure to obtain 3.0 g of crude product A. Purification with acetone yielded 2.52 g of white solid A, with a yield of 78.3% and an HPLC purity of 95%. ESI-MS: [M+H] + 419.30.

[0139] Example 21: Synthesis of A

[0140]

[0141] The A1 (3.2 g, 7.73 mmol) prepared in Example 17 was dissolved in N,N-dimethylformamide (32 mL), and then 0.32 g of 5% palladium on carbon catalyst was added. The reaction mixture was hydrogenated at 25 °C and 0.1 MPa hydrogen for 12 h. After hydrogenation, the mixture was filtered and concentrated under reduced pressure. The crude product was purified by column chromatography (n-hexane:EtOAc = 3:1) to give 2.09 g of white solid A, yield 65%, HPLC purity 91%. ESI-MS [M+H] + 419.30.

[0142] Example 22: Synthesis of A

[0143]

[0144] The A1 (3.2 g, 7.73 mmol) prepared in Example 17 was dissolved in N,N-dimethylformamide (32 mL), and then 0.32 g of 5% platinum-carbon catalyst was added. The reaction mixture was hydrogenated at 25 °C and 0.1 MPa hydrogen for 12 h. After hydrogenation, the mixture was filtered, and the crude product was concentrated under reduced pressure and purified by column chromatography (n-hexane:EtOAc = 3:1) to obtain 1.70 g of white solid A, with a yield of 53% and an HPLC purity of 92%. ESI-MS [M+H] + 419.30.

[0145] Example 23: Synthesis of A1

[0146]

[0147] The Al (5 g, 12.08 mmol) prepared in Example 17 was dissolved in THF (20 mL) and water (10 mL), followed by the addition of 3N NaOH aqueous solution (6 mL, 18 mmol). The reaction mixture was reacted at 25 °C for 1 h. TLC analysis confirmed complete reaction of the starting material. The reaction mixture was cooled to an internal temperature of 0 °C, and 3N HCl aqueous solution (8 mL, 24 mmol) was added dropwise. Extraction was performed with ethyl acetate (30 mL x 2). The organic phases were combined, washed with water (30 mL), washed with saturated brine (30 mL), dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and purified with acetone to obtain 4.38 g of white solid Al-1, yield 94%, HPLC purity 98%. ESI-MS [M+H] + 387.30.

[0148] 1H-NMR (CDCl, 400MHz) δ (ppm): 5.72-5.68 (m, 1H), 3.49-3.41 (m, 1H), 3.10-3.02 (m, 1H), 2.61-2.11 (m, 7H), 2.10-1.63 (m, 9H), 1.49-1.22 (m, 5H), 1.23-1.02(m,3H),0.72-0.71(m,3H).

[0149] Example 24: Synthesis of 7-LCA

[0150]

[0151] The Al-1 (3 g, 7.77 mmol) prepared in Example 23 was dissolved in N,N-dimethylformamide (DMF) (30 mL), and then 0.3 g of Raney nickel was added. The reaction mixture was hydrogenated at 25 °C and 0.1 MPa hydrogen for 12 h. After hydrogenation, the mixture was filtered, concentrated under reduced pressure, and purified with acetone to obtain 2.5 g of white solid 7-LCA, yield 82%, HPLC purity 92%. ESI-MS [M+H] + 391.30.

[0152] The embodiments of the technical solution of the present invention have been described above by way of example. It should be understood that the protection scope of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the protection scope of the claims of this application.

Claims

1. A method for preparing a compound of formula I, characterized in that, include: Compound I-1 was hydrogenated in the presence of a catalyst to obtain compound I. Wherein, R1 is H, C 1-6 alkyl; The reaction is carried out in the presence of a solvent selected from amide solvents.

2. The method according to claim 1, characterized in that, R1 is methyl, ethyl, propyl, or tert-butyl.

3. The method according to claim 1, characterized in that, The catalyst is selected from Raney Ni catalyst, Pd / C catalyst, Pt / C catalyst or Ru / C catalyst.

4. The method according to claim 1, characterized in that, The amide solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, formamide, N-methylpyrrolidone, N-methylformamide, N-methylacetamide, and N,N-dimethylpropenylurea.

5. The method according to claim 1, characterized in that, When R1 in compound I is C 1-6 When alkyl, the method further includes: making R1 C 1-6 Hydrolysis of alkyl compound of formula I yields compound of formula I with R1 being H; 6. The intermediate compound I-1 is shown below: in, R1 has the definition as described in claim 1.

7. A method for preparing compound I-1 according to claim 6, comprising: in, R1 has the definition in claim 1, and R2 is C. 1-6 alkyl; h) Compound I-3 was allylated to give compound I-2; i) Deprotecting compound I-2 with ethylene glycol to obtain R1 as C 1-6 Compound I-1 is an alkyl compound; or compound I-2 is subjected to deglycolization and hydrolysis to obtain compound I-1 with R1 being H.

8. The method according to claim 7, characterized in that, In step h), the reaction is carried out in the presence of an oxidant and a catalyst.

9. The method according to claim 8, characterized in that, Step h) is carried out in the following reaction system h1 or h2: h1: A reaction system in which the oxidant is oxygen or air and the catalyst is N-hydroxyphthalimide and cobalt acetate; h2: The reaction system in which the oxidant is tert-butanol peroxide and the catalyst is manganese(III) acetate, manganese(III) acetate dihydrate or cuprous iodide.

10. The method according to claim 9, characterized in that, H1 also contains a free radical initiator.

11. The method according to claim 10, characterized in that, The free radical initiator is benzoyl peroxide.

12. The method according to claim 7, characterized in that, In step i), the deglycolization protection reaction is carried out under acidic conditions, wherein the acid is selected from at least one of concentrated sulfuric acid, concentrated hydrochloric acid, and p-toluenesulfonic acid; and the hydrolysis reaction is carried out under alkaline conditions.

13. The method according to claim 12, characterized in that, The hydrolysis reaction is carried out in the presence of sodium hydroxide and potassium hydroxide.

14. The method according to claim 7, characterized in that, The preparation method of compound I-3 includes either method one or method two: Method 1: Wherein, R2 has the definition as described in claim 7; b) Mixing compound I-8 with Knoevenagel condensation reaction yields compound I-7; or compound I-8 is reacted with... The Wittig reaction yields compound I-7; wherein R3 and R4 are C6 and C7, respectively. 1-6 alkyl; d) Compound I-7 was protected with ethylene glycol to obtain compound I-5; f) The reduction reaction of compound I-5 yields compound I-3; Method 2: Wherein, R2 has the definition as described in claim 7; c) Mixing compound I-8 with Knoevenagel condensation reaction yields compound I-6; wherein R5 and R6 are C 1-6 Alkyl groups, or R5 and R6, together with the attached carbon atom to form C24. 3-8 cycloalkyl; e) Reaction of compound I-6 with R2OH yields compound I-4; g) Compound I-4 was protected with ethylene glycol to obtain compound I-3.

15. The method according to claim 14, characterized in that, R3 and R4 are ethyl groups; R5 and R6 are methyl groups.

16. The method according to claim 14, characterized in that, The Knoevenagel condensation reaction in step b) is carried out in the presence of a catalyst, namely DMAP.

17. The method according to claim 14, characterized in that, Step d) is carried out under the action of a catalyst, wherein the catalyst is selected from catalyst A and / or catalyst B, wherein catalyst A is selected from p-toluenesulfonic acid or concentrated sulfuric acid, and catalyst B is selected from trimethyl orthoformate, triethyl orthoformate, or trimethyl orthoacetate.

18. The method according to claim 14, characterized in that, Step f) is carried out in the presence of a catalyst, wherein the catalyst is Pd / C.

19. The method according to claim 14, characterized in that, Step e) is carried out in the presence of a catalyst selected from at least one of concentrated sulfuric acid, p-toluenesulfonic acid, and hydrochloric acid.

20. The method according to claim 14, characterized in that, Step g) is carried out under the action of a catalyst, wherein the catalyst is selected from catalyst A and / or catalyst B, wherein catalyst A is selected from p-toluenesulfonic acid or concentrated sulfuric acid, and catalyst B is selected from trimethyl orthoformate, triethyl orthoformate, or trimethyl orthoacetate.

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