Method for preparing cholic acid compound

Abstract

The present application relates to a method for preparing a cholic acid compound. Specifically, the method prepares a compound as shown in formula I, including subjecting a compound of formula 2 to an oxidization reaction to obtain a compound of formula 3; attaching a trimethylsilyl group to the compound of formula 3 to obtain a compound of formula 4; reacting the compound of formula 4 with acetaldehyde to obtain a compound of formula 5; subjecting the compound of formula 5 to a catalytic hydrogenation reaction to obtain a compound of formula 6; and converting a cyano group of the compound of formula 6 to a carboxyl group to give the compound of formula I. ##STR00001## ##STR00002##

Claims

1. A preparation method for a compound of formula I, ##STR00024## comprising the following steps: a) subjecting a compound of formula 2 to an oxidization reaction in a solvent to obtain a compound of formula 3, ##STR00025## b) attaching a protecting group to the compound of formula 3 in a solvent to obtain a compound of formula 4, ##STR00026## c) reacting the compound of formula 4 with acetaldehyde in a solvent to obtain a compound of formula 5, ##STR00027## d) subjecting the compound of formula 5 to a reduction reaction in a solvent under a catalyst to obtain a compound of formula 6, ##STR00028## e) converting cyano group of the compound of formula 6 to a carboxyl group to give the compound of formula I, ##STR00029## wherein, said R.sup.1 and R.sup.2 are each independently selected from a silyl ether protecting group.

2. The preparation method of claim 1, wherein the preparation method for the compound of formula 2 comprises the following steps: f) attaching a formyl group to a compound of formula 7 to obtain a compound of formula 8, ##STR00030## g) converting a carboxyl group at position 23 of the compound of formula 8 to a cyano group at position 22 to obtain a compound of formula 9, and removing a formyl group from the compound of formula, 9 to obtain the compound of formula 2, ##STR00031##

3. The preparation method of claim 1, wherein the silyl ether protecting group is selected from trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, or tert-butyldiphenylsilyl.

4. The preparation method of claim 1, wherein an oxidant used in said step a) is selected from sodium hypochlorite, bromine hypochlorite, N-bromosuccinimide, N-chlorosuccinimide, hydrogen peroxide or potassium dichromate.

5. The preparation method of claim 4, wherein in said step a, the molar ratio of the compound of formula 2 to the oxidant is selected from 1:(1 to 5).

6. The preparation method of claim 1, wherein said step a) is performed in the presence of bromine.

7. The preparation method of claim 1, wherein the solvent of said step a) is selected from dichloromethane, methanol, ethanol, propanol, diethyl ether, isopropyl ether, tetrahydrofuran, methyl tert-butyl ether, ethyl acetate, acetonitrile, acetone, or a mixed solvent thereof.

8. The preparation method of claim 1, wherein said step a) is performed in the presence of an organic acid, which is selected from formic acid, acetic acid, propionic acid, citric acid or malic acid.

9. The preparation method of claim 1, wherein said step b) is performed in the presence of an alkali metal cationic organic base, which is selected from lithium diisopropylamide, n-butyllithium, sodium diisopropylamide, potassium diisopropylamide, sodium hexamethyldisilazide, potassium hexamethyldisilazide or lithium hexamethyldisilazide.

10. The preparation method of claim 1, wherein said step b) is performed in the presence of an acid-binding agent, which is selected from triethylamine, diisopropylethylamine, tributylamine or pyridine.

11. The preparation method of claim 1, wherein said step c) is performed in the presence of boron trifluoride; aluminum trichloride, iron trichloride, zinc chloride, tin tetrachloride or niobium pentachloride.

12. The preparation method of claim 1, wherein the catalyst of said step d) is selected from Pd/C, PVC, Pt/C, Rh(OH).sub.2, Raney Ni, or PtO.sub.2.

13. The preparation method of claim 1, wherein said step e) is performed in the presence of NaOH or KOH.

14. The preparation method of claim 2, Wherein said step f is performed in formic acid.

15. The preparation method of claim 2, wherein in said step g), the compound of formula 8 is converted to the compound of formula 9 in the presence of trifluoroacetic acid or trifluoroacetic anhydride, and sodium nitrite or potassium nitrite.

16. The preparation method of claim 1, wherein said step a) is performed in the presence of sodium bromide or potassium bromide.

17. The preparation method of claim 1 wherein the solvent of said step b) is selected from n-heptane, n-hexane, tetrahydrofuran, methyl tert-butyl ether or toluene.

18. The preparation method of claim 1, wherein the solvent of said step c) is selected from n-heptane, n-hexane, tetrahydrofuran; methyl tert-butyl ether, toluene or dichloromethane.

19. The preparation method of claim 1, wherein the solvent of said step d) is selected from methanol, ethanol, propanol or tetrahydrofuran.

20. The preparation method of claim 2, wherein in step g), a reaction of removing the formyl group from the compound of formula 9 is performed in an aqueous solution of NaOH or KOH.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) For better understanding the content of the present invention, the following detailed description is made in combination with the specific examples, but the specific examples are not intended to limit the content of the present invention.

Preparation Example 1

Preparation of the Compound of Formula I

(2) Step 1-1 Preparation of the Compound of Formula 3

(3) ##STR00017##

(4) 130 mL of dichloromethane, 130 mL of methanol, 390 mL of AcOH, and 130 g of the compound of formula 2 (7α) were added into a reaction flask and stirred to dissolve. 130 mL of aqueous solution of 7.4 g of sodium bromide was added thereto, followed by being cooled down to −30° C. to −20° C., and 268 g of 10% sodium hypochlorite solution was added dropwise. The reaction was monitored by TLC until completed, and an aqueous solution of sodium sulfite (20%) was added thereto. The organic layer was separated, and the aqueous layer was extracted with dichloromethane. The organic phases were combined, washed with purified water, and adjusted to pH 7-8 by adding 15% sodium carbonate aqueous solution. The organic phase was separated, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated to dryness under reduced pressure at 45° C. to obtain the compound of formula 3. The crude product was refluxed by adding 650 mL of ethyl acetate, cooled down to crystallize, and subjected to air pump filtration, and the filter cake was blast dried at 60° C. for 12 h to obtain 114.5 g of the compound of formula 3. The yield was 88.6%. MS: m/z: 358.40 (M+), 340.36 (M−18), 322.36 (M−2×18).

(5) Step 1-2 Preparation of a Compound of Formula 4a

(6) ##STR00018##

(7) 1 L of tetrahydrofuran and 129 g of the compound of formula 3 were added into a reaction flask, and stirred to dissolve at room temperature. Then 235 g of trimethylchlorosilane was added thereto, followed by being cooled down to −70° C. under the protection of nitrogen. LDA (2M) was added dropwise while the temperature was maintained at −70° C. or less, and it was stirred for 0.5 h at a temperature of −70° C. or less after adding. 255 g of triethylamine was added dropwise, which was stirred for 2 h at the same temperature after adding. The reaction was monitored by TLC until completed, followed by being heated up to −30° C. to −20° C., and 1350 g of sodium bicarbonate solution (9%) was added dropwise, which was stirred at 0° C. to 10° C. for 1 h after adding. The organic layer was separated, and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, washed with 1.2 L of sodium bicarbonate solution (5%), 1.2 L of purified water, and 1.2 L of saturated brine successively, dried over anhydrous sodium sulfate and filtered, and the filtrate was concentrated to dryness under reduced pressure at 50° C. to obtain an orange-yellow semi-solid, which was directly used for the next step.

(8) Step 1-3 Preparation of a Compound of Formula 5a

(9) ##STR00019##

(10) 108 mL of dichloromethane and 18.0 g of the compound of formula 4a were added into a reaction flask, and cooled down to a temperature of −75° C. or less under the protection of nitrogen, to which 5.2 mL of acetaldehyde was added, and 40 mL of boron trifluoride diethyl etherate was added dropwise when controlling a temperature at −70° C. or less, followed by being stirred for 2 h when maintaining a temperature at −60° C. or less after adding. The reaction was monitored by TLC until completed, followed by being heated up to 0° C. and stirred for 1 h. 300 g of sodium bicarbonate solution (9%) was added dropwise and stirred for 30 min. The organic layer was separated, and the aqueous phase was extracted with dichloromethane. The organic phases were combined, washed with 5% sodium bicarbonate solution, purified water, and saturated brine successively, dried over sodium sulfate and filtered, and the filtrate was concentrated to dryness under reduced pressure at 40° C. to 50° C. to obtain an orange-yellow foamed solid, which was directly used for the reaction of the next step. MS: m/z: 456.42 (M+), 438.44 (M−18).

(11) Step 1-4 Preparation of the Compound of Formula 6

(12) ##STR00020##

(13) 40 g of the compound of formula 5a was added into 200 mL of methanol, and stirred to dissolve at room temperature, to which 10 g of palladium-carbon (5%) was added, stirred well, and transferred to an autoclave. A reaction was performed with the hydrogen pressure being increased to 1.5 to 2.5 MPa and the temperature being increased to 50° C., until the hydrogen pressure no longer decreased. The reaction was monitored by TLC until completed. The reaction solution was transferred out after being replaced with nitrogen, the palladium-carbon was removed by filtration and the filtrate was concentrated to dryness under reduced pressure. The yield was above 100% and the product was directly used for the next step. MS: m/z: 386.45 (M+), 368.41 (M−18).

(14) Step 1-5 Preparation of the Compound of Formula I

(15) ##STR00021##

(16) 52 g of sodium hydroxide was dissolved in 100 mL of water, to which 100 mL of ethanol and 10 g of the compound of formula 6 were added, followed by being heated to perform a reflux reaction. The reaction was monitored by TLC until completed, followed by being cooled down to room temperature and concentrated under reduced pressure to remove the ethanol. The pH was adjusted to 2-3 with hydrochloric acid. 100 mL of ethyl acetate was added and stirred to dissolve. The organic phase was separated, and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, washed with saturated brine, dried over sodium sulfate, and concentrated to dryness under reduced pressure to obtain 9.8 g of the compound of formula I. The yield was 93.3% (combined yield of steps 1-2 to 1-5). MS: m/z: 405.51 (M+), 387.49 (M−18).

Preparation Example 2

Preparation of the Compound of Formula 2

(17) Step 2-1 Preparation of the Compound of Formula 8

(18) ##STR00022##

(19) 200 g of chenodeoxycholic acid (CDCA) was added into 1 L of formic acid, and stirred and heated up to 40° C. to 50° C. The reaction of the raw materials was monitored by TLC until completed, followed by being cooled down to crystallize, and being subjected to air pump filtration, and the filter cake was added with 2 L of purified water and stirred for 1 h at room temperature, subjected to air pump filtration, and blast dried at 70° C. to obtain 198.1 g of the compound of formula 8 (7α). The yield was 86.7%.

(20) Step 2-2 Preparation of the Compound of Formula 2 (7α)

(21) ##STR00023##

(22) 44.9 g of the compound of formula 8 (7α) was added into a mixed solution of 135 mL of trifluoroacetic acid and 168 g of trifluoroacetic anhydride, stirred and cooled down to −5° C. to 5° C., and 10.3 g of sodium nitrite was added in portions. After adding, it was stirred under a temperature maintained at −5° C. to 5° C. for 1 h, and then heated up to 40° C. for reaction. The reaction was monitored by TLC, and it was cooled down after the reaction. The reaction solution was added dropwise into 640 g of aqueous solution (20%) of sodium hydroxide. Afterward, it was filtered and the filter cake was added into 160 g of aqueous solution (15%) of sodium hydroxide, to which 90 mL of ethanol was added and a reaction is performed at 50° C. The reaction was monitored by TLC until completed, and the ethanol was removed by concentration under reduced pressure. The remaining reaction solution was extracted with 135 mL of ethyl acetate. The organic phases were combined and washed with sodium hydroxide aqueous solution (5%), hydrochloric acid (1 mol/L), and saturated brine, dried over sodium sulfate, and concentrated to dryness under reduced pressure at 50° C. to obtain the crude product of the compound of formula 2 (7α).

(23) The crude product was added with 90 mL of ethyl acetate, stirred at 55° C. for 2 h, cooled down to room temperature and stirred to crystallize, and subjected to air pump filtration, and the filter cake was blast dried to obtain 30.5 g of an off-white solid, which was the compound of formula 2 (7α). The yield was 84.7%. MS: m/z: 342.43 (M−18), 324.38 (M−2×18).