Synthesis method of 1 alpha-hydroxysterol compound

Abstract

The invention discloses a synthesis method of a 1alpha-hydroxysterol compound. The structural formula of the 1alpha-hydroxysterol compound is shown as a formula (1). The method comprises the following steps: taking 1alpha, 2alpha-epoxy-stero-4, 6-diene-3-ketone shown in a formula (2) as a raw material, and preparing the 1alpha-hydroxyl sterol compound through the steps of epoxy ring opening, reduction, hydrogenation and the like. The method has the characteristics of simple technological operation process, mild reaction conditions, good safety, high reaction yield and the like, is suitable for industrial production, and has the following reaction formula: substituent R is C1-C6 alkyl, cycloalkyl, halogenated alkyl, alkoxy or C1-C6 alkyl containing unsaturated bonds, heteroatoms or halogen substitutions.

Description

Technical Field

[0001] This invention belongs to the field of green preparation technology of steroidal compounds, and specifically relates to a method for synthesizing 1α-hydroxysteroidal compounds. Background Technology

[0002] 1α-Hydroxysterols are important intermediates in the synthesis of vitamin D compounds. In existing technologies, most 1α-hydroxysterols are prepared from 1α,2α-epoxy-4,6-ster-dien-3-one (as shown in formula (2)) via Birch reduction in a liquid ammonia-lithium (NH3(l) / Li) system at -78°C (J. Am. Chem. Soc., 1973, 95: 2748-2749.). This method requires stringent reaction conditions, including cryogenic conditions (-78°C) and a strictly anhydrous and oxygen-free reaction system. The reaction exhibits poor reproducibility and low yield, making it unsuitable for industrial production.

[0003] Furthermore, patent CN202211507515.1 reports a route for synthesizing 1α-hydroxycholesterol from 1α-hydroxy-4-cholesten-3-one via four steps: selective ring-opening, isomerization, reduction, and hydrolysis. However, its selective ring-opening step uses highly toxic and odorous selenophenol as a reducing agent, which does not conform to the principles of green chemistry. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the present invention aims to provide a method for preparing 1α-hydroxysterol compounds that is simple to operate, has high process safety, mild reaction conditions, and a fast reaction rate.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for synthesizing 1α-hydroxysterol compounds, using 1α,2α-epoxy-ster-4,6-dien-3-one as shown in formula (2) as a raw material, prepares 1α-hydroxysterol compounds through steps such as epoxide ring opening, reduction, and hydrogenation, specifically including the following steps:

[0007]

[0008] The substituent R is a C1-C6 alkyl, cycloalkyl, haloalkyl, alkoxy, or a C1-C6 alkyl group containing an unsaturated bond, heteroatom, or halogen substitution.

[0009] (i) Epoxy ring opening

[0010] Using 1α,2α-epoxy-ster-4,6-dien-3-one as shown in formula (2) as the starting material, an acid was added to zinc powder in an organic solvent at a temperature of 0–75 °C to undergo a ring-opening reaction, thereby obtaining the compound shown in formula (3). The reaction equation is as follows:

[0011]

[0012] (ii) Restore

[0013] Under the action of catalyst A, the 1α-hydroxy-ster-4,6-dien-3-one of formula (3) prepared in step (i) is dissolved in an organic solvent and reacted with hydroboration at a temperature of -5 to 0 °C.

[0014]

[0015] Calcium undergoes a reduction reaction to produce a compound as shown in formula (4), and the reaction equation is as follows:

[0016] (iii) Hydrogenation

[0017] Under the action of catalyst B, the 1α-hydroxy-ster-4,6-dien-3-one of formula (4) prepared in step (ii) was dissolved in an organic solvent and subjected to hydrogenation reaction with an organic acid and triethylamine at a temperature of 0–75 °C to obtain the compound shown in formula (1). The reaction equation is as follows:

[0018]

[0019] As shown below:

[0020] Furthermore, the substituent R is a C1-C6 alkyl, cycloalkyl, haloalkyl, alkoxy, or a C1-C6 alkyl group containing an unsaturated bond, heteroatom, or halogen substitution.

[0021] Further, in step (i), the molar ratio of zinc powder to 1α,2α-epoxy-ster-4,6-dien-3-one shown in formula (2) is 10 to 30:1, preferably 15 to 20:1.

[0022] Further, in step (i), the organic solvent is methanol or ethanol, preferably ethanol; the acidic medium used is one of the following: acetic acid, hydrochloric acid, or saturated ammonium chloride aqueous solution, preferably saturated ammonium chloride aqueous solution; the volume ratio of the acidic medium to the mass ratio of 1α,2α-epoxy-ster-4,6-diene-3-one shown in formula (2) is 0.5 to 5 mL / g, preferably 1.0 to 1.5 mL / g.

[0023] Further, in step (ii), the molar ratio of calcium borohydride to 1α-hydroxy-ster-4,6-dien-3-one shown in formula (3) is 2 to 10:1, preferably 4 to 6:1.

[0024] Further, in step (ii), catalyst A is one of the following: DMAP, triethylamine, pyridine, preferably DMAP.

[0025] Further, in step (ii), the molar ratio of catalyst A to 1α-hydroxy-ster-4,6-dien-3-one shown in formula (3) is 0.1 to 0.4:1, preferably 0.2 to 0.25:1.

[0026] Further, in step (ii), the organic solvent is a mixture of one or more of the following solvents: methanol, tetrahydrofuran, diethyl ether, and dichloromethane. Preferably, it is a methanol-tetrahydrofuran mixture with a volume ratio of 0.5 to 1:1.

[0027] Further, in step (iii), the organic solvent is tetrahydrofuran, ethyl acetate, or N,N-dimethylformamide, preferably tetrahydrofuran.

[0028] Further, in step (iii), the organic acid is formic acid or acetic acid, preferably formic acid; the molar ratio of the organic acid to 1α,3β-steroid-4,6-diene-1,3-diol as shown in formula (4) is 2 to 10:1, preferably 2.5 to 5:1.

[0029] Further, in step (iii), the molar ratio of triethylamine to 1α,3β-steroid-4,6-diene-1,3-diol as shown in formula (4) is 2 to 12:1, preferably 3 to 6:1.

[0030] Further, in step (iii), catalyst B is one of the following: palladium on carbon with a palladium loading of 5-15%, palladium calcium carbonate with a palladium loading of 5-15%, or palladium barium sulfate with a palladium loading of 5-10%, preferably palladium calcium carbonate with a palladium loading of 5-15%, wherein the mass ratio of palladium calcium carbonate to 1α,3β-steroid-4,6-diene-1,3-diol of the compound shown in formula (4) is 0.1-0.5:1, preferably 0.2-0.3:1.

[0031] The 1α-hydroxysterol compounds synthesized in this invention are key intermediates in the synthesis of vitamin D3 compounds.

[0032] By adopting the above-mentioned technology, the present invention has the following beneficial effects: the present invention is simple to operate, has mild reaction conditions, fast reaction rate, and high yield, and is suitable for large-scale preparation and production, solving the problems of harsh reaction conditions, poor reaction repeatability, and low yield in the prior art. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments.

[0034] Example 1: The target product 1α-hydroxycholesterol was synthesized according to the synthesis method of the present invention.

[0035] (i) Preparation of intermediate compound A2

[0036] Compound A2 was obtained from cholesterol as a raw material via DDQ dehydrogenation and hydrogen peroxide epoxidation. (Reference: China Pharmaceutical Industry Journal, 2023, 54(8):1198-1201.)

[0037] The reaction equation is as follows:

[0038]

[0039] (ii) Preparation of intermediate compound A3

[0040] Compound A2 (3.96 g, 10 mmol) and zinc powder (13.08 g, 200 mmol) were added sequentially to a dry single-necked flask. After dissolving in ethanol (50 mL), a saturated ammonium chloride aqueous solution (6.15 mL) was slowly added dropwise at room temperature (25 °C). The mixture was stirred for 4 h, and the reaction progress was monitored by TLC. After the reaction was completed, the insoluble matter in the reaction solution was removed by filtration, and the filter cake was washed with ethyl acetate. The filtrates were combined, and the pH was adjusted to neutral with a saturated sodium bicarbonate aqueous solution. After standing and separation, the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A mixture of petroleum ether and ethyl acetate in a volume ratio of 6:1 was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound A3 (3.54 g, 89%).

[0041] The reaction equation is as follows:

[0042]

[0043] (iii) Preparation of intermediate compound A4

[0044] In a dry single-necked flask, anhydrous calcium chloride (5.50 g, 50 mmol) and DMAP (0.24 g, 2 mmol) were added sequentially and dissolved in anhydrous methanol (50 mL). Then, a pre-prepared calcium borohydride methanol solution (3.02 g, 8 mol / 50 mL) was added, followed by the slow dropwise addition of anhydrous tetrahydrofuran solution of intermediate A3 (3.98 g, 10 mmol). The reaction temperature was maintained at -5 °C throughout the addition. After the addition was complete, the reaction system was stirred at low temperature for another 3 hours. The reaction progress was monitored by TLC, and the reaction was stopped once the reactants had completely reacted. The reaction system was filtered (to remove undissolved salts), and the filter cake was washed with dichloromethane. The filtrate was then slowly added dropwise with saturated ammonium chloride aqueous solution under vigorous stirring until the solution became clear. After separation, the organic layer was washed with saturated sodium bicarbonate aqueous solution until neutral, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and then separated by column chromatography. A mixture of petroleum ether and ethyl acetate in a volume ratio of 3:1 was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound A4 (3.68 g, 92%).

[0045] The reaction equation is as follows:

[0046]

[0047] (iv) Preparation of intermediate compound A1

[0048] In a dry single-necked flask, 1.03 g of palladium-loaded calcium carbonate (10%), 4.55 g (45 mmol) of triethylamine, 2.07 g (45 mmol) of formic acid, and intermediate A4 (4.00 g, 10 mmol) were added sequentially. After dissolving in THF (50 mL), the mixture was stirred at 25 °C for 3 h. The reaction was monitored by TLC until intermediate A4 was completely reacted, at which point the reaction was stopped. The reaction mixture was filtered (to remove palladium / calcium carbonate), the filter cake was washed with dichloromethane, the pH of the filtrate was adjusted to neutral, the organic layer was collected and washed with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A 3:1 mixture of petroleum ether and ethyl acetate was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound A1 (2.61 g, 65%).

[0049] The reaction equation is as follows:

[0050]

[0051] Characterization data:

[0052] 1H NMR(400MHz,Chloroform-d)δ:5.60-5.57(m,1H),4.01-3.94(m,1H),3.85–3.83(m,1H),2.41 –2.24(m,2H),2.13–2.03(m,1H),2.05–1.92(m,2H),1.89–1.67(m,3H),1.64–1.53(m,4H),1. 51-1.42(m,4H),1.33-1.32(m,2H),1.28-1.25(m,3H),1.13-1.09(m,3H),1.08-1.05(m,2H), 1.03(s,3H),0.91(d,J=6.4Hz,3H),0.87(d,J=1.8Hz,3H),0.85(d,J=1.8Hz,4H),0.67(s,3H) .

[0053] 13 C NMR(100MHz,Chloroform-d)δ:137.48,125.71,73.04,66.47,56.72,56.25,42.42,41.80,41.73,41.46,39.63,3 9.60,38.30,36.30,35.91,31.96,31.90,28.33,28.13,24.47,23.97,22.95,22.69,20.40,19.59,18.85,11.96.

[0054] Example 2 follows the steps and methods of Example 1, except that in step (ii), the molar ratio of zinc powder to compound A2 is adjusted to 10:1. All other operating steps are the same, and the yield of intermediate compound A3 is 75%.

[0055] Example 3 follows the steps and methods of Example 1, except that in step (ii), the molar ratio of zinc powder to compound A2 is adjusted to 30:1. The other operation steps are the same, and the yield of intermediate compound A3 is 84%.

[0056] Example 4 follows the steps and methods of Example 1, except that in step (ii) the saturated ammonium chloride aqueous solution is replaced with an equal volume of dilute hydrochloric acid (1 mol / L). The other operation steps are the same, and the yield of intermediate compound A3 is 53%.

[0057] Example 5 follows the steps and methods of Example 1, except that in step (ii) the saturated ammonium chloride aqueous solution is replaced with an equal volume of acetic acid. All other operating steps are the same, and the intermediate compound A3 is obtained with a yield of 62%.

[0058] Example 6 followed the steps and methods of Example 1, except that in step (ii) the volume of the saturated ammonium chloride aqueous solution was reduced to 2.05 mL. The other operating steps were the same, and the intermediate compound A3 was obtained with a yield of 78%.

[0059] Example 7 followed the steps and methods of Example 1, except that in step (ii), the volume of the saturated ammonium chloride aqueous solution was increased to 10.25 mL. All other operating steps were the same, and the intermediate compound A3 was obtained with a yield of 75%.

[0060] Example 8 follows the steps and methods of Example 1, except that in step (ii), the solvent is replaced with methanol instead of ethanol. All other operating steps are the same, and the intermediate compound A3 is obtained in 85% yield.

[0061] Example 9 follows the steps and methods of Example 1, except that the reaction temperature is adjusted to 10°C in step (ii). All other operating steps are the same, and the intermediate compound A3 is obtained in 50% yield.

[0062] Example 10 follows the steps and methods of Example 1, except that the reaction temperature is adjusted to 75°C in step (ii). All other operating steps are the same, and the intermediate compound A3 is obtained in a yield of 69%.

[0063] Example 11 follows the steps and methods of Example 1, except that the amount of anhydrous calcium chloride and sodium borohydride is adjusted in step (iii) so that the molar ratio of calcium borohydride to compound A4 is 2:1. Other operating steps are the same, and the yield of intermediate compound A4 is 64%.

[0064] Example 12 follows the steps and methods of Example 1, except that the amount of anhydrous calcium chloride and sodium borohydride is adjusted in step (iii) to make the molar ratio of calcium borohydride to compound A4 10:1. DMAP is not added as a catalyst. The other operation steps are the same, and the yield of intermediate compound A4 is 89%.

[0065] A comparison of the experimental results of Examples 11 and 12 shows that: in step (iii) of the reduction reaction, even without the addition of a DMAP catalyst, significantly increasing the amount of calcium borohydride reducing agent can still allow the reaction to proceed normally. However, in Example 1, the use of a DMAP catalyst in the reduction reaction significantly reduces the molar equivalent of calcium borohydride.

[0066] Example 13 follows the steps and methods of Example 1, except that the amount of DMAP is adjusted in step (iii) to make the molar ratio of DMAP to compound A4 0.1:1. The other operation steps are the same, and the yield of intermediate compound A4 is 80%.

[0067] Example 14 follows the steps and methods of Example 1, except that the amount of DMAP is adjusted in step (iii) so that the molar ratio of DMAP to compound A4 is 0.4:1. The other operation steps are the same, and the yield of intermediate compound A4 is 90%.

[0068] Example 15 follows the steps and methods of Example 1, except that DMAP is replaced with triethylamine in step (iii), and the other operation steps are the same, yielding intermediate compound A4 in 70% yield.

[0069] Example 16 follows the steps and methods of Example 1, except that DMAP is replaced with pyridine in step (iii), and the other operation steps are the same, yielding intermediate compound A4 in 65% yield.

[0070] Example 17 follows the steps and methods of Example 1, except that tetrahydrofuran is replaced with dichloromethane in step (iii). All other steps are the same, and intermediate compound A3 is obtained in 62% yield.

[0071] Example 18 follows the steps and methods of Example 1, except that tetrahydrofuran is replaced with diethyl ether in step (iii), and the other operation steps are the same, to obtain intermediate compound A3 in 88% yield.

[0072] Example 19 follows the steps and methods of Example 1, except that formic acid is replaced with acetic acid in step (iv). All other steps are the same, and compound A1 is obtained in 30% yield.

[0073] Example 20 follows the steps and methods of Example 1, except that in step (iv), the molar ratio of formic acid to compound A4 is adjusted to 2:1. All other operating steps are the same, and the yield of compound A1 is 35%.

[0074] Example 21 follows the steps and methods of Example 1, except that in step (iv) the molar ratio of formic acid to compound A4 is adjusted to 10:1. All other operating steps are the same, and the yield of compound A1 is 48%.

[0075] Example 22 follows the steps and methods of Example 1, except that in step (iv) the molar ratio of triethylamine to compound A4 is adjusted to 2:1. All other operating steps are the same, and the yield of compound A1 is 38%.

[0076] Example 23 follows the steps and methods of Example 1, except that in step (iv) the molar ratio of triethylamine to compound A4 is adjusted to 12:1. All other operating steps are the same, and the yield of compound A1 is 45%.

[0077] Example 24 follows the steps and methods of Example 1, except that in step (iv), the mass ratio of palladium calcium carbonate to compound A4 is adjusted to 0.1:1. All other operating steps are the same, and the yield of compound A1 is 30%.

[0078] Example 25 follows the steps and methods of Example 1, except that in step (iv), the mass ratio of palladium calcium carbonate to compound A4 is adjusted to 0.5:1. All other operating steps are the same, and the yield of compound A1 is 40%.

[0079] Example 26 follows the steps and methods of Example 1, except that in step (iv) palladium calcium carbonate is replaced with palladium carbon, and the other operation steps are the same, yielding compound A1 with a yield of 34%.

[0080] Example 27 follows the steps and methods of Example 1, except that in step (iv) palladium calcium carbonate is replaced with palladium barium sulfate. All other operating steps are the same, and compound A1 is obtained with a yield of 32%.

[0081] Example 28 follows the steps and methods of Example 1, except that tetrahydrofuran is replaced with ethyl acetate in step (iv). All other steps are the same, and compound A1 is obtained in 56% yield.

[0082] Example 29 follows the steps and methods of Example 1, except that tetrahydrofuran is replaced with N,N-dimethylformamide in step (iv). All other steps are the same, and compound A1 is obtained in 50% yield.

[0083] Example 30 follows the steps and methods of Example 1, except that the reaction temperature is adjusted to 10°C in step (iv). All other operating steps are the same, and the yield of intermediate compound A1 is 37%.

[0084] Example 31 follows the steps and methods of Example 1, except that the reaction temperature is adjusted to 75°C in step (iv). All other operating steps are the same, and the yield of intermediate compound A1 is 58%.

[0085] Example 32: Synthesis of the target product calcitriol intermediate according to the synthesis method of the present invention.

[0086] (i) Preparation of intermediate B2 compound

[0087] Compound B2 was obtained from 25-hydroxycholesterol via DDQ dehydrogenation and hydrogen peroxide epoxidation. (Reference: China Pharmaceutical Industry Journal, 2023, 54(8):1198-1201.) The reaction equation is as follows:

[0088]

[0089] (ii) Preparation of intermediate B3 compound

[0090] Compound B2 (4.12 g, 10 mmol) and zinc powder (13.08 g, 200 mmol) were added sequentially to a dry single-necked flask. After dissolving in ethanol (50 mL), a saturated ammonium chloride aqueous solution (6.15 mL) was slowly added dropwise at room temperature (25 °C). The mixture was stirred for 4 h, and the reaction progress was monitored by TLC. After the reaction was completed, the insoluble matter in the reaction solution was removed by filtration, and the filter cake was washed with ethyl acetate. The filtrates were combined, and the pH was adjusted to neutral with a saturated sodium bicarbonate aqueous solution. After standing and separation, the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A mixture of petroleum ether and ethyl acetate in a volume ratio of 4:1 was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound B3 (3.72 g, 90%).

[0091] The reaction equation is as follows:

[0092]

[0093] (iii) Preparation of intermediate compound B4

[0094] In a dry single-necked flask, anhydrous calcium chloride (5.50 g, 50 mmol) and DMAP (0.24 g, 2 mmol) were added sequentially and dissolved in anhydrous methanol (50 mL). Then, a pre-prepared calcium borohydride methanol solution (3.02 g, 8 mol / 50 mL) was added, followed by the slow dropwise addition of anhydrous tetrahydrofuran solution of intermediate B3 (4.14 g, 10 mmol). The reaction temperature was maintained at -5 °C throughout the addition. After the addition was complete, the reaction system was stirred at low temperature for another 3 hours. The reaction progress was monitored by TLC, and the reaction was stopped once the reactants had completely reacted. The reaction system was filtered (to remove undissolved salts), and the filter cake was washed with dichloromethane. The filtrate was then slowly added dropwise with a saturated ammonium chloride aqueous solution under vigorous stirring until the solution became clear. After separation, the organic layer was washed with saturated sodium bicarbonate aqueous solution until neutral, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and then separated by column chromatography. A 1:1 mixture of petroleum ether and ethyl acetate was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to give a white solid compound B4 (3.91 g, 94%).

[0095] The reaction equation is as follows:

[0096]

[0097] (iv) Preparation of intermediate compound B1

[0098] In a dry single-necked flask, 1.03 g of palladium-loaded calcium carbonate (10%), 4.55 g (45 mmol) of triethylamine, 2.07 g (45 mmol) of formic acid, and intermediate B4 (4.16 g, 10 mmol) were added sequentially. The mixture was dissolved in THF (50 mL) and stirred at 25 °C for 3 h. The reaction was monitored by TLC until intermediate B4 was completely reacted, at which point the reaction was stopped. The reaction mixture was filtered (to remove palladium / calcium carbonate), the filter cake was washed with dichloromethane, the pH of the filtrate was adjusted to neutral, the organic layer was collected, washed with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A 1:1 mixture of petroleum ether and ethyl acetate was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound B1 (2.63 g, 63%).

[0099] The reaction equation is as follows:

[0100]

[0101] Characterization data:

[0102] 1 H NMR(600MHz,Methanol-d4)δ:5.54–5.50(m,1H),3.94-3.92(m,1H),3.84-3 .83(t,1H),2.36–2.25(m,2H),2.14–1.94(m,4H),1.95–1.86(m,1H),1.77–1 .71(m,2H),1.69–1.52(m,4H),1.48(s,4H),1.38(m,3H),1.35–1.32(m,3H) ,1.27(m,2H),1.21(s,6H),1.05(s,3H),1.00(d,J=6.4Hz,3H),0.76(s,3H).

[0103] 13 C NMR(150MHz,Methanol-d4)δ139.33,125.27,73.57,71.47,66.97,58.14,57.61,45.32,43.53,42.62,42.58,42 .49,40.99,39.24,37.84,37.13,33.23,32.93,29.33,29.28,29.15,25.42,21.89,21.29,20.09,19.28,12.36.

[0104] Example 33 Preparation of intermediate C2 compound of the target product masalcalciferol intermediate (i) according to the synthesis method of the present invention

[0105] Add NaH (60%) (1.6 g, 40 mmol) to a dry double-necked flask. Dissolve (20S)-hydroxy-androst-1,4,6-trien-3-one (3.12 g, 10 mmol) (the synthesis method of (20S)-hydroxy-androst-1,4,6-trien-3-one is described in patent CN202210434236.0) in ultra-dry DMF (35 ml) and slowly add it dropwise to the reaction flask under nitrogen protection. Stir the reaction at 25 °C for 0.5 h, then add 1-bromomethyl-2,2-dimethyl-ethylene oxide (3.28 g, 20 mmol) (the synthesis method of 1-bromomethyl-2,2-dimethyl-ethylene oxide is described in Org. Process Res.Dev., 2005, 9(3): 278–287), stir the reaction for 3 h, and monitor the reaction progress by TLC. After the reaction was completed, a saturated ammonium chloride aqueous solution was added to quench the reaction. The mixture was extracted with ethyl acetate, and the organic layer was washed with saturated brine, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A mixture of petroleum ether and ethyl acetate in a volume ratio of 12:1 was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the mixture was dried to obtain a yellow oily compound.

[0106] The compound was then epoxidized with hydrogen peroxide under alkaline conditions to give compound C2. (The synthesis method of compound C2 is described in Acta Chimica Sinica, 2007, 65(16):1685-1692)

[0107] The reaction equation is as follows:

[0108]

[0109] (ii) Preparation of intermediate C3 compound

[0110] Compound C2 (4.12 g, 10 mmol) and zinc powder (13.08 g, 200 mmol) were added sequentially to a dry single-necked flask. After dissolving in ethanol (50 mL), a saturated ammonium chloride aqueous solution (6.15 mL) was slowly added dropwise at room temperature (25 °C). The mixture was stirred for 4 h, and the reaction progress was monitored by TLC. After the reaction was completed, the insoluble matter in the reaction solution was removed by filtration, and the filter cake was washed with ethyl acetate. The filtrates were combined, and the pH was adjusted to neutral with a saturated sodium bicarbonate aqueous solution. After standing and separation, the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A mixture of petroleum ether and ethyl acetate in a volume ratio of 3:1 was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound C3 (3.81 g, 92%).

[0111] The reaction equation is as follows:

[0112]

[0113] (iii) Preparation of intermediate C4 compound

[0114] In a dry single-necked flask, anhydrous calcium chloride (5.50 g, 50 mmol) and DMAP (0.24 g, 2 mmol) were added sequentially and dissolved in anhydrous methanol (50 mL). Then, a pre-prepared calcium borohydride methanol solution (3.02 g, 8 mol / 50 mL) was added, followed by the slow dropwise addition of anhydrous tetrahydrofuran solution of intermediate C3 (4.14 g, 10 mmol). The reaction temperature was maintained at -5 °C throughout the addition. After the addition was complete, the reaction system was stirred at low temperature for another 3 hours. The reaction progress was monitored by TLC, and the reaction was stopped once the reactants had completely reacted. The reaction system was filtered (to remove undissolved salts), and the filter cake was washed with dichloromethane. The filtrate was then slowly added dropwise with a saturated ammonium chloride aqueous solution under vigorous stirring until the solution became clear. After separation, the organic layer was washed with saturated sodium bicarbonate aqueous solution until neutral, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and then separated by column chromatography. A mixture of petroleum ether and ethyl acetate in a volume ratio of 1:1 was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound C4 (3.95 g, 95%).

[0115] The reaction equation is as follows:

[0116]

[0117] (iv) Preparation of intermediate C5 compound

[0118] Lithium aluminum hydride (0.57 g, 15 mmol) was added to a dry two-necked flask. Under nitrogen protection, it was dispersed with anhydrous tetrahydrofuran (20 mL) and then slowly added dropwise in anhydrous tetrahydrofuran solution of intermediate C4 (4.16 g, 10 mmol). The reaction was stirred at 75 °C for 1.5 h, and the reaction progress was monitored by TLC. The reaction was stopped after the starting materials had completely reacted. The reaction solution was cooled to 0 °C, and water (0.6 mL) was slowly added dropwise to quench the reaction. Then, 10% sodium hydroxide aqueous solution (0.6 mL) and water (1.8 mL) were added sequentially to convert the colloidal precipitate into a non-colloidal precipitate. The reaction system was filtered, the filter cake was washed with dichloromethane, separated, the organic layer was washed with saturated brine, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A mixture of petroleum ether and ethyl acetate in a volume ratio of 1:1 was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated and dried to obtain a white solid compound C5 (3.93 g, 94%).

[0119] The reaction equation is as follows:

[0120]

[0121] (v) Preparation of intermediate C1 compound

[0122] In a dry single-necked flask, 1.03 g of palladium-loaded calcium carbonate (10%), 4.55 g (45 mmol) of triethylamine, 2.07 g (45 mmol) of formic acid, and intermediate C5 (4.18 g (10 mmol) were added sequentially. The mixture was dissolved in 50 mL of THF and stirred at 25 °C for 3 h. The reaction was monitored by TLC until intermediate C4 was completely reacted, at which point the reaction was stopped. The reaction mixture was filtered (to remove palladium / calcium carbonate), the filter cake was washed with dichloromethane, the pH of the filtrate was adjusted to neutral, the organic layer was collected, washed with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and separated by column chromatography. A 1:1 mixture of petroleum ether and ethyl acetate was used as the eluent. The eluent containing the target compound was collected, the solvent was evaporated, and the eluent was dried to obtain a white solid compound C1 (2.86 g, 68%).

[0123] The reaction equation is as follows:

[0124]

[0125] Characterization data

[0126] 1H NMR(600MHz,Chloroform-d)δ5.58–5.57(m,1H),4.00–3.95(m,1H),3.86-3.81(m,2H),3.50– 3.46(m,1H),3.28-3.23(m,1H),2.39-2.35(m,1H),2.32-2.26(m,1H),2.10–2.05(m,1H),2.0 0–1.86(m,4H),1.74–1.70(m,3H),1.67–1.58(m,3H),1.55–1.45(m,3H),1.44–1.39(m,2H),1 .34–1.26(m,2H),1.24(s,3H),1.23(s,3H),1.19(d,J=6.0Hz,3H),1.02(s,3H),0.67(s,3H).

[0127] 13 C NMR(150MHz,Chloroform-d)δ137.58,125.43,78.96,72.98,70.70,66.32,65.62,56.79,56.24,41.82,41.6 9,41.55,41.53,41.50,38.73,38.34,31.86,31.68,29.41,29.08,26.62,24.39,20.10,19.57,18.88,12.56.

[0128] Examples 34-36

[0129] The synthesis steps were the same as in Example 1, except that compound A2 was replaced with compound D2 (synthesis method referred to patent CN119462808A), compound E2 (synthesis method referred to Steroids., 1977, 30(5): 671-677), and compound F2 (synthesis method referred to Chem. Pharm. Bull., 1982, 30(12): 4297-4303). The products and corresponding yields are shown in Table 1.

[0130] Table 1 shows the raw materials, products, and yields for Examples 34-36.

[0131]

[0132] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A method for synthesizing 1α-hydroxysterol compounds, comprising using 1α,2α-epoxy-ster-4,6-dien-3-one as shown in formula (2) as a raw material, and sequentially undergoing epoxide ring-opening, reduction, and hydrogenation reactions to obtain 1α-hydroxysterol compounds, characterized in that... Specifically, the steps include the following: (i) Epoxy ring opening Using 1α,2α-epoxy-ster-4,6-dien-3-one as shown in formula (2) as a raw material, a ring-opening reaction was carried out with zinc powder in an acidic medium in an organic solvent at a temperature of 0–75°C to obtain 1α-hydroxy-ster-4,6-dien-3-one as shown in formula (3). The reaction equation is as follows: (ii) Restore Under the action of catalyst A, the 1α-hydroxy-ster-4,6-dien-3-one obtained in step (i) is dissolved in an organic solvent and reduced with calcium borohydride at a temperature of -5 to 0 °C to obtain 1α,3β-ster-4,6-dien-1,3-diol as shown in formula (4). The reaction equation is as follows: (iii) Hydrogenation Under the action of catalyst B, the 1α,3β-steroid-4,6-diene-1,3-diol of formula (4) prepared in step (ii) is dissolved in an organic solvent and hydrogenated with an organic acid and triethylamine at a temperature of 0–75 °C to obtain a 1α-hydroxysteroid compound of formula (1). The reaction equation is as follows: Wherein, the substituent R is a C1 to C6 alkyl, cycloalkyl, haloalkyl, alkoxy or a C1 to C6 alkyl containing unsaturated bonds, heteroatoms or halogen substitution.

2. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... The molar ratio of zinc powder in step (i) to 1α,2α-epoxy-ster-4,6-diene-3-one shown in formula (2) is 10 to 30:1, preferably 15 to 20:

1.

3. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... The organic solvent in step (i) is methanol or ethanol, preferably ethanol; the acidic medium used is one of the following: acetic acid, hydrochloric acid, or saturated ammonium chloride aqueous solution, preferably saturated ammonium chloride aqueous solution; the volume ratio of the acidic medium to the mass ratio of 1α,2α-epoxy-ster-4,6-diene-3-one shown in formula (2) is 0.5 to 5 mL / g, preferably 1.0 to 1.5 mL / g.

4. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... In step (ii), the molar ratio of calcium borohydride to 1α-hydroxy-ster-4,6-dien-3-one shown in formula (3) is 2 to 10:1, preferably 4 to 6:

1.

5. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... The catalyst A in step (ii) is one of the following: DMAP, triethylamine, or pyridine, preferably DMAP; the molar ratio of the catalyst A to 1α-hydroxy-ster-4,6-dien-3-one shown in formula (3) is 0.1 to 0.4:1, preferably 0.2 to 0.25:

1.

6. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... The organic solvent in step (ii) is a mixture of one or more of the following solvents: methanol, tetrahydrofuran, diethyl ether, dichloromethane; preferably a mixture of methanol and tetrahydrofuran in a volume ratio of 0.5 to 1:

1.

7. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... In step (iii), the organic solvent is tetrahydrofuran, ethyl acetate, or N,N-dimethylformamide, preferably tetrahydrofuran.

8. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... In step (iii), the organic acid is formic acid or acetic acid, preferably formic acid; the molar ratio of the organic acid to 1α,3β-steroid-4,6-diene-1,3-diol as shown in formula (4) is 2 to 10:1, preferably 2.5 to 5:

1.

9. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... In step (iii), the molar ratio of triethylamine to 1α,3β-steroid-4,6-diene-1,3-diol as shown in formula (4) is 2 to 12:1, preferably 3 to 6:

1.

10. The method for synthesizing a 1α-hydroxysterol compound according to claim 1, characterized in that... The catalyst B in step (iii) is one of the following: palladium on carbon with a palladium loading of 5-15%, palladium calcium carbonate with a palladium loading of 5-15%, or palladium barium sulfate with a palladium loading of 5-10%, preferably palladium calcium carbonate with a palladium loading of 5-15%. The mass ratio of catalyst B to 1α,3β-steroid-4,6-diene-1,3-diol shown in formula (4) is 0.1-0.5:1, preferably 0.2-0.3:1.

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