Synthesis method of 25-hydroxysteroid compound, preparation method of side chain thereof and preparation method of side chain intermediate

Abstract

The invention discloses a method for synthesizing a 25-hydroxy steroid compound, a method for preparing a side chain thereof, and a method for preparing a side chain intermediate, screening of a halide L1 structure, screening of a Grignard reagent solvent, a suitable additive, and strict control of the reaction temperature, so that L1 suppresses the degradation and elimination of halide I during the Grignard reaction, improves the reaction yield and selectivity of halide I, and obtains halide I in high yield; thereby halide I improves the yield of halide II in the preparation of halide II. The method for synthesizing a 25-hydroxy steroid compound provided by the present invention, by splitting the 25-hydroxy steroid compound into two parts, a side chain halide II and a 5,7-diene intermediate, the side chain uses halide L1 as a raw material, and halide I is prepared by a specific method and then prepared into halide II, thereby increasing the product yield, and is prepared by one-pot cooking, and the process flow is simple, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of 25-hydroxysteroid compounds, and more specifically, to a method for synthesizing a 25-hydroxysteroid compound, a method for preparing a side chain thereof, and a method for preparing a side chain intermediate. Background Art

[0002] 25-hydroxyvitamin D3 is mainly obtained by total synthesis and semi-synthesis. The total synthesis method usually uses a reverse synthesis analysis method to split 25-hydroxyvitamin D3 into several simple small molecule fragments, and then selects a suitable synthesis method to splice them together. The chemical total synthesis method generally has the problems of too long synthesis route, difficult to obtain raw materials, high price, low total yield, low atomic utilization, etc., and its application prospects are poor. At present, the industrial production of 25-hydroxyvitamin D3 adopts a semi-synthetic method, and its synthesis route mainly uses steroid compounds with a structure similar to the vitamin D3 parent nucleus as raw materials, and then modifies the structure of its ring and side chain to obtain the target product, but the existing semi-synthetic method has the problems of expensive raw materials and low total yield.

[0003] In the synthesis of 25-hydroxyvitamin D3, the semi-synthetic method is obviously more valuable than the total synthesis method. The difficulty lies in the structural modification of natural steroid compounds to obtain 25-hydroxy-7-dehydrocholesterol (25-OH-7-DHC) and finally obtain the target product through light reaction. Summary of the invention

[0004] Based on the above technical problems existing in the prior art, the present invention provides a new method for synthesizing a 25-hydroxy steroid compound, which is split into two fragments:

[0005] 1. 5,7-Diene intermediate;

[0006] 2. Side chain halides II;

[0007] Finally, a 25-hydroxysteroid compound was obtained through a one-pot reaction of format coupling and hydrolysis;

[0008] Wherein, the 5,7-diene intermediate has the following structure:

[0009]

[0010] The side chain halide II has the following structure:

[0011]

[0012] Wherein, R1 is selected from one of -Ac, -THP, -TMS, and -H, and R2 is selected from one of -OTS, -Br, -Cl, and -I.

[0013] In the above scheme, the 25-hydroxysteroid compound is 25-hydroxy-7-dehydrocholesterol.

[0014] In the synthesis process of the side chain halide II, the halide L1 is very easy to be eliminated to generate enone under alkaline conditions because it contains α-H, resulting in a low yield when the Grignard reaction generates the halide I. Based on this, the present invention also provides a preparation method of the halide I (i.e., the side chain intermediate of the 25-hydroxysteroid compound). Through the method of the present invention, the reaction raw material halide L1 can inhibit the degradation and elimination of the halide I during the Grignard reaction, improve the yield and selectivity, and obtain the halide I with a high yield, thereby improving the yield of the halide I in the process of preparing the halide II by TMS protection, thereby improving the yield of the 25-hydroxysteroid compound.

[0015] In order to achieve the above object, the technical solution of the present invention is as follows:

[0016] The preparation method of the halide I comprises the following steps:

[0017] The first Grignard reagent is cooled to -20 to 20°C, an additive and a halide L1 are added in sequence, and a Grignard reaction is performed at -20 to 20°C to obtain a halide I; wherein the halide I has a structure of the following formula I, the halide L1 has a structure of the following formula II, the additive is at least one of anhydrous cupric chloride, anhydrous ferric chloride or anhydrous aluminum chloride; the first Grignard reagent is a solution of RX-Mg in one of tetrahydrofuran, ether, n-hexane and n-heptane;

[0018]

[0019] The R is one of -Me, -OMe, and -OEt, and the X is one of Cl and Br.

[0020] Specifically, the preparation of halide I comprises the following steps:

[0021] The first Grignard reagent is cooled to -20 to 20°C, the additive is added, and then the halide L1 is added dropwise. After the addition is completed, a Grignard reaction is carried out at -20 to 20°C, and then water is added dropwise for quenching, and then dilute hydrochloric acid is added for neutralization. The liquids are separated, and the obtained organic phase is concentrated until there are no droplets, thereby obtaining the halide I.

[0022] The present invention also provides a method for preparing the halide II (i.e., the side chain of the 25-hydroxysteroid compound), which comprises the following steps:

[0023] S1, preparing the halide I;

[0024] S2. Under nitrogen protection, the halide I is dissolved in DCM, then imidazole is added, the temperature is lowered to 0-10° C., and then TMSCl is added for reaction. After the reaction is completed, water is added for quenching, and the mixture is allowed to stand for separation. The obtained organic phase is halide II; wherein the halide II has the following structure of formula III:

[0025]

[0026] The method of step S1 is the above-mentioned preparation method.

[0027] The method for synthesizing a 25-hydroxysteroid compound provided by the present invention comprises the following steps:

[0028] The halide II and the 5,7-diene intermediate are subjected to a one-pot reaction of grignard coupling and hydrolysis to obtain 25-hydroxy-7-dehydrocholesterol; wherein the structure of the 5,7-diene intermediate is as shown in Formula VI:

[0029]

[0030] Wherein, R1 is selected from one of -Ac, -THP, -TMS, and -H, and R2 is selected from one of -OTS, -Br, -Cl, and -I; wherein the halide II is prepared by the above-mentioned preparation method.

[0031] In some embodiments, the method for synthesizing a 25-hydroxysteroid compound comprises the following steps:

[0032] 1) preparing the halide II;

[0033] 2) preparing a second grout reagent: adding magnesium and a first organic solvent into a reaction container, replacing with nitrogen, heating, and then adding 1,2-dibromoethane to react, and when the reaction becomes stable, raising the system temperature again, and dripping the halide II solution obtained in step 1), and keeping the temperature to react until the magnesium chips disappear, thereby obtaining a second grout reagent;

[0034] 3) Preparation of copper-lithium reagent: adding copper chloride and lithium chloride into a reaction vessel, then adding a second organic solvent, replacing with nitrogen, stirring until completely dissolved, to obtain a copper-lithium reagent, and protecting with nitrogen for standby use;

[0035] 4) preparing a 25-hydroxysteroid compound: cooling the second Grignard reagent obtained in step 2) to -20 to -15°C under nitrogen protection, slowly dropping the copper lithium reagent obtained in step 3), keeping the system temperature below -8°C during the dropping process, and keeping the temperature below -8°C after the dropping is completed to completely mix the two, to obtain a Grignard-copper lithium reagent; adding the 5,7-diene intermediate to the Grignard-copper lithium reagent under nitrogen protection, and after the complete addition, raising the temperature to keep the system temperature at 0 to 10°C and reacting;

[0036] 5) After the reaction in step 4) is completed, the reaction system is cooled to below -10°C, a saturated ammonium chloride solution is added to quench the reaction, and then the temperature is raised to room temperature, and then the temperature is lowered to 0-5°C, and glacial acetic acid is added; the temperature is raised again to concentrate and dry the solvent, the temperature is lowered to crystallize, filtered, the solid is dried, DCM / methanol is added to dissolve, the mixture is concentrated under reduced pressure, the material is replaced by methanol, the temperature is lowered to crystallize, and the obtained solid is rinsed with methanol and then dried to obtain a 25-hydroxysteroid compound.

[0037] In some embodiments, the first organic solvent and the second organic solvent are respectively one of tetrahydrofuran, diethyl ether, n-hexane, and n-heptane.

[0038] In some embodiments, in step 2), the mass ratio of magnesium, 1,2-dibromoethane and halide II is 1:5:9.

[0039] In some embodiments, in step 4), the mass ratio of the copper lithium reagent to the Grignard reagent is 1:10-20.

[0040] In some embodiments, in step 4), the mass ratio of the Grignard-copper lithium reagent to the 5,7-diene intermediate is 5 to 10:1.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention screens the structure of the halide L1, screens the solvent of the Grignard reagent, uses suitable additives and strictly controls the reaction temperature, so that L1 inhibits the degradation and elimination of the halide I during the Grignard reaction, improves the reaction yield and selectivity of the halide I, and obtains the halide I with high yield; thereby, the yield of the halide II is improved when the halide I is used to prepare the halide II.

[0043] In addition, the method for synthesizing 25-hydroxysteroid compounds provided by the present invention increases the product yield by splitting the 25-hydroxysteroid compounds into two parts, namely, a side chain halide II and a 5,7-diene intermediate, using halide L1 as a raw material, preparing halide I by a specific method, and then preparing halide II, and the method is prepared in one pot, so the process flow is simple and suitable for industrial production. DETAILED DESCRIPTION

[0044] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0046] Example 1

[0047]

[0048] Preparation of halide I (4-chloro-2-methyl-2-butanol) from halide L1 comprises the following steps:

[0049] 400 ml of a tetrahydrofuran solution (2M) of methylmagnesium chloride was cooled to -20°C, 0.5 g of anhydrous aluminum chloride was added, and 50 g of β-chlorobutanone was slowly added dropwise, with the temperature being controlled below -10°C during the addition process; after the addition was completed, the temperature was maintained at -10°C for 5 h, and then 50 ml of water was added dropwise for quenching; 200 ml of 10% dilute hydrochloric acid was added for neutralization, and the liquids were separated. The obtained organic phase was dried over anhydrous sodium sulfate, filtered, and the organic phase was concentrated under reduced pressure at 40°C until no liquid was dropped to obtain 4-chloro-2-methyl-2-butanol with a yield of 110%, no impurities shown by TLC, and a GC purity of more than 97%.

[0050] Example 2

[0051]

[0052] The preparation of halide II (4-chloro-2-methyl-2-trimethylsilyloxybutane) comprises the following steps:

[0053] S1, prepare 4-chloro-2-methyl-2-butanol by the method of Example 1;

[0054] S2. Under nitrogen protection, 40 g of 4-chloro-2-methyl-2-butanol prepared in step S1 and 250 ml of DCM were added to the reaction bottle, 66 g of imidazole was added under stirring, and then the temperature was lowered to 0-10 ° C, TMSCl was added dropwise, and the system temperature was maintained at about 5 ° C. After the addition, the temperature was maintained at 5-10 ° C for 1 hour, and monitored by TLC. After the reaction, 150 ml of water was added, stirred, allowed to stand for separation, dried over anhydrous sodium sulfate, and concentrated under reduced pressure at 40 ° C until there was no droplet to obtain halide II with a yield of 155%. TLC showed no impurities and the GC purity was greater than 96%.

[0055] Example 3

[0056]

[0057] The preparation of 25-dehydro-7-hydroxycholesterol comprises the following steps:

[0058] 1) Preparation of halide II: halide II was prepared by the method of Example 2;

[0059] 2) Preparation of Grignard reagent: Add 10g Mg and 140ml THF to a clean and dry reaction bottle, replace with nitrogen, stir and heat to about 40°C, then add 5g 1,2-dibromoethane, after the initiation reaction is completed and tends to be stable, heat the system to 60°C, slowly drop a mixture of 90g halide II and 140ml THF, and keep 60°C after the addition is complete until the magnesium chips disappear;

[0060] 3) Preparation of copper-lithium reagent: Add 2g copper chloride and 1.2g lithium chloride to a clean and dry reaction bottle, add 60ml THF under stirring, replace with nitrogen, and stir until all dissolved. At this time, the copper-lithium reagent is prepared and nitrogen protection is used for standby;

[0061] 4) The Grignard reagent prepared in step 2) is cooled to -20 to -15°C under nitrogen protection, and the copper lithium reagent prepared in step 3) is slowly added dropwise, and the system temperature is kept below -8°C during the addition process. After the addition is completed, it is kept below -8°C and stirred for 20 to 30 minutes to obtain a Grignard-copper lithium reagent; under nitrogen protection, 20 g of 5,7-diene intermediate solid is added to the Grignard-copper lithium reagent at a temperature below -8°C, and after the addition is completed, the temperature is slowly raised to 0 to 10°C for reaction;

[0062] 5) After the reaction of the raw materials is completed, the reaction system is cooled to below -10°C, 100 ml of saturated ammonium chloride solution is added dropwise to quench the reaction, and then the temperature is raised to room temperature and stirred until it turns blue, and then the temperature is lowered to 0-5°C, and 25 g of glacial acetic acid is added dropwise; the temperature is raised to concentrate the dry solvent, the temperature is lowered to crystallize and filter, the solid is dried, the dry solid is added with DCM\methanol to dissolve, concentrated under reduced pressure, methanol is replaced to dissolve the material, the temperature is lowered to crystallize, filtered, the solid is rinsed with a small amount of methanol, and dried at 50°C to obtain 25-hydroxy-7-dehydrocholesterol fine product.

[0063] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a side chain intermediate of a 25-hydroxysteroid compound, characterized in that: The following steps are involved: The first Grignard reagent is cooled to -20 to 20°C, an additive and a halide L1 are added in sequence, and a Grignard reaction is performed at -20 to -10°C to obtain a 25-hydroxysteroid compound side chain intermediate; wherein the 25-hydroxysteroid compound side chain intermediate has a structure of the following formula I, the halide L1 has a structure of the following formula II, the additive is at least one of anhydrous cupric chloride, anhydrous ferric chloride or anhydrous aluminum chloride; the first Grignard reagent is a solution of RX-Mg in one of tetrahydrofuran, ether, n-hexane and n-heptane; The R is -Me, and the X is one of Cl and Br.

2. The method for preparing a 25-hydroxysteroid compound side chain intermediate according to claim 1, characterized in that: The following steps are involved: The Grignard reagent is cooled to -20 to 20°C, the additive is added, and then the halide L1 is added dropwise. After the addition is completed, the Grignard reaction is carried out at -20 to -10°C, and then water is added dropwise for quenching, and then dilute hydrochloric acid is added for neutralization. The liquids are separated, and the obtained organic phase is concentrated until there are no droplets, thereby obtaining the 25-dehydrocholesterol side chain intermediate. 3.2 A method for preparing a side chain of a 5-hydroxysteroid compound, characterized in that: The following steps are involved: S1. preparing the 25-hydroxysteroid compound intermediate according to claim 1 or 2; S2. Under nitrogen protection, the 25-hydroxysteroid compound side chain intermediate is dissolved in DCM, then imidazole is added, the temperature is lowered to 0-10° C., and then TMSCl is added for reaction. After the reaction is completed, water is added for quenching, and the liquid is allowed to stand for separation. The obtained organic phase is the 25-hydroxysteroid compound side chain; wherein the 25-hydroxysteroid compound side chain has the following formula III structure: The method of step S1 is the preparation method according to claim 1 or 2.

4. A method for synthesizing a 25-hydroxysteroid compound, characterized in that: The following steps are involved: 1) preparing the 25-hydroxysteroid compound side chain by the method of claim 3; 2) preparing a second grout reagent: adding magnesium and a first organic solvent to a reaction container, replacing with nitrogen, heating, and then adding 1,2-dibromoethane to react, and when the reaction becomes stable, raising the system temperature again, and dripping the solution containing the side chain of the 25-hydroxysteroid compound obtained in step 1), and keeping the temperature to react until the magnesium chips disappear, thereby obtaining a second grout reagent; 3) Preparation of copper-lithium reagent: adding copper chloride and lithium chloride into a reaction vessel, then adding a second organic solvent, replacing with nitrogen, stirring until completely dissolved, to obtain a copper-lithium reagent, and protecting with nitrogen for standby use; 4) preparing a 25-hydroxysteroid compound: cooling the Grignard reagent obtained in step 2) to -15 to -20°C under nitrogen protection, slowly dropping the copper lithium reagent obtained in step 3), keeping the system temperature below -8°C during the dropping process, and keeping the temperature below -8°C after the dropping is completed to completely mix the two, to obtain a Grignard-copper lithium reagent; adding the 5,7-diene intermediate to the Grignard-copper lithium reagent under nitrogen protection, and after the complete addition, raising the temperature to keep the system temperature at 0 to 10°C and reacting; 5) After the reaction in step 4) is completed, the reaction system is cooled to below -10°C, a saturated ammonium chloride solution is added to quench the reaction, and then the temperature is raised to room temperature, and then the temperature is lowered to 0-5°C, and glacial acetic acid is added; the temperature is raised again to concentrate and dry the solvent, the temperature is lowered to crystallize, filtered, the solid is dried, DCM / methanol is added to dissolve, the product is concentrated under reduced pressure, methanol is replaced, the temperature is lowered to crystallize, and the obtained solid is washed with methanol and then dried to obtain a fine product of 25-hydroxysteroid compound; Wherein, the structure of the 5,7-diene intermediate is shown in Formula VI: Wherein, R1 is selected from one of -Ac, -THP, -TMS, and -H, and R2 is selected from one of -OTs, -Br, -Cl, and -I.

5. The method for synthesizing a 25-hydroxysteroid compound according to claim 4, characterized in that: The first organic solvent and the second organic solvent are respectively one of tetrahydrofuran, diethyl ether, n-hexane and n-heptane.

6. The method for synthesizing a 25-hydroxysteroid compound according to claim 4, characterized in that: In step 2), the mass ratio of magnesium, 1,2-dibromoethane and 25-hydroxysteroid compound side chain is 1:5:

9.

7. The method for synthesizing a 25-hydroxysteroid compound according to claim 4, characterized in that: In the step 4), the mass ratio of the copper lithium reagent to the Grignard reagent is 1:10-20.

8. The method for synthesizing a 25-hydroxysteroid compound according to claim 4, characterized in that: In step 5), the mass ratio of the grout-copper lithium reagent to the 5,7-diene intermediate is 5 to 10:1.

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