阅读说明：本技术 一种别孕烷醇酮有关物质的制备方法 (Preparation method of allopregnanolone related substance ) 是由 林成刚 张万朝 张洲洋 刘智慧 张翠霞 刘飞 于 2021-11-24 设计创作，主要内容包括：本发明涉及医药领域,本发明涉及医药领域,具体涉及一种别孕烷醇酮有关物质化合物2的制备方法,,所述方法包含以下步骤：(1)将化合物1与溶剂混合,在无机碱存在的条件下反应,反应完全后,调节pH至6～9,过滤得式3混合物,、；(2)在缚酸剂和催化剂存在的条件下,将所得的式3混合物与三氟乙酸酐反应,得到化合物4,；(3)将化合物4与溶剂混合,在催化剂存在的条件下,制备得到化合物2。(The invention relates to the field of medicines, in particular to a preparation method of an allopregnanolone related substance compound 2, the method comprises the following steps: (1) mixing the compound 1 with a solvent, reacting in the presence of an inorganic base, adjusting the pH value to 6-9 after the reaction is completed, filtering to obtain a mixture shown in a formula 3, 、 (ii) a (2) In the presence of acid-binding agent and catalystReacting the obtained mixture of formula 3 with trifluoroacetic anhydride to obtain a compound 4,)

1. A process for the preparation of Compound 2:

，

the method comprises the following steps:

(1) mixing the compound 1 with a solvent, reacting in the presence of an inorganic base, adjusting the pH value to 6-9 after the reaction is completed, filtering to obtain a mixture shown in a formula 3,

、；

(2) reacting the obtained mixture of the formula 3 with trifluoroacetic anhydride in the presence of an acid binding agent and a catalyst to obtain a compound 4,

；

(3) and mixing the compound 4 with a solvent, and preparing the compound 2 in the presence of a catalyst.

2. The preparation method of compound 2 according to claim 1, wherein in step (1), the inorganic base is selected from one of potassium carbonate, sodium carbonate, cesium carbonate, potassium hydroxide, sodium hydride, potassium phosphate, and sodium phosphate; the amount of the inorganic base is 1.0-8.0 molar equivalents.

3. The preparation method of compound 2 according to claim 1, wherein in step (1), the inorganic base is selected from one of potassium hydroxide, sodium hydroxide and sodium hydride; the amount of the inorganic base is 2.0-5.0 molar equivalents.

4. The preparation method of compound 2 according to claim 1, wherein in step (2), the acid-binding agent is selected from one of triethylamine and pyridine, the amount of the acid-binding agent is 1.05-2.0 molar equivalents, the catalyst is 4-dimethylaminopyridine, and the amount of the catalyst is 0.05-0.2 molar equivalents; the dosage of the trifluoroacetic anhydride is 1.0-2.0 mol equivalent.

5. The method for preparing compound 2 according to claim 1, wherein the trifluoroacetic anhydride is used in an amount of 1.1 to 1.5 molar equivalents in step (2).

6. The method for preparing the compound 2 according to claim 1, wherein in the step (3), the catalyst is sodium acetate, and the amount of the sodium acetate is 1.0-1.5 molar equivalents; the solvent is selected from one of methanol and ethanol or the combination thereof.

7. A process for the preparation of Compound 2:

，

the method comprises the following steps:

(1) reacting the obtained mixture of the formula 3 with trifluoroacetic anhydride in the presence of an acid binding agent and a catalyst to obtain a compound 4,

、；

(2) and mixing the compound 4 with a solvent, and preparing the compound 2 in the presence of a catalyst.

8. The preparation method of compound 2 according to claim 7, wherein in step (1), the acid-binding agent is selected from one of triethylamine and pyridine, the amount of the acid-binding agent is 1.05-2.0 molar equivalents, the catalyst is 4-dimethylaminopyridine, and the amount of the catalyst is 0.05-0.2 molar equivalents; the dosage of the trifluoroacetic anhydride is 1.0-2.0 mol equivalent.

9. The method for preparing compound 2 according to claim 7, wherein the trifluoroacetic anhydride is used in an amount of 1.1 to 1.5 molar equivalents in step (1).

10. The method for preparing the compound 2 according to claim 7, wherein in the step (2), the catalyst is sodium acetate, and the amount of the sodium acetate is 1.0-1.5 molar equivalents; the solvent is selected from one of methanol and ethanol or the combination thereof.

Technical Field

The invention relates to the field of medicines, in particular to a preparation method of allopregnanolone related substances, and particularly relates to a preparation method of 17 alpha-allopregnanolone.

Background

Allopregnanolone (brexanolone), chemical name: (3 alpha, 5 alpha) -3-hydroxy-pregn-20-one, the structural formula of which is shown as the following compound 1, is a neuroactive steroid substance. In 2019, SAGE Therapeutics, Inc. marketed allopregnanolone injection in the United states with the trade name: zulreso, marketed as indicated: adult postpartum depression (PPD).

Allopregnanolone and its derivatives are the hot spots of research in recent years, and several pharmaceutical companies are developing allopregnanolone derivatives. Allopregnanolone has been indicated to be GABA as early as 1986_APositive modulators of the receptor, allopregnanolone, may be primarily related to GABA_AThe alpha and beta subunits of the receptor combine to increase the opening frequency of chloride ion channels on the receptor and reduce the excitability of nerves, thereby producing the effects of tranquilization and antianxiety. Research shows that the reduction of allopregnanolone content is considered to be closely related to the occurrence and development of a plurality of mental disorders such as anxiety, depression and tremor, and the exogenous administration of allopregnanolone can remarkably improve the mental symptoms.

Any substance that affects the purity of a drug is collectively referred to as impurities, which typically include: organic impurities, inorganic impurities and residual solvents. Organic impurities are mainly impurities introduced by a production process or generated by substance degradation, and the chemical structure of the organic impurities is generally similar to or in a source relationship with active ingredients, so the organic impurities can be generally called related substances. "related substances" means "impurities which may be contained or generated during the production and normal storage of a given process and need to be controlled, and additional revision related items need to be considered when changing the production process".

Due to human safety concerns, both domestic and international drug regulatory agencies established very low impurity quality control limits before the commercialization of products of pharmaceutically active ingredients. The quality control limit for known impurities is typically 0.15%, but the quality control limit for unknown impurities will typically be less than 0.10%. The research of impurities is an important content of drug development, and comprises the steps of selecting a proper analysis method, accurately distinguishing and measuring the content of the impurities and determining the reasonable limit of the impurities by integrating the results of pharmaceutical, toxicological and clinical researches.

In the field of pharmaceutical quality analysis, chemical derivatives, synthesis by-products and degradation products of active pharmaceutical ingredients and impurities can be identified or quantified by spectroscopic, chromatographic or other physical methods. Before analyzing impurities in a compound, a substance with higher purity and the same or similar structure as the impurities is used as a reference marker, and the relative position of the reference marker in a chromatogram is taken as the relative position of the impurities in the chromatogram, so as to guide the impurity detection of the compound to be detected. Obviously, the selection and preparation of the reference marker has a direct impact on the scientificity and accuracy of the detection of the impurity content in the active pharmaceutical ingredient.

Disclosure of Invention

The invention aims to provide a preparation method of a high-purity allopregnanolone related substance compound 2 (namely 17 alpha-allopregnanolone), the preparation method is simple in preparation process, a chiral column is not needed for resolution, the prepared compound 2 is high in purity, post-treatment is convenient, and the preparation method is more suitable for industrial large-scale production.

In order to achieve the above purpose, the invention provides the following technical scheme:

in a first aspect, the present invention provides a process for the preparation of compound 2:

，

the method comprises the following steps:

(1) mixing the compound 1 with a solvent, reacting in the presence of alkali, adjusting the pH value to 6-9 after the reaction is completed, filtering to obtain a mixture shown in a formula 3,

、；

(2) reacting the resulting mixture of formula 3 with trifluoroacetic anhydride under reaction conditions sufficient to produce compound 4 to give compound 4,

；

(3) and mixing the compound 4 with a solvent, and preparing the compound 2 in the presence of a catalyst.

In some embodiments of the above method for preparing compound 2, wherein the compound of formula 3 refers to a mixture consisting of compound 1 and compound 2.

In some embodiments of the above method for preparing compound 2, in step (1), wherein the base is an inorganic base. In some embodiments, the inorganic base is selected from one of potassium carbonate, sodium carbonate, cesium carbonate, potassium hydroxide, sodium hydride, potassium phosphate, sodium phosphate. In some embodiments, the inorganic base is one of potassium hydroxide, sodium hydride. In certain embodiments, the inorganic base is used in an amount of 1.0 to 8.0 molar equivalents. In certain specific embodiments, the inorganic base is used in an amount of 2.0 to 5.0 molar equivalents.

In some embodiments of the above method for preparing compound 2, in step (1), wherein the solvent is one selected from methanol, ethanol, tetrahydrofuran; the step (1) reaction may be carried out under heating. In some embodiments, step (1), wherein the solvent is methanol; the step (1) reaction may be carried out by heating to 60 to 80 ℃, for example, may be carried out by heating to 60 to 70 ℃ and 70 to 80 ℃.

In some embodiments of the above method for producing compound 2, in step (2), wherein the reaction conditions comprise an acid-binding agent and a catalyst; the acid-binding agent is selected from one of triethylamine and pyridine, and the dosage of the acid-binding agent is 1.05-2.0 molar equivalent; the catalyst is 4-dimethylaminopyridine, and the dosage of the catalyst is 0.05-0.2 molar equivalent.

In some embodiments of the above method for preparing compound 2, in step (2), wherein trifluoroacetic anhydride is used in an amount of 1.0 to 2.0 molar equivalents; in some embodiments of the invention, trifluoroacetic anhydride is used in an amount of 1.1 to 1.5 molar equivalents.

In some embodiments of the above method for preparing compound 2, in step (2), wherein the solvent is selected from one of dichloromethane and tetrahydrofuran; in some embodiments of the invention, the solvent is selected from dichloromethane.

In some embodiments of the above method for preparing compound 2, in step (3), wherein the catalyst is sodium acetate, the amount of sodium acetate is 1.0 to 1.5 molar equivalents; the solvent is one or the combination of methanol and ethanol.

The specific reaction route of the preparation method of the compound 2 is as follows:

。

in a second aspect, the present invention also provides a process for the preparation of compound 2:

，

the method comprises the following steps:

(1) reacting the resulting mixture of formula 3 with trifluoroacetic anhydride under reaction conditions sufficient to produce compound 4 to give compound 4,

、；

(2) and mixing the compound 4 with a solvent, and preparing the compound 2 in the presence of a catalyst.

In some embodiments of the above method for preparing compound 2, wherein the compound of formula 3 refers to a mixture consisting of compound 1 and compound 2.

In some embodiments of the above method for preparing compound 2, in step (1), wherein the reaction conditions comprise an acid-binding agent and a catalyst; the acid-binding agent is selected from one of triethylamine and pyridine, and the dosage of the acid-binding agent is 1.05-2.0 molar equivalent; the catalyst is 4-dimethylaminopyridine, and the dosage of the catalyst is 0.05-0.2 molar equivalent.

In some embodiments of the above method for preparing compound 2, in step (1), wherein trifluoroacetic anhydride is used in an amount of 1.0 to 2.0 molar equivalents; in some embodiments of the invention, trifluoroacetic anhydride is used in an amount of 1.1 to 1.5 molar equivalents.

In some embodiments of the above method for preparing compound 2, in step (1), wherein the solvent is selected from one of dichloromethane and tetrahydrofuran; in some embodiments of the invention, the solvent is selected from dichloromethane.

In some embodiments of the above method for preparing compound 2, in step (2), wherein the catalyst is sodium acetate, the amount of sodium acetate is 1.0 to 1.5 molar equivalents; the solvent is one or the combination of methanol and ethanol.

The specific reaction route of the preparation method of the compound 2 is as follows:

。

has the advantages that:

the invention provides a preparation method of a high-purity compound 2, and the compound 2 prepared by the method has high purity and simple preparation method, and is suitable for industrial mass production. The compound 2 and the allopregnanolone are stereoisomers, the physical and chemical properties are very similar, the separation is difficult by using a conventional physicochemical method, and the separation and the purification are mostly carried out by a chiral high-performance liquid phase method. The purity of the compound 2 prepared by the preparation method of the compound 2 provided by the invention is more than 99.80%, and special resolution methods such as a chiral high-performance liquid phase method and the like are not needed, so that the preparation method is simple and is suitable for industrial production.

The high-purity compound 2 prepared by the method can be used as a reference marker during impurity detection of the allopregnanolone, can effectively improve the scientificity and accuracy of impurity detection of the allopregnanolone, the allopregnanolone derivatives and the preparations thereof, can effectively and conveniently monitor the impurity content of the allopregnanolone, the allopregnanolone derivatives and the preparations thereof, and ensures the safety and the effectiveness of the allopregnanolone, the allopregnanolone derivatives and the preparations thereof.

Detailed Description

The compounds of the general formula and the preparation and use thereof according to the present invention will be described in further detail with reference to the following examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Definitions and explanations

As used herein, the following terms and phrases are intended to have the following meanings unless otherwise indicated. A particular phrase or term should not be considered as ambiguous or unclear without special definition, but rather construed in a generic sense. When a trade name appears herein, it is intended to refer to its corresponding commodity or its active ingredient.

In the invention, the terms "acid", "peroxide" and "base" can be added directly to the reaction system, or can be diluted or prepared into a solution according to the operation habit of a person skilled in the art, and the amounts of the active ingredient substances are the same; the term "metal hydroxide" may be added in the form of containing no water of crystallization or containing water of crystallization during the reaction if it may contain water of crystallization, based on the same amount of substance.

In the present invention, the term "base" is intended to mean a chemical substance which is a proton acceptor. Suitable bases for use in the present invention are inorganic bases. Examples of inorganic bases include, but are not limited to, potassium hydroxide (KOH), potassium carbonate (K)₂CO₃) Sodium carbonate (Na)₂CO₃) Cesium carbonate (Cs)₂CO₃) Sodium hydride (NaH), potassium phosphate (K)₃PO₄) Sodium phosphate (Na)₃PO₄) And the like.

The term "reaction conditions" is meant to indicate physical and/or environmental conditions under which a chemical reaction is carried out, including, but not limited to, one or more of the following: reaction temperature, solvent, pH, pressure, reaction time, molar ratio of reactants (expressed as molar equivalents), acid or base, presence or absence of catalyst, type of catalyst, and the like. Reaction conditions may be named after the particular chemical reaction in which the conditions are used, e.g., coupling conditions, hydrogenation conditions, acylation conditions, reduction conditions, deuteration conditions, and the like.

In the present invention, "allopregnanolone" and "compound 1" may be used interchangeably and refer to a compound having the structure of formula 1 below:。

in the present invention, "17 α -allopregnanolone" and "compound 2" are used interchangeably and refer to compounds having the structure of formula 2 below:。

the reaction route of the preparation method of the compound shown in the formula 2 provided by the invention is as follows:

。

the inventors of the present invention found in the process of preparing compound 2 that the resulting mixture 3 was a mixture of compound 1 (i.e. allopregnanolone) and compound 2 (i.e. 17 α -allopregnanolone). The compound 2 and the compound 1 are stereoisomers, the physical and chemical properties are very similar, the inventor tries various conventional physical and chemical methods to separate the compound 2 from the compound 1 difficultly, and finally finds that the compound 2 can be separated and purified from the mixture 3 by a chiral chromatographic column high performance liquid method, but the chiral chromatographic column high performance liquid method is difficult to apply to industrial production.

The inventors finally found that the reaction of mixture 3 with trifluoroacetic anhydride allows for efficient isolation of compound 4, and then attempted hydrolysis of compound 4 under different reaction conditions to produce compound 2. The inventors have surprisingly found that when sodium acetate is used as a catalyst for hydrolysis of compound 4, compound 2 with high purity can be obtained, compound 1 is not generated basically, and the compound 2 prepared by the method for preparing compound 2 provided by the invention has purity of more than 99.80% and is not generated basically by compound 1.

The intermediate compounds of the present invention may be prepared by a variety of synthetic methods well known to those skilled in the art, including the specific embodiments listed below, embodiments formed by combinations thereof with other chemical synthetic methods, and equivalents thereof well known to those skilled in the art, with preferred embodiments including, but not limited to, the examples of the present invention.

The chemical reactions of the embodiments of the present invention are carried out in a suitable solvent that is compatible with the chemical changes of the present invention and the reagents and materials required therefor. In order to obtain the compounds of the present invention, it is sometimes necessary for a person skilled in the art to modify or select the synthesis steps or reaction schemes based on the existing embodiments.

The present invention will be specifically described below by way of examples, which are not intended to limit the present invention in any way.

The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. Unless otherwise indicated, percentages and parts are by weight, and the starting materials and reagents used in the following examples are commercially available or may be prepared by known methods.

The test method comprises the following steps:

high Performance Liquid Chromatography (HPLC) analytical methods:

the used instruments are: an angiolent high performance liquid chromatograph 1260, wherein the chromatographic column is Phenomenex-ACE Excel 3C 18-AR 4.6mm multiplied by 150 mm;

the measurement conditions were as follows:

sample introduction volume: 20 mu l of the mixture;

flow rate: 1.0 ml/min;

detection wavelength: 200 nm;

sample concentration: 5.0 mg/ml;

diluting liquid: methanol;

column temperature: 15 ℃;

mobile phase A: water;

mobile phase B: acetonitrile;

the elution gradient is shown in table 1 below:

TABLE 1

Time (min)	%A	%B
			0	60	40
20	20	80
			25	5	95
35	5	95
			35.1	60	40
45	60	40

Preparation of mixture 3

Example 1 preparation of mixture 3

400.0 g of Compound 1 (1256 mmol) and 6000 mL of MeOH were added to a 10L three-necked flask, and the mixture was dissolved with stirring. 100.8 g of NaOH (2520 mmol, 2.0 eq) was dissolved in 400mL of pure water and added to the above system. The reaction system was turbid and a solid precipitated. Heating to 60-80 ℃, stirring for reaction, gradually clarifying the reaction system, and continuously heating and stirring for reaction for more than 48 hours. Cooling, stopping reaction, adjusting pH of the reaction solution to about 6-8 with 1 mol/L HCl, further cooling to room temperature, stirring, precipitating solid, filtering, washing filter cake with cold methanol/water mixed solvent (V/V5: 1), pumping filter cake to obtain mixture 3 (395.0 g), wherein the mixture 3 is a mixture containing compound 1 and compound 2, and the content of compound 2 is about 28.2% by HPLC.

Example 2 preparation of mixture 3

A1.0L three-necked flask was charged with 40.00 g of Compound 1 (125.6 mmol) and 600 mL of EtOH, and the mixture was dissolved with stirring. 35.23g of KOH (628 mmol, 5.0 eq) was weighed out and dissolved in 40 mL of pure water, and this was added to the above system. The reaction system was turbid and a solid precipitated. Heating to 70-80 deg.C, stirring for reaction, clarifying the reaction system, and continuously heating and stirring for reaction for more than 48 h. Cooling, stopping reaction, adjusting the pH of the reaction solution to about 6-8 by using 1 mol/L HCl, further cooling to room temperature, stirring, separating out a solid, filtering, washing a filter cake by using a cold ethanol/water mixed solvent (V/V15: 1), and draining the filter cake to obtain a mixture 3 (39.52 g), wherein the mixture 3 is a mixture containing a compound 1 and a compound 2, and the content of the compound 2 is about 26.4%.

Example 3 preparation of mixture 3

To a 1.0L three-necked flask, 4.00 g of Compound 1 (12.6 mmol) and 60 mL of MeOH were added, and the mixture was dissolved with stirring. 4.02g of NaOH (100.5 mmol, 8.0 eq) was weighed out and dissolved in 5mL of pure water, and added to the above system. The reaction system was turbid and a solid precipitated. Heating to 70-80 deg.C, stirring for reaction, clarifying the reaction system, and continuously heating and stirring for reaction for more than 48 h. Cooling, stopping reaction, adjusting pH of the reaction solution to about 6-8 with 1 mol/L HCl, further cooling to room temperature, stirring, precipitating solid, filtering, washing filter cake with cold methanol/water mixed solvent (V/V12: 1), pumping filter cake to dry to obtain mixture 3 (3.92 g), wherein the mixture 3 is a mixture containing compound 1 and compound 2, and the content of compound 2 is about 25.3% by HPLC (high performance liquid chromatography).

Preparation of Compound 4

Example 4 preparation of Compound 4

390.0 g of mixture 3 (prepared by the method of example 1, 1224 mmol) and 3900 mL of THF were added to a 1L three-necked flask and dissolved with stirring. 136.2 g triethylamine (1346 mmol, 1.1 eq) and 7.48g DMAP (61 mmol, 0.05 eq) were added under nitrogen. The three-necked flask was placed in an ice-water bath, 282.8 g of trifluoroacetic anhydride (1839 mmol, 1.1 eq) was slowly added dropwise and the reaction was continued with stirring until the reaction was complete. After completion of the reaction, the reaction mixture was poured into 2000 mL of ice water to quench the reaction, stirred for 10min, and then the liquid was separated, and the organic phase was washed 2 times with pure water (2000 mL × 2). The solvent was removed under reduced pressure from the organic phase to give 600.0 g of a solid, which was subjected to column chromatography (V petroleum ether (60-90): V ethyl acetate = 100: 1) to give a compound 4 (100.2 g) having a purity of 99.93% by crystallizing the compound with 200ml heptane, cooling to-20 to-10 ℃, filtering, and drying.

¹H-NMR (500 MHz, CDCl3) δ5.24 (m, 1H), 2.82-2.80 (dd, 1H), 2.14 (s, 3H) 1.94-1.92 (m, 1H), 1.84-1.80 (m, 2H), 1.80-1.13 (m, 17H), 1.10-1.02 (m, 1H), 0.94 (s, 3H), 0.80 (s, 3H), 0.76(m,1H)。MS m/z: 437.22 [M+Na]⁺。

Example 5 preparation of Compound 4

39.00 g of mixture 3 (prepared by the method of example 2, 122.4 mmol) and 390 mL of methylene chloride were put into a 1L three-necked flask, and dissolved by stirring. 17.34 g triethylamine (171.36 mmol, 1.40 eq) and 1.50 g DMAP (12.3 mmol, 0.10 eq) were added under nitrogen. The three-necked flask was placed in an ice-water bath, 38.63 g of trifluoroacetic anhydride (183.9 mmol, 1.50 eq) was slowly added dropwise, and the reaction was continued with stirring until the reaction was complete. After completion of the reaction, the reaction mixture was poured into 200mL of ice water to quench the reaction, stirred for 10min, and the organic phase was separated and washed 2 times with pure water (200 mL. multidot.2). The solvent was removed under reduced pressure from the organic phase to give 60.0g of a solid, which was separated by column chromatography (V petroleum ether (60-90): V ethyl acetate = 100: 1), and the resulting compound was crystallized from 20ml of heptane, cooled to-20 to-10 ℃ and filtered to give compound 4 (10.98 g) with a purity of 99.94%.

Example 6 preparation of Compound 4

39.00 g of mixture 3 (prepared by the method of example 2, 122.4 mmol) and 390 mL of methylene chloride were put into a 1L three-necked flask, and dissolved by stirring. 24.77g triethylamine (244.8 mmol, 2.00 eq) and 2.99 g DMAP (24.5 mmol, 0.20 eq) were added under nitrogen. The three-necked flask was placed in an ice-water bath, 51.42 g of trifluoroacetic anhydride (244.8 mmol, 2.00 eq) was slowly added dropwise, and the reaction was continued with stirring until the reaction was complete. After completion of the reaction, the reaction mixture was poured into 200mL of ice water to quench the reaction, stirred for 10min, and the organic phase was separated and washed 2 times with pure water (200 mL. multidot.2). The solvent was removed under reduced pressure from the organic phase to give 60.0g of a solid, which was separated by column chromatography (V petroleum ether (60-90): V ethyl acetate = 100: 1), and the resulting compound was crystallized from 20ml of heptane, cooled to-20 to-10 ℃, and filtered to give compound 4 (9.96 g) with a purity of 99.92%.

Preparation of compound 2:

example 7

To a 250 mL single vial was added 8.5g of Compound 4 (prepared by the method of example 4, 20.50 mmol), 51mL of MeOH, and 1.68 g of anhydrous sodium acetate (20.50 mmol, 1.00 eq), and after the addition was complete, the reaction was heated and stirred under reflux until the reaction was complete. The reaction solution was cooled to room temperature, 42.5 mL of pure water was added dropwise, stirred, a solid was precipitated, filtered, and the filter cake was washed with a methanol/water mixed solvent (V)_MeOH:V_H2O=1: 1), pure compound 2 was obtained after drying (6.09 g, yield 93.2%) with a purity of 99.91%.

¹H-NMR (500 MHz, CDCl3) δ 4.05 (s, 1H), 2.82-2.80 (dd, 1H), 2.14 (s, 3H) 1.94-1.92 (m, 1H), 1.84-1.80 (m, 1H), 1.78-1.59 (m, 6H), 1.55-1.42 (m, 4H), 1.42-1.28 (m, 5H), 1.27-1.13 (m, 4H), 1.10-1.02 (m, 1H), 0.94 (s, 3H), 0.80 (s, 3H), 0.76(m,1H)。

¹³C NMR (500MHz,CDCl3) δ 212.60, 66.42, 61.40, 53.59, 50.37, 45.77, 38.96, 36.06, 35.89, 35.72, 35.35, 32.70, 32.20, 32.15, 28.96, 28.51, 25.84, 24.27, 20.93, 20.70, 11.09. MS m/z: 341.24 [M+Na]⁺。

Example 8

In a 100mL single-neck flask were added 4.15g of Compound 4 (10.0 mmol prepared in example 4), 25 mL of EtOH, and 0.984 g of anhydrous sodium acetate (12.0 mmol, 1.20 eq), and after the addition was completed, the reaction was heated and refluxed with stirring until the reaction was completed. The reaction solution was cooled to room temperature, 20.8 mL of pure water was added dropwise, stirred, a solid was precipitated, filtered, and the filter cake was washed with an ethanol/water mixed solvent (V)_EtOH:V_H2O=1: 1), and drying to obtain a pure product of the compound 2 (2.95 g yield)The rate was 92.8%), and the purity was 99.93%.

Example 9

To a 100mL single-neck flask were added 4.15g of Compound 4 (10.0 mmol prepared in example 4), 24.9 mL of MeOH, and 0.984 g of anhydrous sodium acetate (12.0 mmol, 1.20 eq), and after the addition was completed, the reaction was heated and stirred under reflux until the reaction was complete. The reaction solution was cooled to room temperature, 20.8 mL of pure water was added dropwise, stirred, a solid was precipitated, filtered, and the filter cake was washed with a methanol/water mixed solvent (V)_MeOH:V_H2O=1: 1), and the pure product of the compound 2 is obtained after drying (2.94 g yield 92.6%) and the purity is 99.90%.

Example 10 comparative experiment with different bases as hydrolysis conditions

According to the preparation method of example 7, 1.0eq of inorganic bases (sodium acetate, sodium benzoate, sodium bicarbonate and sodium hydroxide, respectively) are respectively used as hydrolysis reaction catalysts, and the yield and purity of the compound 2 corresponding to each inorganic base are measured, and the specific results are shown in the following table 2.

The specific reaction steps are as follows: to a 250 mL single neck flask were added 8.5g of Compound 4 (20.50 mmol, prepared by the method of example 4), 51mL of MeOH, and 1.00 eq of inorganic base (sodium acetate, sodium benzoate, sodium bicarbonate, sodium hydroxide), and after the addition was complete, the reaction was heated, stirred, and refluxed until the reaction was complete. The reaction solution was cooled to room temperature, 42.5 mL of pure water was added dropwise, stirred, a solid was precipitated, filtered, and the filter cake was washed with a methanol/water mixed solvent (V)_MeOH:V_H2OAnd =1: 1), drying to obtain the compound 2, weighing, calculating the yield, and detecting the purity by HPLC.

TABLE 2 comparison of the hydrolysis experiments catalyzed by different inorganic bases

Serial number	Inorganic base species	Yield of Compound 2 (%)	Purity of Compound 2 (%)	Content of Compound 1 (%)
					1	Sodium acetate	93.2%	99.91	Not detected out
2	Sodium benzoate	92.1%	99.56	0.26%
					3	Sodium bicarbonate	91.7%	99.15	0.74%
4	Sodium hydroxide	90.6%	99.35	0.43%

As can be seen from the data in Table 2 above, when sodium acetate is used as the hydrolysis catalyst, the obtained compound 2 has high purity and good yield, and is suitable for industrial production. The preparation of the high-purity compound 2 can greatly promote the quality control of the allopregnanolone, the allopregnanolone derivatives and the pharmaceutical preparations, and ensure the safety of the medicaments.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.