A preparation method of estradiol cypionate

Abstract

The present invention discloses a method for preparing estradiol cypionate. The method comprises acylation of estradiol in an aprotic polar solvent to obtain estradiol 3,17β-dicyclopentanepropionate, followed by hydrolysis in the presence of a base to obtain estradiol cypionate. The method has the advantages of being simple to operate, having a short production cycle, high yield, low production cost, and being environmentally friendly. Furthermore, the method has an overall yield of 85-95%, an HPLC purity of ≥99.5%, and is suitable for industrialization and promotion.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and in particular to a method for preparing estradiol cypionate. Background Art

[0002] Estradiol cypionate is a sex hormone. CAS: 313-06-4, its structural formula is:

[0003]

[0004] Estradiol cypionate comes in two types: α and β. The α type has a stronger physiological effect. The pharmacological effects of estradiol cypionate are essentially the same as those of estradiol. Estradiol can inhibit ovulation by reducing the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus, leading to a decrease in the release of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and luecotropic hormone (LH) from the pituitary gland. Reduced LH secretion in men can lead to decreased testosterone secretion in the testes.

[0005] Estradiol is a steroidal estrogen that exists in two types: α and β. The α type has a stronger physiological effect. Wintersteiner et al. (1935) extracted it from pregnant horse urine. It can also be obtained from pregnant women's urine, human placenta, and porcine ovaries. Currently, there are no reports on a preparation route for estradiol cypionate using estradiol as a raw material. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of estradiol cypionate, which uses estradiol as a raw material for preparation and synthesis, and promotes the industrial production of estradiol cypionate.

[0007] In view of this, the solution of the present invention is:

[0008] A method for preparing estradiol cypionate comprises the following steps:

[0009] S1. Estradiol is added to an aprotic polar solvent, an acylating agent is added, and an acid-binding agent is added with stirring. The reaction is incubated at 15-25°C for 24-72 hours. After the reaction, the mixture is quenched, separated, and washed. The organic phase is separated, concentrated, and dissolved to precipitate a solid to obtain the intermediate product, estradiol 3,17β-dicyclopentanepropionate.

[0010] S2. Add alkali to the intermediate product of step S1 in an alcohol solution, stir, heat to 40-50°C, and then keep the temperature to react for 2-3 hours. After the reaction is completed, cool it down, add water to precipitate, filter, and purify to obtain the estradiol cypionate.

[0011] Furthermore, the aprotic polar solvent is at least one of dichloromethane and ethyl acetate, and the ratio of estradiol to the aprotic polar solvent is 1 g: (10-15) ml.

[0012] Furthermore, the acylating agent is cyclopentyl propionic anhydride or cyclopentyl propionic acid chloride, and the ratio of the acylating agent to estradiol is (2.5-3) ml: 1 g.

[0013] Furthermore, the acid-binding agent is at least one of pyridine, triethylamine, and DMAP, and the ratio of the acid-binding agent to estradiol is (0.01-1) g:1 g.

[0014] Furthermore, the washing in step S1 uses a sodium bicarbonate solution with a concentration of 10 wt%, and the ratio of the sodium bicarbonate solution to estradiol is (5-5.5) ml: 1 g.

[0015] Furthermore, the alcohol solution in step S2 is methanol, and the ratio of methanol to estradiol 3,17β-dicyclopentane propionate is (5-15) ml:1 g.

[0016] Furthermore, in step S2, the base is at least one of sodium borohydride, sodium hydroxide, sodium carbonate, and sodium methoxide, and the ratio of the base to estradiol 3,17β-dicyclopentane propionate is (0.1-1) g:1 g.

[0017] Furthermore, after the reaction in step S2 is completed, the temperature is lowered to 10-20° C. and stirring is continued for 3 h.

[0018] Furthermore, the mass ratio of water added in the water-adding precipitation process in step S2 to estradiol 3,17β-dicyclopentanepropionate is (8-20):1.

[0019] Furthermore, in the purification process in step S2, anhydrous ethanol is used for recrystallization, and the ratio of anhydrous ethanol to estradiol cypionate is (2-4) ml: 1 g.

[0020] Compared with the prior art, the beneficial effects of the present invention include but are not limited to:

[0021] 1. The present invention uses estradiol as a raw material to synthesize estradiol cypionate through acylation and hydrolysis. At the same time, the process has the advantages of simple operation, short production cycle, high yield, low production cost, and environmental protection.

[0022] 2. The preparation method provided by the present invention has a yield of 85-95% and an HPLC purity of ≥99.5%. The solvent used in the preparation process is single and recyclable, making it suitable for industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a high performance liquid chromatogram of estradiol cypionate obtained by the preparation method of the present invention.

[0024] Figure 2 The figure is a hydrogen nuclear magnetic resonance spectrum of estradiol cypionate obtained by the preparation method of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and beneficial technical effects of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described in this specification are only for the purpose of explaining the present invention and are not intended to limit the present invention.

[0026] In one embodiment, a method for preparing estradiol cypionate (Formula I) is provided, and the process route is as follows:

[0027]

[0028] Specifically, the preparation method comprises the following steps:

[0029] 1) Estradiol (Formula II) is mixed with an aprotic polar solvent, an acylating agent is added, and an acid-binding agent is added under stirring, and the mixture is incubated at 15-25° C. for 24-72 hours. After the incubation period, the mixture is quenched with water, separated, washed twice with sodium bicarbonate solution, and then washed with water. The organic phase is separated, concentrated, dissolved in methanol, and the solid is washed with water to obtain the solid. The solid is filtered, washed with water, and dried to obtain the intermediate product estradiol 3,17β-dicyclopentanepropionate.

[0030] 2) The intermediate estradiol 3,17β-dicyclopentane propionate (Formula III) described in step 1) is mixed with methanol, a base is added, the mixture is heated to 40-50° C. with stirring, and then kept warm for 2-3 hours. After the reaction is completed, the mixture is cooled, water is added to precipitate, filtered, washed with water until neutral, and dried to obtain the target crude product.

[0031] 3) Recrystallizing the crude product in step 2) in anhydrous ethanol to prepare the estradiol cyclopentane propionate, i.e., 17β-estradiol dicyclopentane propionate.

[0032] The aprotic polar solvent is at least one of dichloromethane and ethyl acetate, and the ratio of estradiol to the aprotic polar solvent is 1 g: (10-15) ml. The acylating agent is cyclopentylpropionic anhydride or cyclopentylpropionic acid chloride, and the ratio of the acylating agent to estradiol is (2.5-3) ml: 1 g. The acid-binding agent is at least one of pyridine, triethylamine, and DMAP, and the ratio of the acid-binding agent to estradiol is (0.01-1) g: 1 g.

[0033] In the aforementioned step 1), the washing is performed using a 10 wt% sodium bicarbonate solution, and the ratio of the sodium bicarbonate solution to estradiol is (5-5.5) ml: 1 g.

[0034] In step 2), the ratio of methanol to estradiol 3,17β-dicyclopentane propionate is (5-15) ml:1 g. In step 2), the base is at least one of sodium borohydride, sodium hydroxide, sodium carbonate, and sodium methoxide, and the ratio of the base to estradiol 3,17β-dicyclopentane propionate is (0.1-1) g:1 g.

[0035] In step 2), after the reaction is completed, the temperature is lowered to 10-20° C. and the mixture is stirred for 3 hours. The mass ratio of water added during the water precipitation process to estradiol 3,17β-dicyclopentanepropionate is (8-20):1.

[0036] In the above-mentioned step 3), the ratio of anhydrous ethanol to estradiol cypionate is (2-4) ml:1 g.

[0037] The results of HPLC analysis of estradiol cypionate obtained by the above preparation method are as follows Figure 1 As shown, the HPLC purity of the purified estradiol cypionate is greater than 99.5%; the nuclear magnetic resonance hydrogen spectrum is as shown Figure 2 As shown, the characterization is as follows:

[0038] 1H NMR (400MHz, DMSO) δ8.99(s,1H),7.04(d,J=8.4Hz,1H),6.51(dd,J=8.4,2.6Hz,1H),6.44(d,J =2.6Hz,1H),4.62(dd,J=9.1,7.7Hz,1H),2.71(d,J=5.3Hz,2H),2.30(td,J=7.4,1.7Hz,2H),2 .24(dd,J=8.2,5.3Hz,1H),2.10(tdd,J=12.8,8.9,5.3Hz,2H),1.74(qd,J=21.1,9.9Hz,7H),1 .64–1.42(m,8H),1.33(dtd,J=22.2,14.3,7.6Hz,7H),1.08(s,1H),1.05(s,1H),0.78(s,3H).

[0039] The reaction mechanism of the present invention is as follows: a hydroxyl group undergoes an acylation reaction with an acid anhydride or an acid chloride to form a diester. Since the phenolic acid ester and the benzene ring are conjugated, the charge density on the carbonyl carbon is smaller, and the methoxy anion is more likely to attack the carbonyl carbon. Under alkaline conditions, a portion of the alcohol is selectively removed to form methyl valerate and estradiol cypionate.

[0040] It is worth noting that the synthetic pathway in the field of chemical synthesis not only needs to consider the feasibility of the product, but also the quality, such as product purity and yield indicators. Therefore, the impact of reaction tendency on product feasibility and impurity production needs to be considered. In industrial production, the integrity of the reaction pathway and the convenience of the operation process and its impact on quality should be fully considered. Usually, it is not possible to guarantee the quality by simply optimizing the intermediate process or simply replacing the raw materials through conventional known means. On the other hand, although the basic chemical reaction principles are well known to people in this field, there is uncertainty about the impact of the choice of pathway on the integrity. Therefore, the high quality of the product brought about by the integrity is not something that people in this field can reasonably infer through basic reaction principles.

[0041] The following are preparation examples of the present invention, the basic raw materials of which are standard commercially available chemicals.

[0042] Preparation Example of Intermediate Product Estradiol 3,17β-dicyclopentanepropionate (Formula III)

[0043] Preparation Example 1

[0044] 10g of estradiol was added to the reaction flask, 100mL of dichloromethane and 1g of DMAP were added, and 25ml of cyclopentyl propionyl chloride was added dropwise. The mixture was kept at 20℃ and stirred for 24h. TLC was monitored. After the reaction was complete, 20g of drinking water was added, stirred for 0.5h, allowed to stand for 10min, and the organic layer was separated. 50ml of 10% sodium bicarbonate solution was added to the organic layer, stirred for 0.5h, allowed to stand for 10min, and the organic layer was separated. 50ml of 10% sodium bicarbonate solution was added to the organic layer. The mixture was stirred for 0.5h, allowed to stand for 10min, and the organic layer was separated. 10% sodium bicarbonate solution, stirred for 0.5 hours, allowed to stand for 10 minutes, and the organic layer was separated. 20 g of drinking water was added to the organic layer, stirred for 0.5 hours, allowed to stand for 10 minutes, and the organic layer was separated. All solvents were concentrated in a water bath at 45°C, 20 g of methanol was added to dissolve, the temperature was lowered to 10°C, 30 g of water was added to precipitate the solid, stirred for 1 hour, filtered, washed with a small amount of water, and dried at 45°C to obtain the intermediate estradiol 3,17β-dicyclopentane propionate with an HPLC purity of 98.2% and a yield of 99.38%.

[0045] Preparation Example 2

[0046] Add 10g of estradiol to the reaction flask, add 150mL of ethyl acetate, 0.5g of triethylamine, and then drop 30ml of cyclopentane propionic anhydride, keep warm at 20℃, stir for 24h, monitor by TLC, after the reaction is complete, add 20g of drinking water, stir for 0.5h, let stand for 10min, separate the organic layer, add 50ml of 10% sodium bicarbonate solution, stirred for 0.5 hour, allowed to stand for 10 minutes, and the organic layer was separated. 50 ml of 10% sodium bicarbonate solution was added to the organic layer, stirred for 0.5 hour, allowed to stand for 10 minutes, and the organic layer was separated. 20 g of drinking water was added to the organic layer, stirred for 0.5 hour, allowed to stand for 10 minutes, and the organic layer was separated. All solvents were concentrated in a water bath at 45°C, 20 g of methanol was added to dissolve, the temperature was lowered to 10°C, a solid was precipitated, stirred for 2 hours, and filtered to obtain the intermediate estradiol 3,17β-dicyclopentanepropionate with an HPLC purity of 99.2% and a yield of 95.24%.

[0047] Preparation Example 3

[0048] 10 g of estradiol was added to a reaction flask, 120 mL of dichloromethane and 1 g of pyridine were added, and 25 ml of cyclopentyl propionyl chloride was added dropwise. The mixture was kept at 15° C. and stirred for 48 h. The reaction was monitored by TLC. After the reaction was complete, 20 g of drinking water was added, the mixture was stirred for 0.5 h, the mixture was allowed to stand for 10 min, and the organic layer was separated. 55 ml of 10% sodium bicarbonate solution was added to the organic layer, the mixture was stirred for 0.5 h, the mixture was allowed to stand for 10 min, and the organic layer was separated. 55 ml of 10% sodium bicarbonate solution was added to the organic layer, the mixture was stirred for 0.5 h, the mixture was allowed to stand for 10 min, and the organic layer was separated. 20 g of drinking water was added to the organic layer, the mixture was stirred for 0.5 h, the mixture was allowed to stand for 10 min, and the organic layer was separated. All solvents were concentrated in a water bath at 45° C. to obtain an oily intermediate estradiol 3,17β-dicyclopentyl propionate with an HPLC purity of 98.7%.

[0049] Preparation Example of Estradiol Cypionate

[0050] Example 1

[0051] To the reaction flask, 10 g of the intermediate estradiol 3,17β-dicyclopentane propionate obtained in Preparation Example 1 and 120 mL of methanol were added in sequence, stirred, 1 g of sodium borohydride was added, the temperature was raised to 50° C., and the reaction was kept warm for 2 h, monitored by TLC. After the reaction was completed, the temperature was lowered to 10° C., 200 ml of water was added, and the mixture was kept warm and stirred at 15° C. for 3 hours. The mixture was filtered, washed with water until neutral, and dried at 65° C. to obtain crude estradiol cyclopentane propionate with an HPLC purity of 98.7% and a yield of 98.48% based on the intermediate estradiol 3,17β-dicyclopentane propionate.

[0052] Example 2

[0053] To the reaction flask, 10 g of the intermediate estradiol 3,17β-dicyclopentane propionate obtained in Preparation Example 2 and 150 mL of methanol were added in sequence, stirred, 5 g of sodium hydroxide was added, the temperature was raised to 45°C, and the reaction was kept warm for 2.5 hours, monitored by TLC. After the reaction was completed, the temperature was lowered to 20°C, 200 ml of water was added, and the mixture was kept warm at 10°C and stirred for 3 hours. The mixture was filtered, washed with water until neutral, and dried at 65°C to obtain crude estradiol cyclopentane propionate with an HPLC purity of 99.2%. The yield based on the intermediate estradiol 3,17β-dicyclopentane propionate was 95.86%.

[0054] Example 3

[0055] To the reaction flask were added 10 g of the oily intermediate estradiol 3,17β-dicyclopentanepropionate obtained in Preparation Example 3 and 150 mL of methanol, stirred, 10 g of sodium borohydride was added, the temperature was raised to 40°C, and the reaction was kept warm for 3 h, monitored by TLC. After the reaction was completed, the temperature was lowered to 15°C, 150 ml of water was added, and the mixture was kept warm and stirred at 15°C for 3 hours. The mixture was filtered, washed with water until neutral, and dried at 65°C to obtain crude estradiol cyclopentanepropionate with an HPLC purity of 98.2% and a yield of 99.12% based on estradiol.

[0056] Example 4

[0057] 10 g of the intermediate estradiol 3,17β-dicyclopentane propionate and 100 mL of methanol were added to the reaction flask in sequence, stirred, 1 g of sodium borohydride and 5 g of sodium methoxide were added, the temperature was raised to 50°C, the reaction was kept warm for 2 h, and TLC was monitored. After the reaction was completed, the temperature was lowered to 10°C, 120 ml of water was added, and the mixture was kept warm and stirred at 10°C for 3 hours. The mixture was filtered, washed with water until neutral, and dried at 65°C to obtain crude estradiol cyclopentane propionate with an HPLC purity of 97.2%. The yield based on the intermediate estradiol 3,17β-dicyclopentane propionate was 91.9%.

[0058] Refined Example

[0059] 10 g of the crude estradiol cypionate obtained in Example 1-4 and 20 ml of anhydrous ethanol were added to the reaction flask in sequence. The mixture was heated to 65° C. under stirring to dissolve the clear solution. The mixture was cooled to 5° C. and stirred for 5 hours. The mixture was filtered and dried at 65° C. to obtain the finished estradiol cypionate. The HPLC purity was above 99.5%, and the total yield based on estradiol was 85-95%.

[0060] Comparative Example 1

[0061] 10 g of the intermediate estradiol 3,17β-dicyclopentane propionate obtained in Preparation Example 1 and 120 mL of methanol were added to the reaction flask in sequence, stirred, 10 g of sodium borohydride was added, the temperature was raised to 60° C., and the reaction was kept warm for 2 h, monitored by TLC. After the reaction was completed, the temperature was lowered to 10° C., 200 ml of water was added, and the mixture was kept warm at 15° C. and stirred for 3 hours. The mixture was filtered, washed with water until neutral, and dried at 65° C. to obtain crude estradiol cyclopentane propionate. The yield based on the intermediate estradiol 3,17β-dicyclopentane propionate was only 90%, and it was determined that estradiol was generated due to excessive hydrolysis.

[0062] Comparative Example 2

[0063] 10 g of the intermediate estradiol 3,17β-dicyclopentane propionate obtained in Preparation Example 2 and 150 mL of methanol were added to the reaction flask in sequence, stirred, 20 g of sodium hydroxide was added, the temperature was raised to 55° C., and the reaction was kept warm for 5 h, monitored by TLC. After the reaction was completed, the temperature was lowered to 20° C., 200 ml of water was added, and the mixture was kept warm at 10° C. and stirred for 3 hours. The mixture was filtered, washed with water until neutral, and dried at 65° C. to obtain crude estradiol cyclopentane propionate. The yield based on the intermediate estradiol 3,17β-dicyclopentane propionate was only 85%. It was determined that estradiol was generated due to excessive hydrolysis.

[0064] Comparative Example 3

[0065] 10 g of the oily intermediate estradiol 3,17β-dicyclopentane propionate obtained in Preparation Example 3 and 150 mL of methanol were added to the reaction flask in sequence, stirred, 10 g of sodium borohydride was added, the temperature was raised to 65° C., and the reaction was kept warm for 3 h, monitored by TLC. After the reaction was completed, the temperature was lowered to 15° C., 150 ml of water was added, and the mixture was kept warm at 15° C. and stirred for 3 hours. The mixture was filtered, washed with water until neutral, and dried at 65° C. to obtain crude estradiol cyclopentane propionate. The yield based on the intermediate estradiol 3,17β-dicyclopentane propionate was only 84%. It was determined that estradiol was generated due to excessive hydrolysis.

[0066] Preparation Examples 1-3 and Examples 1-4 above illustrate that this scheme uses estradiol as the starting material, undergoes an acylation reaction, and then selectively hydrolyzes one molecule of alcohol under appropriate conditions to form methyl valerate and estradiol cypionate. The resulting estradiol cypionate has a reasonable yield and high purity. Comparative Examples 1-3 demonstrate that, under alkaline conditions, exceeding the hydrolysis temperature or appropriately extending the hydrolysis time is detrimental to hydrolysis selectivity, resulting in the removal of two molecules of alcohol and the return of estradiol.

[0067] The present invention is not limited to what is described in the specification and embodiments, and additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the present invention is not limited to the specific details, representative schemes, and examples described herein without departing from the spirit and scope of the general concept defined by the claims and their equivalents.

Claims

1. A method for preparing estradiol cypionate, characterized in that: The steps include: S1. Estradiol is added to an aprotic polar solvent, an acylating agent is added, and an acid-binding agent is added with stirring. The reaction is incubated at 15-25°C for 24-72 hours. After the reaction, the mixture is quenched, separated, and washed. The organic phase is separated, concentrated, and dissolved to precipitate a solid to obtain the intermediate product, estradiol 3,17β-dicyclopentanepropionate. S2. The intermediate product of step S1 is added to an alcohol solution, a base is added, the temperature is raised to 40-50°C with stirring, and the reaction is kept warm for 2-3 hours. After the reaction, the temperature is lowered to 10-20°C and stirring is continued for 3 hours. Water is added to precipitate, filtered, and purified to obtain the estradiol cypionate; The aprotic polar solvent is at least one of dichloromethane and ethyl acetate, and the ratio of estradiol to the aprotic polar solvent is 1 g: (10-15) ml; The acid binding agent is at least one of pyridine, triethylamine, and DMAP, and the ratio of the acid binding agent to estradiol is (0.01-1) g:1 g.

2. The preparation method according to claim 1, characterized in that The acylating agent is cyclopentyl propionic anhydride or cyclopentyl propionic acid chloride, and the ratio of the acylating agent to estradiol is (2.5-3) ml:1 g.

3. The preparation method according to claim 1, characterized in that The washing in step S1 uses a sodium bicarbonate solution with a concentration of 10 wt %, and the ratio of the sodium bicarbonate solution to estradiol is (5-5.5) ml:1 g.

4. The preparation method according to claim 1, characterized in that The alcohol solution in step S2 is methanol, and the ratio of methanol to estradiol 3,17β-dicyclopentane propionate is (5-15) ml:1 g.

5. The preparation method according to claim 1, characterized in that In step S2, the base is at least one of sodium borohydride, sodium hydroxide, sodium carbonate, and sodium methoxide, and the ratio of the base to estradiol 3,17β-dicyclopentane propionate is (0.1-1) g:1 g.

6. The preparation method according to claim 1, characterized in that The mass ratio of water added in the water precipitation process in step S2 to estradiol 3,17β-dicyclopentane propionate is (8-20):

1.

7. The preparation method according to claim 1, characterized in that In the purification process of step S2, anhydrous ethanol is used for recrystallization, and the ratio of anhydrous ethanol to estradiol cypionate is (2-4) ml:1 g.

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