The invention relates to a preparation method of 17-(4apos; preparation method and application of-phenylphenyl)-estra-1, 3, 5 (10)-triene-3, 17beta-diol

Abstract

The invention discloses a preparation method of 17-(4 '-phenyl phenyl)-estra-1, 3, 5 (10)-triene-3, 17 beta-diol and an application of the 17-(4'-phenyl phenyl)-estra-1, 3, 5 (10)-triene-3, 17 beta-diol. The method comprises the following steps: by taking estrone as an initial raw material, carrying out hydroxyl protection, carrying out lithium-halogen exchange on n-butyllithium and 4-bromodiphenyl to generate a high-activity biphenyl lithium intermediate, then carrying out nucleophilic addition on the high-activity biphenyl lithium intermediate and a protected estrone derivative, and finally, carrying out hydrolysis deprotection to obtain a target product. According to the method, a traditional and low-efficiency Grignard reaction route is successfully replaced with a lithium-halogen exchange strategy, the technical bottlenecks that the steric hindrance of a substrate is large and the reaction is difficult to carry out are overcome, the method has the advantages of being easy and convenient to operate, mild in reaction condition, high in product yield and good in purity, and a reliable scheme is provided for preparing the key impurity standard substance.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical chemical synthesis technology, specifically to a method for preparing and applying 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol. Background Technology

[0002] As a commonly used intermediate in clinical estrogen drugs, the quality of estradiol directly affects the safety and efficacy of medication. 17-(4'-phenylphenyl)-estrost-1,3,5(10)-trien-3,17β-diol is a characteristic impurity generated during the production of estradiol due to raw material residues or side reactions. This impurity has estrogen-like activity, which may interfere with the efficacy of estradiol, and long-term intake poses potential safety risks. Therefore, it needs to be strictly limited in drug quality standards. Currently, there are few publicly reported methods for synthesizing this specific impurity. Existing estradiol impurity synthesis methods mostly focus on simple methylation and hydroxylation products, which cannot meet the demand for standards of complex aromatic ring substituted impurities. Traditional aromatic ring coupling reactions have problems such as poor regioselectivity, large catalyst dosage, and low product purity, making it difficult to efficiently prepare this impurity. Therefore, developing a highly selective and high-yield method for synthesizing 17-(4'-phenylphenyl)-estrost-1,3,5(10)-triene-3,17β-diol is of great significance for improving the impurity control system of estradiol. Summary of the Invention

[0003] In view of this, the present invention provides a new preparation method using n-butyllithium for lithium-halogen exchange reaction to achieve efficient and high-purity preparation of 17-(4'-phenylphenyl)-estrate-1,3,5(10)-triene-3,17β-diol, in order to meet the requirements for impurity standards in the quality control of estradiol pharmaceuticals.

[0004] On the one hand, this invention proposes a method for preparing 17-(4'-phenylphenyl)-estrate-1,3,5(10)-triene-3,17β-diol. The process route of this invention is as follows:

[0005] The technical solution of this invention is implemented as follows: S1. Using estrone as a raw material, compound 1 is obtained by reaction, and an organic solution of compound 1 is prepared. S2. Mix the organic solution of compound 1, the organic solution of n-butyllithium and 4-bromo-biphenyl, and react to obtain compound 2; S3. 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol was further prepared from compound 2.

[0006] Based on the above technical solution, preferably, in step S1, estrone is reacted with acetyl chloride under alkaline conditions to obtain compound 1.

[0007] More preferably, in step S1, the reagents used for the alkaline conditions are triethylamine or pyridine, 4-dimethylaminopyridine, potassium carbonate, and sodium carbonate.

[0008] More preferably, in step S1, the estrone equivalent is 1, and the acetyl chloride equivalent is 1.1~2, preferably 1.3~1.5.

[0009] More preferably, in step S1, the reaction temperature is -10~30℃, more preferably 0~10℃.

[0010] More preferably, in steps S1 and S2, the organic solvent is either tetrahydrofuran or acetonitrile.

[0011] Based on the above technical solution, preferably, in step S2, under inert gas protection and a temperature range of -75 to -40°C, 4-bromobiphenyl undergoes a lithium-halogen exchange reaction with an organolithium reagent to generate a biphenyl lithium intermediate; subsequently, the biphenyl lithium intermediate undergoes a nucleophilic addition reaction with compound 1 to obtain compound 2.

[0012] More preferably, in step S2, the lithium-halogen exchange reaction and the nucleophilic addition reaction are carried out in a tetrahydrofuran solvent.

[0013] More preferably, in step S2, the tetrahydrofuran solution of compound 1 is added dropwise after the n-butyllithium and 4-bromobiphenyl are mixed. The main purpose is to allow the n-butyllithium to undergo a lithium-halogen exchange reaction with 4-bromobiphenyl first, which requires the formation of a biphenyl lithium active intermediate. Then, the biphenyl lithium active intermediate reacts with compound 1 to obtain compound 2. This avoids the direct attack of n-butyllithium on compound 1, reduces impurity formation, and ensures the selectivity of the reaction.

[0014] More preferably, in step S2, the 4-bromo-biphenyl equivalent is 1, and the n-butyllithium equivalent is 1.2~1.7, preferably 1.4~1.5.

[0015] Furthermore, step S2 utilizes the strong basicity and nucleophilicity of n-butyllithium, as well as the promoting and stabilizing effects of tetrahydrofuran solvent, to achieve a specific organic transformation. This step requires n-butyllithium to first react with 4-bromobiphenyl to form a biphenyllithium intermediate as a strong nucleophile before further reaction to obtain compound 2. Therefore, the tetrahydrofuran solution of compound 1 must be added last; otherwise, the purity of compound 2 will be poor. Under optimized reaction conditions, the target product compound 2 can be obtained with high yield and purity. The generated biphenyl metal reagent exhibits stronger nucleophilicity and stability, which is more conducive to the formation of compound 2. Moreover, it eliminates the need for other initiating reagents, lowers the reaction temperature, reduces side reactions, and simplifies subsequent purification.

[0016] More preferably, in step S2, the reaction temperature is -75~-40℃, more preferably -65~-55℃.

[0017] More preferably, in step S2, the reaction is carried out under the protection of an inert gas, wherein the inert gas is nitrogen.

[0018] Based on the above technical solution, preferably, in step S3, the compound 2 is hydrolyzed under alkaline conditions to remove the hydroxyl protecting group and obtain the 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol.

[0019] More preferably, in step S3, the reagent used for the alkaline condition is sodium hydroxide or potassium hydroxide or potassium carbonate.

[0020] More preferably, in step S3, the equivalent of compound 2 is 1, and the equivalent of sodium hydroxide is 1.2 to 1.9, preferably 1.4 to 1.5.

[0021] More preferably, the reaction temperature in step S3 is 30~80℃, more preferably 60~70℃.

[0022] On the other hand, 17-(4'-phenylphenyl)-estrone-1,3,5(10)-triene-3,17β-diol, prepared by the above method, is used as a standard for impurity detection in the production process of estrone.

[0023] The method for preparing 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol proposed in this invention has the following advantages over the prior art: (1) The method of synthesizing compound 2 using n-butyllithium is superior to other methods in terms of product purity and reaction yield. The advantage of this route is that the biphenyllithium intermediate generated has a nucleophilicity far superior to that of Grignard reagents, which can effectively overcome the steric hindrance of the substrate, thereby ensuring that the nucleophilic addition reaction proceeds smoothly.

[0024] (2) Avoid using Grignard reagents. The preparation of Grignard reagents, especially for less reactive haloalkanes, usually requires the addition of reagents such as iodine and 1,2-dibromoethane as initiators, which is cumbersome. Furthermore, Grignard reagents have weaker nucleophilicity than n-butyllithium, and the steric hindrance of the reaction substrate makes nucleophilic addition difficult. Therefore, using n-butyllithium reagents to synthesize compound 2 is simpler and has fewer side reactions. The reaction does not require an additional initiator, the conditions are mild, and the reproducibility is good, making it more suitable for standardized and large-scale production.

[0025] (3) The order of addition effectively suppressed the occurrence of side reactions, thereby simplifying the purification steps and improving the purity of the final product. As shown in the examples, the total mass yield of the method of the present invention can reach 89.60%, and the HPLC purity of the final product is as high as 99.356% or more, which fully meets the requirements as an impurity standard. This provides a crucial material basis and analytical basis for establishing and improving the impurity control system of estradiol. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a process flow diagram of the preparation method of the present invention; Figure 2 The NMR spectrum of 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol prepared in Example 1 of this invention.

[0028] Figure 3 MS spectrum of 17-(4'-phenylphenyl)-estrate-1,3,5(10)-triene-3,17β-diol prepared in Example 1 of this invention.

[0029] Figure 4 The above is a flowchart of the process for preparing 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol disclosed in the prior art. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Table 1: Material Source Description Table

[0032] Example 1: S1. Take 20.00 g of estradiol and add it to 200 ml of DCM. Stir until fully dissolved. Slowly add 15.47 ml of triethylamine and stir until homogeneous. Cool to 0°C. Then, control the temperature at 0°C and add 7.39 ml of acetyl chloride dropwise. After the addition is complete, react at room temperature (25°C) for 4 h. After the reaction is complete, wash, extract, dry and concentrate. Dry to obtain 22.65 g of off-white compound 1 solid. The yield is 113.25% by mass and the HPLC purity is 99.539%.

[0033] S2. Take 20.00 g of the off-white compound 1 solid from step S1 and add it to 40 ml of tetrahydrofuran solution for later use (referred to as material solution 1). Add 22.40 g of 4-bromo-biphenyl to 240 ml of tetrahydrofuran solution and stir well. Cool to -60℃, purge with nitrogen, and slowly add 57.34 ml of (2.5 M) n-butyllithium reagent (1.45 M). eq After the addition was complete, the mixture was stirred until homogeneous. Then, liquid 1 was added dropwise. The mixture was kept at -60℃ for 2 hours after the addition was complete. After the reaction was complete, the temperature was raised to -20℃ and water was added to quench the reaction. 300 ml of ethyl acetate was added for extraction and separation. The organic layer was washed twice with 50 ml of saturated brine and dried over anhydrous magnesium sulfate. The solvent was evaporated under negative pressure to obtain 29.68 g of oily compound. Column chromatography yielded 19.56 g of off-white compound 2 solid, with a yield of 97.80% and an HPLC purity of 97.236%.

[0034] S3. Take 10 g of the white solid of compound 2, add 50 ml of ethanol and 20 ml of water, stir until fully dissolved, dissolve 1.29 g of sodium hydroxide in 10 ml of water and then add it dropwise to the system, heat to 60℃ and react for 4 h. After the reaction is complete, cool down and add 10% dilute hydrochloric acid to adjust the pH to 2, then wash, extract, dry and concentrate, and dry to obtain 8.96 g of white solid, namely 17-(4'-phenylphenyl)-estrate-1,3,5(10)-trien-3,17β-diol, with a mass yield of 89.60% and HPLC purity of 99.356%.

[0035] Example 2: Unlike Example 1, (2.5 M) n-butyllithium was 45.87 ml (1.2 M). eq For the remainder, please refer to Example 1, which will not be repeated here. Compound 2 had a yield of 87.95% by mass and an HPLC purity of 96.589%; 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol had a yield of 87.90% by mass and an HPLC purity of 99.108%.

[0036] Example 3: Unlike Example 1, (2.5 M) n-butyllithium was 53.52 ml (1.4 M). eq For the remainder, please refer to Example 1, which will not be repeated here. Compound 2 had a yield of 95.20% by mass and an HPLC purity of 96.875%; 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol had a yield of 88.90% by mass and an HPLC purity of 98.985%.

[0037] Example 4: Unlike Example 1, (2.5 M) n-butyllithium was 57.34 ml (1.5 M). eq For the remainder, please refer to Example 1, which will not be repeated here. Compound 2 had a mass yield of 96.40% and an HPLC purity of 96.659%; 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol had a mass yield of 88.70% and an HPLC purity of 99.108%.

[0038] Example 5: Unlike Example 1, (2.5 M) n-butyllithium was 65.00 ml (1.7 M). eq For the remainder, please refer to Example 1, which will not be repeated here. Compound 2 had a mass yield of 89.80% and an HPLC purity of 97.035%; 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol had a mass yield of 88.10% and an HPLC purity of 99.029%.

[0039] Example 6: Unlike Example 1, (2.5 M) n-butyllithium was 38.23 ml (1.0 e) q For the remainder, please refer to Example 1, which will not be repeated here. Compound 2 had a mass yield of 60.79% and an HPLC purity of 82.516%; 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol had a mass yield of 68.85% and an HPLC purity of 89.962%.

[0040] Example 7: Unlike Example 1, (2.5 M) n-butyllithium was 75.45 ml (2.0 e) q For the remainder, please refer to Example 1, which will not be repeated here. Compound 2 had a mass yield of 68.43% and an HPLC purity of 87.279%; 17-(4'-phenylphenyl)-estrate-1,3,5(10)-triene-3,17β-diol had a mass yield of 70.42% and an HPLC purity of 90.273%.

[0041] Example 8: Unlike Example 1, in step S2, 22.40 g of 4-bromobiphenyl and material solution 1 were added to 240 ml of tetrahydrofuran solution, stirred until homogeneous, cooled to -65~-55℃, purged with nitrogen, and then 57.34 ml of (2.5 M) n-butyllithium reagent (1.45 g) was slowly added dropwise. eq For the rest, please refer to Example 1, which will not be repeated here.

[0042] The n-butyllithium reagent will preferentially react with material liquid 1 and will not generate biphenyl lithium active intermediate, resulting in compound 2 with very low purity, which cannot be used for feeding in step S3.

[0043] Comparative Example 9: See attached document Figure 4 Existing techniques use Grignard reagents to prepare the target product: S1. Take 2.70 g of estradiol and add it to 50 ml of DMF and stir to dissolve. Add 6.9 g of potassium carbonate solid and stir evenly. Then add 2.05 g of benzyl bromide and react at 30~35℃ for 24 h. After the reaction is complete, add the reaction liquid dropwise to 500 ml of ice water and stir. Filter and dry to obtain 2.06 g of light yellow compound 1 solid. The yield is 76.3% by mass and the HPLC purity is 97.896%.

[0044] S2. In a 250 ml dry three-necked flask equipped with a thermometer and condenser, add 683 mg of magnesium shavings, a small amount of iodine, and 20 ml of anhydrous tetrahydrofuran. Stir at room temperature under nitrogen protection, and add 0.01 ml of dibromomethane. Heat to reflux with vigorous stirring. The reddish-brown color of iodine fades and the reaction solution turns gray, indicating reaction initiation. Continue to add 8.0 g of 4-bromo-biphenyl. After the addition is complete, continue reflux for 45 min. Cool the reaction solution to 30-35°C, and add a solution of 5.41 g of compound 1 in 30 ml of anhydrous tetrahydrofuran. After the addition is complete, continue stirring for 6 h. Add sufficient saturated ammonium chloride solution to disrupt the reaction. Filter, separate the organic phase, concentrate to dryness, and column chromatography to obtain 1.3 g of white compound 2 solid. LCMS analysis showed no product, and the corresponding compound 2 could not be obtained.

[0045] As shown in Examples 1-5, when the equivalent of n-butyllithium is between 1.2 and 1.7, relatively pure compound 2 can be obtained, which is convenient for direct use in step S3 to obtain 17-(4'-phenylphenyl)-estr-1,3,5(10)-triene-3,17β-diol. Overall, 1.45 equivalent is a better option. As shown in Examples 6-7, adding too much or too little n-butyllithium will worsen the reaction effect. The main reason is that too little n-butyllithium will result in insufficient amount of biphenyl lithium active intermediate, and the purity of the final compound 2 will be low. Too much n-butyllithium will cause a portion of the n-butyllithium to react with the material liquid 1 first, resulting in a lower purity of the final compound 2. As shown in Example 8, when the tetrahydrofuran solution of compound 1 is mixed with 4-bromo-biphenyl and then the n-butyllithium reagent is added dropwise, the material liquid 1 in the reaction will react with the n-butyllithium first, resulting in a lower purity of the final compound 2, which cannot be used for the feeding in step S3.

[0046] As shown in Example 1 and Comparative Example 9, reacting n-butyllithium reagent with 4-bromo-biphenyl to generate the biphenyllithium active intermediate yields a relatively pure compound 2, which ultimately yields 17-(4'-phenylphenyl)-estradiol-1,3,5(10)-trien-3,17β-diol. The possible reason for this phenomenon is that n-butyllithium first undergoes a lithium-halogen exchange reaction with 4-bromo-biphenyl, forming the biphenyllithium active intermediate. The resulting biphenyl metal reagent exhibits stronger nucleophilicity and stability compared to Grignard reagents, thus yielding compound 2, and ultimately 17-(4'-phenylphenyl)-estradiol-1,3,5(10)-trien-3,17β-diol.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing 17-(4'-phenylphenyl)-estradiol-1,3,5(10)-trien-3,17β-diol, characterized in that, Includes the following steps: S1. Using estrone as a raw material, compound 1 is obtained by reaction, and an organic solution of compound 1 is prepared. S2. Mix the organic solution of compound 1, the organic solution of n-butyllithium and 4-bromo-biphenyl, and react to obtain compound 2; S3. 17-(4'-phenylphenyl)-estrate-1,3,5(10)-triene-3,17β-diol was further prepared from compound 2. The structural formulas of compound 1 and compound 2 are as follows: 。 2. The preparation method according to claim 1, characterized in that, In step S2, the n-butyllithium is added to an organic solution of 4-bromo-biphenyl, and then an organic solution of compound 1 is added dropwise to react and obtain compound 2.

3. The preparation method according to claim 1, characterized in that, In step S2, the 4-bromo-biphenyl equivalent is 1, and the n-butyllithium equivalent is 1.2~1.

7.

4. The preparation method according to claim 3, characterized in that, In step S2, the 4-bromo-biphenyl equivalent is 1, and the n-butyllithium equivalent is 1.4~1.

5.

5. The preparation method according to claim 1, characterized in that, In steps S1 and S2, the organic solvent is either tetrahydrofuran or acetonitrile.

6. The preparation method according to claim 2, characterized in that, In step S2, the reaction is carried out under the protection of an inert gas, namely nitrogen.

7. The preparation method according to claim 2, characterized in that, In step S2, the reaction temperature is -75 to -40°C.

8. The preparation method according to claim 1, characterized in that, In step S1, estrone is reacted with acetyl chloride under alkaline conditions, wherein the estrone equivalent is 1 and the acetyl chloride equivalent is 1.1~2.

9. The preparation method according to claim 1, characterized in that, In step S3, compound 2 is reacted under alkaline conditions to give 17-(4'-phenylphenyl)-estroster-1,3,5(10)-triene-3,17β-diol.

10. The application of 17-(4'-phenylphenyl)-estrost-1,3,5(10)-triene-3,17β-diol, prepared by any one of claims 1-9, as a standard for impurity detection in the production process of estradiol.

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