Preparation method of Venoclara intermediate

Abstract

The invention provides a preparation method of a Vickaclara intermediate 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorphenyl)-4, 4-dimethyl cyclohexene-1-) methyl) piperazine-1-) benzoic acid, which comprises the following steps: by taking a compound II, namely 1-((2-(4-chlorphenyl)-4, 4-dimethyl cyclohexene-1-) methyl) piperazine hydrochloride as an initial raw material, reacting at the temperature of 60-80 DEG C under the protection of nitrogen, thereby obtaining the Vickaclara intermediate 2-(7-azaindole-5-oxy)-4-(4-(2-(4-chlorphenyl)-4, 4-dimethyl cyclohexene-1-) methyl) piperazine-1-) benzoic acid. The key intermediate 2-(7-azaindole-5-oxyl)-4-(4-((2-(4-chlorphenyl)-4, 4-dimethylcyclohexene-1-) methyl) piperazine-1-) benzoic acid of the Venoclara bulk drug is prepared by taking 2-(7-azaindole-5-oxyl)-4-(4-(2-(4-chlorphenyl)-4, 4-dimethylcyclohexene-1-) methyl) piperazine-1-) benzoic acid as a raw material through hydrochloric acid removal, nucleophilic reaction, hydrochloride formation and deprotection reaction and adopting a proper purification method. The method does not need a noble metal catalyst, does not need column chromatography purification, is simple and convenient to operate and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical chemistry technology, specifically relating to a method suitable for industrial production of 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid, an intermediate of the Bcl-2 inhibitor Venetoclax. Background Technology

[0002] Veneclare tablets are the world's first Bcl-2 inhibitor, developed by AbbVie Inc. in the United States and approved by the US FDA on April 11, 2016. The brand name is / Vikalai, approved for the treatment of chronic lymphocytic leukemia / small lymphocytic lymphoma and acute myeloid leukemia.

[0003] Bcl-2 (B-cell lymphoma-2 gene) is a proto-oncogene that inhibits apoptosis. Overexpression of the Bcl-2 protein is associated with various cancers and immune system diseases. Venetoclax can bind to and inhibit the activity of the anti-apoptotic Bcl-2 protein, thus achieving therapeutic effects for cancer and other diseases.

[0004] This drug was approved for marketing in China on December 2, 2020. The approved indication is for use in combination with azacitidine to treat newly diagnosed adult patients with acute myeloid leukemia who are unsuitable for intensive induction chemotherapy due to comorbidities, or who are 75 years of age or older. It is a Class B drug covered by medical insurance. The molecular formula of Veneclare is C2. 45 H 50 ClN7O7S, with a molecular weight of 868.44, has the Chinese chemical name 4-(4-{[2-(4-chlorophenyl)-4,4-dimethyl-1-cyclohexen-1-yl]methyl}piperazin-1-yl)-N-({3-nitro-4-[(tetrahydro-2H-pyran-4-ylmethyl)amino]phenyl}sulfonyl)-2-(lH-pyrrolo[2,3-b]pyridin-5-yloxy)benzamide, and its structural formula is:

[0005]

[0006] The original research company's patent application WO2012071336 discloses a method for preparing Venetoclax, with the following reaction route:

[0007]

[0008] This route uses 2-methoxycarbonyl-5,5-dimethylcyclohexanone (1) as a starting material. Compound 2 is obtained by enolization and hydroxysulfonation under strong base NaH. Then, compound 3 is obtained by Suzuki coupling with p-chlorophenylboronic acid under palladium and cesium fluoride catalysis. Compound 4 is then reduced with lithium borohydride. After sulfonation, compound 4 is nucleophilically substituted with N-tert-butoxycarbonyl (Boc)piperazine under alkaline conditions without separation to obtain compound 5. De-Boc reaction of compound 5 yields compound 6, which then undergoes a nucleophilic substitution reaction with compound 7 to generate compound 8. Compound 8 is hydrolyzed with NaOH, and then N-acylated with compound 9 using EDC as a condensing agent to obtain the target product Venclexta. In this route, intermediate 8 is synthesized by reacting compounds 6 and 7 in dimethyl sulfoxide in a solvent with potassium phosphate for 24 hours. After the reaction is complete, the mixture is diluted with diethyl ether, washed with sodium hydroxide solution and brine, concentrated, and purified by silica gel column chromatography. This method has low yield and is cumbersome to operate, making it unsuitable for industrial-scale production.

[0009] US patent 9199992 discloses a synthetic route for Venclexta:

[0010]

[0011] This synthetic route uses inexpensive 3,3-dimethylcyclohexanone (10) as a starting material, and obtains intermediate 6 through a four-step reaction. Intermediate 6 and compound 13 are coupled via a noble metal palladium compound and ligand catalysis to obtain intermediate 14. Finally, intermediate 15 is hydrolyzed and esterified with a condensation agent to obtain the target product Venclexta. The key intermediate compound 14 requires a noble metal catalyst, which is demanding and not suitable for industrial production.

[0012] Chinese patent CN 116496239 A discloses a method for preparing Venetoclax. The key intermediate 4, namely methyl 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoate, is prepared by reacting intermediate 2, namely methyl 2-(7-azaindole-5-oxy)-4-bromobenzoate, with intermediate 3, namely 1-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine, organic solvent, potassium carbonate, and potassium iodide. Although this method does not use a noble metal catalyst, repeated experiments according to the disclosed method showed that the reaction was basically non-reactive, and intermediate 4 could not be obtained.

[0013]

[0014] In the above routes, intermediate 8 disclosed in WO2012071336, intermediate 14 disclosed in US 9199992, and intermediate 4 disclosed in CN116496239A will be further hydrolyzed to yield intermediate 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazin-1-)benzoic acid (Formula I). ​​Compound Formula I then undergoes a condensation reaction with 3-nitro-4-(tetrahydro-2H-pyran-4)-methylaminobenzenesulfonamide, yielding Venetoclax in a single step. Therefore, compound Formula I is a crucial intermediate in the synthesis of Venetoclax.

[0015]

[0016] Given that existing techniques for synthesizing Form I compounds require precious metal catalysts, involve harsh reaction conditions, have low yields, and are cumbersome to operate, it is necessary to study a method for preparing Veneclair intermediate Form I compounds that is more suitable for industrial production. Summary of the Invention

[0017] This invention provides a method for preparing the Veneclair intermediate 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid. The method has mild reaction conditions, simple operation, no need for precious metal catalysts, high yield, and is suitable for industrial production.

[0018] This invention provides a method for preparing the Veneclair intermediate 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid, characterized by the following reaction formula:

[0019]

[0020] The specific steps include the following:

[0021] Step 1: Compound II undergoes a hydrolysis reaction in the presence of an alkaline reagent. The reaction solvents include organic solvents and water. After complete hydrolysis, the organic layer is separated. The organic layer is dried and then evaporated under reduced pressure to obtain the free alkaline product of compound II, namely compound III.

[0022] Step 2: The product compound III obtained in Step 1 undergoes a nucleophilic substitution reaction with methyl 2-(7-azaindole-5-oxy)-4-fluorobenzoate in the solvent dimethyl sulfoxide in the presence of the alkaline reagent diisopropylethylamine. After the reaction is complete, the reaction solution is purified and the reaction to form hydrochloride is carried out. After the reaction is complete, the solid compound IV is obtained by crystallization and filtration.

[0023] Step 3: Compound IV obtained in Step 2 is added to a base reagent and solvent to carry out a deprotection reaction. After the reaction is complete, the reaction solution is purified to obtain compound I.

[0024] The reaction in step one is to prepare compound II into its free base form, product compound III. The base reagent is selected from potassium carbonate, sodium carbonate, diisopropylethylamine, and potassium dihydrogen phosphate, with potassium carbonate being preferred. The organic solvent is selected from toluene, ethyl acetate, and dichloromethane, with dichloromethane being preferred.

[0025] In step two, compound III is first subjected to a nucleophilic substitution reaction with methyl 2-(7-azaindole-5-oxy)-4-fluorobenzoate and further prepared into hydrochloride form to prepare compound IV. That is, compound IV is the hydrochloride salt of methyl 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoate. Compared with simply preparing methyl 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoate, preparing it into hydrochloride form is more convenient for post-processing of the reaction and improves the overall yield.

[0026] The existing technology for synthesizing methyl 2-(7-azaindole-5-oxy)-4-fluorobenzoate from compound III and methyl 2-(7-azaindole-5-oxy)-4-fluorobenzoate requires the use of noble metal catalysts to obtain high yields. To find a suitable industrial-scale production method without noble metal catalysts, this application experimentally explored reagents and reaction conditions. 2.0 g of compound III was reacted with 1.3 g of methyl 2-(7-azaindole-5-oxy)-4-fluorobenzoate, with the solvents (20 mL) listed in the table below added, along with various basic reagents. The reaction was monitored by HPLC using appropriate reaction times and temperatures. The reaction results are shown in the table below.

[0027]

[0028]

[0029] The screening results showed that the nucleophilic reaction in step two, using dimethyl sulfoxide as the reaction solvent and diisopropylethylamine as the base reagent, yielded significantly better reaction results than other solvents and base reagents. Specifically, the molar ratio of the base reagent diisopropylethylamine to compound III was 1:1 to 3, preferably 1:1, and the reaction temperature was 100 to 150°C, preferably 110 to 130°C.

[0030] After the nucleophilic reaction described in step two is complete, the purification method of the reaction solution is as follows: first, the reaction solution is poured into an aqueous solution of an acidic reagent to precipitate the product, and then filtered to remove the solvent. The acidic reagent is selected from potassium dihydrogen phosphate, acetic acid, and hydrochloric acid. When potassium dihydrogen phosphate is used as the acidic reagent, an aqueous solution with a mass percentage concentration ranging from 2% to 5% is prepared, resulting in the shortest solid precipitation time with stirring. Therefore, potassium dihydrogen phosphate is the preferred acidic reagent. Unexpectedly, it was discovered during the research that when the reaction solution obtained from the nucleophilic reaction of this method is poured into an aqueous solution of an acidic reagent such as potassium dihydrogen phosphate, acetic acid, or hydrochloric acid, the product precipitates. Only filtration is needed to remove the high-boiling-point solvent dimethyl sulfoxide, eliminating the need for liquid-liquid separation and time-consuming and energy-intensive vacuum concentration operations, making it more suitable for industrial production.

[0031] The purification method in step two further includes removing other impurities from the filtered solid after removing the solvent dimethyl sulfoxide. This can be done by dissolving the solid in solvents such as ethyl acetate or toluene, followed by washing with aqueous solutions of citric acid, sodium bicarbonate, and sodium chloride. The hydrochloride formation reaction in step two involves adding methanol, ethanol, or isopropanol, along with acetyl chloride, to the purified reaction solution sequentially, or by adding a methanol solution of hydrogen chloride.

[0032] The second step of this invention, which involves further preparing the hydrochloride product after the nucleophilic reaction, is because research has shown that the product methyl 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoate obtained from the nucleophilic reaction is difficult to obtain as a solid product by recrystallization. However, after being prepared into hydrochloride form, the product can be easily precipitated and filtered in a solvent, making the operation simple and suitable for industrial production.

[0033] The alkaline reagent in step three is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, and sodium tert-butoxide, with sodium hydroxide being preferred. The reaction solvent is selected from methanol, ethanol, tetrahydrofuran, and acetonitrile, with acetonitrile being preferred.

[0034] This invention provides a method for preparing 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid, a key intermediate in Veneclare pharmaceutical raw materials. The method uses compound II, namely 1-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine hydrochloride, as the starting material. Through dehydrochlorination, nucleophilic reaction, hydrochloride formation, deprotection reaction, and appropriate purification methods, 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid is obtained. This method requires no precious metal catalysts, no column chromatography purification, is simple to operate, and achieves an overall yield of over 80%, making it suitable for industrial production.

[0035] The present invention will be further described below with reference to specific embodiments and accompanying drawings. Attached Figure Description

[0036] Appendix Figure 1 HPLC purity chromatogram of compound I obtained in Example 3 Detailed Implementation

[0037] Example 1: Preparation of 1-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine (Compound III)

[0038] 1500 g of 1-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine hydrochloride, 15.0 kg of water, and 13.5 kg of ethyl acetate were added to a clean, dry 50 L glass reactor. Then, 1323 g of anhydrous potassium carbonate was added, and the mixture was stirred for 0.5 h. The mixture was then separated. The organic layer was washed with 7.5 kg of 20% sodium chloride aqueous solution. 750 g of anhydrous magnesium sulfate was added to the organic layer, and the mixture was stirred and dried for 0.5 h. The mixture was filtered, and concentrated under reduced pressure at 50 ± 10 °C in a 20 L rotary evaporator until no fraction was distilled off, yielding 1218 g of solid 1-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine.

[0039] Example 2 Preparation of methyl 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoate hydrochloride (compound IV)

[0040] The 1-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine solid obtained in Example 1 was dissolved in 8.3 kg of dimethyl sulfoxide and transferred to a clean and dry 10 L glass reaction flask. 1041 g of methyl 2-(7-azaindole-5-oxy)-4-fluorobenzoate and 495 g of diisopropylethylamine were added. The mixture was purged with nitrogen three times and heated to 120±5 °C for 24 h.

[0041] Separately, 37.5 kg of water and 1042 g of potassium dihydrogen phosphate were added to a 50 L glass reactor and stirred to dissolve, thus preparing an aqueous solution of potassium dihydrogen phosphate. After the reaction solution cooled to room temperature, it was slowly added to the potassium dihydrogen phosphate solution, and a solid precipitated out. After cooling to room temperature, the mixture was centrifuged, and the filter cake was washed with 15.0 kg of water. The solid was dissolved in 20.3 kg of ethyl acetate and transferred to a 50 L glass reactor. It was washed once with 15.0 kg of 3% citric acid aqueous solution, then once with 15.0 kg of 5% sodium bicarbonate solution, and then once with 15.0 kg of 20% saline solution. The liquid was separated. The organic phase was transferred to a transfer tank, anhydrous magnesium sulfate was added, and the mixture was stirred and dried for 0.5 h. The mixture was then filtered through a Buchner funnel and washed with ethyl acetate.

[0042] The filtrates and washings were combined and transferred to a 50L glass reactor. 1.1kg of isopropanol was added, followed by 600g of acetyl chloride and 2.7kg of ethyl acetate. After the addition was complete, the mixture was stirred for 2 hours to precipitate a solid. The solid was centrifuged, and the filter cake was slurried with acetonitrile in a transfer tank until homogeneous. After centrifugation, 2019g of methyl 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoate hydrochloride solid was obtained.

[0043] Example 3 Preparation of 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid (compound I)

[0044] Compound IV obtained in Example 2 and 23.6 kg of acetonitrile were added to a 50 L glass reactor and heated to 60 ± 5 °C. A solution of 760 g sodium hydroxide and 15.0 kg water was then added dropwise, and the reaction was maintained at this temperature until hydrolysis was complete. After the reaction was complete, the mixture was cooled to room temperature, and 13.5 kg of ethyl acetate and 2865 g of potassium dihydrogen phosphate were added. The mixture was stirred for 0.5 h, and the aqueous phase was separated. The organic phase was cooled to 0 ± 5 °C to precipitate a solid, which was then centrifuged and the filtrate was collected.

[0045] The filtrate was transferred to a 50L glass reactor, and 1500g of sodium chloride / 6.0kg of water was added. The mixture was stirred at room temperature for at least 3 hours to allow crystallization. After centrifugation, the mixture was first washed with 7.5kg of water, then with 5.9kg of acetonitrile. The filter cake was placed in a forced-air drying oven and dried at 45±5℃ for 12-24 hours to obtain 1796g of 2-(7-azaindole-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid (compound I). The overall yield was 82%, and the purity was 98.7% (HPLC purity is shown in the appendix). Figure 1 ).

Claims

1. A method for preparing the Veneclair intermediate 2-(7-azaindol-5-oxy)-4-(4-((2-(4-chlorophenyl)-4,4-dimethylcyclohexene-1-)methyl)piperazine-1-)benzoic acid, characterized in that, Prepared using the following reaction formula: The specific steps include the following: Step 1: Compound II undergoes hydrolysis in the presence of an alkaline reagent. The reaction solvents include organic solvents and water. After complete hydrolysis, the organic layer is separated. The organic layer is dried and then evaporated under reduced pressure to obtain the free alkaline product of compound II, namely compound III. Step 2: The product compound III obtained in Step 1 undergoes a nucleophilic substitution reaction with methyl 2-(7-azaindole-5-oxy)-4-fluorobenzoate in the solvent dimethyl sulfoxide in the presence of the alkaline reagent N,N-diisopropylethylamine. After the reaction is complete, the reaction solution is purified and the reaction to form hydrochloride is carried out. After the reaction is complete, the product is crystallized and filtered to obtain solid compound IV. Step 3: Compound IV obtained in Step 2 is added to a base reagent and solvent to carry out a deprotection reaction. After the reaction is complete, the reaction solution is purified to obtain compound I.

2. The preparation method according to claim 1, characterized in that... The alkaline reagent in step one is selected from potassium carbonate, sodium carbonate, N,N-diisopropylethylamine, and potassium dihydrogen phosphate, and the organic solvent is selected from toluene, ethyl acetate, and dichloromethane.

3. The preparation method according to claim 1, characterized in that... The alkaline reagent in step one is potassium carbonate, and the organic solvent is dichloromethane.

4. The preparation method according to claim 1, characterized in that... The molar ratio of the base reagent to compound III in step two is 1:1 to 3.

5. The preparation method according to claim 1, characterized in that... Step two describes a method for purifying the reaction solution, which involves precipitating the product by pouring the reaction solution into an aqueous solution of an acidic reagent, and then filtering to remove the solvent. The acidic reagent is selected from potassium dihydrogen phosphate, acetic acid, and hydrochloric acid.

6. The preparation method according to claim 5, characterized in that... The acidic reagent mentioned in step two is potassium dihydrogen phosphate.

7. The preparation method according to claim 5, characterized in that... The aqueous solution of the acidic reagent mentioned in step two is a potassium dihydrogen phosphate aqueous solution with a mass percentage concentration of 2-5%.

8. The preparation method according to claim 1, characterized in that... The reaction to form hydrochloride in step two involves adding methanol, ethanol or isopropanol, and acetyl chloride to the purified reaction solution in sequence.

9. The preparation method according to claim 1, characterized in that... The alkaline reagent in step three is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, and sodium tert-butoxide, and the reaction solvent is selected from methanol, ethanol, tetrahydrofuran, and acetonitrile.

10. The preparation method according to claim 9, characterized in that... The alkaline reagent in step three is sodium hydroxide, and the reaction solvent is acetonitrile.

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