A method for synthesizing besylate

Abstract

The application belongs to the field of pharmaceutical chemistry and particularly relates to a synthesis method of besuxidil mesylate. First, 2-chloroquinazoline-4-amine a is used as raw material, and then a nucleophilic substitution reaction with 5-bromoindazole b, a Suzuki coupling reaction with 3-hydroxyphenylboronic acid d, a Mitsunobu reaction with 2-hydroxy-N-isopropylacetamide f and a salt reaction with methanesulfonic acid are sequentially performed to obtain besuxidil mesylate. The main route of the application is short, and compared with the existing route, the yield is higher, and the industrial production is facilitated.

Description

Technical Field

[0001] This invention relates to a method for synthesizing besudil mesylate, belonging to the field of medicinal chemistry. Background Technology

[0002] Chronic graft-versus-host disease (cGVHD) is a type of post-transplant complication, generally referring to a clinicopathological syndrome (including classic cGVHD and overlap syndrome) that occurs after allogeneic hematopoietic stem cell transplantation (allo-HSCT) when, during the process of rebuilding the donor's immune system, lymphocytes from the donor attack the recipient's organs. It is one of the major post-transplant complications, with an incidence rate of 30%–70%. Patients exhibit varying degrees of rejection symptoms after onset, severely impacting their post-operative health and quality of life, and in severe cases, even leading to death.

[0003] Belumosudil Mesylate has the following structure;

[0004]

[0005] It is a small molecule drug used to treat chronic graft-versus-host disease (cGVHD). In 2021, belumosudil mesylate, developed by Kadmon, Inc. in the United States, was approved by the FDA for use in adults and children aged 12 years and older with cGVHD.

[0006] The existing synthetic routes include: Route 1: This route has been reported in WO 2006105081, WO 2008054599, WO2010104851 and WO 2012040499, and is as follows:

[0007] .

[0008] This route involves as many as ten reaction steps, requires a large number of reagents, and due to the large number of reaction steps, the yield is correspondingly low.

[0009] Route 2: This route was reported in CN 101208094A:

[0010] .

[0011] The route still involves many steps, and the yield of the key step (the reaction of compound 7 with N-isopropyl-2-chloroacetamide to generate compound 8) is low (45%). Summary of the Invention

[0012] This invention provides a method for synthesizing besudil mesylate to overcome the above-mentioned defects of the prior art. This method has the advantages of short reaction steps, fewer raw materials and reagents, high yield, low cost and environmental friendliness.

[0013] The technical solution of the present invention is as follows:

[0014] A method for synthesizing besudil mesylate, characterized by comprising the following steps:

[0015] (1) In an organic solvent, methyl glycolate reacts with isopropylamine to give 2-hydroxy-N-isopropylacetamide f;

[0016] (2) In an organic solvent, 2-chloroquinazoline-4-amine a reacts with 5-bromoindazole b to give 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine c;

[0017] (3) In an organic solvent, 2-chloro-N-(1H-indazol-5-yl)quinazoline-4-amine c is coupled with 3-hydroxyphenylboronic acid d to give 3-(4-((1H-indazol-5-yl)amino)quinazoline-2-yl)phenol e.

[0018] (4) In an organic solvent, 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenol e and 2-hydroxy-N-isopropylacetamide f react via photo-trailing reaction to obtain 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g;

[0019] (5) In an organic solvent, 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g reacts with methanesulfonic acid to form a salt to give besudil methanesulfonic acid.

[0020] The reaction route for this synthesis method is as follows:

[0021] .

[0022] Preferably, step (1) involves mixing methyl glycolate and isopropylamine in a round-bottom flask equipped with a reflux condenser and a drying tube. The reaction mixture is refluxed for 16 hours. Excess amine is evaporated under reduced pressure. The residue is purified by recrystallization from chloroform and hexane. A white solid, 2-hydroxy-N-isopropylacetamide f, is obtained. The amounts of methyl glycolate and isopropylamine added are 1 mmol: 2.2 mmol.

[0023] Preferably, step (2) includes adding 2-chloroquinazoline-4-amine a, 5-bromoindazole b, and DIEA to DMF, stirring at 65°C, extracting after the reaction is complete, drying, evaporating to dryness, and then performing column chromatography to obtain 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine c. The amounts of 2-chloroquinazoline-4-amine a, 5-bromoindazole b, DIEA, and DMF added are 100 mmol: 100 mmol: 100-110 mmol: 20 mL, respectively.

[0024] Preferably, step (3) involves adding 0.1 mmol of 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine c to a mixed solution of toluene (1 mL), n-BuOH (0.5 mL), and Na2CO3 (0.5 mL, 2M aqueous solution). Nitrogen gas is purged for 20 minutes, and then 0.4 mmol of 3-hydroxyphenylboronic acid d and 0.05 mmol of Pd-catalyst Pd(PPh3)4 are added under nitrogen protection. The mixture is heated to reflux and stirred for 72 hours. The solvent is removed under vacuum, and the residue is passed through preparative silica gel TLC (5% MeOH / CH2Cl2) to obtain 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol e.

[0025] Preferably, step (4) includes dissolving 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol e, 2-hydroxy-N-isopropylacetamide f, and triphenylphosphine in tetrahydrofuran, cooling to zero degrees Celsius, and then slowly adding diethyl azodicarbonate (DEAD) dropwise. After the addition is complete, the mixture is stirred at 70 degrees Celsius. After the reaction is complete, the mixture is concentrated by vacuum evaporation and purified by column chromatography to obtain 2-(3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenoxy)-N-isopropylacetamide g. The amounts of 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol e, 2-hydroxy-N-isopropylacetamide f, triphenylphosphine, DEAD, and tetrahydrofuran added are, in order: 10 mmol: 10-12 mmol: 10 mmol: 20 mL.

[0026] Preferably, step (5) includes adding an ethanol solution of 0.31 mL of methanesulfonic acid to an ethanol solution of 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide (2.0 g) at 25-30°C, heating to 45-55°C, stirring at the same temperature for 2 h, then cooling the reaction mixture to 25-30°C and stirring for 0.5 h. The solid is filtered, washed with ethanol, and dried to obtain besudil methanesulfonic acid.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The main route of this invention is relatively short. The target product, besudil mesylate, can be obtained through steps such as nucleophilic substitution, Suzuki coupling reaction, Mitsunobu reaction, and salt formation. This method has a short reaction route, high yield, and is conducive to industrial production.

[0029] Compared to the existing Route 2, the present invention yields compound g via photoelongation reaction in a higher yield than Route 2, which yields compound 8 via nucleophilic substitution. Of course, any product derived from this invention does not necessarily need to achieve all of the advantages described above simultaneously. Specific Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Improvements and adjustments made by those skilled in the art based on the present invention in practical applications still fall within the scope of protection of the present invention.

[0031] Example 1:

[0032] (1) Synthesis of 2-hydroxy-N-isopropylacetamide f:

[0033] Methyl glycolate (9.00 g, 100 mmol) and isopropylamine (12.9 g, 219 mmol) were added to a 50 mL round-bottom flask equipped with a condenser and a drying tube, and the reaction mixture was refluxed for 16 hours. After the reaction was complete, the excess amine was evaporated under reduced pressure, and the residue was purified by recrystallization from chloroform and hexane. 2-Hydroxy-N-isopropylacetamide f, white crystals (yield 37%), was given.

[0034] (2) Synthesis of 2-chloro-N-(1H-indazol-5-yl)quinazolin-4-amine C:

[0035] 2-Chloroquinazoline-4-amine a (17.9 g, 100 mmol), 5-bromoindazole b (19.6 g, 100 mmol), and DIEA (110 mmol) were added to 20 mL of DMF and stirred at 65 °C. After the reaction was complete as monitored by TLC, heating and stirring were stopped, the mixture was quenched with water, the organic layer was extracted with ethyl acetate, washed with saturated brine, dried over anhydrous Na₂SO₄, evaporated to dryness, and column chromatography was performed to give 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine c, a white solid (yield 83%).

[0036] (3) Synthesis of 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenole:

[0037] 2-Chloro-N-(1H-indazole-5-yl)quinazoline-4-amine c (1 mmol) was dissolved in toluene (10 mL), and n-BuOH (5 mL) and Na2CO3 (5 mL, 2M aqueous solution) were added. Nitrogen gas was purged for 20 minutes, and then 3-hydroxyphenylboronic acid d (4 mmol) and Pd(PPh3)4 (0.5 mmol) were added under nitrogen protection. The mixture was heated to reflux and stirred for 72 hours. After the reaction was complete, it was cooled to room temperature, and DCM (100 mL) and water (50 mL) were added. The organic layer and aqueous layer were separated. The aqueous layer was extracted with DCM (2 x 75 mL), and the combined organic layer was dried on anhydrous sodium sulfate, filtered, and the organic solvent was removed under reduced pressure. Silica gel chromatography was used to obtain 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol e, a yellow solid (91% yield).

[0038] (4) Synthesis of 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g:

[0039] 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenol e (10 mmol), 2-hydroxy-N-isopropylacetamide f (12 mmol), and triphenylphosphine (10 mmol) were dissolved in 20 mL of tetrahydrofuran and cooled to 0°C. Then, diethyl azodicarbonate (DEAD) (10 mmol) was slowly added dropwise, and the mixture was stirred at 70°C after the addition was complete. The reaction was monitored by TLC. After the reaction was completed, the mixture was concentrated by evaporation under reduced pressure and purified by column chromatography to give 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g, a white solid (yield 89%).

[0040] (5) Synthesis of besudil mesylate:

[0041] At 25-30°C, a solution of 0.31 mL of methanesulfonic acid in 4.0 mL of ethanol was added to a solution of 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide in 40.0 mL of ethanol. The mixture was heated to 45-55°C and stirred at the same temperature for 2 h. The reaction mixture was then cooled to 25-30°C and stirred for 0.5 h. The solid was filtered, washed with ethanol, and dried to give besudil methanesulfonic acid, a yellowish-white solid (95% yield).

[0042] Example 2:

[0043] (1) Synthesis of 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenole:

[0044] 5-((2-(3-hydroxyphenyl)quinazolin-4-yl)amino)-1H-indazole-1-carboxylic acid tert-butyl ester 7 can be prepared by referring to the method of existing route two mentioned in patent CN101208094A;

[0045] 7 mmol of tert-butyl 5-((2-(3-hydroxyphenyl)quinazolin-4-yl)amino)-1H-indazole-1-carboxylic acid and 10 mmol of trifluoroacetic acid were added to 20 mL of dichloromethane solution and stirred at room temperature. After the reaction was completed, the mixture was quenched with water, separated into layers, and extracted twice with dichloromethane. The combined dichloromethane layers were then evaporated to dryness to give 3-(4-((1H-indazole-5-yl)amino)quinazolin-2-yl)phenol e, a yellow solid (99%).

[0046] (2) Synthesis of 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g:

[0047] 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenol e (10 mmol), 2-hydroxy-N-isopropylacetamide f (10 mmol), and triphenylphosphine (10 mmol) were dissolved in 20 mL of tetrahydrofuran and cooled to 0°C. Then, diethyl azodicarbonate (DEAD) (10 mmol) was slowly added dropwise, and the mixture was stirred at 70°C after the addition was complete. The reaction was monitored by TLC. After the reaction was completed, the mixture was concentrated by evaporation under reduced pressure and purified by column chromatography to give 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g, a white solid (yield 92%).

[0048] (3) Synthesis of besudil mesylate:

[0049] At 25-30°C, a solution of 0.31 mL of methanesulfonic acid in 4.0 mL of ethanol was added to a solution of 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide in 40.0 mL of ethanol. The mixture was heated to 45-55°C and stirred at the same temperature for 2 h. The reaction mixture was then cooled to 25-30°C and stirred for 0.5 h. The solid was filtered, washed with ethanol, and dried to give besudil methanesulfonic acid, a yellowish-white solid (yield 94%).

[0050] Example 3:

[0051] (1) Synthesis of 2-hydroxy-N-isopropylacetamide f:

[0052] Methyl glycolate (15 mmol) was dissolved in 10 mL of 1,4-dioxane, and then a solution of isopropylamine (15 mmol) in 1,4-dioxane (10 mL) was slowly added. The reaction was carried out at 80 °C. After the reaction was completed, the mixture was cooled to room temperature, and a solid precipitated out. The solid was filtered and dried to give 2-hydroxy-N-isopropylacetamide f, a white crystal (90% yield).

[0053] (2) Synthesis of 2-chloro-N-(1H-indazol-5-yl)quinazolin-4-amine C:

[0054] 2-Chloroquinazoline-4-amine a (17.9 g, 100 mmol), 5-bromoindazole b (19.6 g, 100 mmol), and DIEA (100 mmol) were added to 20 mL of DMF and stirred at 65 °C. After the reaction was complete as monitored by TLC, heating and stirring were stopped, the mixture was quenched with water, the organic layer was extracted with ethyl acetate, washed with saturated brine, dried over anhydrous Na₂SO₄, evaporated to dryness, and column chromatography was performed to give 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine c, a white solid (85% yield).

[0055] (3) Synthesis of 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenole:

[0056] 2-Chloro-N-(1H-indazole-5-yl)quinazoline-4-amine c (1 mmol) was dissolved in toluene (10 mL), and n-BuOH (5 mL) and Na2CO3 (5 mL, 2M aqueous solution) were added. Nitrogen gas was purged for 20 minutes, and then 3-hydroxyphenylboronic acid d (4 mmol) and Pd(PPh3)4 (0.5 mmol) were added under nitrogen protection. The mixture was heated to reflux and stirred for 72 hours. After the reaction was complete, it was cooled to room temperature, and DCM (100 mL) and water (50 mL) were added. The organic layer and aqueous layer were separated. The aqueous layer was extracted with DCM (2 x 75 mL), and the combined organic layer was dried on anhydrous sodium sulfate, filtered, and the organic solvent was removed under reduced pressure. Silica gel chromatography was used to obtain 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol e, a yellow solid (91% yield).

[0057] (4) Synthesis of 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g:

[0058] 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenol e (10 mmol), 2-hydroxy-N-isopropylacetamide f (12 mmol), and triphenylphosphine (10 mmol) were dissolved in 20 mL of tetrahydrofuran and cooled to 0°C. Then, diethyl azodicarbonate (DEAD) (10 mmol) was slowly added dropwise, and the mixture was stirred at 70°C after the addition was complete. The reaction was monitored by TLC. After the reaction was completed, the mixture was concentrated by evaporation under reduced pressure and purified by column chromatography to give 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide g, a white solid (yield 89%).

[0059] (5) Synthesis of besudil mesylate:

[0060] At 25-30°C, a solution of 0.31 mL of methanesulfonic acid in 4.0 mL of ethanol was added to a solution of 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide in 40.0 mL of ethanol. The mixture was heated to 45-55°C and stirred at the same temperature for 2 h. The reaction mixture was then cooled to 25-30°C and stirred for 0.5 h. The solid was filtered, washed with ethanol, and dried to give besudil methanesulfonic acid, a yellowish-white solid (95% yield).

[0061] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for the synthesis of BESUROFIDE mesylate characterized in that, Includes the following steps: (1) Methyl glycolate reacts with isopropylamine in an organic solvent to give 2-hydroxy-N-isopropylacetamide; (2) In an organic solvent, 2-chloroquinazoline-4-amine reacts with 5-bromoindazole to give 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine; (3) In an organic solvent, 2-chloro-N-(1H-indazol-5-yl)quinazoline-4-amine is coupled with 3-hydroxyphenylboronic acid to give 3-(4-((1H-indazol-5-yl)amino)quinazoline-2-yl)phenol; (4) In an organic solvent, 3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenol and 2-hydroxy-N-isopropylacetamide were reacted by photo-trailing reaction to obtain 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide; (5) In an organic solvent, 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)-N-isopropylacetamide reacts with methanesulfonic acid to form a salt to give besudil methanesulfonic acid.

2. The process for synthesis of Besylate according to claim 1, characterized in that, Step (1) involves mixing methyl glycolate and isopropylamine in a round-bottom flask equipped with a reflux condenser and a drying tube, refluxing the reaction mixture for 16 hours, evaporating excess amine under reduced pressure, and purifying the residue by recrystallization with chloroform-hexane to obtain a white solid 2-hydroxy-N-isopropylacetamide, wherein the amount of methyl glycolate and isopropylamine added is 1 mmol: 2.2 mmol.

3. The process for synthesis of Besylate according to claim 1, characterized in that, Step (2) involves adding 2-chloroquinazoline-4-amine, 5-bromoindazole, and DIEA to DMF, stirring at 65°C, extracting after the reaction is complete, drying, evaporating, and column chromatography to obtain 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine, wherein the amounts of 2-chloroquinazoline-4-amine, 5-bromoindazole, DIEA, and DMF added are 100 mmol:100 mmol:100-110 mmol:20 mL, respectively.

4. The process for synthesis of Besylate according to claim 1, characterized in that, Step (3) involves adding 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine to a mixed solution of toluene, n-BuOH, and 2M Na2CO3 aqueous solution, purging with nitrogen for 20 minutes, then adding 3-hydroxyphenylboronic acid and Pd-catalyst Pd(PPh3)4 under nitrogen protection. The mixture is heated to reflux and stirred for 72 hours. The solvent is removed under vacuum, and the residue is passed through preparative silica gel TLC (5% MeOH / CH2Cl2) to obtain 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol. The amounts of 2-chloro-N-(1H-indazole-5-yl)quinazoline-4-amine, toluene, n-BuOH, 2M Na2CO3 aqueous solution, 3-hydroxyphenylboronic acid, and Pd-catalyst Pd(PPh3)4 added are 0.1 mmol, 1 ml, 0.5 ml, 0.5 ml, and 0.4 ml, respectively. mmol, 0.05 mmol.

5. The method for synthesizing besudil mesylate according to claim 1, characterized in that, Step (4) involves dissolving 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol, 2-hydroxy-N-isopropylacetamide, and triphenylphosphine in tetrahydrofuran, cooling to zero degrees Celsius, and then slowly adding diethyl azodicarbonate dropwise. After the addition is complete, the mixture is stirred at 70°C. After the reaction is complete, the mixture is concentrated by vacuum evaporation and purified by column chromatography to obtain 2-(3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenoxy)-N-isopropylacetamide, wherein the amounts of 3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenol, 2-hydroxy-N-isopropylacetamide, triphenylphosphine, diethyl azodicarbonate, and tetrahydrofuran added are 10 mmol: 10-12 mmol: 10 mmol: 20 mL, respectively.

6. The method for synthesizing besudil mesylate according to claim 1, characterized in that, Step (5) involves adding an ethanol solution of methanesulfonic acid to an ethanol solution of 2-(3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenoxy)-N-isopropylacetamide at 25-30°C, heating to 45-55°C, stirring at the same temperature for 2 hours, then cooling the reaction mixture to 25-30°C and stirring for 0.5 hours, filtering the solid and washing with ethanol, and drying to obtain besudil methanesulfonic acid, wherein the amounts of methanesulfonic acid, 2-(3-(4-((1H-indazole-5-yl)amino)quinazoline-2-yl)phenoxy)-N-isopropylacetamide, and ethanol added are 0.31 ml, 2.0 g, and 40.0 ml, respectively.

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