6-Isoquinolinecarbonitrile(9CI)

Preparation Example G-1. Isoquinoline-6-carboxylic acid A solution prepared by adding (4-bromobenzylydene)-(2, 2-diethoxyethyl) amine (synthesized from 4-bromobenzaldehyde, according to the method described in J. Org. Chem., vol. 48, 3344-3346 (1983)) (51.4g, 0.189mmol) to an ice-cold concentrated sulfuric acid (20g) was added to a solution prepared by adding diphosphorus pentoxide (40g) to an ice-cold concentrated sulfuric acid (360g), and the solution was stirred at 160°C for 2 hours. The reaction solution was gradually cooled to 0°C, the solution was filtered through Celite pad, the filtrate was neutralized with sodium carbonate. This solution was further filtrated through Celite pad, this filtrate was extracted with ethyl acetate and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the residue was purified by silica gel column chromatography (hexane:ethyl acetate), and 6-bromoisoquinoline (482mg, 1.2percent) was obtained as an orange oil. Next, to a solution of 6-bromoisoquinoline (382mg, 1.84mmol) in N, N-dimethylformamide (3.8mL) were added zinc cyanide (431 mg, 3.67mmol) and tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) under nitrogen atmosphere, and the mixture was stirred at 100°C for 1 hour. Tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) was further added, and the mixture was stirred for 2.5 hours at 100°C. The reaction mixture was allowed to room temperature, ethyl acetate and water were added for extraction, the organic layer was washed with water and dried over anhydrous magnesium sulfate. The residue was purified by silica gel column chromatography (hexane : ethyl acetate), and isoquinoline-6-carbonitrile (234mg, 83percent) was obtained as a yellow solid. Lastly, isoquinoline-6-carbonitrile (51mg, 0.331 mmol) was dissolved in diethyleneglycol (1.0mL), potassium hydroxide (9mg, 0.166mmol) was added thereto, followed by stirring at 160°C for 3 hours. The reaction mixture was allowed to room temperature, neutralized using hydrochloric acid, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, then, the solvent was evaporated. Water was added to the residue, the precipitated solid was collected, washed with water, dried in vacuo, so as to obtain the title compound (12mg, 21 percent) as a yellow solid.To a suspension of 6-bromoisoquinoline (624 mg, 3.0 mmol) and Pd(PPh3)4 (173 mg, 0.15 mmol) in DMF (6 mL) was added Zn(CN)2 (210 mg, 1.8 mmol), and the reaction mixture was stirred at 90 °C under N2 for 24 h. After cooling to room temperature, H2O (40 mL) was added and the mixture was extracted with ethyl acetate (40 mL x 3). The combined organic layers were washed with brine (30 mL x 3) and dried over Na2SO4. After concentration and purification by column chromatography (petroleum ether/ethylacetate = 3:1), 55 was obtained as a white solid (360 mg, 78percent). 1H NMR (400 MHz, CDCl3) d 9.37 (s, 1H), 8.70 (d, J = 5.6 Hz, 1H), 8.25 (s, 1H), 8.10 (d, J = 8.4 Hz, 1H), 7.77 (d, J = 8.4 Hz, 1H), 7.73(d, J = 5.6 Hz, 1H).A solution prepared by adding (4-bromobenzylydene)-(2, 2-diethoxyethyl) amine (synthesized from 4-bromobenzaldehyde, according to the method described in J. Org. Chem., vol. 48, 3344-3346 (1983)) (51.4g, 0.189mmol) to an ice-cold concentrated sulfuric acid (20g) was added to a solution prepared by adding diphosphorus pentoxide (40g) to an ice-cold concentrated sulfuric acid (360g), and the solution was stirred at 160°C for 2 hours. The reaction solution was gradually cooled to 0°C, the solution was filtered through Celite pad, the filtrate was neutralized with sodium carbonate. This solution was further filtrated through Celite pad, this filtrate was extracted with ethyl acetate and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the residue was purified by silica gel column chromatography (hexane:ethyl acetate), and 6-bromoisoquinoline (482mg, 1.2percent) was obtained as an orange oil. Next, to a solution of 6-bromoisoquinoline (382mg, 1.84mmol) in N, N-dimethylformamide (3.8mL) were added zinc cyanide (431mg, 3.67mmol) and tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) under nitrogen atmosphere, and the mixture was stirred at 100°C for 1 hour. Tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) was further added, and the mixture was stirred for 2.5 hours at 100°C. The reaction mixture was allowed to room temperature, ethyl acetate and water were added for extraction, the organic layer was washed with water and dried over anhydrous magnesium sulfate. The residue was purified by silica gel column chromatography (hexane : ethyl acetate), and isoquinoline-6-carbonitrile (234mg, 83percent) was obtained as a yellow solid. Lastly, isoquinoline-6-carbonitrile (51mg, 0.331 mmol) was dissolved in diethyleneglycol (1.0mL), potassium hydroxide (9mg, 0.166mmol) was added thereto, followed by stirring at 160°C for 3 hours. The reaction mixture was allowed to room temperature, neutralized using hydrochloric acid, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, then, the solvent was evaporated. Water was added to the residue, the precipitated solid was collected, washed with water, dried in vacuo, so as to obtain the title compound (12mg, 21 percent) as a yellow solid.Preparation Example G-1. Isoquinoline-6-carboxylic acid A solution prepared by adding (4-bromobenzylydene)-(2, 2-diethoxyethyl) amine (synthesized from 4-bromobenzaldehyde, according to the method described in J. Org. Chem., vol. 48, 3344-3346 (1983)) (51.4g, 0.189mmol) to an ice-cold concentrated sulfuric acid (20g) was added to a solution prepared by adding diphosphorus pentoxide (40g) to an ice-cold concentrated sulfuric acid (360g), and the solution was stirred at 160C for 2 hours. The reaction solution was gradually cooled to 0C, the solution was filtered through Celite pad, the filtrate was neutralized with sodium carbonate. This solution was further filtrated through Celite pad, this filtrate was extracted with ethyl acetate and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the residue was purified by silica gel column chromatography (hexane:ethyl acetate), and 6-bromoisoquinoline (482mg, 1.2%) was obtained as an orange oil. Next, to a solution of 6-bromoisoquinoline (382mg, 1.84mmol) in N, N-dimethylformamide (3.8mL) were added zinc cyanide (431 mg, 3.67mmol) and tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) under nitrogen atmosphere, and the mixture was stirred at 100C for 1 hour. Tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) was further added, and the mixture was stirred for 2.5 hours at 100C. The reaction mixture was allowed to room temperature, ethyl acetate and water were added for extraction, the organic layer was washed with water and dried over anhydrous magnesium sulfate. The residue was purified by silica gel column chromatography (hexane : ethyl acetate), and A solution prepared by adding (4-bromobenzylydene)-(2, 2-diethoxyethyl) amine (synthesized from 4-bromobenzaldehyde, according to the method described in J. Org. Chem., vol. 48, 3344-3346 (1983)) (51.4g, 0.189mmol) to an ice-cold concentrated sulfuric acid (20g) was added to a solution prepared by adding diphosphorus pentoxide (40g) to an ice-cold concentrated sulfuric acid (360g), and the solution was stirred at 160C for 2 hours. The reaction solution was gradually cooled to 0C, the solution was filtered through Celite pad, the filtrate was neutralized with sodium carbonate. This solution was further filtrated through Celite pad, this filtrate was extracted with ethyl acetate and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the residue was purified by silica gel column chromatography (hexane:ethyl acetate), and 6-bromoisoquinoline (482mg, 1.2%) was obtained as an orange oil. Next, to a solution of 6-bromoisoquinoline (382mg, 1.84mmol) in N, N-dimethylformamide (3.8mL) were added zinc cyanide (431mg, 3.67mmol) and tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) under nitrogen atmosphere, and the mixture was stirred at 100C for 1 hour. Tetrakis(triphenylphosphine)palladium(0) (42mg, 0.0367mmol) was further added, and the mixture was stirred for 2.5 hours at 100C. The reaction mixture was allowed to room temperature, ethyl acetate and water were added for extraction, the organic layer was washed with water and dried over anhydrous magnesium sulfate. The residue was purified by silica gel column chromatography (hexane : ethyl acetate), and A solution of 700 mL of 50% by mass of sulfuric acid solution, Add to four bottles, Then, 200 g of Isoquinoline-6-carbonitrile (1 g, 6.49 mmol) was heated to reflux in 10 mL of concentrated hydrochloric acid for 4 h.After the reaction solution was cooled to room temperature, the pH was adjusted to ~6 with a saturated NaHCO3 solution.The resulting white precipitate is collected by filtration, dried, Isoquinoline-6-carboxylic acid (1.2 g, white solid) was obtained.