Dimethylformamide → 6-Bromo-2-(2-hydroxy-2-methylpropyl)isoquinolin-1(2H)-one

Under nitrogen atmosphere, 23 mg of 60% of sodium hydride was added at 0° C. to 2 ml solution of dimethylformamide with 62 mg of 6-bromo-2H-isoquinoline-1-one, and the mixture was stirred for 30 30 min. Then, 0.055 ml of 3-bromo-2-methyl-propene was added at 0° C., and the mixture was stirred at room temperature for 2 hours. Cold water was added to the reaction solution, extracted with chloroform. Chloroform layer was washed with saturated saline solution, and dried with anhydrous sodium sulfate. The solvents were distilled outunder reduced pressure, and the residues were separated and purified by thin-layer chromatography (hexane/ethyl acetate=3/1). The obtained compounds were dissolved in concentrated hydrochloric acid, stirred at 100° C. for 3 hours, and then cooled down to room temperature. After making it alkaline with 50% sodium hydride aqueous solution, the mixture was stirred at room temperature for 3 hours. Cold water was added to the reaction solution, and extracted with chloroform. Chloroform layer was washed with saturated saline solution, and dried with anhydrous sodium sulfate. The solvents were distilled outunder reduced pressure, and the residues were separated and purified by thin-layer chromatography (hexane/ethyl acetate=3/1) to obtain 20 mg of the above compound as a white solid.