167 μl of a 1.8 M lithium diisopropylamide THF solution (0.3 mmol) was diluted with 1.5 ml of THF. Thereafter, 1 ml of a THF solution containing 27 mg (0.10 mol) of the 4-chloro-2,N-dimethyl-5-morpholin-4-ylbenzamide prepared in Step B was added dropwise to the diluted solution at −78° C. Thereafter, 1 ml of a THF solution containing 17 mg (0.10 mmol) of 2-(trifluoromethyl)benzonitrile was further added thereto, and the obtained mixture was then stirred at −78° C. for 1 hour. The temperature of the reaction solution was increased to 0° C., and a saturated ammonium chloride aqueous solution was added thereto, followed by extraction with ethyl acetate. The extract was washed with a saturated saline solution, and was then dried over anhydrous sodium sulfate, followed by concentration under reduced pressure. Thereafter, the obtained residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:2 to 1:1), so as to obtain 5.4 mg (13%) of 6-chloro-7-morpholin-4-yl-3-(2-trifluoromethylphenyl)-2H-isoquinolin-1-one in the form of a colorless solid.
