Under a nitrogen stream, sodium hydride (47 mg) was suspended in N,N-dimethylformamide (10 mL), pyrrolidin-2-one (74 μL) was added, and the mixture was stirred at room temperature. Then, a solution of [4-(5-cyclopropyl-3-methylpyridin-2-yl)piperazin-1-yl](6-fluoro-4-methylpyridin-3-yl)methanone (210 mg) described in Preparation Example 140 in N,N-dimethylformamide (5 mL) was added, and the mixture was stirred at 95° C. The reaction mixture was cooled, water was added, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated brine, and the solvent was evaporated. The obtained residue was purified by column chromatography to give 1-{5-[4-(5-cyclopropyl-3-methylpyridin-2-yl)piperazine-1-carbonyl]-4-methylpyridin-2-yl}pyrrolidin-2-one. The obtained 1-{5-[4-(5-cyclopropyl-3-methylpyridin-2-yl)piperazine-1-carbonyl]-4-methylpyridin-2-yl}pyrrolidin-2-one was dissolved in dichloromethane, 1N hydrogen chloride/diethyl ether (5 mL) was added, and the precipitate was collected by filtration to give the title compound (12 mg).
