4-(1,1-Dioxo-1λ6-isothiazolidin-2-yl)benzoic acid (253 mg) described in Preparation Example 16, (piperidin-4-yl) (p-tolyl)methanone hydrochloride (252 mg), 1-hydroxybenzotriazole 1 hydrate (142 mg) and triethylamine (0.15 mL) were dissolved in N,N-dimethylformamide (5 mL), 1-ethyl-3-(3′-dimethylaminopropyl)carbodiimide hydrochloride (202 mg) was added, and the mixture was stirred at room temperature overnight. To the reaction mixture was added 5% aqueous sodium hydrogen carbonate solution, 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 (chloroform:methanol) to give the title compound (108 mg).
