A mixture of spiro[isobenzofuran-1(3H),4′-piperidine]-3-one hydrochloride (48 mg), phenyl N-(4-benzoylphenyl)carbamate (58 mg) and triethylamine (0.14 mL) in chloroform (5 mL) was stirred at 80° C. for 2 hours. The 6 reaction mixture was poured into water and extracted with chloroform (20 mL). The organic layer was washed with saturated saline solution (20 mL), then dried over anhydrous Na2SO4 and concentrated. The residue was purified by column chromatography on silica gel (hexane/ethyl acetate=4/1 to 1/2) and recrystallized from ethyl ether-hexane to give the subject compound (81 mg) as colorless crystals (melting point 161-163° C.).
