A mixture of 6-amino-3-[4-(4-phenyl-1,2,3,6-tetrahydropyridin-1-yl)butyl]-1,2,3,4-tetrahydroquinazoline-2,4-dione (390 mg), methanesulfonyl chloride (229 mg), potassium carbonate (276 mg) and dry N,N-dimethylformamide (10 ml) was stirred for 1 hour at room temperature. The mixture was poured into water, neutralized with 1N sodium hydroxide and extracted with ethyl acetate, and the extract was washed with brine. The organic layer was dried and evaporated. The crude residue was chromatographed on a silica gel (50 g), eluting with 10% methanol in dichloromethane to give 3-[4-(4-phenyl-1,2,3,6-tetrahydropyridin-1-yl)butyl]-6-methylsulfonylamino-1,2,3,4-tetrahydroquinazoline-2,4-dione (292 mg). Recrystallization from ethyl acetate gave a crystal thereof (202 mg).
