Methyl Isocyanate → 2-(3-Methylureido)-4-[4-(diphenylmethoxy)piperidinomethyl]thiazole

To a stirred solution of 2-amino-4-[4-(diphenylmethoxy)piperidinomethyl]thiazole (1.0 g) in dry tetrahydrofuran (10 ml) was added dropwise methyl isocyanate (0.34 ml) at ambient temperature. After the addition had been completed, the reaction mixture was stirred for 3 hours. 1N Sodium hydroxide solution (3 ml) was added thereto and stirring was continued for 30 minutes. The reaction mixture was concentrated under reduced pressure and the residue was extracted with ethyl acetate. The extract was washed with a saturated aqueous solution of sodium chloride and dried over magnesium sulfate. After removal of solvent, the residue was subjected to column chromatography on silica gel and eluted with a mixture of chloroform and methanol (20:1 V/V). The fractions containing the object compound were combined and concentrated under reduced pressure. The residue was triturated with 70% ethanol to give white powder. Recrystallization from 70% ethanol gave 2-(3-methylureido)-4-[4-(diphenylmethoxy)piperidinomethyl]thiazole (0.3 g).