To a solution of N-{4-[2-(4-hydroxyphenyl)ethyl]-1,3-thiazol-2-yl}acetamide (655.8 mg, 2.50 mmol) in anhydrous tetrahydrofuran (12 ml) was added 1,1′-carbonyldiimidazole (608.1 mg, 3.75 mmol). After stirring at 45° C. for 1 hr, the mixture was cooled to room temperature. tert-Butyl carbazate (495.6 mg, 3.75 mmol) was added, and the mixture was stirred at room temperature for 15 hr. The reaction mixture was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (FUJI SILYSIA CHEMICAL LTD. BW-300SP 80 g, ethyl acetate:hexane=1:1→3:2) and chemically modified silica gel column chromatography (FUJI SILYSIA CHEMICAL LTD. DM-2035 45 g, dichloromethane:methanol=50:1→20:1) to give 4-{2-[2-(acetylamino)-1,3-thiazol-4-yl]ethyl}phenyl tert-butyl hydrazine-1,2-dicarboxylate (526.4 mg, 1.252 mmol, yield 50.0%) as a white solid.
