A 1.0 N lithiumbis(trimethlylsilyl)amide/THF solution (2.0 ml) was added to a solution of 0.44 g of 7-(N-methoxy-N-methylsulfamoyl)imidazo[5,1-b]thiazole in 9 ml of dry THF in an argon atmosphere at −4° C. The mixture was stirred at the same temperature for 30 min. Tri-n-butylstannyl chloride (0.58 ml) was added thereto. The mixture was stirred for 30 min. Further, a 1.0 N lithiumbis(trimethylsilyl)amide/THF solution (2.5 ml) was then added, followed by stirring for 30 min. Tri-n-butylstannyl chloride (0.1 ml) was added thereto. The mixture was stirred at the same temperature for 30 min. A saturated aqueous ammonium chloride solution was added thereto, and the ethyl acetate was then added, followed by washing with water and saturated brine in that order. The organic layer was dried over anhydrous magnesium sulfate. The solvent was removed by distillation. The residue was purified by column chromatography on silica gel (hexane:ethyl acetate=1:2) to give 0.39 g of the title compound.
