In 2 ml of methylene chloride was dissolved 130 mg of anhydrous piperazine, and 200 mg of ethyl 2-[2-(2,4-difluorophenylamino)-5-fluoro-6-(2,4,6-trimethylbenzenesulfonyloxy)nicotinoyl]acetate was added thereto with ice-cooling, after which the resulting mixture was subjected to reaction at the same temperature for 40 minutes. Subsequently, the reaction mixture was added to a mixture of 10 ml of ethyl acetate and 10 ml of water, and the organic layer was separated, washed successively with 2 ml of saturated aqueous sodium hydrogencarbonate solution and 2 ml of saturated aqueous sodium chloride solution, and then dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure, and to the crystalline material thus obtained was added 1 ml of n-hexane, after which crystals were collected by filtration to obtain 110 mg (yield 69.9%) of ethyl 2-[2-(2,4-difluorophenylamino)-5-fluoro-6-(1-piperazinyl)nicotinoyl]acetate. The physical properties of this compound were identical with those of the compound obtained in Example 30.
