In 1.5 ml of ethanol was dissolved 140 mg of anhydrous piperazine, and to the resulting solution was added 150 mg of ethyl 2-[6-chloro-2-(2,4-difluorophenylamino)-5-fluoronicotinoyl]acetate in portions, and the resulting mixture was subjected to reaction at room temperature for 30 minutes. Subsequently, the reaction mixture was added to a mixture of 5 ml of chloroform and 5 ml of water, and the organic layer was separated, washed successively with 3 ml of water and 3 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 2 ml of n-hexane, after which crystals were collected by filtration to obtain 70 mg (yield 41.2%) of ethyl 2-[2-(2,4-difluorophenylamino)-5-fluoro-6-(1-piperazinyl)nicotinoyl]acetate.
