A solution of 2-methylthio-4-(3-chloro-4-methoxybenzylamino)-5-[N-(2-pyridylmethyl)carbamoyl]pyrimidine (prepared in Example 80) 150.0 mg in chloroform 5.0 ml is treated with m-chloroperbenzoic acid (80%) 85.6 mg at 0° C. for 30 minites. Piperazine 0.263 g is added thereto and the mixture is stirred at room temperature overnight. To the reaction mixture is added ethyl acetate and an aqueous saturated sodium hydrogen carbonate solution, and the organic layer is separated. The organic layer is washed with an aqueous saturated sodium hydrogen carbonate solution, water and a saturated brine, dried over anhydrous sodium sulfate, filtered and then concentrated in vacuo. The residue is purified with silica gel chromatography (solvent; ethyl acetate) to give 2-(1-pyperazinyl)-4-(3-chloro-4-methoxybenzylamino)-5-[N-(2-pyridylmethyl)carbamoyl]pyrimidine as a colorless amorphous solid, 128.4 mg.
