Triethylamine (0.185 g) and benzenesulfonyl chloride (0.210 g) were added to a solution of 0.340 g of 1-(4-aminobenzyl)-2-methyl-6-[(2-pyridylmethyl)carbamoyl]benzimidazole in 10 ml of chloroform, and the mixture was stirred at room temperature for 8 hours. Water was added thereto to stop the reaction, and the reaction mixture was extracted with chloroform. The organic layer was washed three times with water, dried, and concentrated. The residue was then purified through silica-gel column chromatography (eluent: a mixture of ethyl acetate and methanol at a ratio of 100:1 to 4:1) to give 0.300 g of 1-[4-(benzenesulfonylamino)benzyl]-2-methyl-6-[(2-pyridylmethyl)carbamoyl]benzimidazole (263).
