A dioxane (1.5 ml) solution of the 2,5-dichloro-4-[(4-chlorophenylthio)(2,5-difluorophenyl)methyl]pyridine (218 mg, 0.523 mmol) obtained in Example 54 and 3,4-dimethoxybenzylamine (400 μl) was heated at 120° C. for 3 days in a sealed tube. The reaction mixture was cooled to room temperature and then, concentrated under reduced pressure. The residue thus obtained was subjected to silica gel column chromatography. The fraction obtained from the hexane:ethyl acetate=4:1 eluate was concentrated under reduced pressure to give the title compound (140 mg, 0.256 mmol, 49%) as an amorphous substance.
