To a suspension of 0.68 g (17.9 mmol) of lithium aluminum hydride in 100 mL of tetrahydrofuran was added dropwise a solution of 6.65 g (17.9 mmol) of 3-[α-{(1-benzylpiperidin-4-yl)imino}benzyl]-4-aminopyridine in tetrahydrofuran 30 ml under reflux, and the mixture was heated under reflux for 1 hour. After being cooled, the mixture was added sequentially with 0.7 mL of water, 0.7 mL of an aqueous 15% sodium hydroxide solution and 2 mL of water, under ice-cooling. After being stirred for 1 hour at ambient temperature, the reaction mixture was filtered through cerite. The filtrate was concentrated and the residue was purified by means of column chromatography (silica gel, 1:9 methanol:chloroform) to give 4.2 g (11.3 mmol) of the title compound.
