Benzaldehyde (0.76 g) was added to a solution of 4-amino-N-(1-(5-aminopentyl)piperidin-4-ylmethyl)-5-chloro-2-methoxybenzamide (2.0 g) in ethanol (50 ml), and the mixture was stirred at refluxing temperature for 3 hr. Sodium borohydride (0.53 g) was added to the reaction mixture under ice-cooling, and the mixture was stirred overnight at room temperature. Water was added to the reaction mixture, and the mixture was extracted with chloroform. The organic layer was washed with saturated brine, dried and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography (chloroform:methanol:ammonia=50:5:1) to give 1.78 g of 4-amino-N-((1-(5-benzylaminopentyl)piperidin-4-yl)methyl)-5-chloro-2-methoxybenzamide.
