To a solution of 7-[4-(2-butoxyethoxy)phenyl]-N-[4-[(S)-hydroxy(1-oxidopyridin-2-yl)methyl]phenyl]-2,3-dihydro-1H-1-benzazepine-4-carboxamide (200 mg) and benzaldehyde (0.22 g) in 1,2-dichloroethane (10 ml) were added sodium triacetoxyborohydride (0.22 g) and acetic acid (1 droplet) at room temperature and the mixture was stirred for 24 hours. To the reaction solution were added benzaldehyde (0.22 g) and sodium triacetoxyborohydride (0.22 g), and the mixture was further stirred for 24 hours. To the reaction solution was added water and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over magnesium sulfate and concentrated under reduced pressure. The residue was separated and purified by column chromatography (ethanol:ethyl acetate 1:4) and further recrystallized from ethyl acetate-diisopropylether to give 1-benzyl-7-[4-(2-butoxyethoxy)phenyl]-N-[4-[(S)-hydroxy(1-oxidopyridin-2-yl)methyl]phenyl]-2,3-dihydro-1H-1-benzazepine-4-carboxamide (Compound 90) (168.0 mg) as yellow crystals.
