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 2-furaldehyde (0.2 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 20 hours. To the reaction solution were added 2-furaldehyde (0.2 g) and sodium triacetoxyborohydride (0.22 g), and the mixture was further stirred for 3 days. 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 7-[4-(2-butoxyethoxy)phenyl]-1-(2-furyl)-N-[4-[(S)-hydroxy(1-oxidopyridin-2-yl)methyl]phenyl]-2,3-dihydro-1H-1-benzazepine-4-carboxamide (Compound 91) (150.0 mg) as yellow crystals.
