Sodium triacetoxyborohydride (4.66 g, 22 mmol) was added to a stirred mixture of 4-(4-phenylbenzoylamino)butyraldehyde (3.92 g, 15 mmol) and 7-methoxy-1,2,3,4-tetrahydroisoquinoline [Daniel J. Sall et al., J. Med. Chem., 1987, 30, 2208] (2.40 g, 14.7 mmol) in 1,2-dichloroethane (200 ml) at room temperature. After stirring for 16 h, dichloromethane (100 ml) was added and the mixture was then washed with saturated aqueous K2CO3 (2×100 ml) and brine (100 ml). Drying (Na2SO 4) and evaporation in vacuo afforded a viscous oil which was chromatographed on silica gel, eluting with ethyl acetate, to give the title compound as a pale pink solid (5.04 g, 83%).
