Sodium triacetoxyborohydride (340 mg, 1.6 mmol) was added to a stirred mixture of trans-1,2,3,4,4a,5,6,10b-octahydrobenzo[f]quinoline (D8a, 200 mg, 1 mmol), 4-(4-phenylbenzoylamino)butyraldehyde (286 mg, 01.1 mmol) and acetic acid (1 drop) in 1,2-dichloroethane (10 ml) at room temperature. After stirring for 16 h, dichloromethane (20 ml) was added and the mixture was then washed with saturated aqueous K2CO3 (2×25 ml) and brine (25 ml). Drying (Na2SO4) and evaporation in vacuo afforded an oil which was purified by preparative TLC on Kieselgel using 10% methanol-ethyl acetate as eluent to give the title compound as a colourless solid (200 mg, 46%).
