To a mixture of (3aR*,4S*,9bS)-4-phenyl-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo[3,2-c]quinoline (620 mg, 2.47 mmol), (1S,2R)-2-(benzoylamino)cyclohexanecarboxylic acid (671 mg, 2.7 mmol), triethylamine (0.72 ml, 5.2 mmol), acetonitrile (17 ml) and tetrahydrofuran (17 ml) was added dropwise DEPC (440 mg, 2.7 mmol) under ice-cooling, and the mixture was stirred for 10 min. The mixture was allowed to return to room temperature and the mixture was stirred for 1 hr. Saturated aqueous sodium hydrogen carbonate solution was added to the reaction mixture and the mixture was extracted with ethyl acetate. The extract was dried (over anhydrous Na2 SO4), and the solvent was evaporated. The residue was subjected to column chromatography using silica gel (30 g), and eluted with hexane-ethyl acetate (9:1-7:3, v/v) to give the title compound (735 mg, 62%) as an amorphous form.
