To a suspension of (3aS,4R,9bR)-4-[4-(methylthio)phenyl]-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo[3,2-c]quinoline (1.10 g, 3.0 mmol) and (1S,2R)-2-(benzoylamino)cyclohexanecarboxylic acid (0.74 g, 3.0 mmol) in DMF (20 ml) were added under ice-cooling, triethylamine (0.91 g, 9.0 mmol), and then a solution of DEPC (0.49 g, 3.0 mmol) in DMF (5 ml). The reaction mixture was stirred at room temperature for 16 hrs., the reaction mixture was poured into ice water and the mixture was extracted with diethyl ether. The extract was washed with saturated brine, dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography, and eluted with hexane-ethyl acetate (2:1-1:1, v/v) to give N-[(1R,2S)-2-({(3aR,4R,9bR)-4-[4-(methylthio)phenyl]-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo[3,2-c]quinolin-1-yl}carbonyl)cyclohexyl]benzamide (0.45 g, 29%) from the first eluted fraction.
