A solution of N′-(4-methoxyquinolin-2-yl)propane-1,3-diamine dihydrochloride (200 mg, 0.66 mmol) [4a] in methanol (50 ml) was treated with glacial acetic acid (20 drops) and sodium methoxide (95%, 71 mg, 1.31 mmol) followed by a solution of 1-benzyl-3-indole carboxaldehyde (155 mg, 0.66 mmol) in methanol (5.0 ml). The reaction stirred at ambient temperature for 24 hours then was treated with a solution of sodium cyanoborohydride (83 mg, 1.31 mmol) in methanol (2.0 ml). The reaction stirred at ambient temperature for 24 hours. The solution was evaporated under reduced pressure to a residue that was taken into a mixture of saturated aqueous sodium chloride (20 ml) and 10% sodium hydroxide solution (20 ml). It was extracted in ethyl acetate and the extracts were dried (sodium sulfate) then concentrated to an oil. Column chromatography on silica (95/5 dichloromethane/methanolic ammonia) gave N-(1-benzyl-1H-indol-3-ylmethyl)-N′-(4-methoxyquinolin-2-yl)propane-1,3-diamine (126 mg, 84%) as a white solid. [M+H]+ 451.
