To a suspension of tert-butyl [4-(4-formyl-piperidin-1-yl)-phenyl]carbamate (0.20 g, 0.66 mmol) in methanol (5 mL) is added N,N′-dimethyl-3-aminopyrrolidine (0.15 g, 1.3 mmol). The reaction mixture is stirred for 20 minutes and then a mixture of zinc chloride (53 mg) and sodium cyanoborohydride (50 mg) in methanol (2 mL) is added in a dropwise fashion. After stirring overnight at room temperature, the reaction mixture is diluted with water and extracted 3× with ethyl acetate. The combined extracts were washed once with saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to give tert-butyl [4-(4-{[methyl-(1-methyl-pyrrolidin-3-yl)-amino]-methyl}-piperidin-1-yl)-phenyl]-carbamate as a foam (0.27 g, 100%).
