a mixture of ethanol (2 ml), an appropriate amino alcohol (1 mmol), and aldehyde (1 mmol) was stirred at room temperature until the starting meterials were totally consumed (monitored by TLC). to the yellow mixture was added NaBH4 (37.8 mg, 1 mmol) with stirring to give a colorless solution. the reaction was then quenched with dill. HCl. after neutralization (sat. NaHCO3), the reaction mixture was concentrated under reduced pressure and the residue was extracted with ethyl acetate and washed with water. the organic layer was dried over anhydrous Na2SO4 and the solvent removed. the products were purified by flash column chromatography (hexanes/ethyl acetate).