To a solution of 0.163 g (1.021 mmol) of 4,5,6,7-tetrahydrofuro[3,2-c]pyridine hydrochloride, 0.29 g (1.1 mmol) of 3-(3-phenethylphenyl)propionic acid and 0.57 ml (4.1 mmol) of triethylamine in 30 ml of dichloromethane, 0.23 ml (1.5 mmol) of diethyl cyanophosphonate was added dropwise under ice-cooling, followed by overnight stirring at room temperature. The reaction mixture was poured into aqueous sodium hydroxide and extracted with dichloromethane 3 times. The combined organic layer was dried over anhydrous magnesium sulfate; the solvent was distilled off under reduced pressure. The resulting crude product was purified by silica gel chromatography (hexane/ethyl acetate=6/1 to 3/1) to yield the desired product.
