Water → Ethyl 3-(pyrrolidin-3-YL)propanoate

To a solution of ethyl diethylphosphonoacetate (15.9 g) in tetrahydrofuran (200 mL) was added sodium hydride (60% in oil, 2.88 g) at room temperature, and the mixture was stirred for 30 min. To the reaction mixture was added benzyl 3-formylpyrrolidine-1-carboxylate (15.0 g) and the mixture was stirred for 4 hr. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated brine, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated and the residue was dissolved in methanol (500 ml), palladium hydroxide/carbon (2.0 g) was added, and the mixture was stirred under a hydrogen atmosphere (3 atm) at 40° C. for 4 hr. The reaction solution was allowed to cool to room temperature, the reaction system was substituted by nitrogen, filtered, and the solvent was evaporated to give the title compound (8.0 g, yield 73%) as a colorless oil.