Under an atmosphere of argon, to a solution of 2,5-dioxopyrrolidin-1-yl O-benzyl-N-t-butoxycarbonyl-L-serinate (4.41 g) in tetrahydrofuran(30 mL) was added sodium borohydride (644 mg) in ice bath and the mixture was stirred at room temperature overnight. Water was added to the reaction solution, which was extracted with ethyl acetate. The organic layer was washed with an aqueous saturated ammonium chloride solution and brine, dried over anhydrous magnesium sulfate, and concentrated to give N-Boc-(S)-2-amino-3-benzyloxy-1-propanol.
