To a solution of (2R)-oxiran-2-ylmethyl 4-methylbenzenesulfonate (23.0 g, 0.101 mol) in 500 mL of methylene chloride was added 2.000 M of trimethylaluminum in Toluene (50.4 mL) at −78 Celsius, under an atmosphere of nitrogen. After stirred at −78 Celsius for 10 min, to the mixture was added a solution of (S)-2-benzylamino-succinic acid 1-benzyl ester 4-methyl ester (30.0 g, 0.0916 mol) in 150 mL of methylene chloride. The resulting reaction mixture was stirred at −78 Celsius for 30 min. The dry ice-acetone bath was changed to an ice-water bath to warm the mixture up to 0 Celsius. The mixture was stirred at 0 Celsius for 30 min. To the reaction mixture was added sodium fluoride (16.2 g, 0.385 mol) followed by Water (10.4 mL, 0.577 mol) at 0 Celsius. The resulting suspension was rapidly stirred for 1 h at 0 Celsius and filtered through a short column of of Celite and the column was subsequently washed with 600 mL of methylene chloride. The combined filtrates were dried over sodium sulfate, concentrated to dry and purified by column purification (eluting with 0 to 30% EtOAc in hexane) to give The titled compound (43.0 g, 84.4%). MS (ESI): (M+H)+=556.1.
