72080-83-2

501-53-1

107-15-3

72080-83-2

Dichloromethane (100 mL), ethylenediamine (39 mL, 0.58 mol) and potassium carbonate (32.4 g, 0.23 mol) were added to a 500 mL three-necked flask under nitrogen protection. The temperature of the reaction system was controlled at -5 to 0°C and a solution of benzyl chloroformate (20.0 g, 0.12 mol) in dichloromethane (100 mL) was slowly added dropwise under stirring. The dropwise addition process was completed in about 1 hour, followed by continued stirring of the reaction for 2 hours at room temperature. Upon completion of the reaction, the reaction mixture was washed with water (200 mL x 2). The organic layer was separated and dried over anhydrous sodium sulfate (10 g). The organic layer was concentrated under reduced pressure to give a light yellow foamy product of 23.4 g. To the residue, ethyl acetate (80 mL) was added and stirred at room temperature until completely dissolved, then petroleum ether (80 mL) was added dropwise to precipitate a white solid (N-Cbz-1,2-diaminoethane). The solid was collected by filtration, and the mother liquor was concentrated to obtain 15.1 g of light yellow oil, the total yield was 66.5%.