L-Aspartic acid 4-benzyl ester

56-84-8

100-51-6

2177-63-1

100 mL of anhydrous ether was added to a 500 mL beaker and 20 mL of concentrated sulfuric acid was added slowly and dropwise while stirring and cooling to room temperature. Subsequently, 150 mL of benzyl alcohol was added and the ether was removed by stirring well. Under reduced pressure, 26 g of L-aspartic acid was added to the reaction flask in 5 batches. The reaction was stirred for 24 h at room temperature, after which 300 mL of 95% ethanol was added, and 80 mL of pyridine was slowly added dropwise through a dropping funnel with vigorous stirring while dropping. The reaction mixture was placed in a refrigerator overnight and the solid was collected by filtration. The solid was dissolved with 80% ethanol with stirring, heated and filtered. The filtrate was frozen for 8 hours, filtered again and finally lyophilized to obtain pure β-aspartic acid benzyl ester in 90% yield.