30 g of (R)-methyl 2-amino-3-chloropropionate was suspended in 400 mL of diethyl ether and cooled to 0-5°C. 20 mL of ethanoic anhydride was slowly added dropwise with stirring, maintaining the reaction temperature at 0-5°C, and stirring was continued for 40 minutes after completion of the dropwise addition. Subsequently, the reaction mixture was slowly warmed to 15-25°C and stirring was continued for 1-2 hours. Upon completion of the reaction, the precipitated solid product was collected by filtration and washed with cold diethyl ether. The resulting solid was dried under vacuum to afford 33.3 g of methyl (R)-2-acetamido-3-chloropropionate in 85% yield.
