Hydrochloric Acid → Ethyl 3-amino-3-(2,5-difluorophenyl)propanoate

Acetyl chloride (4 ml) was added dropwise at room temperature to a round-bottom flask containing ethanol (50 ml). 3-Amino-3-(2,5-difluorophenyl)propionic acid (2.94 g) was added to the ethanolic hydrochloric acid solution thus prepared, and the mixture was stirred at 50° C. for three hours. Subsequently, the mixture was concentrated under reduced pressure, and the residue was admixed with 1N sodium hydroxide solution (100 ml) and extracted immediately with dichloromethane (3×50 ml). The combined organic phases were dried (Na2SO4), filtered and concentrated. The product (3.2 g) was used without further purification.