The general procedure for the synthesis of 2-(2,2,2-trifluoroacetamido)acetic acid from ethyl trifluoroacetate and glycine was carried out as follows: the TFA-α-amino acid was prepared by the method reported in references [1,2] with slight modifications. First, triethylamine (33 mmol, 1.5 eq.) was added to a methanolic solution (22 mL) of glycine (22 mmol). after 5 min, ethyl trifluoroacetate (29 mmol, 1.3 eq.) was added and the reaction mixture was stirred for 24 h. The reaction was carried out by rotary evaporation. Upon completion of the reaction, the solvent was removed by rotary evaporation. The remaining residue was dissolved in water (35 mL) and acidified with concentrated hydrochloric acid (4 mL). After acidification, the mixture was stirred for 15 minutes and then extracted with ethyl acetate. The organic layers were combined, washed sequentially with water and brine, and dried with anhydrous magnesium sulfate. After drying, filter and concentrate by rotary evaporation. If cured products (e.g., L-1a, D-1a, L-2a, D-2a, 3a, L-4a, D-4a to D-8a) are desired, they can be further dried overnight under high vacuum.
