Methyl trifluoroacetate (89.6 μL, 891 μmoles) and triethylamine (104 μL, 743 μmoles) were added to a suspension of 4-benzoylphenylalanine (200 mg, 743 μmoles) in methanol (0.5 mL). The reaction was stirred vigorously for 24 h and then acidified with 1 N HCl until a pH of 2 was obtained. The mixture was added to ethyl acetate (10 mL), washed with 1 N HCl (2×10 mL), dried over MgSO4, and concentrated in vacuo to yield a white solid (49.7 mg, 136 μmoles, 18%). LRMS: not performed. 1H NMR: spectrum is consistent with the predicted structure.
