To a stirred solution of ammonium salt (1.0 equiv.) in dry DCM (0.05 M) at 0°C was added dropwise NEt3 (2.2 equiv.) followed by TFAA (2.0 equiv.). The reaction mixture was allowed to warm up to room temperature and stirred for 16 h. After this time, a saturated aqueous solution of NaHCO3 was added to the mixture and it was extracted with DCM. The combined organic layers were dried over MgSO4 and concentrated under reduced pressure. The crude residue was purified by flash chromatography on silica gel affording the desired amide.