Triethylamine → Benzyl 2-{[(trifluoroacetyl)amino]methyl}morpholine-4-carboxylate

To a stirred solution of Intermediate 1 (6.37 g) in methanol (250 ml) under nitrogen was added benzylchloroformate (4.7 ml) and triethylamine (6.3 ml). The mixture was stirred at 22° C. for 1 h before the volatiles were removed in vacuo. The residue was purified by Biotage flash chromatography on a 90 g silica cartridge eluting with 33% ethyl acetate in cyclohexane, to give the title compound as a white solid (4.4 g).