2,2,2-Trifluoroethyl formate → benzyl-(N-hydroxy)formamide

A suspension of N-benzyl-N-hydroxylamine hydrochloride (1.0 g, 6.26 mmol; Aldrich Chemical Company, Milwaukee, Wis.) in methyl tert-butyl ether (10 mL) was vigorously stirred 10% potassium bicarbonate solution and separated into an aqueous fraction and an organic fraction. The organic fraction was treated with the 2,2,2-trifluoroethyl formate reagent (92% (w/w), 4.35 g, 31.3 mmol, 5 equiv), and heated at reflux for 6 hours. The mixture was washed sequentially with water, 15% potassium bicarbonate, and 15% brine, then concentrated to provide 0.90 g (96%) of the desired product as a mixture of rotamers. 1H NMR (300 MHz, CDCl3) δ 8.28, 7.86 (2s, 1H total), 7.35-7.15 (m, 5H total), 7.10, 6.90 (2 br s, 1H total), 4.64, 4.56 (2s, 2H total).