1: 94.8 percent / CF3COOH / acetonitrile / 4 h 2: 88.6 percent / 1.8 N aq. sodium hypochlorite, 2.6 N aq. NaOH / ethanol / 1 h / 70 °C 3: 93 percent / 66percent aq. AcOH / 1 h / Ambient temperature 4: 1.) 10percent aq. H2SO4, 2.) Ac2O, pyridine / 1.) ethanol, 3.5 h View Scheme

1: 94.8 percent / CF3COOH / acetonitrile / 4 h 2: 88.6 percent / 1.8 N aq. sodium hypochlorite, 2.6 N aq. NaOH / ethanol / 1 h / 70 °C 3: 93 percent / 66percent aq. AcOH / 1 h / Ambient temperature 4: 1.) 10percent aq. H2SO4, 2.) Ac2O, pyridine / 1.) ethanol, 3.5 h 5: sodium cyanoborohydride, AcOH View Scheme