1: 84 percent / hydroxylamine-O-sulphonic acid, 1 M NaOH / H2O / 5 °C / pH 7-8 2: 72 percent / formic acid; CH2Cl2 / 1) < 10 deg C, 20 min, 2) 25 deg C, 3 h 3: 88 percent / acetic anhydride, HClO4 (70percent) / 0.33 h / 25 °C 4: 73 percent / sodium ethanolate / ethanol / 0.33 h View Scheme