2: trifluoromethanesulfonic anhydride, pyridine, 2.) NaOH / 1.) dichloromethane, 0 deg C, 1 h, 2.) dioxane-water, room temperature, 3 h 3: 100 percent / NaOH / dioxane View Scheme

2: trifluoromethanesulfonic anhydride, pyridine, 2.) NaOH / 1.) dichloromethane, 0 deg C, 1 h, 2.) dioxane-water, room temperature, 3 h 3: 100 percent / NaOH / dioxane 4: 64 percent / diethylaminosulfur trifluoride / CH2Cl2 / 8 h / Ambient temperature 5: 60 percent / 80percent acetic acid / 45 h / 60 °C View Scheme