1: 69 percent / MnO2 / benzene / 36 h / Ambient temperature 2: 81 percent / LiClO4 / 45 °C / electrolysis at 0.06 A, 10 V 3: 94 percent / H2 / 5percent Pd/C / ethyl acetate / 6 h / 760 Torr / Ambient temperature 4: 75 percent / aq. 1 M HCl / dioxane / 10 h / Heating View Scheme