1: 68 percent / polyposphoric acid / 0.75 h / 100 °C 2: 80 percent / formic acid / 1 h / 80 °C 3: 88 percent / BBr3 / CH2Cl2 / 15 h / 0 - 20 °C 4: 75 percent / O2; TPP / CHCl3 / 0.17 h / 20 - 40 °C / Irradiation 5: 62 percent / H2 / Pt-black / dioxane / 8 h / 2280 Torr View Scheme