2: 40 percent / toluene / 1 h / Heating 3: 100 percent / acetic acid / 0.17 h / 110 °C 4: 100 percent / acetic acid, silica / toluene / 80 °C 5: 10 percent / chromium trioxide / acetic acid / 0.03 h / 10 °C 6: LiI / dimethylformamide View Scheme

1: ammonium cerium (IV) nitrate; sodium hydrogencarbonate / tetrahydrofuran / 1 h / 20 °C / Inert atmosphere 2: boron tribromide / dichloromethane / 1.5 h / -78 - -20 °C / Inert atmosphere View Scheme