1: dihydrogen peroxide; sodium hydroxide / methanol / 1.5 h / 60 - 120 °C 2: oxalyl dichloride / acetonitrile / 0.17 h / 80 °C 3: AlCl3, aluminium chloride / dichloromethane / 2.5 h / 20 °C 4: boron tribromide / dichloromethane / 24 h / -40 °C 5: hydrogenchloride / ethanol; water / 2 h / 90 °C 6: triethylamine; silver carbonate / acetone / 0.5 h / 20 °C View Scheme