1: potassium hydroxide / water; dimethyl sulfoxide / 3 h / 95 °C 2: potassium hydroxide / polyethylene glycol (PEG 300) / 3.5 h / 120 °C 3: potassium dichromate; ammonium sulfate / sulfuric acid / 1.67 h / 45 - 60 °C View Scheme

1: potassium hydroxide / water; dimethyl sulfoxide / 3 h / 95 °C 2: 3-chloro-benzenecarboperoxoic acid / dichloromethane / 2 h / 35 °C 3: bismuth trifluoromethanesulphonate / dichloromethane / 2 h / 20 - 25 °C View Scheme