1: 82 percent / p-toluenesulfonic acid / methanol / 3 h / Ambient temperature 2: 81 percent / pyridinium chlorochromate, Celite / CH2Cl2 / 2 h / Ambient temperature 3: 81 percent / BF3*Et2O / CH2Cl2 / 1 h / Ambient temperature 4: 51 percent / benzophenone / benzene / 0.42 h / Irradiation 5: 78 percent / CH3I / aq. ethanol / 48 h / Heating View Scheme

1: 68 percent / diethyl ether / 2 h 2: 90 percent / p-TsOH / methanol / 2 h / Ambient temperature 3: 87 percent / pyridine / CH2Cl2 / 12 h / Ambient temperature 4: 90 percent / n-Bu4NF / tetrahydrofuran / 1.5 h / Ambient temperature 5: 96 percent / 1N aq.KOH / methanol / 0.17 h / Ambient temperature View Scheme