sodium hydrogencarbonate in toluene 2 h; Heating;

1: 70 percent / (CF3CO)2O / 72 h / Ambient temperature 2: 74 percent / NasBH4 / aq. ethanol / 12 h / Ambient temperature 3: 79 percent / vanadyl acetylacetonate, 45percent tert-butylhydroperoxide / benzene / 2 h / Heating 4: 34 percent / CrO3-2py complex / CH2Cl2 / 1.5 h / Ambient temperature View Scheme

1: 70 percent / (CF3CO)2O / 72 h / Ambient temperature 2: 74 percent / NasBH4 / aq. ethanol / 12 h / Ambient temperature View Scheme