1: 83 percent / PCC, NaOAc / CH2Cl2 / 2.5 h / Ambient temperature 2: 58 percent / BF3*MeOH / 17 h / Ambient temperature 3: BBr3 / CH2Cl2 / 18 h / -78 °C 4: 40 percent / Fremy's salt, KH2PO4 / H2O; acetone / 0.5 h / Ambient temperature View Scheme

1: 83 percent / PCC, NaOAc / CH2Cl2 / 2.5 h / Ambient temperature 2: 58 percent / BF3*MeOH / 17 h / Ambient temperature View Scheme

With  sodium hydroxide; water in  1,4-dioxane  Heating;   

With  pyridinium chlorochromate in  dichloromethane