1: pyridinium p-toluenesulfonate / dichloromethane / 20 °C 2: 9-bora-bicyclo[3.3.1]nonane; dihydrogen peroxide / tetrahydrofuran / 3 h / Inert atmosphere; Cooling with ice 3: tetrabutyl ammonium fluoride / tetrahydrofuran 4: Jone's reagent / water; acetone / 1 h / 0 °C 5: trifluoroacetic acid / dichloromethane / 20 °C 6: trifluoroacetic acid / dichloromethane / 20 °C View Scheme

1: pyridinium p-toluenesulfonate / dichloromethane / 20 °C 2: 9-bora-bicyclo[3.3.1]nonane; dihydrogen peroxide / tetrahydrofuran / 3 h / Inert atmosphere; Cooling with ice 3: tetrabutyl ammonium fluoride / tetrahydrofuran 4: Jone's reagent / water; acetone / 1 h / 0 °C 5: trifluoroacetic acid / dichloromethane / 20 °C View Scheme