1.1: 81 percent / Amberlite<*> IR-118 ion-exchange resin; Na; EtOH / diethyl ether / 2.5 h / 0 °C 2.1: 72 percent / PPh3; diisopropyl azodicarboxylate / tetrahydrofuran / 25 h / 0 - 20 °C 3.1: 73 percent / H2O2 / (NH4)6Mo7O24*4H2O / aq. ethanol / 240 h / 20 °C 4.1: NaHMDS / diethyl ether; tetrahydrofuran / 1 h / -78 °C 4.2: Dess-Martin periodinane / CH2Cl2 / 0.5 h / 20 °C 4.3: diethyl ether; tetrahydrofuran / -100 - 20 °C 5.1: Bu4NF*3H2O / tetrahydrofuran / 20 °C / overnight View Scheme