1: 93 percent / DIBAH / CH2Cl2 / 1 h / -90 °C 2: 81 percent / EtAlCl2 / diethyl ether; hexane / 2.5 h / -40 to -20 deg C 3: 77 percent / 40percent aq. HF / acetonitrile / 12 h / 0 deg C to RT 4: 70 percent / Bu4NF / tetrahydrofuran / 0.25 h / -90 °C 5: 50 percent / PPh3, diethyl azodicarboxylate / tetrahydrofuran / 1.5 h / 0 deg C to RT View Scheme