1: PBr3 / diethyl ether / 1.5 h / 0 °C 2: 72 percent / 1.) hexamethylphosphoric triamide, BuLi / tetrahydrofuran; hexane / 2 h / -70 - 0 °C 3: 70 percent / EtOH, Na / tetrahydrofuran / -20 - 0 °C 4: 70 percent / ceric ammonium nitrate / CH2Cl2; acetonitrile; H2O / 0.5 h / 0 - 20 °C View Scheme