1: 97 percent / PCl5 / CCl4 / 1.5 h / -12 °C 2: Mg, 1,2-dibromoethane / tetrahydrofuran / Irradiation; 1.) 50 deg C, 45 min then, 2.) 40 deg C, 30 min then room temp. 3: 1.) Br2; 2.) tBuOK / 1.) pentane, -15 deg C; 2.) 0 deg C, 120 min 4: 92 percent / NaNH2 in liq NH3 / pentane; diethyl ether / 0.3 h 5: 59 percent / HgSO4, 6NH2SO4 / diethyl ether; pentane / 2.75 h / Ambient temperature View Scheme

1: 97 percent / PCl5 / CCl4 / 1.5 h / -12 °C 2: 90 percent / KOtBu / pentane / 2 h / Ambient temperature View Scheme

1: 97 percent / PCl5 / CCl4 / 1.5 h / -12 °C 2: Mg, 1,2-dibromoethane / tetrahydrofuran / Irradiation; 1.) 50 deg C, 45 min then, 2.) 40 deg C, 30 min then room temp. 3: 1.) Br2; 2.) tBuOK / 1.) pentane, -15 deg C; 2.) 0 deg C, 120 min View Scheme

1: 97 percent / PCl5 / CCl4 / 1.5 h / -12 °C 2: Mg, 1,2-dibromoethane / tetrahydrofuran / Irradiation; 1.) 50 deg C, 45 min then, 2.) 40 deg C, 30 min then room temp. 3: 1.) Br2; 2.) tBuOK / 1.) pentane, -15 deg C; 2.) 0 deg C, 120 min 4: 92 percent / NaNH2 in liq NH3 / pentane; diethyl ether / 0.3 h View Scheme