1: 80 percent / Br2, Ph3P / CH2Cl2 / 1 h / 0 °C 2: 1) BuLi / 1) THF, hexane, 20 degC, 10 min, 2) HMPT, 20 degC, 0.5 h 3: 93 percent / Na / diethyl ether; liquid ammonia / -40 °C 4: 95 percent / TsOH / methanol; H2O / 3 h / Heating View Scheme

1: 80 percent / Br2, Ph3P / CH2Cl2 / 1 h / 0 °C 2: 1) BuLi / 1) THF, hexane, 20 degC, 10 min, 2) HMPT, 20 degC, 0.5 h 3: 93 percent / Na / diethyl ether; liquid ammonia / -40 °C 4: 95 percent / TsOH / methanol; H2O / 3 h / Heating 5: 81 percent / PCC / CH2Cl2 View Scheme