1: 1) LDA / 1) THF, HMPT, -80 deg C, 10-15 min, 2) THF, -80 to 0 deg C, 4h 2: 82 percent / DIBAL / diethyl ether; hexane / 1) -80 deg C, 3h, 2) -80 to -20 deg C 3: 86 percent / PPh3 / CH2Cl2 / 0.58 h / 0 °C View Scheme

pyridine; phosphorus tribromide in diethyl ether T=50°C; 2.5 h;

bromine; triphenylphosphine in dichloromethane T=0°C; 1.5 h;

sodium hydride in tetrahydrofuran Heating;