1: 73 percent / DIBAL-H / CH2Cl2 / -78 °C 2: 90 percent / tetrahydrofuran / -78 °C 3: 77 percent / DMAP / CH2Cl2 4: 76 percent / Bu3SnH, AIBN / toluene / 80 °C 5: 80 percent / TsOH*H2O / CH2Cl2 6: 76 percent / Bu3SnH, AIBN / toluene / 110 °C 7: 95 percent / O3, Me2S, Sudan III / CH2Cl2; methanol / -78 °C View Scheme

1: 1) CuBr*Me2S, 2) BF3*Et2O / 1) Et2O, -40 deg C, 45 min, 2) Et2O, -78 deg C, 15 min, 3) -78 deg C to RT, 45 min 2: 70 percent / 1N KOH / ethanol; H2O / 168 h / Ambient temperature View Scheme