1: 91 percent / Yb(OTf)3 / CH2Cl2 / 1 h / 0 °C 2: diisopropylethylamine / CH2Cl2 / 10 h / Ambient temperature 3: CBr4, Ph3P / CH2Cl2 / 0.5 h 4: 1.) n-BuLi, 2.) HMPA / 1.) THF, hexane, 15 min, -78 deg C, 2.) THF, hexane, a.) -78 deg C, 10 min, b.) 0 deg C, 4 h 5: H2 / 10percent Pd/C / ethanol / 20 h / 760 Torr 6: CBr4, Ph3P / CH2Cl2 / 0.5 h / 0 °C View Scheme