1: 1.) DMSO, (CF3CO)2O, 2.) Et3N / 1.) CH2Cl2, -78 deg C, 15 min, 2.) CH2Cl2, -78 deg C, 30 min 2: 1.) NaH, HMPA / 1.) THF, 0 deg C, 1 h, 2.) THF, RT, 6.5 h 3: tetrabutylammonium fluoride / tetrahydrofuran / 2.5 h / 0 °C 4: 77 percent / PCC, AcONa, molecular sieves 3 Angstroem / CH2Cl2 / 1 h / Ambient temperature 5: 1.) n-BuLi / 1.) THF, -20 deg C, 15 min, 2.) THF, -20 deg C, 3 h 6: 1.) DMSO, (CF3CO)2O, 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min, 2.) CH2Cl2, -78 deg C, 1 h 7: 88 percent / Ph3P / toluene / 8.5 h / Heating 8: 62 percent / 5percent HCl / methanol / 10 h / Ambient temperature View Scheme