1: 100 percent / TBAF / tetrahydrofuran / 5.5 h / 25 °C 2: 80 percent / Dess-Martin periodinane / CH2Cl2 / 2 h / 25 °C 3: 86 percent / molecular sieves 4 Angstroem / toluene / 1.) -78 deg C, 2 h, 2.) -78 deg C to r.t. 4: 85 percent / t-BuOOH / VO(acac)2 / CH2Cl2 / 7 h / 25 °C 5: 92 percent / Et3N, DMAP / CH2Cl2 / 2.5 h / 3 °C 6: 90 percent / LiEt3BH / tetrahydrofuran / 1 h / 3 °C 7: 95 percent / PDC, molecular sieves 3 Angstroem / CH2Cl2 / 1 h / 25 °C 8: Et3N / CH2Cl2 / 1 h / 3 °C 9: TiCl4 / CH2Cl2 / 3 h / -78 - -15 °C 10: aq. HF / acetonitrile / 2 h / Ambient temperature 11: 72 percent / O2, CuCl, H2O / PdCl2 / dimethylformamide / 15 h / 25 °C 12: 41 percent / TESOTf, 2,6-lutidine / CH2Cl2 / 4 h / 25 °C View Scheme