1: 99 percent / imidazole / dimethylformamide / 18 h / 25 °C 2: 80 percent / p-TsOH*H2O / methanol / 0.83 h / 25 °C 3: 1.) (COCl)2, DMSO, 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min, 2.) 25 deg C, 30 min 4: BF3*Et2O / CH2Cl2 / 1.) -86 deg C, 15 min; -86 to -70 deg C, 45 min, 2.) 0 deg C, 1 h 5: 100 percent / i-Pr2NEt / CH2Cl2 / 18 h / 25 °C 6: 1.) 9-BBN, 2.) 3 N aq. NaOH, 31percent aq. H2O2 / 1.) THF, 25 deg C, 17 h, 2.) 25 deg C, 7 h 7: 87 percent / pyridine, n-Bu3P / 45 h / 25 °C 8: 100 percent / 80percent m-CPBA, NaHCO3 / CH2Cl2 / 1.5 h / 25 °C 9: n-BuLi / diethyl ether; hexane / 1.) -78 deg C, 30 min, 2.) 25 deg C, 4.5 h 10: 1.) (COCl)2, DMSO, 2.) Et3N / 1.) CH2Cl2, -78 deg C, 30 min, 2.) 5 deg C, 30 min 11: 51 percent / SmI2 / tetrahydrofuran; methanol / 0.33 h / -78 °C 12: 91 percent / K2CO3 / methanol / 2.5 h / 60 °C 13: 79 percent / TMSBr / CH2Cl2 / 1.) -30 deg C, 5 min, 2.) 3 deg C, 30 min 14: 100 percent / TBAF / tetrahydrofuran / 5.5 h / 25 °C 15: 80 percent / Dess-Martin periodinane / CH2Cl2 / 2 h / 25 °C 16: 86 percent / molecular sieves 4 Angstroem / toluene / 1.) -78 deg C, 2 h, 2.) -78 deg C to r.t. 17: 85 percent / t-BuOOH / VO(acac)2 / CH2Cl2 / 7 h / 25 °C 18: 92 percent / Et3N, DMAP / CH2Cl2 / 2.5 h / 3 °C 19: 90 percent / LiEt3BH / tetrahydrofuran / 1 h / 3 °C 20: 95 percent / PDC, molecular sieves 3 Angstroem / CH2Cl2 / 1 h / 25 °C 21: Et3N / CH2Cl2 / 1 h / 3 °C 22: TiCl4 / CH2Cl2 / 3 h / -78 - -15 °C 23: aq. HF / acetonitrile / 2 h / Ambient temperature 24: 72 percent / O2, CuCl, H2O / PdCl2 / dimethylformamide / 15 h / 25 °C 25: 41 percent / TESOTf, 2,6-lutidine / CH2Cl2 / 4 h / 25 °C View Scheme