1.1: 95 percent / 2,6-lutidine / CH2Cl2 / 2 h / 0 °C 2.1: 92 percent / tetrabutylammonium fluoride; acetic acid / tetrahydrofuran / 24 h / 20 °C 3.1: 95 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -78 - 20 °C 4.1: benzene / 4 h / Heating 5.1: 94 percent / trimethylsilyl chloride / tetrahydrofuran / 4 h / -78 °C 6.1: DIBAL-H / CH2Cl2 / 0.25 h / -78 °C 7.1: imidazole / dimethylformamide / 2 h / 0 °C 8.1: 90 percent / NaHMDS / tetrahydrofuran / 0.25 h / 0 °C 9.1: 9-BBN / tetrahydrofuran / 4 h / 20 °C 9.2: 60 percent / Cs2CO3; AsPh3 / PdCl2(dppf) / H2O; tetrahydrofuran / 1.5 h 10.1: 93 percent / HF*pyridine / tetrahydrofuran / 36 h / 20 °C 11.1: 92 percent / Dess-Martin periodinane / CH2Cl2 / 1 h / 20 °C 12.1: 87 percent / TiCl4 / CH2Cl2 / 0.25 h / -78 °C 13.1: 89 percent / tetrabutylammonium fluoride / tetrahydrofuran / 0.17 h / 0 °C 14.1: 91 percent / imidazole / dimethylformamide / 36 h / 20 °C 15.1: 95 percent / Dess-Martin periodinane / CH2Cl2 / 2 h / 20 °C 16.1: 62 percent / 2 N NaOH / H2O / 1.5 h / Heating 17.1: Et3N; 2,4,6-trichlorobenzoyl chloride / tetrahydrofuran / 0.08 h / 0 °C 17.2: 73 percent / DMAP / toluene; tetrahydrofuran / 0.5 h / 20 °C 18.1: 82 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone / CH2Cl2; H2O / 2.5 h 19.1: 90 percent / trifluoroacetic acid / CH2Cl2 / 2.5 h / 20 °C 20.1: 30 percent aq. H2O2; KHCO3 / methanol; acetonitrile / 24 h / 20 °C View Scheme

1.1: 95 percent / 2,6-lutidine / CH2Cl2 / 2 h / 0 °C 2.1: 92 percent / tetrabutylammonium fluoride; acetic acid / tetrahydrofuran / 24 h / 20 °C 3.1: 95 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -78 - 20 °C 4.1: benzene / 4 h / Heating 5.1: 94 percent / trimethylsilyl chloride / tetrahydrofuran / 4 h / -78 °C 6.1: DIBAL-H / CH2Cl2 / 0.25 h / -78 °C 7.1: imidazole / dimethylformamide / 2 h / 0 °C 8.1: 90 percent / NaHMDS / tetrahydrofuran / 0.25 h / 0 °C 9.1: 9-BBN / tetrahydrofuran / 4 h / 20 °C 9.2: 60 percent / Cs2CO3; AsPh3 / PdCl2(dppf) / H2O; tetrahydrofuran / 1.5 h 10.1: 93 percent / HF*pyridine / tetrahydrofuran / 36 h / 20 °C 11.1: 92 percent / Dess-Martin periodinane / CH2Cl2 / 1 h / 20 °C 12.1: 87 percent / TiCl4 / CH2Cl2 / 0.25 h / -78 °C 13.1: 89 percent / tetrabutylammonium fluoride / tetrahydrofuran / 0.17 h / 0 °C 14.1: 91 percent / imidazole / dimethylformamide / 36 h / 20 °C 15.1: 95 percent / Dess-Martin periodinane / CH2Cl2 / 2 h / 20 °C 16.1: 62 percent / 2 N NaOH / H2O / 1.5 h / Heating 17.1: Et3N; 2,4,6-trichlorobenzoyl chloride / tetrahydrofuran / 0.08 h / 0 °C 17.2: 73 percent / DMAP / toluene; tetrahydrofuran / 0.5 h / 20 °C 18.1: 82 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone / CH2Cl2; H2O / 2.5 h 19.1: 90 percent / trifluoroacetic acid / CH2Cl2 / 2.5 h / 20 °C View Scheme