di-isopropyl azodicarboxylate; triphenylphosphine in tetrahydrofuran Etherification; 3 h; Heating;

1: 96 percent / imidazole / CH2Cl2 / 4 h / 0 - 20 °C 2: 1.) LDA / 1.) THF, hexane, 30 min, 2.) THF, hexane, 3 h 3: 97 percent / 49percent aq. HF / acetonitrile / 18 h / Ambient temperature 4: 96 percent / 2,6-lutidine / CH2Cl2 / 1.5 h / 0 °C 5: 83 percent / (i-Pr)2NEt / propan-2-ol / 3.5 h 6: aq. LiOH / 1,2-dimethoxy-ethane / 0.5 h 7: imidazole / 1,2-dimethoxy-ethane / 20 h / 0 - 20 °C 8: 92 percent / 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, HOBt, Et3N / dimethylformamide / 18 h / 0 - 20 °C 9: 69 percent / 8N HCl / propan-2-ol / 6 h / Ambient temperature 10: 76 percent / Et3N / dimethylformamide / 12 h View Scheme

1: 98 percent / imidazole / dimethylformamide / 1 h / Ambient temperature 2: 1) lithium hexamethyldisilazide / 1) THF, -78 deg C, 1h, 2) room temperature, 30 min 3: tetrahydrofuran / -78 °C 4: DIBAL-H / toluene / 2 h / -78 °C 5: 96 percent / pyridine, DMAP / CH2Cl2 / 2 h / 0 °C 6: 1) hexamethyldisilazane (HMDS), ammonium sulfate, 2) trimethylsilyl triflate (TMSOTf) / 1) reflux, 1 h, 2) 1,2-dichloroethane, a) -22 deg C, 15 min, b) room temperature, 0.5 h 7: 85.5 percent / methanol; H2O / 18 h / 85 °C 8: 96.5 percent / 30percent aq. H2O2, pyridine / CH2Cl2 / Ambient temperature 9: 90 percent / TBAF / tetrahydrofuran / Ambient temperature View Scheme

1: 98 percent / imidazole / dimethylformamide / 1 h / Ambient temperature 2: 1) lithium hexamethyldisilazide / 1) THF, -78 deg C, 1h, 2) room temperature, 30 min 3: tetrahydrofuran / -78 °C 4: DIBAL-H / toluene / 2 h / -78 °C 5: 96 percent / pyridine, DMAP / CH2Cl2 / 2 h / 0 °C 6: 1) hexamethyldisilazane (HMDS), ammonium sulfate, 2) trimethylsilyl triflate (TMSOTf) / 1) reflux, 1 h, 2) 1,2-dichloroethane, a) -22 deg C, 15 min, b) room temperature, 0.5 h 7: 93 percent / n-Bu3SnH, Et3B / benzene; hexane / Ambient temperature 8: 83 percent / TBAF / tetrahydrofuran / Ambient temperature View Scheme

1: pyridine; CH2Cl2 / 6 h / 24 °C 2: NaOMe / 0.33 h 3: 79 percent / n-BuLi, CuCN / diethyl ether / -70 - -50 °C 4: DIBAL-H / toluene / 3 h / -78 °C 5: toluene / 15 h / 23 °C 6: DMAP, Et3N / pyridine / 26 h / 45 °C 7: DIBAL-H / toluene / 1 h / -78 °C 8: CBr4, PPh3 / CH2Cl2 / 1 h 9: Ph3P / acetonitrile / 6 h 10: 62 percent / 1) n-BuLi / tetrahydrofuran; hexamethylphosphoric acid triamide / 1) -78 deg C, 1 h, 2) -78 to -50 deg C, 1.5 h 11: 90 percent / n-Bu4NF / tetrahydrofuran / 12 h 12: LiOH / tetrahydrofuran; H2O View Scheme

1: 46 percent / imidazole 2: 92 percent / DIBAL / 0.08 h / -78 °C 3: CCl4, tris(dimethylamino)phosphane / tetrahydrofuran / 4 h / -80 °C 4: 29 percent / KOH, tris<2-(2-methoxyethoxy)ethyl>amine / acetonitrile / 0.5 h / Ambient temperature 5: 54 percent / Bu4NF / tetrahydrofuran / 0.5 h / Ambient temperature View Scheme

in methanol 24 h;

1: 71.5 percent / triethylamine, 4,4-dimethylaminopyridine / CH2Cl2 / 3.5 h / Ambient temperature 2: 1.) lithium hexamethyldisilazide / 1.) THF, hexane, -78 deg C, 25 min; 2.) THF, hexane 3: 30percent H2O2 / 0 °C View Scheme

1: 98 percent / imidazole / dimethylformamide / 1 h / Ambient temperature 2: 1) lithium hexamethyldisilazide / 1) THF, -78 deg C, 1h, 2) room temperature, 30 min 3: tetrahydrofuran / -78 °C 4: DIBAL-H / toluene / 2 h / -78 °C 5: 96 percent / pyridine, DMAP / CH2Cl2 / 2 h / 0 °C 6: 1) hexamethyldisilazane (HMDS), ammonium sulfate, 2) trimethylsilyl triflate (TMSOTf) / 1) reflux, 2 h, 2) 1,2-dichlorethane, a) 5 deg C, 10 min, b) room temperature, 10 min 7: 71 percent / 30percent aq. H2O2, pyridine / CH2Cl2 / Ambient temperature 8: 90 percent / TBAF / tetrahydrofuran / 3 h / Ambient temperature View Scheme

1: PBr3 / CH2Cl2 / -20 °C 2: 3.5 g / sodium / ethanol / 2 h / Heating 3: 1.8 g / H2O, NaCl / dimethylsulfoxide / 6 h / 145 - 180 °C 4: methanesulfonic acid, formic acid / 6 h / Heating View Scheme