1: ammonium cerium (IV) nitrate / water; acetonitrile / 20 °C 2: 4-(N,N-dimethlyamino)pyridine; triethylamine / tetrahydrofuran / 20 °C / Reflux 3: tetrabutyl ammonium fluoride; acetic acid / tetrahydrofuran / 20 °C 4: N,N,N',N',N'',N''-hexamethylphosphoric triamide; lithium diisopropyl amide / tetrahydrofuran; hexane / 4 h / -78 °C 5: trifluoroacetic acid / dichloromethane / 4 - 20 °C 6: water; sodium hydroxide / 64 h / 4 °C View Scheme

1: 4-(N,N-dimethlyamino)pyridine; triethylamine / tetrahydrofuran / 20 °C / Reflux 2: tetrabutyl ammonium fluoride; acetic acid / tetrahydrofuran / 20 °C 3: N,N,N',N',N'',N''-hexamethylphosphoric triamide; lithium diisopropyl amide / tetrahydrofuran; hexane / 4 h / -78 °C 4: trifluoroacetic acid / dichloromethane / 4 - 20 °C 5: water; sodium hydroxide / 64 h / 4 °C View Scheme

1.1: sodium tetrahydroborate / tetrahydrofuran; acetic acid / 20 °C 2.1: hydrogenchloride; 2,2,2-trifluoroethanol / 1,3-dimercaptopropane 3.1: 1H-imidazole / N,N-dimethyl-formamide / 20 °C 4.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 1 h / 0 °C 4.2: 20 °C 5.1: trifluoroacetic acid / dichloromethane; water / 20 °C 6.1: Dess-Martin periodane / dichloromethane / 0 - 20 °C 7.1: chloro-trimethyl-silane / tetrahydrofuran / 2 h / -40 °C 8.1: palladium 10 on activated carbon; hydrogen / ethanol 9.1: 4-(N,N-dimethlyamino)pyridine / pyridine / 0 - 20 °C 10.1: ammonium cerium (IV) nitrate / water; acetonitrile / 20 °C 11.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / tetrahydrofuran / 20 °C / Reflux 12.1: tetrabutyl ammonium fluoride; acetic acid / tetrahydrofuran / 20 °C 13.1: N,N,N',N',N'',N''-hexamethylphosphoric triamide; lithium diisopropyl amide / tetrahydrofuran; hexane / 4 h / -78 °C 14.1: trifluoroacetic acid / dichloromethane / 4 - 20 °C 15.1: water; sodium hydroxide / 64 h / 4 °C View Scheme

1.1: potassium tert-butylate / tert-butyl alcohol / Reflux 2.1: sodium tetrahydroborate / tetrahydrofuran; acetic acid / 20 °C 3.1: hydrogenchloride; 2,2,2-trifluoroethanol / 1,3-dimercaptopropane 4.1: 1H-imidazole / N,N-dimethyl-formamide / 20 °C 5.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 1 h / 0 °C 5.2: 20 °C 6.1: trifluoroacetic acid / dichloromethane; water / 20 °C 7.1: Dess-Martin periodane / dichloromethane / 0 - 20 °C 8.1: chloro-trimethyl-silane / tetrahydrofuran / 2 h / -40 °C 9.1: palladium 10 on activated carbon; hydrogen / ethanol 10.1: 4-(N,N-dimethlyamino)pyridine / pyridine / 0 - 20 °C 11.1: ammonium cerium (IV) nitrate / water; acetonitrile / 20 °C 12.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / tetrahydrofuran / 20 °C / Reflux 13.1: tetrabutyl ammonium fluoride; acetic acid / tetrahydrofuran / 20 °C 14.1: N,N,N',N',N'',N''-hexamethylphosphoric triamide; lithium diisopropyl amide / tetrahydrofuran; hexane / 4 h / -78 °C 15.1: trifluoroacetic acid / dichloromethane / 4 - 20 °C 16.1: water; sodium hydroxide / 64 h / 4 °C View Scheme

1.1: hydrogenchloride; 2,2,2-trifluoroethanol / 1,3-dimercaptopropane 2.1: 1H-imidazole / N,N-dimethyl-formamide / 20 °C 3.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 1 h / 0 °C 3.2: 20 °C 4.1: trifluoroacetic acid / dichloromethane; water / 20 °C 5.1: Dess-Martin periodane / dichloromethane / 0 - 20 °C 6.1: chloro-trimethyl-silane / tetrahydrofuran / 2 h / -40 °C 7.1: palladium 10 on activated carbon; hydrogen / ethanol 8.1: 4-(N,N-dimethlyamino)pyridine / pyridine / 0 - 20 °C 9.1: ammonium cerium (IV) nitrate / water; acetonitrile / 20 °C 10.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / tetrahydrofuran / 20 °C / Reflux 11.1: tetrabutyl ammonium fluoride; acetic acid / tetrahydrofuran / 20 °C 12.1: N,N,N',N',N'',N''-hexamethylphosphoric triamide; lithium diisopropyl amide / tetrahydrofuran; hexane / 4 h / -78 °C 13.1: trifluoroacetic acid / dichloromethane / 4 - 20 °C 14.1: water; sodium hydroxide / 64 h / 4 °C View Scheme

View Scheme