trifluoroacetic acid 3 h; Ambient temperature;

sulfuric acid in dichloromethane; acetone

sulfuric acid in ethylene glycol dimethyl ether T=55°C; 24 h;

1: 1) 60percent sodium hydride, 2) bromine / 1) DME, room temperature, 0.5 h, 2) room temperature, 1 h 2: 76 percent / acetic acid; dimethylformamide / 2 h / 80 °C 3: 1) 60percent sodium hydride / 1) DMF, 0 deg C, 0.5 h, 2) room temperature, 3 h 4: 100 percent / H2 / Raney Ni / acetic acid / 3 h 5: NaNO2, HOAc / acetic anhydride / 4 h / 0 °C 6: CCl4 / 5 h / Heating 7: 33.5 percent / 1 M H2SO4 / 1,2-dimethoxy-ethane / 24 h / 55 °C View Scheme

1: 76 percent / acetic acid; dimethylformamide / 2 h / 80 °C 2: 1) 60percent sodium hydride / 1) DMF, 0 deg C, 0.5 h, 2) room temperature, 3 h 3: 100 percent / H2 / Raney Ni / acetic acid / 3 h 4: NaNO2, HOAc / acetic anhydride / 4 h / 0 °C 5: CCl4 / 5 h / Heating 6: 33.5 percent / 1 M H2SO4 / 1,2-dimethoxy-ethane / 24 h / 55 °C View Scheme

1: 1) 60percent sodium hydride / 1) DMF, 0 deg C, 0.5 h, 2) room temperature, 3 h 2: 100 percent / H2 / Raney Ni / acetic acid / 3 h 3: NaNO2, HOAc / acetic anhydride / 4 h / 0 °C 4: CCl4 / 5 h / Heating 5: 33.5 percent / 1 M H2SO4 / 1,2-dimethoxy-ethane / 24 h / 55 °C View Scheme

1: 100 percent / H2 / Raney Ni / acetic acid / 3 h 2: NaNO2, HOAc / acetic anhydride / 4 h / 0 °C 3: CCl4 / 5 h / Heating 4: 33.5 percent / 1 M H2SO4 / 1,2-dimethoxy-ethane / 24 h / 55 °C View Scheme

1: 85 percent / K2CO3, O2 / methanol / 24 h 2: 80 percent / 2N aq. H2SO4 / 1,2-dimethoxy-ethane / 24 h / 50 °C View Scheme

1: 43 percent / SeO2 / dioxane; H2O / 4 h / 160 °C 2: 45 percent / pyridinium dichromate, 4-Angstroem molecular sieves / CH2Cl2 / 3.5 h / 0 °C View Scheme

1: 92 percent / Et3N / ethanol / 65 h / Ambient temperature 2: 1) tBuOK / 1) DME, -70 deg C, 20 min, 2a) -70 deg C to room temperature, b) room temperature, 30 h 3: 95 percent / aq. H2SO4 / dioxane / 24 h / 107 °C 4: 53 percent / 48percent aq. HBr / 18 h / 105 °C 5: 43 percent / SeO2 / dioxane; H2O / 4 h / 160 °C 6: 45 percent / pyridinium dichromate, 4-Angstroem molecular sieves / CH2Cl2 / 3.5 h / 0 °C View Scheme