1: 1percent HCl / methanol / 30 h / Ambient temperature 2: pyridine / 3 h / Ambient temperature 3: AcOH, conc. H2SO4 / Ambient temperature View Scheme

1.1: 99 percent / acetic acid; sulfuric acid / 16 h / 20 °C 2.1: 1,1,1,3,3,3-hexamethyldisilazane / Heating 2.2: 81 percent / trimethylsilyl trifluoromethanesulfonate / acetonitrile / 20 °C 3.1: 94 percent / sodium methoxide / methanol / 20 °C View Scheme

1: 1percent HCl / methanol / 30 h / Ambient temperature 2: pyridine / 3 h / Ambient temperature 3: AcOH, conc. H2SO4 / Ambient temperature View Scheme

1: 1percent HCl / methanol / 30 h / Ambient temperature 2: pyridine / 3 h / Ambient temperature 3: AcOH, conc. H2SO4 / Ambient temperature 4: 1.) HCl(g), AcCl, 2.) H2O / 1.) CH2Cl2, 0 deg C, 2.) CH3CN View Scheme

1: 1percent HCl / methanol / 30 h / Ambient temperature 2: pyridine / 3 h / Ambient temperature 3: AcOH, conc. H2SO4 / Ambient temperature 4: 1.) HCl(g), AcCl, 2.) H2O / 1.) CH2Cl2, 0 deg C, 2.) CH3CN 5: 1.) SO2Cl2 / 1.) CH2Cl2, DMF, from -40 deg C to RT, 3.5 h, 2.) CH2Cl2, DMF, RT, 15 h 6: 65 percent / KHF2, 48percent aq. HF / various solvent(s) / 1 h / 160 °C View Scheme

1.1: 99 percent / acetic acid; sulfuric acid / 16 h / 20 °C 2.1: 1,1,1,3,3,3-hexamethyldisilazane / 3 h / Heating 2.2: 73 percent / trimethylsilyl trifluoromethanesulfonate / acetonitrile / 20 °C 3.1: 96 percent / sodium methoxide / methanol / 20 °C View Scheme

1.1: 99 percent / acetic acid; sulfuric acid / 16 h / 20 °C 2.1: 1,1,1,3,3,3-hexamethyldisilazane / Heating 2.2: 81 percent / trimethylsilyl trifluoromethanesulfonate / acetonitrile / 20 °C 3.1: 94 percent / sodium methoxide / methanol / 20 °C View Scheme

1.1: 99 percent / acetic acid; sulfuric acid / 16 h / 20 °C 2.1: 1,1,1,3,3,3-hexamethyldisilazane / 3 h / Heating 2.2: 73 percent / trimethylsilyl trifluoromethanesulfonate / acetonitrile / 20 °C 3.1: 96 percent / sodium methoxide / methanol / 20 °C 4.1: 91 percent / diphenyl carbonate; NaHCO3 / dimethylformamide / 1 h / 150 °C View Scheme