1: 96 percent / pyridinium dichromate, Ac2O / CH2Cl2 / 1.5 h / Heating 2: 79 percent / NaBH4, H2O / ethanol / 4 h / Ambient temperature 3: 98 percent / pyridine / 3 h / Ambient temperature 4: 1percent HCl / methanol / 30 h / Ambient temperature 5: pyridine / 3 h / Ambient temperature 6: AcOH, conc. H2SO4 / Ambient temperature View Scheme

1: 96 percent / pyridinium dichromate, Ac2O / CH2Cl2 / 1.5 h / Heating 2: 79 percent / NaBH4, H2O / ethanol / 4 h / Ambient temperature 3: 98 percent / pyridine / 3 h / Ambient temperature 4: 1percent HCl / methanol / 30 h / Ambient temperature 5: pyridine / 3 h / Ambient temperature 6: AcOH, conc. H2SO4 / Ambient temperature View Scheme

1: 100 percent / imidazole / pyridine / 24 h / 30 °C 2: 88 percent / Na; MeOH / toluene / 1 h / 0 °C 3: DMSO; DCC; Cl2CHCO2H / hexane; pyridine; benzene / 23 h / 20 °C View Scheme

1: 96 percent / pyridinium dichromate, Ac2O / CH2Cl2 / 1.5 h / Heating 2: 79 percent / NaBH4, H2O / ethanol / 4 h / Ambient temperature 3: 98 percent / pyridine / 3 h / Ambient temperature 4: 1percent HCl / methanol / 30 h / Ambient temperature 5: pyridine / 3 h / Ambient temperature 6: AcOH, conc. H2SO4 / Ambient temperature 7: 1.) HCl(g), AcCl, 2.) H2O / 1.) CH2Cl2, 0 deg C, 2.) CH3CN View Scheme

1: 96 percent / pyridinium dichromate, Ac2O / CH2Cl2 / 1.5 h / Heating 2: 79 percent / NaBH4, H2O / ethanol / 4 h / Ambient temperature 3: 98 percent / pyridine / 3 h / Ambient temperature 4: 1percent HCl / methanol / 30 h / Ambient temperature 5: pyridine / 3 h / Ambient temperature 6: AcOH, conc. H2SO4 / Ambient temperature 7: 1.) HCl(g), AcCl, 2.) H2O / 1.) CH2Cl2, 0 deg C, 2.) CH3CN 8: 1.) SO2Cl2 / 1.) CH2Cl2, DMF, from -40 deg C to RT, 3.5 h, 2.) CH2Cl2, DMF, RT, 15 h 9: 65 percent / KHF2, 48percent aq. HF / various solvent(s) / 1 h / 160 °C View Scheme