1: 61 percent / 1.) aq. HCl, NaNO2, 2.) aq. KOAc / 1.) 0 deg C, 2.) 5-10 deg C, 4 h, 3.) RT, 24 h 2: 89 percent / Fe/H(+) 3: 81 percent / pyridine / 0.5 h / 0 °C 4: 91 percent / polyphosphoric acid / 0.25 h / 150 °C 5: 34 percent / aq. H2SO4, CrO3 / 0.5 h / 95 - 100 °C 6: 1,1'-carbonyldiimidazole / dimethylformamide View Scheme

1: 81 percent / pyridine / 0.5 h / 0 °C 2: 91 percent / polyphosphoric acid / 0.25 h / 150 °C 3: 34 percent / aq. H2SO4, CrO3 / 0.5 h / 95 - 100 °C 4: 1,1'-carbonyldiimidazole / dimethylformamide View Scheme

1: 81 percent / pyridine / 0.5 h / 0 °C 2: 91 percent / polyphosphoric acid / 0.25 h / 150 °C 3: 34 percent / aq. H2SO4, CrO3 / 0.5 h / 95 - 100 °C 4: 1,1'-carbonyldiimidazole / dimethylformamide View Scheme

1: 89 percent / Fe/H(+) 2: 81 percent / pyridine / 0.5 h / 0 °C 3: 91 percent / polyphosphoric acid / 0.25 h / 150 °C 4: 34 percent / aq. H2SO4, CrO3 / 0.5 h / 95 - 100 °C 5: 1,1'-carbonyldiimidazole / dimethylformamide View Scheme

1: 34 percent / aq. H2SO4, CrO3 / 0.5 h / 95 - 100 °C 2: 1,1'-carbonyldiimidazole / dimethylformamide View Scheme

1: 91 percent / polyphosphoric acid / 0.25 h / 150 °C 2: 34 percent / aq. H2SO4, CrO3 / 0.5 h / 95 - 100 °C 3: 1,1'-carbonyldiimidazole / dimethylformamide View Scheme

1: 61 percent / 1.) aq. HCl, NaNO2, 2.) aq. KOAc / 1.) 0 deg C, 2.) 5-10 deg C, 4 h, 3.) RT, 24 h 2: 89 percent / Fe/H(+) 3: 81 percent / pyridine / 0.5 h / 0 °C 4: 91 percent / polyphosphoric acid / 0.25 h / 150 °C 5: 34 percent / aq. H2SO4, CrO3 / 0.5 h / 95 - 100 °C 6: 1,1'-carbonyldiimidazole / dimethylformamide View Scheme

1,1'-carbonyldiimidazole in N,N-dimethyl-formamide