potassium carbonate in N,N-dimethyl-formamide T=20 - 80°C;

1: NaNO2, AcOH / H2O / 2 h / Ambient temperature 2: Na2S2O4, 25percent aq. NH4OH / 20 - 50 °C 3: 2.) 2.2 M aq. NaOH / 1.) reflux, 2 h, 2.) reflux, 45 min 4: K2CO3 / dimethylformamide / 20 - 80 °C View Scheme

1: 1.) acetic anhydride, 2.) 10percent aq. NaOH / 1.) 70 deg C, 2 h, 2.) from 20 to 70 deg C, 1 h 2: NaNO2, AcOH / H2O / 2 h / Ambient temperature 3: Na2S2O4, 25percent aq. NH4OH / 20 - 50 °C 4: 2.) 2.2 M aq. NaOH / 1.) reflux, 2 h, 2.) reflux, 45 min 5: K2CO3 / dimethylformamide / 20 - 80 °C View Scheme

1: 2.) 2.2 M aq. NaOH / 1.) reflux, 2 h, 2.) reflux, 45 min 2: K2CO3 / dimethylformamide / 20 - 80 °C View Scheme

1: Na2S2O4, 25percent aq. NH4OH / 20 - 50 °C 2: 2.) 2.2 M aq. NaOH / 1.) reflux, 2 h, 2.) reflux, 45 min 3: K2CO3 / dimethylformamide / 20 - 80 °C View Scheme