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 View Scheme

formic acid; sodium nitrite

triethylamine in dichloromethane 18 h; Inert atmosphere;

in chloroform

1: aq. NaNO2, HCO2H 2: H2O View Scheme