1.1: sodium nitrite; hydrogenchloride; 1-phenylphosphoran / water / 0.25 h / 0 - 5 °C / |Inert atmosphere 1.2: 0 - 5 °C / |Inert atmosphere 2.1: dihydrogen peroxide; potassium hydroxide / methanol / 1.17 h / 65 °C 3.1: oxalyl dichloride; N,N-dimethyl-formamide / dichloromethane / 3 h / |Inert atmosphere 4.1: dichloromethane / 0.5 h / |Inert atmosphere View Scheme