1.1: hydrogenchloride; sodium nitrite / water / 0.5 h / 0 - 5 °C / |Inert atmosphere 1.2: 1 h / 10 - 90 °C / |Inert atmosphere 2.1: oxalyl dichloride; N,N-dimethyl-formamide / dichloromethane / 2 h / |Inert atmosphere 3.1: oxalyl dichloride / dichloromethane / 0.5 h / |Inert atmosphere View Scheme

oxalyl dichloride in dichloromethane 0.5 h; Inert atmosphere;