in chloroform T=0 - 20°C; 10 h; Inert atmosphere;

1: chlorosulfonic acid / dichloromethane 2: thionyl chloride; hydrogenchloride / N,N-dimethyl-formamide; diethyl ether / |Cooling with ice 3: chloroform / 2 h / |Inert atmosphere; |Cooling with ice View Scheme

1.1: thionyl chloride; hydrogenchloride / N,N-dimethyl-formamide / 3 h / 5 °C / |Inert atmosphere 1.2: 0 °C / |Inert atmosphere 2.1: chloroform / 10 h / 0 - 20 °C / |Inert atmosphere View Scheme