bromine in dichloromethane T=20°C; 24 h;

1.1: anhydrous iron chloride / dichloromethane / 0.33 h / 25 °C 1.2: 0.08 h / 25 °C 2.1: n-butyllithium / tetrahydrofuran; hexane / 0.25 h / -78 °C / |Inert atmosphere 2.2: 1 h / -78 - 25 °C / |Inert atmosphere View Scheme

1.1: anhydrous iron chloride / dichloromethane / 0.33 h / 25 °C 1.2: 0.08 h / 25 °C 2.1: n-butyllithium / tetrahydrofuran; hexane / 0.25 h / -78 °C / |Inert atmosphere 2.2: 1 h / -78 - 25 °C / |Inert atmosphere View Scheme