bromine in dichloromethane T=0 - 20°C;

1.1: bromine; acetic acid / 60 °C 2.1: n-butyllithium / tetrahydrofuran; cyclohexane / 0.25 h / -78 °C 2.2: -78 - 20 °C 3.1: n-butyllithium / tetrahydrofuran; cyclohexane / 0.33 h / -78 °C 3.2: -78 - 20 °C 4.1: bromine / dichloromethane / 0 - 20 °C View Scheme

1.1: n-butyllithium / tetrahydrofuran; cyclohexane / 0.25 h / -78 °C 1.2: -78 - 20 °C 2.1: n-butyllithium / tetrahydrofuran; cyclohexane / 0.33 h / -78 °C 2.2: -78 - 20 °C 3.1: bromine / dichloromethane / 0 - 20 °C View Scheme

1.1: n-butyllithium / tetrahydrofuran; cyclohexane / 0.33 h / -78 °C 1.2: -78 - 20 °C 2.1: bromine / dichloromethane / 0 - 20 °C View Scheme