boron tribromide in dichloromethane T=-78 - 25°C; 5.5 h;

1.1: sec-BuLi; CuBr*Me2S / tetrahydrofuran; cyclohexane / -78 - -15 °C 1.2: 76 percent / tetrahydrofuran; cyclohexane / 1 h / -78 °C 2.1: 81 percent / BBr3 / CH2Cl2 / 5.5 h / -78 - 25 °C View Scheme

1.1: 85 percent / NaH2PO4; aq. NaClO2 / dimethylsulfoxide / 20 °C 2.1: thionyl chloride / benzene / 2 h / Heating 3.1: 4.82 g / benzene / 0 - 20 °C 4.1: sec-BuLi; CuBr*Me2S / tetrahydrofuran; cyclohexane / -78 - -15 °C 4.2: 76 percent / tetrahydrofuran; cyclohexane / 1 h / -78 °C 5.1: 81 percent / BBr3 / CH2Cl2 / 5.5 h / -78 - 25 °C View Scheme

1.1: thionyl chloride / benzene / 2 h / Heating 2.1: 4.82 g / benzene / 0 - 20 °C 3.1: sec-BuLi; CuBr*Me2S / tetrahydrofuran; cyclohexane / -78 - -15 °C 3.2: 76 percent / tetrahydrofuran; cyclohexane / 1 h / -78 °C 4.1: 81 percent / BBr3 / CH2Cl2 / 5.5 h / -78 - 25 °C View Scheme

1: 6 h / 0 °C / |Inert atmosphere 2: |Inert atmosphere 3: thionyl chloride / benzene / 2 h / |Reflux 4: 0 - 20 °C / |Inert atmosphere 5: sec.-butyllithium / cyclohexane / 1 h / -78 °C / |Inert atmosphere 6: boron tribromide / dichloromethane / 5.5 h / -78 - 25 °C / |Inert atmosphere View Scheme

in dichloromethane T=20°C; 20 h;