boron tribromide in dichloromethane T=0 - 20°C;

1: potassium carbonate / acetonitrile / 4 h / 20 °C 2: bromine / acetic acid / 60 °C 3: sodium tetrahydroborate / methanol / -20 - 20 °C 4: triethylamine; p-toluenesulfonyl chloride / acetonitrile / Reflux 5: boron tribromide / dichloromethane / 0 - 20 °C View Scheme

1: triethylamine; p-toluenesulfonyl chloride / acetonitrile / Reflux 2: boron tribromide / dichloromethane / 0 - 20 °C View Scheme

1: sodium tetrahydroborate / methanol / -20 - 20 °C 2: triethylamine; p-toluenesulfonyl chloride / acetonitrile / Reflux 3: boron tribromide / dichloromethane / 0 - 20 °C View Scheme

1: bromine / acetic acid / 60 °C 2: sodium tetrahydroborate / methanol / -20 - 20 °C 3: triethylamine; p-toluenesulfonyl chloride / acetonitrile / Reflux 4: boron tribromide / dichloromethane / 0 - 20 °C View Scheme

1: bromine / acetic acid / 2 h / 20 °C 2: potassium carbonate / acetonitrile / 4 h / 20 °C 3: bromine / acetic acid / 60 °C 4: sodium tetrahydroborate / methanol / -20 - 20 °C 5: triethylamine; p-toluenesulfonyl chloride / acetonitrile / Reflux 6: boron tribromide / dichloromethane / 0 - 20 °C View Scheme