1: 1.) PBr3, pyridine / 1.) ether, 2.) DMF, ambient temperature 2: 1.) n-BuLi, 3.) H2O, KOH 3: 70 percent / Li, ethylamine / diethyl ether 4: 1.) n-BuLi / 1.) THF, HMPA, 2.) -78 deg C 5: 50 percent / Li, ethylamine / diethyl ether / -78 °C View Scheme

1.1: phosphorus tribromide / tetrahydrofuran / 0.5 h / 0 °C / |Inert atmosphere; |Cooling with acetone-dry ice 2.1: sodium hexamethyldisilazane / tetrahydrofuran; N,N-dimethyl-formamide / 0.83 h / -20 °C / |Inert atmosphere; |Cooling with acetone-dry ice 3.1: Pd(1,2-bis(diphenylphosphino)ethane)Cl2 / tetrahydrofuran / 0.08 h / |Inert atmosphere; |Cooling with acetone-dry ice 3.2: 5 h / 0 °C / |Inert atmosphere 4.1: ammonium cerium (IV) nitrate / water; dichloromethane; acetonitrile / 0.25 h / 0 °C View Scheme