1: 81 percent / triethylamine / bis(triphenylphosphino)palladium chloride, CuI / dimethylformamide / 5 h / Ambient temperature 2: toluene / 60 h / Heating 3: oxalic acid, water / diethyl ether; ethanol / 6 h / Heating View Scheme

in N,N-dimethyl-formamide T=80°C; 1 h;