1: pyridine; potassium permanganate / water / |Reflux 2: oxalyl dichloride; N,N-dimethyl-formamide / dichloromethane / 2 h / 0 °C 3: dichloromethane / 20 °C 4: caesium carbonate; copper(I) thiophene-2-carboxylate; N,N,N',N,-tetramethylethylenediamine / water / 0.17 h / 300 °C / 12929 Torr / |Microwave irradiation 5: boron tribromide / dichloromethane / 0 °C / |Inert atmosphere View Scheme