1: oxalyl dichloride; N,N-dimethyl-formamide / dichloromethane / Inert atmosphere 2: 0.5 h / Inert atmosphere View Scheme

1: oxalyl chloride; DMF / CH2Cl2 / 2 h / 20 °C 2: 49 percent / sodium hydride / tetrahydrofuran / 36 h / 20 °C 3: 77 percent / bis(triphenylphosphine)palladium(II) chloride; triphenylphosphine; copper(I) iodide / various solvent(s) / 20 h / Heating 4: 30 percent / various solvent(s) / 24 h / 320 °C View Scheme

1.1: 6.8 g / (COCl)2 / CH2Cl2; dimethylformamide / 2 h 2.1: 2.41 g / Et3N / CH2Cl2 / 0 - 20 °C 3.1: 86 percent / NaH / tetrahydrofuran / 0 - 20 °C 4.1: i-PrMgBr / tetrahydrofuran / 0.5 h / -25 °C 4.2: 39 percent / FeCl3; 1,2-dibromoethane / tetrahydrofuran / 1 h / 20 °C View Scheme