1: 1.) oxalyl chloride, DMF 2.) Et3N / 1. THF, r. t., 3h 2. THF, H2O, r. t., 1.5h 2: 75 percent / SnCl2*H2O / methanol / 0.67 h / Heating 3: 68 percent / HgCl2, CaCO3 / acetonitrile; H2O / 24 h / Ambient temperature 4: 89 percent / 1,4-cyclohexadiene / Pd-C / ethanol / 3 h / 20 °C View Scheme