Multi-step reaction with 2 steps 1: 61 percent / triethylamine / CH2Cl2 / -78 °C2: 1.) 2,6-lutidine, trifluoroacetic anhydride, 2.) mercuric chloride (aq.) / 1.) acetonitrile, -40 deg C, 1 h, 2.) 25 deg C, 2 h