1: 36 percent / methanesulphonyl chloride, triethylamine, barium carbonate / CH2Cl2 / 1.) 0 deg C, 3 h; 2.) 20 deg C, 20 h 2: 44 percent / barium carbonate / methanol / 4 h / Heating 3: 76 percent / 80percent acetic acid / 3 h / 85 °C View Scheme