1: 99 percent / H2SO4 / 1 h / 0 °C 2: 88 percent / BF3*Et2O / CH2Cl2 / 0.25 h / 0 °C 3: 65 percent / NIS, AgOTf / CH2Cl2 / 0 °C View Scheme

alpha-chloropyridine; trifluoromethylsulfonic anhydride; bis-(phenyl)-sulfoxide 1.) toluene, CH2Cl2, -78 deg C, 20 min; -40 deg C, 1 h, 2.) -40 deg C to room temperature; Yield given. Multistep reaction;