1: 1.) thionyl chloride / 1.) methanol, 2.) reflux 2: NaH / dimethylformamide / 90 - 100 °C 3: 1.) triflic anhydride, collidine, 2.) H2O / Multistep reaction. Intramolecular <2+2> cycloaddition of keteniminium salt. View Scheme

1: NaH / dimethylformamide / 90 - 100 °C 2: 1.) triflic anhydride, collidine, 2.) H2O / Multistep reaction. Intramolecular <2+2> cycloaddition of keteniminium salt. View Scheme

2,3,5-trimethyl-pyridine; trifluoromethylsulfonic anhydride; water 1.) ClCH2CH2Cl, 90 deg C, 90 min, 2.) H2O-CCl4, reflux, 2 h; Yield given. Multistep reaction. Yields of byproduct given;