Trifluoromethide as a strong base: [CF3-] mediates dichloromethylation of nitrones by proton abstraction from the solvent.

An unprecedented reactivity of CF3-TMS has been revealed, which exploits the basic character of the generated [CF3(-)] capable of delivering dichloromethide from dichloromethane with subsequent transfer to nitrones under smooth conditions. The proton-abstraction pathway was demonstrated through isotopic labeling experiments in CD2Cl2. The same reaction was achieved in acetonitrile with the introduction of a cyanomethyl group onto the nitrones.