TBAF-promoted carbanion-mediated sulfonamide cyclization of CF3-substitutedN-allenamides: an access to fluorinated γ-sultams

γ-Sultams bearing a trifluorinated ethyl- or an ene- gem -difluorinated tether were obtained from CF 3 -substituted N -allenamides; experimental and DFT calculations suggested that this transformation involves a 5- endo-dig cyclization on the ene-ynamide generated in situ .