Upon treatment with TBAF, CF3-substituted N-allenamides were transformed into γ-sultams. Cyclic sulfonamides bearing an ene-gem-difluorinated tether could be obtained by addition of acetic acid to the ammonium salt whereas TBAF alone provided the correspondingtrifluorinated ethyl sultams. A combined experimental and computationnal mechanistic study suggested that this transformation involves a 5-endo-dig cyclization on the ene-ynamide generated in situ.
TBAF-promoted carbanion mediated sulfonamide cyclization of CF3-substituted N-allenamides an access to fluorinated gamma-sultams
Clément Gommenginger, Yongxiang Zheng, Daniele Maccarone, Ilaria Ciofini and Laurence Miesch
Organic Chemistry Frontiers , 2023 (invited paper) - DOI: 10.1039/D3QO00781B
Laurence Miesch (team SOPhy), Institut de Chimie de Strasbourg (UMR 7177).