Ultrafast Click Chemistry with Fluorosydnones

• DOI: 10.1002/anie.201606495
• Publication Date: 2016-08-25T13:38:25Z
• Authors: Hui Liu; Davide Audisio; Lucie Plougastel; Elodie Decuypere; David‐Alexandre B...; Oleksandr Koniev; Sergii Kolodych; Alain Wagner; Mourad Elhabiri; Anna Krzyczmonik; Sarita Forsback; Olof Solin; Véronique Gouverneur; Frédéric Taran
• Keywords: Mesoionic; Reactivity; Selectfluor; Sydnone

Abstract We report the synthesis and reactivity of 4‐fluorosydnones, a unique class mesoionic dipoles displaying exquisite towards both copper‐catalyzed strain‐promoted cycloaddition reactions with alkynes. Synthetic access to these new compounds was granted by electrophilic fluorination σ‐sydnone Pd II precursors in presence Selectfluor. Their terminal cyclic alkynes were found proceed very rapidly selectively, affording 5‐fluoro‐1,4‐pyrazoles bimolecular rate constants up 10 4 m −1 s , surpassing those documented literature cycloalkynes. Kinetic studies carried out unravel mechanism reaction, value 4‐fluorosydnones further highlighted successful radiolabeling [ 18 F]Selectfluor.