title: Ultrafast Click Chemistry with Fluorosydnones.
abstract: We report the synthesis and reactivity of 4-fluorosydnones, a unique class of mesoionic dipoles displaying exquisite reactivity towards both copper-catalyzed and strain-promoted cycloaddition reactions with alkynes. Synthetic access to these new mesoionic compounds was granted by electrophilic fluorination of σ-sydnone Pd(II) precursors in the presence of Selectfluor. Their reactions with terminal and cyclic alkynes were found to proceed very rapidly and selectively, affording 5-fluoro-1,4-pyrazoles with bimolecular rate constants up to 10(4)  m(-1)  s(-1) , surpassing those documented in the literature with cycloalkynes. Kinetic studies were carried out to unravel the mechanism of the reaction, and the value of 4-fluorosydnones was further highlighted by successful radiolabeling with [(18) F]Selectfluor.
authors: Service de Chimie Bio-organique et Marquage (SCBM), IBITECS, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France.
authors: Hui
authors: H
authors: Liu
authors: Service de Chimie Bio-organique et Marquage (SCBM), IBITECS, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France.
authors: Davide
authors: D
authors: Audisio
authors: Service de Chimie Bio-organique et Marquage (SCBM), IBITECS, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France.
authors: Lucie
authors: L
authors: Plougastel
authors: Service de Chimie Bio-organique et Marquage (SCBM), IBITECS, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France.
authors: Elodie
authors: E
authors: Decuypere
authors: Service de Chimie Bio-organique et Marquage (SCBM), IBITECS, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France.
authors: David-Alexandre
authors: DA
authors: Buisson
authors: Syndivia SAS, 650 Boulevard Gonthier O'Andernach, 67400, Illkirch, France.
authors: Oleksandr
authors: O
authors: Koniev
authors: Syndivia SAS, 650 Boulevard Gonthier O'Andernach, 67400, Illkirch, France.
authors: Sergii
authors: S
authors: Kolodych
authors: Laboratory of Functional Chemo-Systems UMR 7199 CNRS-UdS, 67401, Illkirch, France.
authors: Alain
authors: A
authors: Wagner
authors: Laboratory of Bioorganic and Medicinal Chemistry, UMR 7509 CNRS, ECPM, 25, rue Becquerel, 67200, Strasbourg, France.
authors: Mourad
authors: M
authors: Elhabiri
authors: Turku PET Centre and Department of Chemistry, University of Turku, 20520, Turku, Finland.
authors: Anna
authors: A
authors: Krzyczmonik
authors: Turku PET Centre and Department of Chemistry, University of Turku, 20520, Turku, Finland.
authors: Sarita
authors: S
authors: Forsback
authors: Turku PET Centre and Department of Chemistry, University of Turku, 20520, Turku, Finland.
authors: Olof
authors: O
authors: Solin
authors: Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
authors: Véronique
authors: V
authors: Gouverneur
authors: Service de Chimie Bio-organique et Marquage (SCBM), IBITECS, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France. frederic.taran@cea.fr.
authors: Frédéric
authors: F
authors: Taran
keywords: click chemistry; electrophilic fluorination; fluorine-18; kinetics; radiolabeling