Dynamic Covalent Metathesis in the C═C/C═N Exchange between Knoevenagel Compounds and Imines.
Fiche publication
Date publication
avril 2018
Journal
Journal of the American Chemical Society
Auteurs
Membres identifiés du Cancéropôle Est :
Pr LEHN Jean-Marie
Tous les auteurs :
Gu R, Flidrova K, Lehn JM
Lien Pubmed
Résumé
Fast and reversible dynamic covalent C═C/C═N exchange takes place without catalyst in nonpolar solvents between barbiturate-derived Knoevenagel (Kn) compounds and imines. A detailed study of the reaction indicates that it proceeds by an associative organo-metathesis mechanism involving the formation of a four-membered ring azetidine intermediate by addition of the imine C═N group to the C═C bond of the Kn compound. This intermediate could be generated cleanly and stabilized at low temperature by condensation of the o,p-dinitrophenyl Kn derivative with the cyclic imine 1-azacyclohexene. It was characterized by extensive NMR and mass spectrometric studies. The process described represents a genuine dynamic covalent organo-metathesis through a four-membered ring adduct as intermediate. It paves the way for the exploration of a wide set of dynamic systems involving (strongly) polarized C═C bonds and various imines, extending also into covalent dynamic polymers and polymolecular assemblies.
Référence
J. Am. Chem. Soc.. 2018 Apr 25;140(16):5560-5568