Titre: ‘‘ Electron Catalysis’’
Endroit : Pavillon Roger-Gaudry, salle S-142
Heure : 11:00 AM
Hôte : Professeur André Charette
In the lecture the concept of using the electron as a catalyst will be discussed.[1,2] It will be shown that the electron is an efficient catalyst for conducting various types of radical cascade reactions that proceed via radical and radical ion intermediates. It will be emphasized how a negative charge can significantly weaken the neighbouring C-H bond and activate this bond towards H-atom transfer.[3e,j] Moreover, the activation of a C-H bond next to a C-radical towards deprotonation is a key point in the field of electron-catalysis. Extending that concept, the use of a negative charge to activate a C-C sigma-bond towards homolysis is also discussed.[3i,k] For example, electron catalyzed transition metal-free b-alkenylation-a-perfluoroalkylation of unactivated alkenes via radical 1,4 or 1,5-alkenyl migration will be presented.
It will be further shown, that readily generated vinyl boron ate complexes, generally used as substrates in the Suzuki-Miyaura coupling, are efficient radical acceptors to conduct electron-catalyzed modular synthesis comprising a radical polar cross over step.[3h] This approach has recently been successfully applied to the development of a novel method for the preparation of highly enantioenriched a-chiral ketones[3l] and a new method for radical borylation is introduced.[3n]