Probing the utility of palladium complexes supported by morpholine-functionalized N-heterocyclic carbene ligands in Buchwald-Hartwig amination

Convenient and high-yielding syntheses of two new morpholine-substituted N-heterocyclic carbene ligands, 1-Ar-3-{2-(4-morpholinyl)phenyl}imidazolidin-2-ylidene (Ar = Dipp, Mes), are described. An investigation of corresponding palladium complexes reveals hemilability, and examples of both monodentate and bidentate coordination are observed. A preliminary investigation of the activity of these palladium complexes for Buchwald-Hartwig amination catalysis is presented. Key words: N-heterocyclic carbene, palladium, Buchwald-Hartwig amination, ligand design, hemilabile. On decrit les syntheses commodes et a haut rendement de deux nouveaux ligands carbene N-heterocyclique substitues par la morpholine, 1-Ar-3-{2-(4-morpholinyl)phenyl}imidazolidin-2-ylidene (Ar = Dipp, Mes). Une etude des complexes de palladium correspondants revele une hemilabilite et l'on observe des exemples de coordination monodente ainsi que bidente. On presente une etude preliminaire de l'activite de ces complexes de palladium pour la catalyse de la reaction d'amination de Buchwald-Hartwig. [Traduit par la Redaction] Mots-cles: carbene N-heterocyclique, palladium, amination de Buchwald-Hartwig, conception de ligands, hemilabile.
Introduction The combination of a strong and weak donor within a bidentate ligand set can lead to interesting reactivity in the derived metal complexes, owing to the electronic asymmetry and [...]