Electronic Effects on the Selectivity of Pd-Catalyzed C-N Bond-Forming Reactions Using Biarylphosphine Ligands: The Competitive Roles of Amine Binding and Acidity

摘要

In 2003, we reported that aniline derivatives could be selectively coupled to aryl halides in the presence of aliphatic amines using Pd catalysts with biarylphosphine ligands[1] - chemoselectivity that was not well-understood at the time.[2] To clarify the origin of this selectivity, we have studied the formation of amine complexes using an aryl palladium oxidative addition complex recently reported by our lab.[3] From these studies, we have isolated and characterized the first neutral aryl palladium amine complex that is a competent intermediate in a CN cross-coupling reaction. For various amines, we have determined the relative binding constants to the oxidative addition complex and described how selectivity in the catalytic arylation of amines is influenced by the electronic properties of the amine. Additionally, we have shown how selectivities observed in CN cross-coupling reactions using neutral amines can be reversed through use of the corresponding lithium amides.