Nitrogen ligands in copper-catalyzed arylation of phenols: Structure/activity relationships and applications

In spite of the importance of ligand/ copper-catalyzed arylations of nucleophiles in organic chemistry, the structural and electronic features that make a ligand efficient in these reactions have not been determined until now. In this work, several bidentate ligands involving pyridine and/or imine nitrogen binding sites such as our lead ligand I have been synthesized, and tested in phenol arylations with a view to highlight relationships between the structure of the chelates and their efficacy. This study allowed us to more precisely define the role of each type of N-binding site during the catalytic process, and to discover new efficient ligands. Among them, the iminopyridine 6a, which is cheap and easy-to-prepare in high yield, is very attractive for industrial applications. Some examples of its field of application are presented here. In the future, the development of this work could allow a more rational design of efficient ligands in arylation reactions, without resorting to classical ligand screening.