Amination of Aminopyridines via η6-Coordination Catalysis.

ABSTRACT

Pyridine, a widespread aromatic heterocycle, features a sp2-hybridized nitrogen atom that can readily coordinate to metals, leading to distinctive achievements in catalysis. In stark contrast, π-coordination of pyridine and derivatives with transition metals is notably scarce, and the involvement of such activation mode in catalysis remains to be developed. Herein, we present amination reactions of aminopyridines that leverages the reversible π coordination with a ruthenium catalyst as the arenophilic π acid, rather than relying on the conventional κ-N coordination. Specifically, a transient η6-pyridine complex functions as the electrophile in the nucleophilic aromatic substitution with amines, providing a diverse array of products via the cleavage of the pyridyl C-N bond. In addition, this method can be employed to incorporate chiral amines and 15N-labeled amines.