Room Temperature Access to Bridged Nitrogen Ligands via Electroreductive Annulation of 1,10-Phenanthrolines and Imines

An electroreductive annulation reaction of 1,10-phenanthrolines and imines has been developed. This method proceeds with broad substrate and functionality tolerance, high selectivity, and no need for pressurized H2 gas or transition metal catalysts. Mechanistic studies reveal that the products are formed via simultaneous electroreduction of both proton-activated reactants followed by radical cross-coupling and intramolecular cyclization of the coupling adduct.