Multichromophoric perylene–iridium triad as a homogeneous photocatalyst for the efficient synthesis of tetrahydroquinoline derivatives

Abstract

This study presents the design and synthesis of a multichromophoric catalyst system, namely, Ir-triad 1, which incorporates a perylene monoimide (PMI) as the central chromophore, with naphthalimide (NMI) positioned at its 1- and 7-bay positions, and the catalyst features an iridium (Ir) metal ion coordinated with a cyclopentadienyl (Cp*) unit, a chloride ligand and a cyclometalating ligand attached to PMI. Following photophysical and electrochemical characterization, Ir-triad 1 was utilized as a homogeneous photocatalyst to efficiently synthesize tetrahydroquinolines from N,N-dimethylanilines and maleimides under an aerobic atmosphere. The reaction involves direct cyclization via an sp³ C–H bond functionalization, yielding products in high yields from a diverse range of substrates, with up to 82–83% yields under blue LED (450 nm) irradiation.