Visible-Light-Induced C–C Coupling Reaction to Synthesize Bipyridine From 3-Cyano-1,4-Dihydropyridines

A concise and efficient photocatalytic C–C coupling of 1-benzyl-3-cyano-1, 4-dihydropyridine for synthesis of 1,1′-dibenzyl-3, 3′-dicyano-1,1′,4,4′-tetrahydro-4, 4′-bipyridine is described. The reporter system provides a novel technique that facilitates synthesis of C–C coupling derivatives without addition of transition metals and oxidants or other additives. A plausible synthetic pathway is proposed, and the coupling product was characterized via nuclear magnetic resonance spectroscopy (1H and 13C NMR), high-resolution electrospray ionization mass spectrometry (ESI-HRMS) and X-ray analyses.