Annulation of α,β-unsaturated imines and alkynes via cobalt-catalyzed olefinic C-H activation.

A cobalt-triarylphosphine catalyst promotes an annulation reaction of an α,β-unsaturated imine and an internal alkyne to afford a polysubstituted dihydropyridine derivative in good yield under mild conditions. The reaction likely involves alkenylation of the olefinic C-H bond via cobalt-mediated nitrogen-assisted C-H activation followed by facile 6π electrocyclization of the resulting azatriene intermediate.