Photoredox/Cobalt-Catalyzed Cascade Rearrangement-Cyclization of Alkene

A photoredox/cobalt-catalyzed sequential rearrangement-cyclization of unactivated alkenes is reported. 1,1diarylalkenes bearing tethered nucleophiles undergo a selective 1,2-aryl migration, initiated by metal-hydride hydrogen atom transfer and radical-polar crossover, and followed by intramolecular cyclization. Evaluating the catalytic reaction manifolds suggested that this system offers high reactivity and migratory selectivity. The preference for the 1,2-aryl shift over direct cyclization was rationalized by DFT calculations. This catalytic protocol enables accessing diverse spirocyclic and heterocyclic architectures.