Ligand-ModulatedNickel/Photoredox-Catalyzed <i>exo</i>-Arylalkylation ofAlkynes

A ligand-modulated synergetic nickel/photoredox-catalyzed <i>exo</i>-arylalkylation of unactivated alkynes was developed that was strikingly different from the known <i>endo</i>-arylalkylation of activated arylacetylenes. The unique arylalkylation pathway was due to the formation of a π-allyl-Ni complex from alkyne where the nickel species was engaged in a distinctive dual-catalytic cycle. The nickel/photoredox-catalyzed <i>exo</i>-alkenylation was applied to the divergent synthesis of tryptamines and benzofurylethylamines.