Visible-Light Promoted Polycyclizations of Dienynes

A variety of linear dienynes can deliver complex tetracyclic frameworks in the presence of an Ir(III) complex and visible light. Products feature the assembly of four new C-C bonds and six contiguous stereocenters, which decorate two [3.1.0] bicyclic units tethered through their bridging quaternary carbons. The internal alkyne acts as a formal dicarbenoid to assemble two cyclopropanes in these radical cationic cascades. This behavior has not been previously observed among organic reactive intermediates and can be extended to intermolecular reactions and diendiynes.