Photoredox cobalt dual catalysis toward C3-functionalization of quinoxalinones with alkenes and alkynes.

A site-selective coupling involving quinoxalin-2-ones with alkenes and alkynes has been developed through synergistic visible-light photoredox cobalt catalysis. This method enables C3-selective alkylation and alkenylation of both -substituted and -unsubstituted quinoxalin-2-ones, achieving high yields under mild conditions. Of note, the protocol facilitates the incorporation of two alkene units, leading to a formal three-component coupling, whereas a two-component coupling is preferred for alkynes.