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.

A Visible-Light-Induced α-Aminoalkyl-Radical-Mediated Halogen-Atom Transfer Process: Modular Synthesis of Phenanthridinone Alkaloids.

A halogen-atom transfer (XAT) strategy utilizing α-aminoalkyl radicals allows the generation of aryl radicals at room temperature, which is applied for intramolecular cyclization reactions en route to biologically relevant alkaloids. Starting from simple halogen-substituted benzamides under visible light irradiation in the presence of an organophotocatalyst (4CzIPN) and BuN allows the modular construction of the phenanthridinone core, which gives facile access to drug analogs and alkaloids, e.g.