Photochemical Cobalt-Catalyzed Selective Olefin Hydrogenation and One-Bond Transposition

Olefins are important linchpins in organic synthesis, and the hydrogenation and isomerization of C═C double bonds represent two canonical transformations. We have developed a cobalt metallaphotoredox-catalyzed platform that enables the divergent hydrogenation and monoisomerization of olefins. Employing the same (salen)cobalt catalyst and nongaseous hydrogen source, both reaction pathways proceed via a common alkyl/Co(II) geminate radical pair generated through metal-catalyzed hydrogen atom transfer (MHAT) to the olefin. Selectivity between hydrogenation and monoisomerization is governed primarily by the effective hydrogen-source loading and moderately adjusted by light power, demonstrating the singular efficacy of this unified catalytic system.