Photoinduced cobaloxime catalysis for allylic mono- and diphosphinylation of alkenes with hydrogen evolution

Abstract

The visible-light-induced cobalt-catalyzed hydrogen evolution radical coupling reaction has emerged as a powerful strategy for the synthesis of structurally diverse compounds, whereas transformations with phosphorus-centered radicals remain largely unexplored. Herein, a photoinduced allylic radical phosphinylation of alkenes with secondary phosphine oxides by cobaloxime catalysis is described. The reaction tolerates a wide range of alkenes, including activated electron-deficient alkenes and nonactivated aryl- and alkylsubstituted alkenes, affording allylic phosphine oxides in good yields with high site-selectivities. Furthermore, this photoinduced cobaloxime catalytic system can be extended to the radical diphosphinylation of simple alkenes to construct DPPP-dioxide analogues. The new phosphine–olefin and diphosphine ligands are generated smoothly by reduction of mono- and diphosphinylation products.