Photoinduced Radical Phosphonylation of Alkyl Thianthrenium Salts with P(III) Reagents via Electron Donor–Acceptor Complexes

A photoinduced radical phosphonylation protocol has been developed for the efficient synthesis of alkyl phosphonates. This transformation proceeds through the formation of electron donor–acceptor (EDA) complexes between alkyl thianthrenium salts and P(III) reagents, which can be directly activated by light irradiation without the need for external photocatalysts or additives. The reaction exhibits broad substrate scope, tolerating various functional groups, offering a sustainable approach for C(sp 3 )–P bond formation.