Photoelectrocatalyzed Alkylation of Phosphonites by Direct Decarboxylative C(sp³)‐P Coupling

Abstract A photoelectrocatalytic method is presented that achieves direct decarboxylative C(sp 3 )‐P coupling, providing a modular route to alkylphosphinates and alkylphosphonates from readily available carboxylic acids. The success of this reaction hinges on the synergistic combination of electrochemical anodic oxidation and photocatalytic ligand to metal charge transfer (LMCT) decarboxylation. By employing P(III) reagents as limiting reagents, our approach enables efficient alkyl modification of medicinally important nucleosides and complex molecules derived phosphonites, which were challenging to access by existing methods. Detailed mechanistic studies elucidate the critical roles of Fe catalysts and additives, offering valuable insights into the reaction pathway and laying the foundation for future advancements in photoelectrocatalytic C(sp 3 )‐heteroatom bond‐forming reactions.