Iron-Catalyzed Decarboxylative Phosphonylation of Aliphatic Carboxylic Acids with Succinimidyl Phosphites as Bifunctional Reagents

Aliphatic carboxylic acids are abundant, stable, and cost-effective, rendering them ideal substrates for site-specific C(sp3)–P bond formation via decarboxylative pathways. However, the direct catalytic decarboxylative phosphonylation of these acids remains a significant challenge. Herein, we report that the use of dialkyl succinimidyl phosphites as bifunctional reagents enables the iron-catalyzed decarboxylative phosphonylation of aliphatic carboxylic acids to proceed smoothly at room temperature under visible light irradiation. The transformation accommodates primary, secondary, and tertiary alkyl acids, delivering the corresponding alkylphosphonates in satisfactory yields with broad functional group tolerance. A reaction mechanism involving photoinduced ligand-to-metal charge transfer (LMCT) of ferric carboxylates, β-scission of phosphoranyl radical intermediates leading to N–O bond cleavage, and single-electron oxidation of ferrous ions by succinimidyl radicals, is proposed.