Photoinduced Ligand-to-iron Charge Transfer Enabled C(sp3)-H Phosphorylation of Hydrocarbons

Organophosphine compounds are of high significance in organic synthesis, organometallic chemistry, and materials science. The high demand for the incorporation of phosphine moieties into molecular structures has witnessed significant progress. However, synthetic methods of C(sp(3))-H phosphorylation on unactivated hydrocarbons still remain scarce. Herein, we describe the development of an iron-catalyzed C(sp(3))-H phosphorylation reaction enabled by a photoinduced ligand-to-metal charge transfer (LMCT) process. The reaction exhibits remarkably broad substrate scope (>66 examples), including various alkanes, halides, ketones, esters, nitriles, ethers, thioethers, and silanes as viable substrates. Notably, unconventional site selectivity of C-H phosphorylation is achieved, with the occurrence of phosphorylation preferentially at sterically unhindered C-H bonds. The procedure is operationally simple and readily scalable under continuous-flow, and provides access to high-value organophosphines from simple hydrocarbons in one step. Preliminary studies on the reaction mechanism and site selectivity have also been carried out.