Visible-Light-Induced External Oxidant-Free Oxidative Phosphonylation of C(sp2)–H Bonds

Considering the synthetic value of phosphonates, developing powerful catalytic methods for the phosphonylation of C­(sp2)–H bonds is important. Herein, we achieve a visible-light-induced external oxidant-free oxidative phosphonylation of C­(sp2)–H bonds via the combination of photocatalysis and proton-reduction catalysis. Mechanistic studies indicate that the visible-light-induced electron-rich arene radical cation is the key reactive intermediate. The synthetic application of this approach is demonstrated in the late-stage functionalization of pharmaceutical molecules. This study may have significant implications for the functionalization of C­(sp2)–H bonds, especially for those that are sensitive to oxidative conditions.