Photoinduced Phosphination of Arenes Enabled by an Electron Donor–Acceptor Complex Using Thianthrenium Salts

Herein, we describe a metal-free approach for the cross-coupling of arenes or styryl–thianthrenium salts (TTs) with diarylphosphines via an electron donor–acceptor (EDA) complex. Various tertiary phosphines were obtained with high site selectivity and good functional group tolerance. This method enables straightforward construction of C–P bonds via C–H activation of arenes and allows the late-stage functionalization of natural products or pharmaceutical molecules. Mechanistic studies support the approach involving a photoinduced EDA complex.