Visible-Light-Driven Benzylation of In Situ-Formed Imines Using Toluenes and Acridine Photocatalysis

The selective formation of benzyl radicals through the homogeneous photooxidation of toluene derivatives, followed by deprotonation, is difficult to implement when the involved chemical species have low oxidation potentials. Here, we present a successful application of this approach for the modular construction of biologically important 1,2-diarylethylamines from toluene derivatives, aldehydes, and anilines. This three-component reaction is driven by acridine photocatalysis under visible light, with trifluoroacetic acid (TFA) (or p-TsOH) serving as an acid additive that plays a triple role. The method is reliable, easy to use, metal-free, compatible with a wide range of functional groups, and more efficient under flow conditions. Unlike previous methods, no cocatalysts are required for the turnover of the acridine photocatalyst.