Blue Light Irradiated, Para Site-Selective C-H/C-H Cross-Dehydrogenative Coupling of Electron-Rich Arenes with Quinones.

A metal-free, regioselective C-H/C-H dehydrogenative arylation of electron-rich arenes with quinones has been developed. Utilizing Eosin-Y as a photocatalyst and K2S2O8 as the terminal oxidant, this protocol enables the para selective quinonylation of phenols and anisoles under mild, open flask conditions. The reaction is promoted by trifluoroacetic acid (TFA) and visible light, providing a sustainable route to biologically active arylated quinone derivatives, including those with potential therapeutic applications for Alzheimer's disease. The methodology is scalable to gram level synthesis and tolerates a broad range of functional groups, delivering the desired cross-coupled products in moderate to high yields.