Photoinduced, Metal-Free Hydroacylation of Aromatic Alkynes for Synthesis of α,β-Unsaturated Ketones via C(sp3)–H Functionalization

Despite the notable advancements made over the past decade in achieving carbon-carbon bonds by transition-metal-catalyzed cross-coupling processes, metal-free cross-coupling reactions for hydroacylation of aromatic alkynes via C(sp³)-H functionalization are still rare and highly desired. Here we report a metal-free reliable approach for the synthesis of α,β-unsaturated ketones (chalcones) via C(sp³)-H functionalization using MeCN:H₂O as green solvent, Eosin Y as organic photocatalyst, and ambient air as oxidant. More significantly, this strategy can effectively transform a variety of methyl arenes and aromatic alkynes into the desired product. With high atom efficiency, use of green solvents, metal-free nature, environmental friendliness, and visible light as a renewable energy source, this method is compatible with biologically active molecules.