Visible Light-Induced Regioselective Intermolecular [2 + 2]-Cycloaddition of Alkyne and 2(1 H )-Quinolone Derivatives.

We have developed a visible light-induced intermolecular [2 + 2]-cycloaddition reaction between alkenes and alkynes using thioxanthone and Cu(OTf) 2 as cocatalysts. Various quinolin-2(1 H )-ones, featuring diverse substituted groups, were successfully employed in this reaction, resulting in the synthesis of a series of 4,8b-dihydrocyclobuta[ c ]quinolin-3(2a H )-ones. Our methodology presents a novel synthetic approach for alkene-alkyne [2 + 2]-cycloaddition, delivering cyclobutene derivatives with exceptional regioselectivity.