Sulfonyl-Directed Photoinduced Dehydro-Diels–Alder Reaction of Aryl Maleimides: Enabling Regioselective Naphthalene Synthesis

Light-mediated intermolecular dehydro-Diels-Alder (DDA) reactions have emerged as a powerful strategy for constructing multisubstituted naphthalenesprivileged scaffolds found in natural products, pharmaceuticals, and functional materials. However, developing a general [4 + 2] cycloaddition system that accommodates electron-deficient dienes with both electron-rich and electron-deficient alkynes has remained challenging. Herein, we report a catalyst-free DDA reaction between sulfonyl-substituted aryl maleimides, serving as electron-deficient dienes, and alkynes under visible-light irradiation. By proceeding via a triplet intermediate manifold that bypasses conventional single-electron-transfer pathways and their redox matching constraints, this protocol enables efficient and regioselective access to diverse multisubstituted naphthalenes and exhibits broad compatibility with alkynes of varying electronic nature. Mechanistic studies reveal the essential dual role of the sulfonyl group in promoting the [4 + 2] cycloaddition with high chemoselectivity and facilitating the final aromatization step.