Visible Light-Induced Three-Component 1,2-Acylarylation of Quinoxalin-2(1H)-Ones with Styrenes and Oxime Esters

초록

Visible light-driven transformations offer an attractive strategy for sustainable synthesis by simplifying reaction systems while maintaining high efficiency. Herein, we report an exogenous photocatalyst-free visible light-induced three-component 1,2-acylarylation of quinoxalin-2(1H)-ones with styrenes and acyl oxime esters under mild conditions. Exploiting the intrinsic photoactivity of quinoxalin-2(1H)-ones, direct excitation under purple LED irradiation enables single electron transfer (SET) to acyl oxime esters, generating acyl radicals without the need for external photocatalysts. The resulting radicals undergo a sequential addition to alkenes and quinoxalin-2(1H)-ones, affording structurally diverse C3-functionalized products in moderate to good yields. The current three-component coupling protocol exhibits broad substrate scope, tolerating a range of styrenes, quinoxalin-2(1H)-ones, and benzoyl oxime esters. Mechanistic studies, including radical trapping experiments, fluorescence quenching, and UV–Vis analysis, support a SET-driven radical relay pathway involving a photoexcited quinoxalin-2(1H)-one. This operationally simple and modular approach highlights the dual role of quinoxalin-2(1H)-ones as both substrate and photoactive species, expanding the scope of exogenous photocatalyst-free multicomponent radical transformations.

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