Visible light-mediated NHCs and photoredox co-catalyzed radical 1,2-dicarbonylation of alkenes for 1,4-diketones

Abstract

Alkenes are ubiquitous, and the difunctionalization of alkenes represents one of the most practical approaches for the construction of value-added compounds. Dicarbonylation of alkenes provides direct access to value-added 1,4-dicarbonyl compounds. However, selectivity control for unsymmetric 1,2-dicarbonylation is of great challenge. We herein describe NHCs and photocatalysis co-catalyzed three-component radical 1,2-dicarbonylation of alkenes by distinguishing two carbonyl groups, providing structurally diversified 1,4-diketones. Distinct properties of acyl radical and NHCs-stabilized ketyl radical contributed to selectivity control. Acyl radicals are rapidly added to alkenes delivering alkyl radicals, which undergo subsequent radical-radical cross-coupling with NHCs-stabilized ketyl-type radicals, affording 1,2-dicarbonylation products. This transformation features mild reaction conditions, broad substrate scope, and excellent selectivity, providing a general and practical approach for the dicarbonylation of olefins.