Visible-Light-Induced NHC-Catalyzed Carboacylation Reaction of Alkenes from Aryl Thianthrenium Salts and Aldehydes.

A metal-free, visible-light-induced NHC-catalyzed multiple-component reaction involving aldehydes and aryl thianthrenium salts for the carboacylation reaction of alkenes is reported. In this reaction, NHC-activated aldehydes afforded Breslow intermediates, which reduced thianthrenium salts and generated aryl radicals. The resulting aryl radicals underwent radical addition reactions to yield arylacylation products, in the presence of iodoalkane, and participated in the halogen atom transfer process to generate alkyl radicals and facilitate olefin alkylacylation.