NHC-Catalyzed C3-Acylation of 2-Oxindoles by Selective Aerobic Oxidation of Aryl Aldehydes

We here report an effective NHC-catalyzed acylation of 2-oxindoles using aldehydes with the aid of aerobic oxidation to prepare 3-alkylideneoxindoles - a biologically active moiety. This protocol is the first report on the use of oxidized Breslow intermediate for the carbon nucleophile and applies to a wide variety of aryl aldehydes, cyclohexanal, and metallocene-aldehyde. Lower catalyst loading, milder base, greener oxidant, easily available substrates, and ambient reaction temperature exemplify this as a sustainable methodology. Organocatalysis: An effective NHC-catalyzed acylation of 2-oxindoles using aldehydes with the aid of aerobic oxidation.The first report on the use of oxidized Breslow intermediate for the carbon nucleophile and applies to a wide variety of aryl aldehydes and cyclohexanal,. Lower catalyst loading, milder base, greener oxidant, easily available substrates, and ambient reaction temperature exemplify this as a sustainable methodology.image