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

Abstract

AbstractWe 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.