Iodine-Catalyzed One-Pot Multicomponent Synthesis of Pyrrolo/indolo[1,2-a]quinoxalines Substituted with ortho-Carbonyl Alkyl Benzoates/Benzoic Acids via Spirocyclic Ring Opening

Abstract

AbstractAn efficient iodine-catalyzed cascade coupling protocol was developed for the synthesis of tetracyclic and pentacyclic pyrrolo[1,2-a]quinoxaline and indolo[1,2-a]quinoxaline derivatives via the iodine-mediated oxidative Pictet–Spengler reaction of 2-(1H-pyrrol-1-yl)aniline or 2-(1H-indol-1-yl)aniline with ninhydrin followed by spirocyclic ring opening with alcohol/water. The target compounds were obtained in good-to-excellent yields with a broad substrate scope.