Transition-metal-free catalyzed [3+2] cycloadditions/oxidative aromatization reactions for the synthesis of annulated indolizines

Abstract

In this study, transition-metal-free catalyzed [3+2] cycloadditions/oxidative aromatization three-component reactions for the successful direct construction of pyrrolo[3,4-a]indolizine-1,3(2H)-diones via pyridinium ylides are reported. This method utilizes readily available pyridines, acetophenones and maleimides as starting materials in the presence of TBAI (N-tetrabutylammonium iodide)/TBHP (tert-butyl hydroperoxide), with a wide substrate scope and moderate to good yields, avoiding the use of metal catalysts and generation of halides.