MHAT-enabled cascade radical annulation to access N-fused indoles and pyrroles

Abstract

Iron-mediated hydrogen atom transfer (HAT) cascade annulation for the synthesis of N-fused indole and pyrrole is disclosed. This robust cascade annulation assembles intricate heterocyclic motifs, such as tetrahydropyrido[1,2-a]indoles and tetrahydroindolizines, equivalent to a formal [4+2] cycloaddition. The synthetic utility of the developed protocol was showcased in the synthesis of substituted tricyclic and tetracyclic heterocycles as well as an analogue of the natural product tashiromine.