Direct synthesis of 2-sulfonated 9H-pyrrolo[1,2-a]indoles via NaI-catalyzed cascade radical addition/cyclization/isomerization

Abstract

Pyrrolo[1,2-a]indole and organosulfone are common structural motifs found in many pharmaceuticals. An efficient approach for the synthesis of 2-sulfonated 9H-pyrrolo[1,2-a]indoles via a NaI-catalyzed sulfonyl-radical-involved cascade cyclization–isomerization process is described. By using sodium iodide as a catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant, various N-propargyl-substituted indoles and sulfonyl hydrazides are tolerated in this transformation, affording the corresponding products in moderate to good yields.