Efficient synthesis of pyrrolo[1,2-a]indol-3-ones through a radical-initiated cascade cyclization reaction

Abstract

A radical cascade cyanoisopropylation/cyclization reaction of 2,2′-azobis(2-methylpropionitrile) (AIBN) with 1-methacryloyl-3-phenyl-1H-indole-2-carbonitrile has been realized, providing an efficient strategy to access various pyrrolo[1,2-a]indol-3-ones in good to excellent yields with good functional group compatibility. The notable features of this protocol include avoiding the use of a photocatalyst and a transition metal, scalability, and ethanol as the green solvent. Moreover, mechanistic studies have been conducted and a plausible mechanism has been proposed.