Green synthesis of pyrrolo[1,2-α]quinoxalines by palladium-catalyzed transfer hydrogenation with nitriles as carbon synthons

Abstract

Green palladium-catalyzed nitroarene/nitrile reductive cross-annulation chemistry that facilitates straightforward access to pyrrolo[1,2-a]quinoxaline derivatives is described herein. A range of nitriles are activated as carbon synthons to form intramolecular CN and CC bonds using this chemistry. The synthetic protocol has the advantages of broad substrate scope, excellent functional group tolerance, and the use of environment-friendly water and inexpensive HCOONa/HCOOH as the solvent and hydrogen donors, respectively. The catalyst is conveniently recycled by filtration and can be reused at least five times without obvious deactivation. This study offers an important platform for converting bulk chemical motifs into value-added functional frameworks.