Sulfur‐Catalyzed Oxidative Condensation of Aryl Alkyl Ketones with o‐Phenylenediamines: Access to Quinoxalines

Abstract While elemental sulfur has been largely used as oxidant or sulfurating agent, its role as a catalyst has not been developed. We report here its catalytic activity in the oxidative condensation of o ‐phenylenediamines with acetophenones in DMSO to provide quinoxalines. The method was also extended to α‐tetralones, propiophenones (R=Me) as well as higher homologues (R=Et, n ‐Pr) in place of acetophenones, leading to a wide range of naphthoquinoxalines and 3‐substituted 2‐arylquinoxalines. magnified image