Copper-catalyzed oxidative cyclization of α-hydroxyketones with o-phenylenediamines leading to quinoxalines

α-Hydroxyketones are oxidatively cyclized with o-phenylenediamines in toluene at 120 °C under an atmosphere of air in the presence of a catalytic amount of a copper catalyst along with powdered 4A molecular sieves to afford the corresponding quinoxalines in high yields. The reaction is applicable to a wide range of α-hydroxyketones which have various aryl and alkyl groups attached to carbonyl carbon.

Graphical abstracto-Phenylenediamines react with an array of α-hydroxyketones in toluene in the presence of a catalytic amount of a copper catalyst to afford quinoxalines.Figure optionsDownload full-size imageDownload as PowerPoint slide