Synthesis of 8-Aza- and 8,8′-Diaza-BINOL Derivatives through Cu(II)-TMEDA-Catalyzed Aerobic Oxidative Coupling
Résumé
A practical Cu(II)-TMEDA-catalyzed oxidative coupling of 7-hydroxyquinoline was developed with air as an oxidant, affording 8-aza- and 8,8′-diaza-BINOL derivatives in moderate to good yields. In addition, a series of post-transformations further demonstrated the utility of the current process, especially for the synthesis of novel hetero[5]helicenes with unique fluorescence properties.