Synthesis of Heteroannulated Indolopyrazines through Domino N–H Palladium-Catalyzed/Metal-Free Oxidative C–H Bond Activation

A convenient
approach to [1,2,5]­oxadiazolo­[3′,4′:5,6]­pyrazino­[2,3-b]­indoles and their heteroannulated analogues bearing various
aryl substituents in the backbone has been developed. This synthetic
protocol is based on Pd-catalyzed Buchwald–Hartwig and subsequent
annulation by intramolecular oxidative cyclodehydrogenation. The photophysical
properties for new polycycles have been measured.