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-<i>b</i>]­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.