C–H functionalization of highly electrophilic azolopyridines as a way to donor–acceptor conjugated indoles

The DDQ-assisted oxidative aromatization of 1,4-adducts of indoles to [1,2,5]chalcogenadiazolo[4,3-b]pyridines or 6,8-dinitro[1,2,4]triazolo[1,5-a]pyridines affords the corresponding new indole-type donor–acceptor compounds. Studying their photophysical properties revealed correlations between the substitution pattern and absorption spectra.