Double head-to-tail direct arylation as a viable strategy towards the synthesis of the aza-analog of dihydrocyclopenta[hi]aceanthrylene – an intriguing antiaromatic heterocycle

Abstract

The first case of double head-to-tail direct arylation of aromatic compounds and the unusual photophysical properties of the resulting 2,2a^1,5b^1,7-tetraazacyclopenta[hi]aceanthrylene are reported. This molecule, comprising of two imidazo[1,2-a]pyridine units, is antiaromatic due to the changes in the efficiency of π-electron ring current and it belongs to a class of seldom encountered compounds with a dark lowest electronically excited singlet state.