Paradigms and paradoxes: en route to the understanding of the aromaticity of the 'iso-species' isobenzofuran, anthranil, benzofurazan and 2,1,3-benzothiadiazole.

Using a model reaction, we recently investigated the thermochemistry and aromaticity systematics of nitrogen, oxygen and sulfur-containing heterocycles that are isoelectronic to the carbocyclic indane and its unsaturated counterpart indene. In this study all of the benzo-annelated species, e.g. indole, indoline, phthalic anhydride, phthalan and benzothiazole, all corresponding to annelation on a formal double bond of the 5-membered ring of the single ring species. In that study we asked 'What is to be done about the so-called iso-species?' such as isobenzofuran, anthranil, benzofurazan and 2,1,3-benzothiadiazole, wherein it is annelation of the formal single bond in the 5-membered ring. A modified model reaction is suggested in the current paper where we admit that it is quantitatively untested. [ABSTRACT FROM AUTHOR]