Polycyclic aromatic compounds. The conversion of 1,1,4-triarylbuta-1,3-diene-2,3-dicarboxylic anhydrides and 1,4-diarylnaphthalene-2,3-dicarboxylic anhydrides into polycyclic compounds

Abstract

When 1,1,4-triarylbuta-1,3-diene-2,3-dicarboxylic anhydrides (II) are cyclised by aluminium chloride in a polar solvent (e.g., nitrobenzene) they give β-(3-aryl-1-oxoinden-2-yl)styrene-β-carboxylic acids (III), whereas in a non-polar solvent (e.g., benzene) the corresponding 7-oxobenzo[c]fluorene-6-carboxylic acids (IV) are obtained. However when irradiated, heated just above their m.p.s, or heated in acetic anhydride or nitrobenzene, they are converted into the corresponding 1,4-diarylnaphthalene-2,3-dicarboxylic anhydrides (VI).

Fusion of anhydrides (VI) with aluminium chloride–sodium chloride converted them into benz[c]indeno[2,1-a]-fluorene-13,14-diones (IX). However, when they are heated with aluminium chloride in carbon disulphide they are converted into 5-aryl-7-oxobenzo[c]fluorene-6-carboxylic acids (VII) or (VIII). Ring expansion of some of the latter acids is effected by diazomethane.