Octaphenylnaphthalene and Decaphenylanthracene

Octaphenylnaphthalene ( 2 ) was synthesized by the addition of tetraphenylbenzyne to tetraphenylcyclopentadienone, and decaphenylanthracene ( 3 ) was synthesized by the addition of the same aryne to hexaphenylisobenzofuran followed by deoxygenation of the adduct. The structures of both compounds were determined by X-ray analysis. Compound 2 adopts a conformation of approximate C i symmetry with a slightly undulating naphthalene nucleus, but compound 3 exhibits C 2 (and approximate D 2 ) symmetry with a 63° twist of the central anthracene.