Fused Polycyclic Aromatics via Electrophile-Induced Cyclization Reactions: Application to the Synthesis of Graphite Ribbons.

The development of a novel reaction for the synthesis of fused polycyclic benzenoid arom. hydrocarbons is reported. In the reaction’s simplest form, the attack of an electrophile on a substituted 2-(ethynyl)biphenyl would provide a substituted phenanthrene. To demonstrate the utility of the reaction the authors have synthesized in all carbon conjugated ladder polymer or graphite ribbon. En route to this target, model systems of the general structure 2′,5′-di(4-alkoxyphenylethynyl)-p-terphenyl were synthesized for characterization and optimization purposes. Cyclization to give substituted dibenz[a,h]anthracenes consistently proceeded in very high to quant. yield. The graphite ribbon polymer, a yellow-orange material, was synthesized by TFA treatment of the colorless poly[2,5-di(dodecyl)-2′,5′-di(4-(dodecyloxy)phenylethynyl)-p-biphenylene]. All compds. were characterized using 1H and 13C NMR, IR, UV-VIS and luminescence spectroscopy, high resoln. mass spectrometry, and elemental anal. [on SciFinder(R)]