A Direct One-Pot Synthesis of Asymmetric Dehydrobenzopyrido[12]annulenes and Their Physicochemical Properties

A direct one-pot synthesis of asymmetric dehydrobenzopyrido[12]annulenes 2 and 3 containing one or two pyridine rings is reported that employs a Stephens–Castro mediated cross-coupling of mixtures of ethynylcuprate precursors. The spectroscopic and theoretical properties of 2 and 3 are compared to those of the threefold symmetric dehydrotribenzo[12]annulene 1, and dehydrotripyrido[12]annulenes 4 and 5 and dehydrodibenzodipyrido[16]annulene byproduct 6, and showed 1–5 to be essentially isoelectronic band gap materials whose electron accepting ability increases with increasing nitrogen incorporation. The structures of 2, 4 and 6 were also unambiguously characterized by X-ray crystallography. The results highlight the potential dehydroaryl[12]annulenes incorporating pyridines offer for the construction of high carbon content electronic materials.