Septulene: the heptagonal homologue of kekulene.

A family likeness: The seven-sided homologue of kekulene, septulene (see structure), has been synthesized in seven steps by ring-closing metathesis. Its properties (spectroscopic and structural) are strikingly similar to those of kekulene despite its sevenfold symmetry and resulting non-alternant structure. The chair-type conformation in the crystal arises from packing forces. Septulene is probably a free pseudorotor in the gas phase.