Synthesis of Polycyclic Arenes Composed of Four‑, Five‑, Six‑, and Eight-Membered Rings via an Unexpected Four-Membered Ring Formation Reaction

The synthesis of polycyclic arenes composed of four-,
five-, six-,
and eight-membered rings via an unexpected four-membered ring formation
reaction is reported. The carbonylation of an octalithiated tetraphenylene
yielded a tricarbonylated arene containing a four-membered ring or
a tetracarbonylated one, depending on the carbonyl reagents. The structures
were determined by X-ray crystallography, and their electronic properties
were examined by using absorption spectroscopy and cyclic voltammetry.
The antiaromaticity of the four-, five-, and eight-membered rings
of these compounds was studied by theoretical calculations.