Tricyclobutabenzene

Tricyclobutabenzene is an aromatic hydrocarbon consisting of a benzene core with three cyclobutane rings fused onto it. This compound and related compounds are studied in the laboratory because they are often display unusual conformations and because of their unusual reactivity. Tricyclobutabenzenes are isomers of radialenes with which they are able to interconvert.

The parent tricyclobutabenzene C8H8 was first synthesized in 1979 via a procedure depicted in Scheme 1. This compound is stable up to 250°C.



A polyoxygenated tricyclobutabenzene with an extraordinary bond length of 160 pm for the bond connecting two carbonyl groups was synthesized according to scheme 2.



An ordinary bond of this type is only 148 pm and for comparison the C-C bond in isatin is 154 pm long. On the other hand, no change is recorded in the aromatic bond length alternation.

Applying similar chemistry derivatives are now known with 6 carbonyl groups or 12 methoxy groups. . A key starting material is the iodo-triflate depicted below which is a benztriyne synthon with triple aryne functionality.