Hexamethyl Dewar benzene has been prepared by bicyclotrimerization of dimethylacetylene with aluminium chloride. It undergoes an unusual rearrangement reaction with hydrohalic acids to form a pentamethylcyclopentadiene derivative, and consequently can be used as a starting material for synthesising some pentamethylcyclopentadienyl organometallic compounds.
Read more about this topic: Dewar Benzene