Benzocyclobutadiene is the simplest polycyclic hydrocarbon, being composed of an aromatic benzene ring fused to an anti-aromatic cyclobutadiene ring. It has chemical formula . Though the benzene ring is stabilized by aromaticity, the cyclobutadiene portion has a destabilizing effect. This results into it being a non-aromatic compound - neither behaving as aromatic nor an antiaromatic one.Observation of benzocyclobutadiene by flow nuclear magnetic resonance https://doi.org/10.1021/ja00168a059 For this reason, benzocyclobutadiene will readily dimerize or polymerize and it reacts as a dienophile in Diels-Alder reactions.
Benzocyclobutadiene is used in the production of the pharmaceutical drug naflocort.
See also Pentalene
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