Kinetic stabilization allows structural analysis of a benzoborirene

Formal reduction of (2-bromophenyl)chloro(2,2′′,4,4′′,6,6′′-hexaisopropyl-[1,1′:3′,1′′-terphenyl]-2′-yl)borane with tert-butyl lithium at low temperatures yields a highly strained benzoborirene that is kinetically stabilized by the bulky terphenyl substituent. The target compound withstands heating to 80 °C, and represents the first benzoborirene fully characterized by single-crystal X-ray crystallography. The bond length pattern of the six-membered ring of the parent benzoborirene follows an anti-Mills–Nixon distortion.