A Seven-Membered Zirconacyclocumulene Complex as a source of Cyclobutadiene: Trapping of Cyclobutadiene by the Diels-Alder Reaction

The interaction of the seven-membered zirconacyclocumulene complex of zirconocene with acenaphthenequinone leads to the cyclobutadiene formation with its subsequent dimerization in cyclooctatetraene in addition to tetraoxadizirconacycle consists of two zirconocene and two acenaphthenequinone fragments. If this reaction is carried out in the presence of the excess of cyclopentadiene or acenaphthylene, the trapping of cyclobutadiene by the Diels-Alder reaction takes place. Cyclobutadiene can act both as dienophile and diene source in these reactions. © 2022 Wiley-VCH GmbH.