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Synthesis 1994; 1994(4): 422-426
DOI: 10.1055/s-1994-25490
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Oxokohlenstoffe und verwandte Verbindungen; 21. Mitteilung.1 Diels-Alder Reaktion von 3-Halogeno-3-cyclobuten-1,2-dionen mit 1,1′-Bi-1-cycloalkenylen: Synthese dicycloalkano-anellierter Dihydrobenzocyclobutendione und Benzocyclobutendione

Arthur H. Schmidt* , Christian Künz, Marianne Malmbak, Jörg Zylla
  • *Abteilung für Organische Chemie und Biochemie Fachhochschule Fresenius, Kapellenstraße 11-15, D-65193 Wiesbaden, Germany
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Publication Date:
17 September 2002 (online)

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Oxocarbons and Related Compounds; Part 21.1 Diels-Alder Reactions of 3-Halogeno-3-cyclobutene-1,2-diones with 1,1′-Bi-1-cycloalkenyls. Synthesis of Dicycloalkano-annulated Dihydrobenzocyclobutenediones and Benzocyclobutenediones On controlled heating to 100°C, 3-chloro-3-cyclobutene-1,2-diones (5a) reacted with 1,1′-bi-1-cyclohexenyl (6) and 1, 1′-bi-1-cyclopentenyl (13) to give the dicycloalkano-annulated dihydrobenzocyclobutenediones 7 and 16, respectively. Treatment of carbon tetrachloride solutions of 7 and 16 with bromine at reflux temperature afforded the corresponding benzocyclobutenediones 9 and 17. Surprisingly, the reaction of 5a with 1,1′-bi-1-cycloheptenyl (14) and 1,1′-bi-1-cyclooctenyl (15) gave directly the benzocyclobutenediones 20 and 21. The hitherto unknown 3-bromo-3-cyclobutene-1,2-dione (5c) was prepared by treatment of 3-hydroxy-3-cyclobutene-1,2-dione (5b) with oxalic dibromide in 76% yield. Its reaction with the dienes 6, 13, 14 has been investigated.