Diels–Alder Adducts on the b Side of Naphthalene: Rapid Cycloreversion of o-Quinodimethanes

Authors

  • Prof. Dr. Wolfram Grimme,

    Corresponding author
    1. Institut für Organische Chemie der Universität, Greinstrasse 4, D-5000 Köln 41 (FRG)
    • Institut für Organische Chemie der Universität, Greinstrasse 4, D-5000 Köln 41 (FRG)
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  • Peter Höner,

    1. Institut für Organische Chemie der Universität, Greinstrasse 4, D-5000 Köln 41 (FRG)
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  • Dr. Heinz Theo Kämmerling,

    1. Institut für Organische Chemie der Universität, Greinstrasse 4, D-5000 Köln 41 (FRG)
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  • Dr. Robert Waldraff,

    1. Institut für Organische Chemie der Universität, Greinstrasse 4, D-5000 Köln 41 (FRG)
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  • Prof. Dr. Jakob Wirz

    Corresponding author
    1. Institut für Physikalische Chemie der Universität, Klingelbergstrasse 80, CH-4056 Basel (Switzerland)
    • Institut für Physikalische Chemie der Universität, Klingelbergstrasse 80, CH-4056 Basel (Switzerland)
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  • This work was supported by the Fonds der Chemischen Industrie, BASF AG, Ludwigshafen, and the Swiss National Science Foundation.

Abstract

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The cycloreversion of the naphthalene adduct 1 is extremely fast, since, in contrast to reaction of adducts of type 2, the full resonance energy is released. The most unstable alicyclic Diels–Alder adduct of type 1 is the benzene derivative, compound 3, for which the free energy of cycloreversion is only 12.2 kcal mol−1. The corresponding gain in resonance energy is 50.5 kcal mol−1. The thermally and photochemically accessible adducts 1 can be trapped by Diels–Alder reactions owing to their o-quinodimethane structural elements.

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