Experimental and Computational Investigations of the Reactions between α,β-Unsaturated Lactones and 1,3-Dienes by Cooperative Lewis Acid/Brønsted Acid Catalysis |
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Authors: | Dr Anja Weber Priv-Doz?Dr Martin Breugst Prof?Dr Jörg Pietruszka |
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Institution: | 1. Institut für Bioorganische Chemie, Heinrich-Heine-Universität Düsseldorf im Forschungszentrum Jülich, Stetternicher Forst, Geb. 15.8, 52426 Jülich, Germany;2. Department für Chemie, Universität zu Köln, Greinstraße 4, 50939 Köln, Germany |
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Abstract: | The reactions of α,β-unsaturated δ-lactones with activated dienes such as 1,3-dimethoxy-1-(trimethylsilyl)oxy]-1,3-butadiene (Brassard's diene) are barely known in literature and show high potential for the synthesis of isocoumarin moieties. An in-depth investigation of this reaction proved a stepwise mechanism via the vinylogous Michael-products. Subsequent cyclisation and oxidation by LHMDS and DDQ, respectively, provided six mellein derivatives (30–84 %) and four angelicoin derivatives (40–78 %) over three steps. DFT-calculations provide insights into the reaction mechanism and support the theory of a stepwise reaction. |
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Keywords: | catalysis computational chemistry density functional calculations Michael additions natural products |
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