Biomimetic synthesis of xuxuarines E alpha and E beta: Structure revision of Rzedowskia bistriterpenoids
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2008-02-15
Autores
Jacobsen, Neil E.
Wijeratne, E. M. Kithsiri
Corsino, Joaquim [UNESP]
Furlan, Maysa [UNESP]
Bolzani, Vanderlan da Silva [UNESP]
Gunatilaka, A. A. Leslie
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Pergamon-Elsevier B.V. Ltd
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Reaction of pristimerin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) resulted in a biomimetic-type coupling leading to xuxuarines E alpha and E beta and not the previously reported Rzedowskia bistriterpenoids I and II suggesting that the structures proposed for these natural products need revision. A product obtained in this reaction by an unusual Diels-Alder addition followed by retro-Diels-Alder-type elimination was characterized as pristimerin dicyanophenalenedione. Complete H-1, and C-13 NMR spectral assignments of xuxuarines Ea and Eb have been made by the application of 1D and 2D NMR techniques. (c) 2007 Elsevier Ltd. All rights reserved.
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Bioorganic & Medicinal Chemistry. Oxford: Pergamon-Elsevier B.V. Ltd, v. 16, n. 4, p. 1884-1889, 2008.