Synthesis of 2-hydroxy-3-methylbut-3-enyl substituted coumarins and xanthones as natural products. Application of the Schenck ene reaction of singlet oxygen with ortho-prenylphenol precursors |
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Authors: | Jean-Jacques Helesbeux Caroline Dartiguelongue Denis Séraphin Jean-Michel Oger Pascal Richomme |
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Institution: | SONAS, UFR des Sciences Pharmaceutiques et Ingénierie de la Santé, 16 Bd Daviers, 49100 Angers, France |
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Abstract: | Application of our original photooxidation-reduction methodology to prenylated dihydroxycoumarin and trihydroxyxanthone compounds led to the corresponding ortho-(2-hydroxy-3-methylbut-3-enyl)phenol derivatives with yields ranging from 8 to 65%. In most of the reported experiments, the oxidation products distribution, after the photooxygenation step, was controlled by the competition between the large group effect and the stabilising phenolic assistance effect. We also showed that ortho-(3-hydroxy-3-methylbut-1-enyl)phenol derivatives could be considered as biogenetic precursors of 2,2-dimethylbenzopyranic structures. |
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Keywords: | Schenck ene reaction Photooxygenation Regioselectivity ortho-(2-Hydroxy-3-methylbut-3-enyl)phenols Coumarin Xanthone |
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