Highly oxygenated coumarins from Pelargonium sidoides
1995
Kayser, O. | Kolodziej, H.
The range of natural simple coumarins is extended by discovery of the highly oxygenated representatives 6,8-dihydroxy-7-methoxycoumarin, 6,7,8-trihydroxycoumarin, 6,8-dihydroxy-5,7-dimethoxycoumarin, and 7-acetoxy-5,6-dimethoxycoumarin. They are accompanied in the roots of Pelargonium sidoides by the widely occurring scopoletin, associated with the uncommon analogues 5,6,7-trimethoxycoumarin, 7-hydroxy-5,6-dimethoxycoumarin (umckalin), and 5,6,7,8-tetramethoxycoumarin (artelin), these being reported from a plant source for the second time. The structures of these compounds were established from chemical and spectroscopic studies. Differentiation between oxygenation patterns is discussed on the basis of chemical shift data.
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