Macropodumines A-C: novel pentacyclic alkaloids with an unusual skeleton or zwitterion moiety from Daphniphyllum macropodum Miq |
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Authors: | Zhang Wen Guo Yue-Wei Krohn Karsten |
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Affiliation: | State Key Laboratory of Drug Research, Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, P.R. China. |
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Abstract: | Three novel alkaloids, macropodumines A-C (1-3), were isolated from the stem of Daphniphyllum macropodum Miq. Interestingly, the structure of macropodumine A (1) was characterized as having a fused pentacyclic system including an unusual eleven-membered macrolactone ring, whereas macropodumine B (2) contains a rare cyclopentadienyl carbanion, which is stabilized as a zwitterion by an internal iminium cation. The structures of these new metabolites were established on the basis of their detailed spectroscopic analysis. In particular, the unique structure of zwitterion 2 was further confirmed by using single-crystal X-ray diffraction analysis. |
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Keywords: | alkaloids macropodumines natural products structure elucidation zwitterions |
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