Stilbene Oligomers from <i>Parthenocissus laetevirens</i>: Isolation, Biomimetic Synthesis, Absolute Configuration, and Implication of Antioxidative Defense System in the Plant
作者:Shan He、Bin Wu、Yuanjiang Pan、Liyan Jiang
DOI:10.1021/jo8001112
日期:2008.7.1
Five new stilbene oligomers, laetevirenol A-E (4-8), were isolated from Parthenocissus laetevirens, together with three known stilbene oligomers (2, 3, and 9). The structures of the new compounds were elucidated by spectroscopic analysis, including 1D and 2D NMR experiments. Afterward the absolute configurations were determined. Biornimetic transformations revealed a possible biogenetic route, where stilbene trimers were enzymatically synthesized for the first time. In addition, their antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The results showed that stilbene oligomers with an unusual phenanthrene moiety exhibited much stronger antioxidant activities. Thus, the photocatalyzed cyclization of stilbenes was supposed to be an antioxidant activity promoting transformation, which was hypothesized to play a role in the antioxidative defense system of the plant.
Total Synthesis of Laetevirenol A via Regioselective Gold‐Catalyzed and Acid‐Promoted Cyclizations
作者:Ana Milián、Lucía Sánchez‐Jiménez、Jaime Tostado、Juan J. Vaquero、Manuel A. Fernández‐Rodríguez、Patricia García‐García
DOI:10.1002/adsc.202301136
日期:2024.1.30
nature selectively located. The reaction is proposed to proceed via carbocationic intermediate I, which is formed by nucleophilic attack of the alkene to the gold-coordinated alkyne. The same reaction using tetrahydrofuran instead of dichloromethane as solvent triggers a different evolution of intermediate I, allowing the selective synthesis of dihydrophenanthrenes 4. Scheme 1 Open in figure viewerPowerPoint