Crystal and molecular structure of cinnamylidene-butenolides fromPiper sanctum |
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Authors: | H. Bradaczek H. J. Hecht R. Reinhardt |
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Affiliation: | (1) Institut für Kristallographie der Freien Universität Berlin, Takustrae 6, D-1000 Berlin 33, Germany |
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Abstract: | An x-ray analysis of two natural compounds isolated fromPiper sanctum confirmed thetrans configuration for 5-(8-methoxy)cinnamyliden-4-methoxy-but-3-enolide [piperolide (I)] and for 5-[trans-(z)-,-epoxy--methoxycinnamyliden]-4-methoxy-2(5H)-furanon [epoxypiperolide (II)]. The space groups arePbca [a = 44.174(3),b = 8.056(3),c = 7.515(4) Å] for (I) andP21/c [a = 11.351(4),b = 8.292(5),c = 14.292(2) Å, = 96.28(2) °] for (II). The structures were solved by direct methods and refined by least-squares techniques toR = 4.8% (I) andR = 7.5% (II). The stereochemistry of the semicyclic double bond is in favor of theZ-isomers. |
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