Revision of the Absolute Configurations of Bethosides B and C and Their Aglycone

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• 作者：Victoria L. Challinor ; Patricia Y. Hayes ; Paul V. Bernhardt ; William Kitching ; Reginald P. Lehmann ; James J. De Voss
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：September 2, 2011
• 年：2011
• 卷：76
• 期：17
• 页码：7275-7280
• 全文大小：816K
• 年卷期：v.76,no.17(September 2, 2011)
• ISSN：1520-6904

文摘

The absolute stereochemistry of the steroidal saponins bethosides B and C was previously assigned as (22R,25R) on the basis of work that employed Horeau鈥檚 method. Our studies of helosides A and B created doubt about both the original assignment and consequently our conclusion that relied upon it. The absolute configurations of bethosides B and C are revised to (22S,25R) following X-ray crystallographic analysis of their aglycone. Synthesis and full spectral characterization of both the 22R and 22S aglycones is reported to facilitate future stereochemical assignments in this series of saponins.