Fluorination Studies on Glycyrrhetic Acid Derivatives

Sh Rozen, I. Shahak, E. D. Bergmann

Research output: Contribution to journalArticlepeer-review


Attempts to introduce a fluorine atom directly at the C‐3 position of the triterpenoidal glycyrrhetic acid 1 by reacting the tosylate 2 with KF, or methyl glycyrrhetate 5 with Et2NCF2CHCIF, failed. The ring A olefin 3 and the rearrangement product 4 were obtained. The homoannular diene 7 was treated with NOF, but only nitroso‐fluorine compounds 8, 9 were isolated. Nitrosyl fluoride was also reacted with olefin 3. A difluoro compound 10 and the expected 2‐keto‐3α‐fluoro compound 11 were obtained. The above two olefins were also reacted with bromine fluoride. Although the diene 7 gave only fluorine‐free compounds 13, 14, the expected fluoro‐bromine compound 16 was obtained from 3. When the 2β‐fluoro‐3α‐bromo compound was treated with Bu3SnH, the bromine atom was replaced by hydrogen and the 2β‐fluoro compound 17 was formed.

Original languageEnglish
Pages (from-to)825-833
Number of pages9
JournalIsrael Journal of Chemistry
Issue number6
StatePublished - 1973
Externally publishedYes


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