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Reactions and rearrangements of triterpenoids - 3-epitaraxerol and its transformation products
J BANERJI, A CHATTERJEE, M SAHA, K P DHARA, S KANRAR, , A NEUMAN, T PRANGE
Published in NATL INST SCIENCE COMMUNICATION
1999
Volume: 38
   
Issue: 12
Pages: 1322 - 1330
Abstract
An interesting rearrangement has been observed with 2,14-taraxeradiene 1 using m-chloroperbenzoic acid. With this reagent compound 1, in methylene chloride, affords olean-2α-epoxy-12-ene-15α-ol 3 (confirmed by X-ray crystallographic analysis) through the intermediate 2α, 14α- diepoxytaraxerane 4. The latter 4 has also been isolated from the same reaction mixture. This backbone rearrangement from the Δ14-taraxarene skeleton 4 to Δ12-oleanane structure 3, with C15-α-ol, confirms α- orientation of the epoxy ring formed at Δ14 in 4. Subsequent opening of the intermediate oxirane at Δ14 therefore must occurr via the generation of an incipient carbonium ion at C(14) to allow the migration of C(13)CH3 to C(14) from the same α-phase. Compound 4 also undergoes rearrangement to olean-12-ene-2α,3β,15α-triol 5 with boron trifluoride etherate in methylene chloride.
About the journal
JournalIndian Journal of Chemistry - Section B Organic and Medicinal Chemistry
PublisherNATL INST SCIENCE COMMUNICATION
ISSN0376-4699
Open AccessNo