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Sesquiterpene lactones and other constituents from eremanthus seidelii eremanthus goyazensis and vanillosmopsis erythropappa


, : Sesquiterpene lactones and other constituents from eremanthus seidelii eremanthus goyazensis and vanillosmopsis erythropappa. Phytochemistry (Oxford) 28(5): 1441-1452

Extraction of the aerial parts of Eremanthus seidelii and reinvestigation of E. goyazensis gave four new 4,5-dihydrofuranoheliangolides and two new 4,5-dihydroeremantholides as well as some known sesquiterpene lactones. X-RAY analysis of one of the 4,5-dihydroeremantholides showed that the new lactones from E. seidelii and E. goyazensis differ in C-4 stereochemistry from isomers previously isolated from Eremanthus and related species. Criteria based on NMR spectroscopy for distinguishing between the two series are given. The C-4 stereochemistry of zexbrevin is discussed and the tentative conclusion is reached that int eh earlier correlation between tagitinin A an zexbrevin C-4 epimerization took place at the oxidation stage. Reinvestigation of Vanillosmopsis erythropappa wood resulted in isolation of several lactones not previously reported from this species.

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