Article révisé par les pairs
Résumé : A combination of chemical and spectral evidence is presented demonstrating that the pentacyclic triterpene lactones, thurberogenin and stellatogenin, previously believed to have structures I and II, respectively, are in fact correctly represented as III (thurberogenin) and IV (stellatogenin). By optical rotatory dispersion measurements on appropriate derivatives, the C-19 stereochemistry of III and IV has been shown to be the same (19α side chain) as in betulinic acid (XIII) and other lupane derivatives. The results of certain previously described experiments which appeared to support the earlier structural assignments (I and II) for thurberogenin and stellatogenin, respectively, are discussed and shown to be in accord with the revised structures. © 1967, American Chemical Society. All rights reserved.