Abstract: | The circular dichroism method has been used to establish the stereochemical features of the structure of the withasteroids. The 22S-configuration of the asymmetric center has been confirmed for physangulide. The 22R-configuration has been confirmed for 14-hydroxyixocarpanolide, vamonolide, ixocarpanolide, 24,25-epoxywithanolide D, and withanolide T. On the basis of changes in the circular dichroism spectra in acid and alkaline media it is suggested that in compounds having a 4-hydroxy-1-oxo-5,6-epoxy-2,3-ene grouping the 2,3 bond disappears, while in compounds having a 5-hydroxy-1-oxo-6,7-epoxy-2,3-ene grouping dehydration takes place at C-4-C-5. These characteristics can be used in the identification of the withasteroids. The isolation of withanolide T from the leaves ofPhysalis angulata L. is described and its spectral characteristics are given.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 371–376, May–June, 1990. |