Alloglaucotoxigenin, Strukturbestimmung Glykoside und Aglykone, 280. Mitteilung

The structure of alloglaucotoxigenin is shown to be that of 3β, 14β, 15β‐trihydroxy‐19‐oxo‐5α‐carda‐20:22‐enolide (IV) in the following way: The 19‐oxo group could be eliminated by reduction of the corresponding mercaptal. The structure of the resulting 3β, 14β, 15β‐trihydroxy‐5α‐carda‐20:22‐enolide, obtained in the acetylated form, was established through degradation and through partial synthesis by treatment of Δ14‐anhydro‐uzarigenin (XIII) with osmium tetroxide. The isomeric 3β,14α, 15α‐trihydroxy‐cardenolide was also formed in large quantities. The substance XI showed in its optical rotatory dispersion curve a positive, and substance XIV a negative COTTON effect.