Abstract
Reduction of 16-anhydrogitoxigenin 3-acetate (II) with NaBH4-transition metal chloride systems as well as with transition metal hydrides gave geometrically isomeric card-17 (20)-enolides, V and VI, new type of cardenolide. Stereochemistry of the products was discussed on the basis of Cotton effect, 1H-and 13C-nuclear magnetic resonance spectra. The structure and ratio of the products varied depending on the kind of transition elements.
