Studies on Syntheses of Epoxycardenolides and on Their Cleavage. IV. Cleavage of 3β-Hydroxy-14β, 15β-epoxy-5β, 17α-card-20 (22)-enolide with Hydrochloric Acid or Hydrogen Chloride

Abstract

Cleavage of 3β-hydroxy-14β, 15β-epoxy-5β, 17α-card-20 (22)-enolide (Ia) or its acetate (Ib) with hydrochloric acid in methanol or hydrogen chloride in chloroform resulted in the formation of 14β, 15β-dihydroxy-17α-cardenolide (III) and 14β-chloro-15β-hydroxy-17α-cardenolide (IIa or IIb), thus demonstrating an unusual cis-opening of the epoxide ring.