Studies on Synthesis of Epoxides of Anhydrocardenolides and on Their Cleavage. II. Synthesis of Epoxides of Anhydrogitoxigenins and Their Cleavage.

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Epoxidation of Δ^{14, 16}-dianhydrogitoxigenin (I) with 1.2 molar equivalents of perbenzoic acid gave 3β-hydroxy-14β, 15β-epoxy-5β-carda-16, 20 (22)-dienolide (III) which was hydrogenated over palladium-on-charcoal to afford 17α-digitoxigenin and digitoxigenin, both being obtained and identified as their acetates (IX, X). The preparation of 3β, 16β-diacetoxy-14α, 15α-epoxy-5β-carda-16, 20 (22)-dienolide (XII) from Δ¹⁴-anhydrogitoxigenin diacetate (XI) and some reactions of XII were described.