Steroids and related products. XXV. Cardiotonic steroids. II. The synthesis of 17β-substituted 14(15)-unsaturated steroids of the A/B-cis series. Part I

Abstract

The synthesis, from smilagenin, progesterone, and pregnenolone, of Δ14-3β-hydroxy-5β-etienic acid and some of its ester derivatives, as well as of β-anhydrodigitoxigenin acetate, is described. Since these 14-unsaturated products have served as starting materials for our previously published syntheses of 3β,14β-dihydroxy-5β-etianic acid and of digitoxigenin, the present work establishes that these 17β-substituted 14β-hydroxylated products are available from readily accessible materials and that the syntheses of these 14β-hydroxylated products must be regarded, from a formal point of view, as total syntheses. We have thus elaborated a general pathway from common steroids—also available by total synthesis—to 14β-hydroxylated derivatives, in particular to steroid cardiotonics.