C14-Labeled Cardiac Glycosides
An essential structural and pharmacological characteristic of cardenolides is an a, ß-unsaturated γ-lactone ring (the butenolide ring) in the 17 β-position. Ruzicka, Reichstein, and Fürst  and others [2–5] first demonstrated the possibility of its synthesis from steroids other than cardenolides by means of the Reformatsky reaction [6,7]. By reaction of various 21-acyloxypregnanone-(20) derivatives with bromacetic acid ethyl ester and zinc, they obtained the hydroxylactone after acid cleavage of the organozinc compound and the corresponding ∆ 20,22-steroid lactone after subsequent dehydration. These studies were performed only with 14-deoxy derivatives because of the relatively strong nature of the reactions, but in 1947 Plattner and coworkers  achieved partial synthesis of a 14 β-OH compound for the first time. However, the yields were at most 20%, as was also the case for the partial synthesis of digitoxigenin-3-acetate-23-C14 later described by Turba and Scholtissek , probably because the lability of the 14 β -OH compounds is higher than usual for the Reformatsky reaction.
KeywordsSodium Methylate Steroid Glycoside Acid Cleavage Partial Synthesis Antimony Trichloride
Unable to display preview. Download preview PDF.
- 7.Shriner, R. L., Org. Reactions 1: 1 (1942).Google Scholar
- 11.Okita, G.T., Kelsey, F.E., Walaszek, E. J., and Geiling,E.M.K., J. Pharmacol. Exp. Therap. 110: 244 (1954).Google Scholar
- 12.Rabitzsch, G., Second International Symposium on the Chemistry of Natural Products, Prague (August 27 to September 2, 1962 ).Google Scholar
- 13.Rabitzsch, G., Monatsber. Deut. Akad. Wiss. Berlin 5: 299 (1963).Google Scholar
- 15.Straub, W., Biochem. Z. 28: 392 (1910).Google Scholar
- 16.Rabitzsch, G., International Conference on Medicinal Plant Research, Sofia (September 16–18, 1963 ).Google Scholar