By acid or enzymic hydrolysis of glycosides present in several species of Strophanthus, Apocynaceae. Isoln: Jacobs, Heidelberger, J. Biol. Chem. 54, 253 (1922). Structure: Kon, Chem. Ind. (London) 53, 593, 956 (1934); Jacobs, Elderfield, Science 80, 533 (1934). Identity with corchorin, corchorgenin and corchsularin: Sen et al., Helv. Chim. Acta 40, 588 (1957). Synthesis from pregnenolone acetate, q.v.: E. Yoshii et al., J. Org. Chem. 43, 3946 (1978). Toxicity study: Graebner, Geisel, Arzneim.-Forsch. 22, 1854 (1972). Reviews: Elderfield, Chem. Rev. 17, 187 (1935); Tschesche, Ergeb. Physiol. 38, 31 (1936); Stoll, The Cardiac Glycosides (Pharmaceutical Press, London, 1937); Strain in Organic Chemistry vol. II, Gilman, Ed. (New York, 2nd ed., 1943); Fieser, Fieser, Steroids (Reinhold, New York, 1959) pp 729-730, 736-750.