Glycosylation of cardenolides. VIII. Structures of the by-products of the synthesis by the orthoester method of strophanthidol rhamnosides
The by-products formed in the preparation of strophanthiodol 19-rhamnoside and 3, 19-bisrhamnoside by the orthoester method are 3β,5-dihydroxy-8,19-epoxy-5β,14β, 17α-card-20(22)-enolide and its 3-α-L-rhamnoside. 3β,5-Dihydroxy-8,19-epoxy-5β, 14α,17β-card-20(22)-enolide has been obtained by the action of a solution of HBr in nitromethane on strophanthidol.
Optische Rotationsdispersion und Konfiguration bei Cardenoliden
In accordance with the results of Weiss & ZIFFER, the ORD spectra of cardenolides with few exceptions show a distinct Cotton effect, caused by the butenolide ring. The two extrema lie at about 260 and 228 nm; the extremum at shorter wave length is very difficult to measure, and that at longer wavelength shows fine structure in dioxane. 14α,17β-cardenolides having either a hydrogen atom or a hydroxyl group at C-14 and no double bond in rings C and D show a negative Cotton effect, whereas compounds of the other three stereoisomeric types (14α,17α; 14β,17α and 14β,17β) show a positive Cotton effect. In the case of cardenolides having an oxo group, the extremum of the oxo group at shorter wavelength overlaps that of the butenolide ring at longer wavelength. In spite of this the latter extremum could still be seen distinctly in all cases investigated to date.
Determination of iodide with 1,3-dibromo-5,5-dimethylhydantoin (DBH) in comparison with the ICl-method. Analytical methods of pharmacopeias with DBH in respect to environmental and economical concern. Part 3.
USP 1995 (The United States Pharmacopeia, 23rd Edit., (1995), potassium iodide p. 1265, sodium iodide p. 1424), PH. EUR. 1997 (European Pharmacopoeia, third ed., Council of Europe, Strasbourg, (1997), potassium iodide p. 1367, sodium iodide p. 1493) and JAP 1996 (The Japanes Pharmacopoeia, 13th ed. (1996), potassium iodide p. 578, sodium iodide p. 630) determine iodide with the ICl-method (J. Am. Chem. Soc. 25 (1903) 756-761; Z. Anorg. Chem. 36 (1903) 76-83; Fresenius Z. Anal. Chem. 106 (1936) 12-23; Arzneibuch-Kommentar, Wissenschaftliche Erläuterungen zum Europäischen Arzneibuch, Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart, Govi-Verlag - Pharmazeutischer Verlag GmbH, Eschborn, 12th suppl. (1999), K10 p. 2), using chloroform, which is toxic and hazardous to environment. Without the application of chlorinated hydrocarbons USP 2000 (The United State Pharmacopeia, 24th ed. (2000), potassium iodide p. 1368, sodium iodide p. 1535) and Brit 1999 (British Pharmacopoeia London, (1999), Appendix VIII C, p. A162) titrate iodide with the redox indicator amaranth. A titration with potentiometric indication giving two end-points at the step of I(2) and [ICl(2)](-) is described. Due to the high concentration of hydrochloric acid required for the ICl-method, the determination with DBH (1,3-dibromo-5,5-dimethylhydantoin; 1,3-dibromo-5,5-dimethyl-2,4-imidazolidinedione) can be recommended and is performed easily. Similarly, the iodide content of gallamine triethiodide may be analyzed with DBH by application of a visual two-phase titration in water and ethyl acetate or with potentiometric indication in a mixture of 2-propanol and water. During the removal of the excess of DBH 4-bromo-triethylgallamine (2,2',2"-[1-bromo-benzene-2,3,4-triyltris(oxy)]N,N,N-triethylethanium) is formed.