| | 1 | Author
| Zofia Plesnar3, Stanisław Malanowski3, Zenon Lotowskib, JacekW. Morzyckib, Jadwiga Frelek, Jacek Wójcikd | Requires cookie* | | | Title
| Stereospecific Association of C-20 Epimers of 3/?-Hydroxy-16-oxo-24-nor-17-azachol-5-eno-23-nitryle  | | | | Abstract
| The cryoscopic measurements show that title compounds are strongly associated in CHC13 solutions. The association of the 20 R epimer is distinctly less pronounced than that of the 205 epipmer. Self-association of the 205 epimer leads to the formation of very large com plexes. The 20 R epimer forms associates via water molecules. The dissimilarity may be ex plained in terms of different accessibility of the lactam carbonyl groups in the two epimers for the association. It is proposed that the association process is controlled by the configura tion at the carbon atom C(20) and conformation around the C(20)-C(22) bond. Populations of side chain conformations of both epimers were determined by means of proton nuclear magnetic resonance. It was found for the 20 R epimer that the t and the -g rotamers are almost equally populated, and the rotamer +g is excluded. For the 205 epimer the +g rotamer predominates over the t one, and the -g rotamer is excluded. The N M R data are fully consistent with the results of the molecular modelling studies. | | | |
Reference
| Z. Naturforsch. 52b, 749—756 (1997); received | | | |
Published
| 1997 | | | |
Keywords
| Self-Association, Cryoscopic Measurements, Conformational Analysis, CD Spectra, Azasteroids | | | |
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| default:Reihe_B/52/ZNB-1997-52b-0749.pdf | | | | Identifier
| ZNB-1997-52b-0749 | | | | Volume
| 52 | |
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