Conformations of the Nine-Membered Ring in theB-Nor-5,10-secosteroids. X-Ray and NMR Analysis
| Autor: | Vladimir D. Pavlović, Mira S. Bjelaković, János Csanádi, Bernard Tinant, Jaroslav Kalvoda, Natalija M. Krstić |
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| Rok vydání: | 2005 |
| Předmět: |
010405 organic chemistry
Chemistry Stereochemistry Organic Chemistry X-ray Nuclear magnetic resonance spectroscopy 010402 general chemistry Ring (chemistry) 01 natural sciences Biochemistry Carbonyl group NMR Catalysis 0104 chemical sciences Conformations Inorganic Chemistry Secosteroids chemistry.chemical_compound Drug Discovery Acetone Moiety X‐ray crystallographic analysis Steroids Physical and Theoretical Chemistry |
| Zdroj: | Helvetica Chimica Acta |
| ISSN: | 1522-2675 0018-019X |
| DOI: | 10.1002/hlca.200590221 |
| Popis: | The conformations of (Z)- and (E)-5-oxo-B-nor-5,10-secocholest-1(10)-en-3 beta-yl acetates (2 and 3, resp.) were examined by a combination of X-ray crystallographic analysis and NMR spectroscopy, with emphasis on the geometry of the cyclononenone moiety. The H-1- and C-13-NMR spectra showed that the unsaturated nine-membered ring of (E)-isomer 3 in C6D6 and (D-6)acetone solution exists in a sole conformation of type B-1, which is similar to its solid-state conformation. The (Z)-isomer 2 in C6D6 CDCl3, and (D-6)acetone solution. however, exists in two conformational forms of different families, with different orientation of the carbonyl group, the predominant form (85%) corresponding to the conformation of type A, and the minor (15%) to the conformation A(2) present also in the crystalline state. In this solid-state conformations of the nine-membered ring of both compounds, the 19-Me and 5-oxo groups are 'beta'-oriented. The NMR analysis suggests that the nine-membered ring of 4 has a conformation of type C-1 in CDCl3 solution. |
| Databáze: | OpenAIRE |
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