A conformational NMR analysis of methymycin aglycones: complete and unambiguous assignments of stereochemically diverse glycosylated methymycin analogs by 1D and 2D NMR techniques and molecular modeling.
| Autor: | Akhmedov NG; C. Eugene Bennett Department of Chemistry, West Virginia University, P.O. Box 6045, Morgantown, WV 26506-6045, USA. Novruz.Akhmedov@mail.wvu.edu, Gannett PM, Wu B, Cummings MM, Train BC |
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| Jazyk: | angličtina |
| Zdroj: | Magnetic resonance in chemistry : MRC [Magn Reson Chem] 2013 Mar; Vol. 51 (3), pp. 156-67. Date of Electronic Publication: 2013 Jan 31. |
| DOI: | 10.1002/mrc.3922 |
| Abstrakt: | The (1)H and (13)C NMR spectra of 10-deoxymethynolide (1), 8.9-dihydro-10-deoxymethynolide (2) and its glycosylated derivatives (3-9) were analyzed using gradient-selected NMR techniques, including 1D TOCSY, gCOSY, 1D NOESY (DPFGSENOE), NOESY, gHMBC, gHSQC and gHSQC-TOCSY. The NMR spectral parameters (chemical shifts and coupling constants) of 1-9 were determined by iterative analysis. For the first time, complete and unambiguous assignment of the (1)H NMR spectrum of 10-deoxymethynolide (1) has been achieved in CDCl(3), CD(3)OD and C(6)D(6) solvents. The (1)H NMR spectrum of 8,9-dihydro-10-deoxymethynolide (2) was recorded in CDCl(3), (CD(3))(2)CO and CD(3)OD solutions to determine the conformation. NMR-based conformational analysis of 1 and 2 in conjugation with molecular modeling concluded that the 12-membered ring of the macrolactones may predominantly exist in a single stable conformation in all solvents examined. In all cases, a change in solvent caused only small changes in chemical shifts and coupling constants, suggesting that all glycosylated methymycin analogs exist with similar conformations of the aglycone ring in solution. (Copyright © 2013 John Wiley & Sons, Ltd.) |
| Databáze: | MEDLINE |
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