Chemical shift assignment and conformational analysis of monoalkylated acylguanidines
2010 John Wiley & Sons, Ltd.
| Veröffentlicht in: | Magnetic resonance in chemistry : MRC. - 1985. - 48(2010), 9 vom: 25. Sept., Seite 678-84 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
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2010
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| Zugriff auf das übergeordnete Werk: | Magnetic resonance in chemistry : MRC |
| Schlagworte: | Journal Article Guanidines |
| Zusammenfassung: | 2010 John Wiley & Sons, Ltd. Monoalkylated acylguanidines are important functional groups in many biologically active compounds and additionally applied in coordination chemistry. Yet a straightforward assignment of the individual NH chemical shifts and the acylguanidine conformations is still missing. Therefore, in this study, NMR spectroscopic approaches for the chemical and especially the conformational assignment of protonated monoalkylated acylguanidines are presented. While NOESY and (3)J(H, H) scalar couplings cannot be applied successfully for the assignment of acylguanidines, (4)J(H, H) scalar couplings in (1)H,(1)H COSY spectra allow for an unambiguous chemical shift and conformational assignment. It is shown that these (4)J(H, H) long-range couplings between individual acylguanidinium NH resonances are observed solely across all-trans (w) pathways. Already one cis orientation in the magnetisation transfer pathway leads to signal intensities below the actual detection limit and significantly lower than cross-peaks from (2)J(NH, NH) couplings or chemical exchange. However, it should be noted that also in the case of conformational exchange being fast on the NMR time scale, averaged cross-peaks from all-trans (4)J(H, H) scalar couplings are detected, which may lead at first glance to an incomplete or even wrong conformational analysis |
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| Beschreibung: | Date Completed 20.01.2011 Date Revised 02.09.2010 published: Print Citation Status MEDLINE |
| ISSN: | 1097-458X |
| DOI: | 10.1002/mrc.2648 |