ISSN:
0749-1581
Keywords:
1,3-dioxolanes
;
NOE
;
vicinal proton-proton coupling
;
configurational analysis
;
conformational analysis
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The configurational and conformational properties of six 4-trimethylammoniummethyl 2,2-disubstituted 1,3-dioxolanes were studied using NOE experiments and vicinal coupling constants. Selective 1D NOE experiments proved to be effective tools in the configurational assignment of C-2 relative to C-4. The preferred conformation of the dioxolane ring and the exocyclic group at C-4 was obtained by employing vicinal coupling constants and NOE results. The 1H and 13C NMR chemical shifts show stereochemically dependent trends. Quantitative analysis of conformer populations was performed using Haasnoot et al's equation. The —N+(CH3)3 group was found to be synclinal with respect to the heterocyclic O-3 atom and points outside the ring. When a phenyl group is present at C-2, the 4-CH2N+ - group in a trans relationship to the 2-phenyl ring was found to occur prevalently in a pseudo-axial orientation, whereas it was established to be prevalently pseudo-equatorial when cis with respect to the phenyl ring.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260330303
Permalink