ISSN:
0749-1581
Keywords:
20(R,S)-Hydroxy-23-norcholanoic acid derivatives
;
1H NMR
;
Pyridine-induced shifts
;
Molecular mechanics calculations
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Proton chemical shifts for the C-18, C-21, —CO2CH2CH3 and —CO2CH2CH3 protons of epimeric ethyl esters of 20(R,S)-hydroxy-23-norcholanoic acids were measured in deuteriochloroform and pyridine-d5. The observed solvent shifts due to specific OH - pyridine hydrogen-bonded complexes allowed the quantification of the epimeric mixtures by analysis of the pyridine-d5 1H NMR spectra. The main features of the pyridine-induced shifts are rationalized in terms of the preferred conformations for the 20R- and 20S-epimers, which are predicted by molecular mechanics calculations.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260290208
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