## Abstract The NMR parameters of (β)βscopolamine free base in CDCl~3~ determined by Sarazin __et al.__ were used to reevaluate some of the stereochemical conclusions recently reported by the authors. Similarly to the case with the protonated salt, the major contributor to the fast exchange limit t
Determination of the conformation in solution of three 1,2-3,4-Di-O-methylenepyranoses: NMR and molecular mechanics studies
β Scribed by Bouchra Giraud; Robert Nouguier; Carlos Jaime; Albert Virgili
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 281 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0749-1581
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β¦ Synopsis
Abstract
The conformational analysis of three 1,2β3,4βdiβOβMethylenepyranoses was carried out using NMR (coupling constants and homonuclear Overhauser effect) and theoretical (MM2 calculations) methods. A preferred twistβboat conformation was found.
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Potential energy calculations (MM2), low-temperature 'H and I3C NMR spectra and 'H-'H COSY spectra are reported for four octane derivatives, the central portions of which constitute tetrasubstituted succinates. The existence of several conformers differing in stereochemistry in this central moiety i
Two conformations of the cis-cyclohexano-8-crown-3 molecule were detected at 185 K. From relative 13 C NMR peak area measurements, the conformation with the O-CH 2 -O unit equatorial was found to be favoured by 4.4 Ε‘ 0.4 kJ mol 1 . In the spectrum of the minor conformer at low temperature, a 9.6 ppm
The conformational difference of the title compound (1) in the solid state and in solution has been investigated by X-ray crystallography and high-field proton n.m.r. spectrometry. In the solid state, compound 1 adopts the "c,(D) conformation (la), whereas 1 exists preferentially in the 'C4(D) confo
## Abstract 1,2,3,4,6βPentaβ__O__βgalloylβΞ²βDβglucopyranose (PGG) is a polyphenolic compound found in substantial amounts in a number of medicinal herbs. We report (i) its conformational analysis by solution NMR and molecular dynamics calculation and (ii) theoretical study of its interaction with a