ISSN:
0749-1581
Keywords:
N-Propynylnormetazocine
;
Conformation
;
Relaxation times
;
Motional analysis
;
Molecular Modelling
;
1H and 13NMR spectra
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The analysis of high-frequency 1H and 13C NMR spectra and both 1H—1H homonuclear and 1H—13C heteronuclear chemical shift correlation experiments indicate that N-propynlnormetazocine (NPMH+) is configurationally heterogeneous in solution, with the N-equatorial isomer being more populated than the N-axial isomer. The experimental proton-proton coupling constants measured for both diastereoisomers were in agreement with the calculated values for a chair conformation of the piperidine ring. AM1 and MM2 theoretical calculations both indicated the chair conformation as that preferred by the piperidine ring, and the N-equatorial isomer as being energetically favoured with respect to the N-axial form. The best fit of the 13C T1 relaxation time data and the related motional analysis of NPMH+ was carried out using the anisotropic model of reorientation with superimposed internal motion. The results showed an increase of the rotational anisotropy of the molecule on passing from the gas phase to the solution state.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260300106
