ISSN:
0749-1581
Keywords:
1H NMR
;
13C NMR
;
Benzomorphans
;
2D NMR
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The high-frequency 1 and 13C NMR spectra (at 500 and 75.47 MHz, respectively) of metazocine (MTZ) fumarate, pentazocine (PTZ) and cyclazocine (CLZ) hydrochlorides in 2H2O solution were recorded and analysed with the aid of both homonuclear 1H—1H and heteronuclear 13C—1H chemical shift correlation experiments. At neutral pH all compounds were found to be configurationally heterogeneous, with the N-equatorial isomer more populated than the N-axial isomer (ratio ca 80:20). The low-intensity peaks of the superimposed spectral pattern of the less populated isomer were also assigned on correlative grounds in both the 1H and 13C NMR spectra of MTZ, PTZ and CLZ. The occurrence of distinct spectra for the two configurational isomers was diagnostic of a ‘slow’ exchange process on the NMR time-scale at the field frequencies employed for the experiments, thus suggesting a high-energy barrier to interconversion. The experimental proton-proton coupling constants measured for the N-equatorial form of MTZ, PTZ and CLZ were consistent with a chair conformation of the piperdinic ring in all compounds. The distinct relative agonist-antagonist potencies of the drugs investigated could therefore not be correlated with the above-described configurational and conformational features.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260260811
Permalink
