| 2 | Author
| Bruno Perly, Patricia Le Bail-Richer, GiuseppeC. Pappalardo, Antonio Grassi | Requires cookie* | | Title
| Molecular Determinants for Drug Receptor Interactions, 9 1H and 13C NMR Spectra of the Narcotic Antagonist N-Allyl-N-normetazocine by Two-Dimensional Chemical Shift Correlation Spectroscopy  | | | Abstract
| The high frequency 'H and l3C NM R spectra (at 500 and 75.47 M Hz, respectively) of N-allyl-N-norm etazocine (NAM) hydrochloride in :H 20 solution were run and fully analyzed with the aid of both homonuclear 'H —'H and heteronuclear 13C — 'H chemical shift correlation experiments. Selective broadening of the signals of the protons in 3-, 4-, 8-, 9-, 12-positions was observed at tem peratures < 350 K. This was found to be consistent with an inversion process occurring be tween the N -equatorial and N -axial configurational isomers of NAM whose rate of exchange is of the same order of magnitude of the chemical shifts differences at 500 MHz. The increase of tem perature at 350 K is thus adequate to make "fast" the process in the N M R time scale and then to resolve the spectral portions. The experim ental proton-proton coupling constants were found to be consistent with a slightly distorted chair conformation of the piperidinic ring in NAM hydrochloride. The 13C NM R spectrum showed the distinct spectra of the two conform ers, which are present in the ratio of ca. 80 (N -equatorial) : 20 (N -axial). The field frequency em ployed for the experim ent was therefore sufficient to make "slow" the exchange process betw een the two isomeric forms, whose resonance peaks could be isolated in the non-acidified solution. | | |
Reference
| Z. Naturforsch. 42b, 1021 (1987); received D ecem ber 18 1986 | | |
Published
| 1987 | | |
Keywords
| Drug R eceptor, Interaction, 'H NM R Spectra, 13C NM R Spectra, Narcotic Antagonist | | |
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| ZNB-1987-42b-1021 | | | Volume
| 42 | |
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