ISSN:
0899-0042
Keywords:
chiral complexing agent
;
nuclear magnetic resonance spectroscopy
;
tobacco alkaloids
;
nicotine-like compounds
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The enantiomeric purity of several tobacco alkaloids and nicotine-like compounds was determined using 1H NMR (300 MHz) spectroscopy in the presence of (-)-(R)-1,1′binaphthyl-2,2′-diylphosphoric acid (BNPPA) as a chiral complexing agent. The most significant signal splitting resulting from diastereoisomeric complexation are seen for chemical shifts in the proximity of the pyridinyl nitrogen. Chemical shift data exclude any contribution of the pyrrolidinyl protons to chiral recognition, but when the pyrrolidine ring is replaced by a piperidine ring, i.e., for compounds such as rac-anabasine and rac-anatabine, non-equivalence between enantiomers was observed for protons close to the piperidine ring. A new approach for the preparation of the pure (-)-(S)-and (+)-(R)-enantiomers of nornicotine, a tobacco alkaloid and metabolite of nicotine, was developed. The optically pure enantiomers thus obtained were used to establish the minimum sensitivity of the NMR spectroscopic method of chiral analysis. These findings provide a new, general, and facile method for the determination of enantiomeric purity of tobacco alkaloids and nicotine-like compounds. © 1996 Wiley-Liss, Inc.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
