Saturated amine oxides: part 10. hydroacridines: part 32. linear 17O/13C and 13C/13C chemical shift correlations between saturated azaheterocyclic N‐methylamine N‐oxides,and the methiodides of their parent amines |
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| Authors: | Francisc Potmischil |
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| Affiliation: | Department of Organic Chemistry, Biochemistry and Catalysis, University of Bucharest, Bucharest‐1, Romania |
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| Abstract: | Two kinds of good linear correlations were found between the chemical shifts of saturated six‐membered azaheterocyclic N‐methylamine N‐oxides and the chemical shifts of the methiodides of their parent amines. One of the correlations occurs between the 17O chemical shift of the N+―O– oxygen in the N‐oxides and the 13C chemical shift of the N+―CH3 methyl group analogously situated in the appropriate methiodide (r = 0.9778). This correlation enables unambiguous configuration assignment of the N+―O– bond, even if the experimentally observed 17O chemical shift of only one N‐epimer is available, provided the 13C chemical shifts of both N+―CH3 groups in the methiodide are known and assigned; furthermore, it can be used also for the estimation of 17O chemical shifts of the N+―O– oxygens in N‐epimeric pairs of N‐oxides, for which observed 17O data hardly become available. The second correlation is observed between the 13C chemical shift of the N+―CH3 methyl group in the N‐oxides and the 13C chemical shift of the N+―CH3 methyl group analogously situated in the appropriate methiodide (r = 0.9785). It can be used for safe configuration assignment of the N+―CH3 group and, indirectly, also of the N+―O– bond in an amine N‐oxide, even if no 17O NMR data, and the 13C chemical shift of only one N‐epimer is available. Copyright © 2015 John Wiley & Sons, Ltd. |
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| Keywords: | NMR 17O NMR 13C NMR saturated amine oxides quaternary ammonium salts piperidines tetradecahydroacridines tropane alkaloids linear correlations |
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