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15N NMR studies of guanidines. II—the fused-in guanidine unit of some oxoheterocycles: A combined 15N NMR, 13C NMR and IR study

✍ Scribed by Geoffrey R. Bedford; Peter J. Taylor; Graham A. Webb


Publisher
John Wiley and Sons
Year
1995
Tongue
English
Weight
492 KB
Volume
33
Category
Article
ISSN
0749-1581

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✦ Synopsis


N NMR spectroscopy was used to extend previous studies, by "C NMR and IR spectroscopy, of fused oxoheterocycles which contain the guanidine unit. These compounds fall into three clearly definable structural types, through-conjugated, ring-conjugated or imide-like, any or all of which may result from the cyclization reactions used for their synthesis. It is shown that "N NMR and IR criteria are of equal value in distinguishing these, whereas 13C NMR is in general unhelpful. A qualitative correlation exists between v(C=N) for the guanidine unit, and the summed "N NMR chemical shifts for the two ndonor nitrogen atoms. The present observations should help to establish spectroscopic criteria for structural elucidation.


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