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15 N NMR study of bi‐ and tricyclic 1,2,3,5‐tetrazepin‐4‐ones
Author(s) -
JeanClaude Bertrand J.,
Williams Christopher I.
Publication year - 1998
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199802)36:2<87::aid-omr221>3.0.co;2-e
Subject(s) - chemistry , moiety , substituent , delocalized electron , ring (chemistry) , triazene , diazo , chemical shift , stereochemistry , nmr spectra database , carbon 13 nmr , fluorine 19 nmr , proton nmr , medicinal chemistry , nuclear magnetic resonance spectroscopy , spectral line , organic chemistry , physics , astronomy
The 15 N NMR spectra of the novel seven‐membered 1,2,3,5‐tetrazepinone ring systems were studied. The chemical shift of N‐2 was found to be significantly responsive to substituent changes at the phenyl ring. As the electron‐withdrawing character of the substituents increased, N‐2 became more deshielded. Studies on the diazo‐tization of the 2‐aminourea 6c using specific labeling showed that the tetrazepinones are in equilibrium with their acyclic diazourea form 9 , and that this equilibrium lies towards the formation of the 1,2,3,5‐tetrazepinone at neutral or basic pH. Solid‐state NMR data indicated that N‐3 was significantly more delocalized in the 1,2,3‐triazene moiety of the tetrazinone 2 than in the electron‐deficient tetrazepinone 5f . © 1998 John Wiley & Sons, Ltd.