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A 15 N NMR investigation of a series of benzotriazinones and related antitumour heterocycles
Author(s) -
Vaughan Keith,
Wilman Derry E. V.,
Wheelhouse Richard T.,
Stevens Malcolm F. G.
Publication year - 2002
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/mrc.994
Subject(s) - chemistry , tautomer , chemical shift , singlet state , spectral line , nmr spectra database , nitrogen atom , ring (chemistry) , carbon 13 nmr , stereochemistry , nitrogen , computational chemistry , crystallography , organic chemistry , physics , astronomy , nuclear physics , excited state
A series of 3‐substituted 1,2,3‐benzotriazin‐4‐ones, 1 and 2, were synthesized by standard methods and the 15 N NMR spectra were recorded. All spectra were obtained using the natural abundance of the nitrogen‐15 isotope. The chemical shifts appear in the normal range for N‐1, N‐2 and N‐3 of the triazine ring, and also correlate with the chemical shifts in the spectra of the imidazolotriazinone, 4, and the imidazolotetrazinone, 5. Significantly, the spectra of 1a, 2 and 4, recorded with full NOE, show inversion of the singlet assigned to N‐3, demonstrating that these compounds exist in the tautomeric form shown. The structure of the 4‐iminobenzotriazinone (3) was confirmed by this 15 N NMR analysis. The spectrum shows a signal for the NH‐bearing imino‐nitrogen atom, which is an inverted singlet in the NOE spectrum, whereas the signal from the N‐3 atom of 3 is not inverted in the NOE spectrum. Copyright © 2002 John Wiley & Sons, Ltd.