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13 C NMR studies of tautomerism in imidazo[4,5‐ c ]pyridines
Author(s) -
Barraclough P.,
Lindon J. C.,
Nobbs M. S.,
Williams J. M.
Publication year - 1989
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.1260271016
Subject(s) - tautomer , chemistry , pyridine , stereochemistry , carbon 13 nmr , derivative (finance) , medicinal chemistry , financial economics , economics
A detailed analysis of the 13 C NMR spectra of the 1‐ N ‐ and 3‐ N ‐methyl derivatives of 1 H ‐2‐(2,4‐dimethoxyphenyl)imidazo[4,5‐ c ]pyridine, utilizing long‐range couplings and 2D 1 H 13 C correlation experiments, has led to an unambiguous assignment of all carbons. Comparison of these definitive assignments of C‐3a and C‐7a, in particular, with those of the tautomers of 1 H ‐2‐(2,4‐dimethoxyphenyl)imidazo[4,5‐ c ]pyridine has permitted confirmation of the predominance of the 1 H ‐tautomer for the latter. In addition, previous conflicting assignments for 1 H ‐imidazo[4,5‐ c ]pyridine and its 3‐ N ‐methyl derivative are now resolved. Revision of these assignments leads to the conclusion that the 1 H ‐tautomer of 1 H ‐imidazo[4,5‐ c ]pyridine is predominant.