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13C NMR studies of tautomerism in imidazo[4,5-c]pyridines

✍ Scribed by P. Barraclough; J. C. Lindon; M. S. Nobbs; J. M. Williams

Publisher
John Wiley and Sons
Year
1989
Tongue
English
Weight
211 KB
Volume
27
Category
Article
ISSN
0749-1581

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✦ Synopsis

A detailed analysis of the I3C NMR spectra of the 1-N-and 3-N-methyl derivatives of lH-2-(2,4-dimethoxyphenyI)imidazo[4,5-~]pyridine, utilizing long-range couplings and 2D 'H-I3C 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 lH-2-(2,4-dimethoxyphenyI)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-clpyridine and its 3-N-methyl derivative are now resolved. Revision of these assignments leads to the conclusion that the 1H-tautomer of lH-imidazo[4,5-c~pyridine is predominant.

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