An NMR study of the tantomerism of 2-acylaminopyridines

Abstract

Application of the SIMPLE (secondary isotope multiplet NMR spectroscopy of partially labelled entities) technique to heteroaromatic tautomerism proves that N-(pyridin-2-yl)acetamide 1 exists in [²H]chloroform, [²H₆]acetone or [²H₆]benzene solutions as the amide tautomer-rotamer A-I. The corresponding amide tautomeric form of N-(pyridin-2-yl)benzamide 2 was also found in [²H]chloroform. These results confirm long-established patterns of heteroaromatic tautomerism, and illustrate the utility of SIMPLE in tautomerism studies.