Abstract
Tautomerism of hydroxypyridines is investigated by a version of the modified intermediate neglect of differential overlap method to show that the predominance of tautomerism depends on the total energy of tautomer. The calculations are carried out for 4-hydroxyaminopyridine 1-oxide (I) and 4-hydroxyaminoquinoline 1-oxide (II), leading to a conclusion that the predominant tautomer of I is formulated to be the N-oxide form and that of II is the N-hydroxy form. This structural difference is discussed in relation to difference in the biochemical behaviours of these compounds.
