Structure et réactivité des benzoxazoles: étude par résonance magnétique nucléaire du carbone-13

Abstract

Thirty-four benzoxazoles, oxazole, and 10 o-aminophenols have been studied by 13C nmr spectroscopy. All the signals have been attributed from substituent effects. The structure of products obtained by nitration of benzoxazole have been determined by 13C nmr. The shifts induced by substitution at the 2 position have been discussed as a function of an empirical model using the structural parameters F, R, and Q*. Azido–tetrazole equilibria (N3 in position 2) and prototropic tautomerism (NH2, OH, and SH in position 2) have been also discussed. The chemical shifts and coupling constants of oxazole and unsubstituted benzoxazole have been compared.