Influence of intramolecular hydrogen bonds on the acid hydrolysis of di(ethoxycarbonyl)pyridine N-oxides

Abstract

Acid hydrolysis of 2,4-, 2,5-, and 2,6-di(ethoxycarbonyl)pyridine N-oxides yields monoesters of picolinic acid N-oxides in high yield. Selective hydrolysis of the ethoxycarbonyl group at the 2-position is caused by intramolecular hydrogen-bond formed in the first step of the hydrolysis reaction. FTIR studies of HAuCl₄ salts of (4R)-2-ethoxycarbonylpyridine N-oxides show that a complex tautomeric equilibrium, depending on the substituent, exists in acetonitrile solution.