Reactivity of 2-(Hydroxyimino)-1-pyridylbutane-1,3-diones in the Synthesis of p-Nitrosophenols

Abstract

Completely substituted p-nitrosophenols were synthesized by cyclocondensation of dimethyl 3-oxopentanedioate with 2-(hydroxyimino)-1-pyridylbutane-1,3-diones. The yield of the final product depended on the position of the nitrogen atom in the pyridyl substituent and was considerably lower for the pyridin-2-yl derivative. According to the DFT B3LYP-D3/6-311G(d,p) quantum chemical calculations, the reason for the reduced reactivity of the carbonyl group linked to C² of the pyridine ring is their nearly coplanar arrangement. Pyridin-3-yl and pyridin-4-yl substituents are located at a larger angle with respect to the carbonyl group, so that the reactivity of the latter increases.