Chemistry of Salicylic Acid and Anthranilic Acid. II. Formation of 2-Alkyl-3-(2-carboxyphenyl)-4-quinazolone from 2-Alkyl-4-oxo-4H-3, 1-benzoxazine by Dimeric Condensation

Abstract

Treatment of 2-alkyl-4-oxo-4H-3, 1-benzoxazines (Ia-d, f, i, l) with ethanol gave 2-alkyl-3-(2-carboxyphenyl)-4-quinazolones (VIIa-d, f, i, l) along with the liberation of ethyl alkanoate. This dimeric condensation may be explained in terms of the contribution of the C=N double bond of Ia-d, f, i, l. It was also revealed that the intermediate of the formation of 4-quinazolone (XVIII) in the reaction of Ia with aniline, was the amidine (XVII), which was produced by the addition of aniline to the C=N double bond of Ia.