Ring Transformation of 1,2‐Disubstituted 4(1<i>H</i>)‐Quinazolone Oximes to 3,5‐Disubstituted 1,2,4‐Oxadiazoles

Abstract

Abstract In basic media O ‐Benzoyl‐ and O ‐acetyl‐2‐benzylaminobenzamide oxime ( 8b , c ) give 5‐substituted 3‐(2‐benzylaminophenyl)‐1,2,4‐oxadiazoles ( 9a , b ), while on heating in pure water 2‐amino‐1‐benzylbenzimidazole ( 10 ) is formed. Reaction of 2‐( N ‐acylbenzylamino)benzonitrile ( 12 ) with hydroxylamine, or treatment of O ‐acyl‐2‐( N ‐benzoylbenzylamino)benzamide oximes ( 8f , g ) with acid give the novel 1,2‐disubstituted 4(1 H )‐quinazolone oximes 13 , which isomerize on heating with alkali by an ANRORC mechanism to the 1,2,4‐oxadiazoles 9a , b .