Oxazole ring cleavage in the course of the synthesis of heterocyclic azo dyes

Abstract
The formation of azo dyes by coupling the diazonium salts of aminophenyloxazolopyridines with N,N‐di‐ethylaniline was shown to be a suitable probe to check the stability of the oxazole ring in the course of their preparation. Depending on experimental conditions, “closed” and “opened” systems could be obtained separately.