Formation and Destruction of Diazine Ring under Conditions of the Vilsmeier–Haack Formylation of 4-Dialkylaminonaphthalic Acid Derivatives

The quaternized 1,3-diazine ring formation qualified as a particular case of the t-amino effect has been found under conditions of the Vilsmeier–Haack formylation of 4-dialkylaminonaphthalic acid derivatives. The diazinium ring is hydrolyzed in alkaline media with dealkylation, and 3-dimethylamino-4-alkylamino derivatives are formed.