Heterocyclic transformations. Part 7. Unprecedented transformations of 1,3-dialkyl-5-formyluracils to 1,3-dialkyl-7-hydroxyquinazolines

Abstract

1,3-Dialkyl-5-formyluracil reacts with ethyl acetoacetate, acetylacetone, benzoylacetone, acetoacetamide and acetoacetanilide under phase transfer catalytic conditions to provide exclusively the annulation products: 6-substituted-1,3-dialkyl-7-hydroxyquinazolines or/and also 4-hydroxybenzamide derivatives. Similar reaction with cyanoacetamide provides 6-cyano-7-hydroxy-1,3-dimethylpyrido[2,3-d]pyrimidine. The reaction mechanism prevailing in these reactions has been rationalized.