Brønsted acid-hydrotrope combined catalyst (BAHC) for the synthesis of pyrano[2,3-d]pyrimidines and isoindolo[2,1- a]quinazolines in aqueous medium

We have developed an efficient and high-yielding protocol for the synthesis of pyrano[2,3-d]pyrimidines via a one-pot, multicomponent reaction of aldehyde(s), malononitrile, and thio-barbituric acid or barbituric acid in aqueous medium, utilizing a Brønsted acid-hydrotrope combined catalyst (BAHC). This catalytic system was further extended to the synthesis of isoindolo[2,1-a]quinazolines through a multicomponent reaction of various amines, isatoic anhydride, and 2-carboxybenzaldehyde, furnishing the desired products in good yields. Key advantages of present method include high atom economy, energy efficiency, the use of water as a sustainable reaction medium, operational simplicity, and the elimination of organic solvents, making it an eco-friendly and practical approach for synthesis of complex heterocyclic compounds.