Introduction of [C4(DABCO)2]·(CuCl4) as an efficient catalyst for the green synthesis of pyrano[2,3-d]pyrimidinones and dihydropyrano[3,2-c]chromenes and dual pathway synthesis of 2,3-dihydroquinazolinone derivatives

Abstract

In this study, an environmentally friendly and highly efficient one-pot procedure was introduced for the synthesis of pyrano[2,3-d]pyrimidinones via a three-component reaction featuring malononitrile, aldehydes, and barbituric acid. This methodology was executed with remarkable efficiency using 1,1′-(butane-1,4-diyl)bis(1,4-diazabicyclo[2.2.2]octane) monocopper(II) tetrachloride ([C₄(DABCO)₂]·(CuCl₄)) as an efficient catalyst under solvent-free conditions, yielding the desired products in substantial quantities. Furthermore, the replacement of barbituric acid with 4-hydroxycoumarin within the devised procedure led to the efficient synthesis of dihydropyrano[3,2-c]chromene derivatives. Additionally, in the presence of this reagent, 2,3-dihydroquinazolinone derivatives were successfully synthesized through two distinct reaction pathways, with high to excellent yields. In the mentioned reaction, which was performed for acceptable reaction times under mild conditions, the catalyst could be recovered and reused without considerable loss of its activity.