Catalyst-Efficient Green Synthesis of 2,4-Diaminopyrimido[2,3-d]quinolines Using 1,3-Binucleophiles: A Sustainable Approach to Nitrogen-Fused Heterocycles

Abstract

This study describes a quick and convenient procedure for the synthesis of 2-4 diamino pyrimido[2,3d]quinoline  starting from 2-aminoquinoline-3-carbonitriles. The method employs guanidine hydrochloride as an nucleophilic reagent, and sodium acetate as a mild base and iodine in DMF at 90 °C. In situ oxime formation and hypervalent-iodine-mediated dehydration leads to an isolated yield of the desired nitrile of 82%. The method does not involve toxic cyanide sources, and uses mild reaction conditions. It is also safer and environmentally friendly method for the synthesis of quinoline nitrile. The paper also explores some of the iron- and copper-catalysed multicomponent reactions, which have been introduced as methods to assist in the wider significance of quinoline scaffolds in medicinal and synthetic chemistry.