Modified magnetic chitosan with mono(6-amino-6-deoxy)-β-cyclodextrin as a novel catalyst toward the synthesis of pyrazolopyranopyrimidines and pyrano[2,3-c]pyrazole-3-carboxylates

In this study, we successfully fabricated a novel biocomposite composed of 6-amino beta-cyclodextrin (CDNH2) grafted onto magnetic chitosan (Fe3O4@Cs). This biocomposite was thoroughly characterized using FT-IR, NMR, PXRD, EDX mapping, SEM, TEM, TGA, and VSM techniques. Subsequently, the innovative biocomposite was harnessed to serve as a heterogeneous catalyst to facilitate two series of multicomponent reactions (MCRs) aimed at synthesizing pyrazole-fused heterocycle derivatives. The first reaction involved the combination of hydrazine hydrate, ethyl 3-oxobutanoate, barbituric acid, and various benzaldehyde derivatives. In a separate reaction, dimethyl acetylenedicarboxylate (DMAD), hydrazine hydrate, benzaldehyde derivatives, and malonitrile were used as starting materials. By optimizing the reaction conditions and employing the Fe3O4@Cs@CDNH2 catalyst, we successfully synthesized valuable pyrazole structures with high yields in both reactions. The ability to optimize conditions and produce new pyrazole structures with impressive yields highlights the effectiveness of using Fe3O4@Cs@CDNH2 to direct these reactions.