Microwave-assisted multicomponent synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]quinoline]-2,5'(6'H)-diones catalyzed by Ionic liquid-coated magnetic carbon nanotubes

We synthesized CNTs-Fe ₃ O ₄ -IL, which are multi-walled carbon nanotubes modified with an imidazolium-ionic liquid. Then, we conducted a comprehensive analysis of the structure, morphology, and properties of the nanocomposites using various characterization techniques. These techniques included VSM, FT-IR, TEM, TGA, DTA, SEM, and XRD. In this manuscript, a novel and efficient microwave-assisted multicomponent synthesis method for spiroindoline-3,4'-pyrazolo[3,4- b ]quinoline-2,5'(6' H )-diones using ionic liquid-coated magnetic carbon nanotubes as the catalyst is presented. The synthesis involves the condensation of 3-methyl-1 H -pyrazole-5-amins, cyclohexane-1,3-diones, and isatin derivatives under microwave irradiation in the presence of ionic liquid-coated magnetic carbon nanotubes. Ionic-liquid-coated magnetic carbon nanotubes serve as a catalyst for this synthesis, providing improved efficiency and separation ability. The catalyst was also tested for reuse and retained almost all of its activity after several cycles, proving that this method is highly sustainable. This study proves that this approach is an effective and environmentally friendly method for obtaining various spirocondensed heterocyclic compounds. This new method will allow the rapid synthesis of biologically active compounds with potential applications in drug discovery and materials science .