Synthesis of spiro[pyrazoloquinoline-oxindoles] and spiro[chromenopyrazolo-oxindoles] promoted by guanidine-functionalized magnetic Fe3O4 nanoparticles
Magnetic nanoparticles (MNPs) Fe3O4-immobilized guanidine (Fe3O4 MNPs-guanidine) have been used as an efficient catalyst for the preparation of spiro[pyrazoloquinoline-oxindoles] and spiro[chromenopyrazolo-oxindoles] by four-component reactions of phenylhydrazine or hydrazine hydrate, isatins, ketoesters and naphthylamine or 2-naphthol under reflux condition in ethanol. This method provides several advantages including mild reaction conditions, the applicability to a wide range of substrates, the reusability of the catalyst and low catalyst loading.
KeywordsFe3O4 nanoparticles Heterogeneous catalyst Spirooxindoles One pot reaction
The authors gratefully acknowledge the financial support of this work by the Research Affairs Office of the Islamic Azad University Tehran Branch, Tehran, I. R. Iran.