Novel organometallic nanomagnetic catalyst for multicomponent synthesis of spiroindoline derivatives

A novel, green, reusable polyaniline (PANI)/Fe₃O₄/carbon nanotube (CNT) nanomagnetic catalyst has been prepared, characterized by Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) analysis, and applied for four-component synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole] derivatives from isatin, hydrazine hydrate or phenylhydrazine, ethyl acetoacetate, and malononitrile or ethyl cyanoacetate in aqueous medium at room temperature. Use of water as safe and environmentally benign solvent, short reaction time, high product yield, easy workup procedure, and easy separation and reusability of the catalyst are noteworthy advantages of this approach.