Amino Functionalized Nano Fe₃O₄@SiO₂ as a Magnetically Green Catalyst for the One-Pot Synthesis of Spirooxindoles Under Mild Conditions

ABSTRACT

(3-Aminopropyl)-triethoxysilane attached to Fe₃O₄@SiO₂ nanoparticles has been characterized by powder X-ray diffraction, vibrating sample magnetometer, scanning electronic microscope, transmission electron microscope, energy dispersive X-ray, thermal gravimetric analysis, and Fourier transform infrared spectroscopy. The prepared nanoparticles employed as a heterogeneous catalyst in the synthesis of spirooxindoles derivatives in one-pot four-component reactions of isatin, methyl cyanoacetate or malononitrile, hydrazine hydrate, and ethyl acetoacetate. Amino-functionalized magnetic nanoparticles showed high catalytic activity in mild reaction conditions and excellent yields of products in short reaction times. Also, this nanocatalyst can be easily recovered by a magnet and reused for subsequent reactions for at least 5 times without noticeable loss in catalytic activity.

KEYWORDS:

• Core–shell
• Fe₃O₄@SiO₂–NH₂
• multicomponent reactions
• one-pot synthesis
• spirooxindoles

Acknowledgments

The authors are grateful to the Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran for supporting this work.