CoFe2O4@SiO2-NH2-CoIIMagnetic Nanoparticles as a Highly Efficient Nanocatalyst for the Synthesis of Spirooxindole Derivatives

The synthesis of oxindole derivatives as an important type of heterocyclic compounds is stilla challenge in the field of organic chemistry and industrial science. Oxindole derivatives possessgood biological and pharmaceutical activities [1]. Spirooxindoles have a wide range ofbiological activities including antiviral, anticancer, anti-inflammatory and antimicrobial activities.Therefore, the synthesis of spirooxindole derivatives is still the subject of extensive research[2]. Numerous homogeneous and heterogeneous catalysts were used for the synthesisof spirooxindole derivatives. In this study, CoFe2O4 was synthesized from Fe(NO3)3 and Co(NO3)2 in aqueous media. Core-shell nanoparticles (CoFe2O4@SiO2) were prepared by precipitatingsilica on the surface CoFe2O4 [2]. In the following step, functionalization ofCoFe2O4@SiO2 NPs was performed by the treatment with (3chloropropyl) triethoxysilane andfurther reaction with triethylenetetramine to afford aminated CoFe2O4@SiO2 followed byimmobilization of CoII corresponding heterogeneous magnetic nanocatalyst (CoFe2O4@SiO2-NH2-CoIINPs). (***) The synthesis of spirooxindole derivatives was investigated in the presence ofCoFe2O4@SiO2-NH2-CoII NPs in H2O/EtOH (1:1) at reflux conditions and the results shownthat the corresponding products were synthesized in excellent yields.