Nano sphered-shape MgAl2O4: a recyclable, green and efficient catalyst for the one-step synthesis of 1 -aryl-2 -(2-oxoindolin-3- yl)spiro[indoline-3,5 -pyrroline]-2,3 -diones

In this paper, nano MgAl2O4 has been synthesized via a modified co-precipitation route using poly ethylene glycol (PEG) 5000 as an non-ionic surfactant, and characterized by fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) techniques. The synthesized anocatalyst has been used for the one-pot and one-step condensation of isatins, arylamines, and acetone. The desired 1 -aryl-2 -(2-oxoindolin-3-yl)spiro[indoline-3,5 -pyrroline]-2,3 -diones has been prepared in excellent yields using an easily to handle, non-toxic, inexpensive, and non-moisture sensitive nano reagent. The reaction proceeded well undersolvent-free conditions to avoid hazardous solvent usage. The reusability of the recovered nanosphered-shape MgAl2O4 has been performed during four run without activity loss