Spirooxindoles: Recent report of green synthesis approach

Spirooxindole is a compound with a unique framework and broad bioactivities in medicine. In this study, we have reviewed various approaches or methods in synthesizing spirooxindole derivatives focused on green synthesis. Synthesis of spirooxindoles is mainly carried out through multicomponent reactions combined with various green approaches such as the use of heterogeneous catalysts (nano-sized, magnetic, metal-complex, and metal-organic framework catalysts), deep eutectic solvent, solvent-free reactions, catalyst-free reactions, as well as the use of ultrasonic and microwaves irradiation. The green method is carried out in addition to obtaining high yields, it also offers reductions in the use of hazardous chemicals, energy use, purification processes, and waste generation. As a result, green synthesis methods in the synthesis of spirooxindole derivatives are more environmentally friendly.