Green Synthesis of Novel Spirooxindole Derivatives in Deep Eutectic Solvent

A series of novel spirooxindole derivatives were synthesized by three-component domino Knoevenagel-Michael reaction between aldehydes, indole and 6,10-dioxaspiro[4.5]decane-7,9-dione using the deep eutectic solvent (DES) choline chloride-oxalic acid as a catalyst in 70%similar to 97% yields. This method has some distinct advantages such as easy work-up, mild reaction conditions, short reaction time, environmental friendliness and accessibility of catalyst.