Three‐Component Synthesis of Indanone‐Fused Spirooxindole Derivatives

A simple, straightforward and versatile multicomponent protocol for the synthesis of indanone‐fused spirooxindole derivatives has been developed. The strategy involves the one‐pot three‐component reaction of heterocyclic ketene aminals, 1H‐indene‐1,3(2H)‐dione and the dicarbonyl compounds isatins or acenaphthenequinone in an ethanol/water medium catalysed by p‐TSA at reflux. Mild reaction conditions, operational simplicity, wide substrate scope and overall excellent yields make this method highly efficient for the library synthesis of indanone‐fused spirooxindole.