Synthesis of 3,3‐Disubstituted Oxindoles via a Three‐Component Condensation Reaction in H2O

An efficient method has been developed for the synthesis of a novel series of unsymmetrically 3,3‐disubstituted oxindoles in good‐to‐high yields by a one‐pot three‐component condensation reaction of 2‐hydroxynaphthalene‐1,4‐dione, an isatin, and a barbituric acid derivative, in H₂O, and with p‐toluenesulfonic acid as a catalyst, at 90°. The effects of solvent, temperature, and the amount of catalyst on the yield of the reaction have been investigated. Additionally, the influence of hydrophilicity and hydrophobicity of the reactants on the selectivity of products has been examined.