One-pot, organocatalytic synthesis of spirooxindoles using citric acid in aqueous media

Spirooxindoles are important synthetic targets possessing extended biological activity and drug discovery applications.The development of multicomponent reactions designed to produce elaborate biologically active compounds has become an important area of research in organic, combinatorial, and medicinal chemistry. in this Manuscript, a facile and efficient multicomponent synthesis of functionalized spirooxindoles has been described through the reaction of isatin, malononitrile or ethyl cyanoacetate, and CH- acids (1,3-dicarbonyl compounds) in the presence of catalytic amount of citric acid in excellent yields with short reaction times in aqueous ethanol. Also citric acid catalyzed synthesis of 3,3-diindolyl oxindoles by the condensation of isatin with substituted indoles.