An Efficient Method for Multicomponent Synthesis of Spiro[4H-pyran-oxindole] Derivatives Catalyzed by Magnesium Perchlorate

A simple and efficient method for the synthesis of spiro[4H-pyran-oxindole] derivatives by means of three-component reactions between isatins, malononitrile or ethyl cyano-acetate, and 1,3-clicarbonyl compounds in the presence of catalytic amount of magnesium perchlorate in 50% aqueous ethanol medium has been described.