“…16,17 Due to the pharmacological properties of oxindoles, development of synthetic methods enabling easy access to these compounds are desirable. In continuation of our work on the synthesis of biologically important compounds using simple, efficient and nontoxic catalysts, [18][19][20][21][22] in this paper we report synthesis of spirocyclic (5,6,7,8-tetrahydro-4H-chromene)-4,3 0oxindole and dihydro[pyrano [3,2-c]quinoline]-4,3-indoline derivatives by the coupling of malononitrile, 1,3-dicarbonyl/ 4-hydroxycoumarine and isatin derivatives in the presence of nano-NiO as an inexpensive and efficient catalyst in aqueous medium (Scheme 1).…”