Polystyrene@graphene oxide-Fe3O4 as a novel and magnetically recyclable nanocatalyst for the efficient multi-component synthesis of spiro indene derivatives

Polystyrene (PS)-coated magnetic graphene oxide (GO-Fe3O4) nanocomposite has been prepared and characterized by FT-IR, TEM and VSM techniques, and its catalytic activity has been evaluated in the multi-component synthesis of two series of indene derivatives. The three-component condensation of ninhydrin/isatin, malononitrile and active methylene-containing compounds and also the four-component condensation of ninhydrin, o-phenylenediamines, malononitrile and active methylene-containing compounds were satisfactorily performed in the presence of PS@GO-Fe3O4 magnetic nanocomposite, and corresponding 2 '-aminospiro[indene-2,4 '-pyran]-3 '-carbonitriles, 2 '-aminospiro[indoline-3, 4 '-pyran]-3 '-carbonitriles and 2 '-aminospiro[indeno[1,2-b]quinoxaline-11,4 '-pyrane]-3 '-carbonitriles were obtained in good-to-excellent yields, respectively. Very shorter reaction times than the reported methods, easy workup procedure and easy separation and reusability of the catalyst are noteworthy advantages of the current method.