An efficient one-pot multi-component synthesis of spirooxindoles using Fe3O4/g-C3N4 nanocomposite as a green and reusable catalyst in aqueous media

•Introduction of Fe3O4/g-C3N4 nanocomposite as an efficient magnetic nanocatalyst.•Application of Fe3O4/g-C3N4 in the promotion of the synthesis of spirooxindoles.•Simple and easy experimental procedure.•Availability and reusability of the catalyst.•Use of water as an eco-friendly solvent. In this study, an efficacious method is described for the synthesis of spirooxindole derivatives using Fe3O4/g-C3N4 as a green catalyst. This is a one-pot three-component condensation in water as a clean and environmentally favorable media. The present procedure proposes various remarkable privileges such as mild reaction conditions, simple work-up procedure and environment friendly. Moreover, the catalyst used is easily recovered by the external magnetic field and reused without significant deterioration in catalytic activity after at least six times. [Display omitted]