Fe3O4@SiO2@D‐NHCS‐Tr as an efficient and reusable catalyst for the synthesis of indol‐3‐yl‐4H‐chromene via a multi‐component reaction under solvent‐free conditions

Fe3O4@SiO2@D‐NHCS‐Tr was used as an efficient catalyst in the three‐component reaction between indole derivatives, salicylaldehyde, and active methylene compounds under solvent‐free conditions to the synthesis of indol‐3‐yl‐4H‐chromene derivatives. The features of this method include the green conditions of the reaction, easy separation, eco‐friendly and cost‐effectiveness of the catalyst, and high yield in short reaction times.