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

Fe 3 O 4 @SiO 2 @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‐4 H ‐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.