Amine Modified β‐Cyclodextrin: An Ionic Water Soluble Supramolecular Catalyst for Ultrasound Promoted Synthesis of Bis(Indolyl/Coumarinyl) Methane Derivatives

An eco‐friendly and highly efficient method has been developed for the synthesis of bis(indole/coumarinyl)methanes via condensation that has been successfully achieved by using indoles/coumarins with various aryl/alkyl‐substituted aldehydes in the presence of a catalytic amount of a water‐soluble ionic modified diamine‐β‐cyclodextrin ( i DA‐β@CD ( 3 )) in good‐to‐excellent yields under ultrasonic irradiation in water is reported. The synthesized supramolecular catalyst is extensively characterized using NMR, ESI‐MS, and IR spectroscopic techniques. The reaction occurs smoothly with i DA‐β@CD ( 3 ) in a water medium at room temperature in a very short reaction time, making it an ecologically friendly substitute for the current methods. The catalyst can be easily recovered and reused for five consecutive reaction cycles without significant loss of activity. Compared to the documented conventional methods, this synthetic pathway satisfies many important green chemistry principles, including the avoidance of harmful additives and solvents, the use of a water‐soluble catalyst made from native cyclodextrin, and reusability of the catalyst.