Nano crystalline ZnO: a competent and reusable catalyst for one pot synthesis of novel benzylamino coumarin derivatives in aqueous media

A green, efficient and facile protocol was developed for the synthesis of a series of benzylamino coumarin derivatives by the reaction of 4-hydroxycoumarin, cyclic secondary amine, and aromatic aldehyde in aqueous media in the presence of nano crystalline ZnO at room temperature. A wide range of functional groups were tolerated in the developed protocol. The target molecules were obtained in good to excellent yield applying the current method. The nano crystalline ZnO can be recycled five times with almost the same catalytic activity.