Nanozeolite clinoptilolite as a highly efficient heterogeneous catalyst for the synthesis of various 2-amino-4H-chromene derivatives in aqueous media

The preparation of pharmaceutically active 2-amino-4H-chromene derivatives has been achieved using a nano powder of natural clinoptilolite (CP) zeolite. A wide range of these worthy structures having diverse substituents on the 4H-chromene ring were efficiently synthesized via the reaction of an aromatic aldehyde and variety of enolizable C–H activated acidic compounds. Nano sized natural clinoptilolite zeolite was prepared mechanically by planetary ball milling and was confirmed by X-ray diffraction patterns (XRD), scanning electron microscopy images (SEM) and Transmission electron microscopy (TEM). The catalytic activity of nano CP was evaluated in aqueous media and the results show its applicability as a novel, green, reusable and promising catalyst in organic synthesis.