Microwave Assisted Expeditious and Green Cu(II)-Clay Catalyzed Domino One-Pot Three Component Synthesis of 2H-indazoles

Abstract

A simple and efficient synthesis of 2H-indazoles is achieved from 2-primary amines, bromobenzaldehydes and sodium azide through domino condensation, C-N and N-N bond formations, catalyzed by a heterogeneous Cu(II)-Clay catalyst. The recyclable heterogeneous Cu(II)-Clay catalyst exhibited a remarkable activity for the title reaction without any additives. An assortment of structurally diverse 2H-indazoles were prepared in good to excellent yields from easily available starting materials by using this protocol. The Cu(II)-Clay catalyst was characterized by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Brunauer-Emmett-Teller (BET) techniques.