Regioselective Synthesis of Fused Azo-linked Pyrazolo[4,3-e]pyridines Using Nano-Fe3O4

A multicomponent reaction for the synthesis of fused azo-linked pyrazolo[4,3-e]pyridines from 3-amino-5-methylpyrazole, indan-1,3-dione and synthesized azo-linked aldehydes using nano-Fe3O4 as an effective and reusable catalyst is reported. The present methodology offers several advantages, such as a simple procedure with an easy work-up, short reaction times, high yields, and the absence of any volatile and hazardous organic solvents.