Synthesis of Novel Azo Fused Dipyrazolopyridine Derivatives using Waste Orange Peel Derived C-SO3H Nano-Powder as an Efficient and Reusable Catalyst

A new series of structurally diverse azo fused dipyrazolopyridines has been synthesized via one pot pseudo six component reaction of various substituted aryl azo-salicylaldehydes with ethyl acetoacetate, hydrazine hydrate and ammonium acetate using waste orange peel derived carbon modified sulfonic acid (C-SO3H) as a mild, efficient and inexpensive heterogeneous catalyst. The prepared catalyst was characterized by FT-IR, XRD, SEM, EDX and XPS studies. The catalytically synthesized compounds were characterized by FT-IR, 1H NMR and 13C NMR. Use of recyclable powder catalyst (C-SO3H) for the excellent yields with rapid formation of the targeted azo fused dipyrazolopyridines with simple work-up procedure are the notable advantages of this protocol.