Green Synthesis of Fused Polycyclic Pyrazolo[3,4-b][1,6]naphthyridine Derivatives in Ionic Liquids via Three-Component Reaction

Abstract

A green synthesis of fused polycyclic 4-aryl-3-methyl-1-phenyl-7,8-dihydro- 1H-pyrazolo[3,4-b][1,6]naphthyridin-5(4H)-one derivatives is described in ionic liquids. Under the protection of nitrogen, this three-component reaction including aromatic aldehyde, 3-methyl-1-phenyl-1H-pyrazol-5-amine, and piperidine-2,4-dione gives un-aromatized products in high yields. This new procedure to pyrazolonaphthyridines has the advantages of one pot reaction, milder reaction conditions, high yields, and is environmentally benign.