Ionic Liquids for the Synthesis of Pyrazolo[3,4-b]quinoline-3,5-diones

Multicomponent reactions (MCRs) are considered as one of the best routes in organic and medicinal findings.1,2 heterocyclic compounds containing quinoline and pyrazole ring systems, such as pyrazolo[4,3-c]quinoline3 and pyrazolo[3,4-b]quinoline4 play an important role in medicinal chemistry and drug discovery.5,6 Among these compounds, pyrazolo[3,4-b]quinoline framework provides significant pharmacological activities such as antiviral,7 antimalarial,8 and anti-inflammatory.9 A great number of reports on the synthesis of pyrazolo[3,4-b]quinoline by the multicomponent reactions have been published thus-far.10Herein, we report the synthesis of pyrazolo[3,4-b]quinoline derivatives 4 by a multi-component reaction of dimedone 1, 5-amino pyrazolone 2 and aromatic aldehydes 3a-i in the presence of [Msim]Cl ionic liquid under solvent-free conditions (Fig. 1). Good yields of products, short experimental time, and low cost of the catalyst are advantages of this procedure.

Keywords:

Multi-component reactions , pyrazolo[3 , 4-b]quinoline-3 , 5-diones , ionic Liquids