Chemodivergent, multicomponent-tandem facile synthesis of novel 1H-pyrazolo[1,2-b]phthalazine-5,10-dione using acetic acid functionalized imidazolium salt {[cmdmim]I} as a recyclable catalyst

Abstract

A novel one-pot four-component, highly efficient and environmentally benign approach for the synthesis of a wide range of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives in the presence of acetic acid functionalized imidazolium salt (1-carboxymethyl-2,3-dimethylimidazolium iodide {[cmdmim]I}) as a newly synthesized Brønsted acid catalyst is described. The reaction occurs via tandem Knoevenagel-cyclocondensation of phthalic anhydride, hydrazine hydrate, aromatic aldehydes and 3-(1-methyl-1H-pyrrol-2-yl)-3-oxopropanenitrile (or 3-(1H-indol-3-yl)-3-oxopropanenitrile) in the presence of acetic acid functionalized imidazolium salt {[cmdmim]I} in ethanol under reflux conditions. This adequate procedure possesses some advantages like atom economy, cost-effectiveness, operational simplicity, short reaction times, straightforward work-up procedure, high yields, and reusability of the catalyst in 5 consecutive runs without any appreciable decrease in activity.