Efficient synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives using succinimidinium N-sulfonic acid hydrogen sulfate as a new ionic liquid catalyst

Abstract

Succinimidinium N-sulfonic acid hydrogen sulfate is prepared as a new ionic liquid and characterized with a variety of techniques including FT-IR, 1H and 13C NMR, SEM, mass spectra method as well as Hammett acidity function. After identification, this reagent was used as an efficient catalyst for the multi-component synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives. The simple work-up, mild reaction conditions, excellent yields and relatively short reaction times are the notable advantages of this protocol. In addition, the ionic liquid could be recycled several times without appreciable reduction in its catalytic activity.