Microwave-Promoted Facile and Rapid Access to Novel Spirooxindole-furo[2,3-c]pyrazole Derivatives Using Pyridinium Ylide-Assisted Domino Reaction

Abstract

Novel spirooxindole-furo[2,3-c]pyrazole derivatives containing both biologically active pyrazole and spirooxindole-furan templates are synthesized via single-pot two-step four-component reaction involving hydrazine, β-keto ester, isatin derivatives and pyridinium ylide catalyzed by triethylamine in EtOH under microwave irradiation (MWI). In this domino protocol, five bonds (2C–C, C – O, C–N, C = N) and two new rings are efficiently formed via initial Knoevenagel, subsequent Micheal and final heterocyclization reactions. High yields, short reaction time (10–15 min), operational simplicity, absence of any tedious workup or purification and avoidance of hazardous or toxic reagents/solvents are the salient features of this eco-friendly methodology.