NaCl as a Novel and Green Catalyst for the Synthesis of Biodynamic Spiro Heterocycles in Water Under Sonication

Abstract

An efficient and novel green catalytic protocol for the synthesis of biologically important spirooxindole derivatives is developed in a one-pot, three-component approach involving substituted isatin, activated methylene reagent, and 3-methyl-1-phenyl-2-pyrazolin-5-one in water under sonication. This report describes the use of sodium chloride as a nonacidic and green catalyst for a variety of substrates. The advantageous features of this methodology are the environmentally benign character, operational simplicity, high yield processing, easy handling, and the fact that the products do not need to be purified.

Keywords:

• Green chemistry
• multicomponent reaction
• ring-closing metathesis
• sodium chloride
• sonication

ACKNOWLEDGMENTS

Financial assistance from the University Grants Commission (34-349/08/SR) and Council for scientific and Industrial Research (01/2248/08/EMR-II), New Delhi, is gratefully acknowledged. We are also thankful to the Central Drug Research Institute (CDRI), Lucknow, for the elemental and spectral analyses.

Notes

^a The reaction was carried out with isatin, ethylcynoacetate, and 3-methyl-1-phenyl-2-pyrazolin-5-one under sonication.

^b The amount of each additive was 10 mol%.

^c Isolated yield.

^a Isolated yield.

^a Isolated yield.