Green synthesis of indol-2-one derivatives from N-alkylisatins in the presence of KF/clinoptilolite nanoparticles.

KF/clinoptilolite nanoparticles were used as an effective heterogeneous catalyst for the synthesis of spiro[indole-3,2'-pyran] derivatives via three-component reactions of N-alkylisatins, 1,3-dicarbonyl compounds, and electron-deficient acetylenic compounds under solventfree conditions at 80°C. The present protocol has significant advantages, such as high yields, easy purification, and low environmental impact. [ABSTRACT FROM AUTHOR]