An efficient approach for the synthesis of pharmacologically important spiro[indoline-3,4’-pyrano[2,3-c] pyrazole] derivatives from tandem, four component reaction of various hydrazines, isatins, β-ketoesters, and malononitrile or methyl(ethyl)cyanoester in the presence of N,N,N’,N’-tetrabromobenzene-1,3- disulfonamide [TBBDA] and poly(N,N’-dibromo-N-ethyl-benzene-1,3-disulfonamide) [PBBS] as efficient organocatalysts was reported.
