Sodium carbonate sesquiperhydrate catalyzed efficient one-pot synthesis of novel spiro[indoline-3,2'- oxirane]dicarboxamides was achieved via Knoevenagel adduct of isatin with malononitrile as the key step followed by a sequential tandem reaction. The Knoevenagel adduct transpires into oxirane with the geminal dicyano functionality being hydrolysed in to corresponding dicarboxamide. Further extension of the scope of reaction with various other cyclic ketone such as 9H-fluoren-9-one, 1H-indene-1,2,3-trione and cycloheptanone was found to be equally feasible as well as efficient, rendering the final spiro compounds in good yields. This method has the advantages of short synthetic route, operational simplicity, shorter reaction times, for small scale high-speed synthesis and is environmentally benign. The structure elucidation and attribution of relative stereochemistry were unequivocally determined by X-ray structural analysis.
Keywords: Epoxidation, spirooxindole, Knoevenagel adduct, geminal dicyano functionality, sodium hypochlorite, rhodium(II)acetate catalyst, trichloroisocyanuric acid, dimethyldioxirane, peptide hydrolase inhibitors, scaffold, melanoma, Na2CO3, column chromatography, mechanistic pathway, malononitrile