Enantioselective Synthesis of Spiro[Indoline‐3,4‐Pyrrolo[3,4‐<i>b</i>]Pyridines] <i>Via</i> an Organocatalysed Three‐Component Cascade Reaction

Asymmetric synthesis of derivatives of spiro[indoline-3,4-pyrrolo[3,4-b]pyridines] were first developed through the organocatalytic cascade of Knoevenagel/Michael/cyclization reactions using a quinidine-derived squaramide. Under the optimized conditions, the three-component reactions of isatins, cyanoacetates, and 3-aminomaleimides yield the desired heterocycle-fused spirooxindoles in good yields (78-91 %) with 53 %-99 % enantiomeric excess (ee). Notably, this reaction enables a broad substrate scope under mild conditions and provides a convenient method for the enantioselective construction of diverse spirooxindoles combined with dihydropyridine and maleimide skeletons, which has great potential for the construction of new bioactive chemical entities.