Enantioselective synthesis of spiro[indoline-3,1′-pyrazolo[1,2- b ]phthalazine] derivatives via an organocatalytic three-component cascade reaction

]phthalazine] derivatives was first developed through an organocatalysed cascade Knoevenagel/Michael/cyclization reaction using a quinidine-derived squaramide. Under the optimized conditions, the three-component reaction of isatins, malononitrile (cyanoacetate) and phthalhydrazide yields the desired pyrazolophthalazinyl spirooxindoles in good yields (73-90%) with up to >99% enantiomer excess (ee).