Three-Component Synthesis of Spiro[indoline-3,4′-pyrazolo[3,4-b]pyridines] under Microwave Irradiation

A domino three-component strategy with high efficiency for the synthesis of spiro[indoline-3,4′-pyrazolo[3,4-b]pyridines] from easily available isatins, pyrazol-5-amines and β-ketonitriles under microwave heating. During reaction process, HOAc plays dual roles as reaction media as well as a Bronsted acid-promoter. Flexible structural modification, broad functional group compatibility and mild reaction conditions make this strategy a useful and attractive process of library generation for drug discovery.