An efficient synthesis of pyrazolo[3,4-b]pyridine-4-spiroindolinones by a three-component reaction of 5-aminopyrazoles, isatin, and cyclic β-diketones

Novel pyrazolopyridine-spiroindolinones were prepared by the three-component reaction of 5-aminopyrazoles, isatin, and cyclic beta-diketones in aqueous media and catalyzed by p-TSA. This protocol provides a simple one-step procedure with the advantages of easy work-up, mild reaction conditions and environmentally benign. (C) 2011 Elsevier Ltd. All rights reserved.