An efficient domino strategy for synthesis of novel spirocycloalkane fused pyrazolo[3,4-b]pyridine derivatives

A concise and efficient three-component domino strategy promoted by acetic acid has been established for the synthesis of novel spirocycloalkane fused pyrazolo[3,4-b]pyridine-dicarbonitrile derivatives in 73-90% yields. The domino reaction is easy to perform by mixing 1H-pyrazol-5-amines or isoxazol-5-amine, 2-arylidenemalononitriles, and cyclic ketones in the presence of acetic acid at 80 degrees C in 2-4 h. The present procedure shows attractive properties including inexpensive and easy starting materials, simple one-pot operation, large substrate scope, highly isolated yields, and easy purification process. This chemistry provides a promising synthetic strategy to construction of N-containing spirocycle skeleton with stereogenic centers. (C) 2020 Elsevier Ltd. All rights reserved.