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 1 H -pyrazol-5-amines or isoxazol-5-amine, 2-arylidenemalononitriles, and cyclic ketones in the presence of acetic acid at 80 °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. Image 1 • A reaction for synthesis of spirocycloalkane fused pyrazolo[3,4- b pyridines has been established. • The reaction can be finished within 2–4 h with water as sole byproduct. • This chemistry provides a strategy to construction of N -containing spirocycles with stereogenic center. [ABSTRACT FROM AUTHOR]