A Multicomponent Approach to Highly Substituted 1H-Pyrazolo[3,4-b]pyridines

Abstract

Multicomponent reactions make up an important subclass of azaheterocycle syntheses. In this report, a mild and catalyst-free multicomponent preparation of 1H-pyrazolo[3,4-b]pyridines is described. This one-pot synthesis uses simple aldehyde, 3-oxopropanenitrile, and 1H-pyrazol-5-amine starting materials to rapidly access structurally diverse products. Additionally, the impact of 1H-pyrazol-5-amine C3 substituents on the formation of 1H-pyrazolo[3,4-b]pyridines vs pyrazolo[1,5-a]pyrimidine structural isomers is discussed.

Key words

1H-pyrazolo[3,4-b]pyridine - multicomponent reaction - dehydrative cyclization - Knoevenagel condensation - 7-azaindazole

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