Facile Three-Component Synthesis of Macrocyclane-Fused Pyrazolo[3,4-b] pyridine Derivatives

A series of new functionalized macrocyclane-fused pyrazolo[ 3,4-b]pyridine derivatives with an aryl group at the 2-position of the pyridine nucleus have been synthesized by microwave-assisted three-component reactions of aldehydes, aminopyrazole and cycloketones in HOAc using 1.0 equiv. of TFA as a promoter. The procedure is facile, avoiding time-consuming and costly syntheses, tedious work-ups and purifications of precursors as well as protection/deprotection of functional groups. This method is very efficient due to short reaction times and easy work-up and provides an efficient and promising synthetic strategy for the construction of the macrocyclane-fused pyrazolo[3,4-b] pyridine skeleton.