“On Water” Direct C‑3 Arylation of 2<i>H</i>‑Pyrazolo[3,4‑<i>b</i>]pyridines

An “on water” palladium-catalyzed direct (hetero)­arylation of 2<i>H</i>-pyrazolo­[3,4-<i>b</i>]­pyridines has been developed. The reactions proceeds smoothly with at low catalytic loading at low temperature providing the C3 (hetero)­arylated products in good to excellent isolated yields. Free <i>NH</i> 3-arylated 7-azaindazoles were also prepared by simple cleavage of the <i>N</i>-protected groups