A novel series of [1-(1H-benzimidazol-7-yl)-1H-pyrazolo [3, 4-d] pyrimidin-4-yl] arylhydrazones was synthesized and shown to potently inhibit glycogen synthase kinase-3 (GSK-3). In light of detailed structure–activity relationships and structural knowledge of the GSK-3 binding pocket, a benzimidazole substituent was incorporated onto the pyrazolopyrimidine core resulting in improved potency over previous analogs. More ...