Synthesis and biological evaluation of imidazo[4,5-b]pyridine and 4-heteroaryl-pyrimidine derivatives as anti-cancer agents

► We prepared imidazo[4,5-b]pyridine and 4-heteroaryl-pyrimidine derivatives. ► The structure and biological activity relationship was evaluated. ► Many exhibited potent anti-proliferative and CDK9 inhibitory activities. ► A lead 18b activated caspase 3/7 activity and induced apoptosis.