Synthesis of novel pyrazolo[3,4-d]pyrimidine derivatives as potential anti-breast cancer agents

► New 4-benzylidenehydrazinyl-pyrazolo[3,4-d]pyrimidines 6a-p were synthesized. ► The cytotoxic activity of the synthesized compounds against MCF7 was investigated. ► The compounds showed potent antitumor activity comparable to that of doxorubicin. ► Compound 6d was the most active compound with IC50 equal to 7.5 nM.