Synthesis and anti-breast cancer activity of new indolylquinone derivatives

► A series of novel indolylquinone derivatives were synthesized by a mild method. ► The compounds were tested in vitro on MDA-MB-231 and MCF-7 breast cancer cell. ► The compounds are novel with decent cytotoxic activities. ► 3d and 3g displayed the most potent antiproliferative activity of the series. ► They inhibited breast cancer cells proliferation by triggering apoptotic cell death.