ERα degrader 4 is an excellent and selective estrogen receptor α ( ERα ) degrader ( IC 50 of 0.31, 0.41 and 0.48 μM in MDA-MB-231, MCF-7 and MCF-7/ADR cells, respectively). ERα degrader 4 has potent inhibitory activity against MCF-7 cell lines. ERα degrader 4 is a potential SERDs candidate for the research of breast cancer.