Bcl-xL antagonist 2 is a potent, selective, and orally active antagonist of BCL-XL with an IC50 and Ki of 0.091 μM and 65 nM, respectively. Bcl-xL antagonist 2 promotes the apoptosis of cancer cells. Bcl-xL antagonist 2 has the potential for the research of the chronic lymphocytic leukemia (CLL) and non-Hodgkin’s lymphoma (NHL).