An allosteric HDAC3 inhibitor (Ki = 0.16 nM); selective for HDAC3 over HDAC1 and HDAC2 (IC50s = 0.95, 11.81, and 95.45 nM, respectively, using recombinant HDACs; selective for acute myeloid, monocytic, and lymphoblastic leukemia cell lines (EC50s = 36.37, 76.64, and 151.7 nM, respectively) over chronic myeloid, acute promyelocytic, and acute lymphoblastic cells (EC50s = 2,160, >10,000, and >10,000 nM, respectively),