The present invention relates to compound of formula I, II, III, or IV, and/or a pharmaceutical acceptable addition salt thereof and/or a stereoisomer thereof and/or a solvate thereof, Formulas (I), (II), (III) and (IV) wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R11, and R12 are as defined in the claim 1 or as described in detail in the description of the invention, and to the use of said compounds to treat or prevent proliferative disorders and their use to manufacture a medicine to treat or prevent proliferative disorders, particularly cancer such as leukemia. The present invention also relates to pharmaceutical compositions of said compounds and the use of said pharmaceutical compositions to treat or prevent proliferative disorders. The present invention further relates to the use of said compounds as biologically active ingredients, more specifically as medicaments for the treatment of proliferative disorders and pathologic conditions such as, but not limited to, cancer such as leukemia.