Methods for the treatment of a proliferative disorder are provided in which a subject in need of such treatment is administered an effective amount of a compound selected from: compounds of formula (I) or a pharmaceutically acceptable salt thereof, wherein X.sup.1 and X.sup.2 are independently H, Cl, F, Br, I, CN, CF.sub.3 or NO.sub.2, and Ar.sup.1 is a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl; and compounds of formula (II) wherein X.sup.3 and X.sup.4 are each independently H, Cl, F, Br, I, CN, CF.sub.3 or NO.sub.2; Y is (C.sub.2 C.sub.6)alkylene or (C.sub.2 C.sub.6)heteroalkylene; and Z is Cl, F, Br, I, CN, CF.sub.3 or NO.sub.2.