Compounds for treating proliferative disorders

A compound represented by formula (XIII):

• or a tautomer, pharmaceutically acceptable salt, clathrate, or prodrug thereof, wherein:
• X13 is —C(O)—;
• —S(O)—, —S(O)2—, —P(O)(OR12)—, —S(O)2R13S(O)2—, —S(O)2OS(O)2—, —S(O)2SS(O)2—, —S(O)2N(R5)S(O)2, P(O)(OR12)R13P(O)(OR12)—, —P(O)(OR12)OP(O)(OR12)—, —P(O)(OR12)SP(O)(OR12)—, —C(O)R13S(O)2—, —C(O)C(═NNHR26)C(O)—, —S(O)2NR27C(O)— or —P(O)(OR12)N(R5)P(O)(OR12)—;
• R1 and R2 are independently an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted heterocyclyl, an optionally substituted aryl, an optionally substituted heteroaryl, halo, nitro, cyano, guanidino, —OR17, —NR19R20, —C(O)R17, —C(O)OR17, —OC(O)R17, —C(O)NR19R20, —NR18C(O)R17, —OP(O)(OR17)2, —SP(O)(OR17)2, —SR17, —S(O)pR17, —OS(O)pR17, —S(O)pOR17, —NR18S(O)pR17, or —S(O)pNR19R20;
• provided that when R3, R4, R5, and R6 are all —H, then neither R1 or R2 is —OR17, —NR19R20, —NR18C(O)R17, or phenyl;
• R3 and R4 are independently —H, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted heterocyclyl, an optionally substituted aryl or an optionally substituted heteroaryl;
• R5 and R6 are independently —H, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted heterocyclyl, an optionally substituted aryl or an optionally substituted heteroaryl, or R5 and R6, taken together with the nitrogen atoms to which they are bonded and X13, form the following ring structure:
• R12 is independently —H, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted heterocyclyl, an optionally substituted aryl, an optionally substituted heteroaryl, or halo;
• R13 is a covalent bond, or a substituted or unsubstituted C1-C6 alkylene group;
• R17 and R18, for each occurrence, are, independently, —H, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted heterocyclyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted aralkyl, or an optionally substituted heteraralkyl;
• R19 and R20, for each occurrence, are independently —H, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted heterocyclyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted aralkyl, or an optionally substituted heteraralkyl;
• or R19 and R20, taken together with the nitrogen to which they are attached, form an optionally substituted heterocyclyl or an optionally substituted heteroaryl;
• R26 is an optionally substituted alkyl or an optionally substituted phenyl group;
• R27 is —H or an optionally substituted alkyl group;
• and
• p is 1 or 2.