Materials and methods to potentiate cancer treatment

A compound having a formula

• or a pharmaceutically acceptable salt thereof, wherein:
• n is an integer 0 through 2;
• R1 is selected from the group consisting of carboxy, cyano, thiocarboxamide, RaC(═O)—;
• R2 is OH;
• or
• R1 and R2 are taken together with the carbon atoms to which each is attached to form a monocyclic 5- or 6-membered partially saturated ring, wherein 1, 2, or 3 carbon atoms of R1 and R2 optionally are a heteroatom selected from the group consisting of O, N, S, and P, said ring optionally substituted with one or more ═O, ═S, ═NH, ORh, N(Rh)2, aryl, substituted aryl, heteroaryl, or substituted heteroaryl, said nitrogen or phosphorus heteroatom optionally substituted with a group consisting of aryl, substituted aryl, alkyl, alkyl substituted with RaC(═O), and RaC (═O)
• R3, independently, is selected from the group consisting of hydrogen, sulfonamido, sulfamyl, sulfonyl chloride, and sulfo;
• wherein Ra is selected from the group consisting of alkyl, substituted alkyl, cycloalkyl, heteroaryl, substituted heteroaryl, heterocycloalkyl, and substituted heterocycloalkyl;
• wherein Rh, independently, is selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, heteroaryl, and substituted heteroaryl;
• and
• R4, independently, is selected from the group consisting of ORh, alkyl, substituted alkyl, aryl, and substituted aryl;
• and wherein cycloalkyl is a nonaromatic cyclic hydrocarbon group having three to six carbon atoms;
• heterocycloalkyl is a monocyclic, bicyclic, or tricyclic nonaromatic partially unsaturated or saturated ring system having 3 to 10 members and having one to four heteroatoms independently selected from the group consisting of oxygen, nitrogen, and sulfur;
• heteroaryl is a cyclic aromatic ring system having five- to ten-ring atoms, wherein one- to four-ring atoms independently are selected from the group consisting of oxygen, nitrogen, and sulfur, and the remaining ring atoms are carbon;
• substituted alkyl is an alkyl group having a substituent selected from the group consisting of cycloalkyl, aryl, heteroaryl, heterocycloalkyl, substituted aryl, substituted heteroaryl, substituted heterocycloalkyl, N(Rh)2, ORh, SRh, sulfoxide, sulfonyl, halo, RaC(═O), carboxy, hydrazino, hydrazono, and hydroxy-amino;
• substituted aryl is an aryl group having one to three substituents selected from the group consisting of halo, ORh, N(Rh)2, CN, alkyl, substituted alkyl, mercapto, nitro, CHO, carboxy, carboxamide, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, O(CH2)1-3N (Rh)2, O(CH2)1-3CO2H, and trifluoromethyl;
• substituted heteroaryl is a heteroaryl group having one to three substituents selected from the group consisting of halo, ORh, N(Rh)2, CN, alkyl, substituted alkyl, mercapto, nitro, CHO, carboxy, carboxamide, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, O(CH2)1-3N(Rh)2, O(CH2)1-3CO2H, and trifluoromethyl;
• and
• substituted heterocycloalkyl is a heterocycloalkyl group having one to three substituents selected from the group consisting of halo, ORh, N(Rh)2, CN, alkyl, substituted alkyl, mercapto, nitro, CHO, carboxy, carboxamide, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, O(CH2)1-3N(Rh)2, O(CH2)1-3CO2H, and trifluoromethyl.