O-substituted hydroxamic acids

A compound of formula (I), formula (II) or formula (III):

• or a pharmaceutically acceptable salt thereof, wherein:
• R and R1 are independently selected from the group consisting of hydrogen, (C1-C6)alkyl, (C1-C4)haloalkyl, (C1-C4)perhaloalkyl, (C6-C10)aryl, (C1-C6)heteroalkyl, (C5-C7)heterocycloalkyl, (5- or 6-membered)heteroaryl, phenylsulfanyl, phenylsulfonyl, phenylsulfinyl and (C3-C6)cycloalkyl;
• R2 is selected from the group consisting of hydrogen, (C1-C6)alkyl, —C(═O)R4, —C(═S)R4, C(═NR4)R5, —C(═NOR4)R5, (5- or 6-membered)heteroaryl and (C6-C10)aryl;
• R3 is selected from the group consisting of hydrogen, (C1-C6)alkyl, (C6-C10)aryl, —NR6R7, and —OR8;
• R4, R5, R6, R7, and R8 are each independently selected from the group consisting of hydrogen, (C1-C6)alkyl, phenyl and benzyl;
• X1 and X2 are each independently selected from the group consisting of O, NR9, S, CR10, and CR10R11;
• Y is selected from the group consisting of C(═O), C(═S), C(═NR9), and CR10R11;
• Z is selected from the group consisting of O and S;
• R9, R10 and R11 are each independently selected from the group consisting of hydrogen and (C1-C6)alkyl,
• wherein said alkyl, aryl, phenyl, benzyl, heteroalkyl, heterocycloalkyl and heteroaryl are unsubstituted or substituted with 1, 2, 3, 4 or 5 substituent(s) selected from halo, (C1-C6)alkyl, (C1-C4)haloalkyl, (C1-C4)perhaloalkyl, (C1-C6)alkoxy, (C1-C4)haloalkoxy, (C1-C4)perhaloalkoxy, —C(═O)OH, —C(═O)O(C1-C6)alkyl, —C(═O)NR4R5, —C(═O)—(C5-C7)heterocycloalkyl, (C5-C7)heterocycloalkyl, (C1-C6)alkylsulfanyl, (C1-C4)haloalkylsulfanyl, (C1-C4)perhaloalkylsulfanyl, (C1-C6)alkylsulfinyl, (C1-C6)alkylsulfonyl, (C3-C6)cycloalkylsulfonyl, (C1-C4)haloalkylsulfinyl, (C1-C4)haloalkylsulfonyl, (C1-C4)perhaloalkylsulfinyl, (C1-C4)perhaloalkylsulfonyl, —S(O)2—NH2, —S(O)2—NR6R7, —S(O)2-phenyl, —S(O)2—(C5-C7)heterocycloalkyl, —S(═O)(═NR8)(C1-C6)alkyl, —NR4R5, N—(C1-C6)alkylaminosulfonyl, and N,N-di(C1-C6)alkylaminosulfonyl.