Substituted hydroxamic acids and uses thereof

A compound of formula (I):

• or a pharmaceutically acceptable salt thereof;
• wherein:
• X1 is CH or N;
• X2 is CH or N;
• n is 1;
• R1a is hydrogen, fluoro, C1-4 alkyl, or C1-3 fluoroalkyl;
• R1b is hydrogen, fluoro, C1-4 alkyl, or C1-3 fluoroalkyl;
• or R1a and R1b are taken together to form an oxo group;
• each occurrence of R1c is independently hydrogen, fluoro, C1-4 alkyl, or C1-3 fluoroalkyl;
• each occurrence of R1d is independently hydrogen, fluoro, C1-4 alkyl, or C1-3 fluoroalkyl;
• G is —R3, —V1—R3, —V1-L1-R3, -L2-V1—R3, -L2-V2—R3, or -L1-R3;
• or when R1a and R1b are taken together to form an oxo group, G is —R3, or -L1-R3;
• L1 is an unsubstituted or substituted C1-3 alkylene chain;
• L2 is an unsubstituted or substituted C2-3 alkylene chain;
• V1 is —C(O)—, —C(S)—, —C(O)—CRA═CRA—, —C(O)—N(R4a)—, —C(O)—O—, or —S(O)2—;
• V2 is —N(R4a)—, —N(R4a)—C(O)—, —SO2—N(R4a)—, —N(R4a)—SO2—, —O—, —S—, —S(O)—,
• —N(R4a)—C(O)—N(R4a)—, —N(R4a)—C(O)—O—, —O—C(O)—N(R4a)—, or —N(R4a)—SO2—N(R4a)—;
• R3 is unsubstituted or substituted C1-6 aliphatic, unsubstituted or substituted 3-10-membered cycloaliphatic, unsubstituted or substituted 4-10-membered heterocyclyl having 1-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur, unsubstituted or substituted 6-10-membered aryl, or unsubstituted or substituted 5-10-membered heteroaryl having 1-5 heteroatoms independently selected from nitrogen, oxygen, and sulfur;
• each occurrence of RA is independently hydrogen, fluoro, or unsubstituted or substituted C1-4 aliphatic;
• and
• each occurrence of R4ais independently hydrogen, or unsubstituted or substituted C1-4 aliphatic;
• provided that the compound of formula (I) is other than:
• N-hydroxy-5-(4-methoxybenzyl)-4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-2-carboxamide;
• or
• N-hydroxy-5-(3-(trifluoromethyl)benzyl)-4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-2-carboxamide.