Substituted hydroxamic acids and uses thereof

A compound of formula (I):

• or a pharmaceutically acceptable salt thereof;
• wherein:
• ring A is a heteroaromatic 5-membered ring connected through one of positions (a) or (b);
• X1 is CR1, O, or S;
• (i) when ring A is connected through position (a), X2 is C;
• and X3 is CR1, O, S, or N;
• or
• (ii) when ring A is connected through position (b), X3 is C;
• and X2 is CR1, O, S, or N;
• provided that only one of X1, X2, or X3 is O or S;
• and further provided that at least one of X1, X2, and X3 is O, S, or N;
• each occurrence of R1 is independently hydrogen, halogen, C1-4 alkyl, C1-3 fluoroalkyl, —O—C1-3 alkyl, —O—C1-3 fluoroalkyl, cyano, hydroxy, —NHC(O)C1-3 alkyl, —C(O)NHC1-3 alkyl, —NHC(O)NHC1-3 alkyl, or —NHS(O)2C1-3 alkyl;
• ring A is further substituted at a substitutable nitrogen atom with R1a;
• R1a is hydrogen, or C1-4 aliphatic;
• R2 is C1-6 aliphatic, C1-6 fluoroaliphatic, or unsubstituted or substituted 6-10-membered aryl;
• R4b is hydrogen, or C1-4 aliphatic;
• G is —R3, —V1—R3, —V1-L1-R3, -L2-V1—R3, -L2-V2—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(O)—CRA═CRA—, —C(O)—N(R4a)—, —C(O)—O—, or —S(O)2—;
• V2 is —C(S)—, —N(R4a)—, —N(R4a)—C(O)—, —SO2—N(R4a)—, —NR4a)—SO2—, —O—, —S—, —S(O)—, NR4a)—C(O)—NR4a)—, —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 1-5 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 R4a is independently hydrogen, or unsubstituted or substituted C1-4 aliphatic.