Rifamycin analogs

A compound of formula (I):

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is selected from hydrogen, C1-C6 alkyl, C1-C6 heteroalkyl, —C(O)Ra, —N(Rb)2, —ORc, —SR4, —CH═N—Z, and heterocyclyl, wherein the heterocyclyl is unsubstituted or substituted with one substituent selected from C1-C6 alkyl, C1-C6 alkenyl, —C(O)Ra1, —C(O)ORb1, —C(O)NHRc1, —(CH2)n1—X1a, —SO2—X1b, aryl, heteroaryl, cycloalkyl, and heterocyclyl, wherein when the substituent is aryl, heteroaryl, cycloalkyl, or heterocyclyl, the substituent is optionally further substituted with C1-C6 alkyl or —O—X1c;
• X is selected from O, S, SO2, NHSO2, NRX, and a bond;
• RX is selected from hydrogen and C1-C3 alkyl;
• R2 is selected from hydrogen, C1-C6 alkyl, C1-C6 alkenyl, C3-C6 cycloalkyl, heterocyclyl, aryl, heteroaryl, —(CH2)m1-aryl, —(CH2)m2-heterocyclyl, and —CH2-Ph-CH2-heterocyclyl, wherein each alkyl, alkenyl, cycloalkyl, heterocyclyl, aryl, and heteroaryl is independently unsubstituted or substituted with one or two substituents independently selected from C1-C6 alkyl, hydroxy, amino, —C(O)Ra2, —C(O)ORb2, —C(O)NHRc2, —(CH2)n2—X2a, —SO2—X2b, aryl, heteroaryl, cycloalkyl, and heterocyclyl;
• each Ra, Rb, Rc, and Rd is independently selected from hydrogen, C1-C6 alkyl, C3-C6 cycloalkyl, and aryl;
• Ra1 and Ra2 are each independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkenyl, cycloalkyl, heterocyclyl, aryl, heteroaryl, and —(CH2)p—Y, wherein each alkyl, alkenyl, cycloalkyl, heterocyclyl, aryl, and heteroaryl is independently unsubstituted or substituted with one substituent selected from aryl, heteroaryl, C1-C6 alkyl, halo, and nitro, and when the substituent is aryl or heteroaryl, it is unsubstituted or substituted with one substituent selected from halo, hydroxy, and —CONH2;
• Rb1 and Rb2 are each independently selected from hydrogen, C1-C6 alkyl, and heterocyclyl, wherein the heterocyclyl is optionally further substituted with one substituent selected from C1-C6 alkyl, hydroxy, halo, and nitro;
• Rc1 and Rc2 are each independently selected from hydrogen, C1-C6 alkyl, and aryl, wherein the aryl is unsubstituted or substituted with one substituent selected from C1-C6 alkyl, halo, and nitro;
• X1a, X1b, X1c, X2a, and X2b are each independently selected from aryl, heteroaryl, cycloalkyl, heterocyclyl, —O-heterocyclyl, —COOH, and —N(CH3)2, wherein each aryl, heteroaryl, cycloalkyl, or heterocyclyl is independently unsubstituted or substituted with one substituent selected from C1-C6 alkyl, hydroxy, halo, and nitro;
• Y is selected from aryl, heteroaryl, cycloalkyl, and heterocyclyl, each of which is independently unsubstituted or substituted with one substituent selected from C1-C6 alkyl, halo, and nitro;
• Z is selected from aryl and heteroaryl, each of which is optionally substituted with one substituent selected from heterocyclyl;
• and
• m1, m2, n1, n2, and p are each independently 1, 2, 3, 4, 5, or 6;
• wherein when R1 is hydrogen, —X—R2 is not:
• —CH3,
• and when R1 is
• —X—R2 is not:
• —CH3, —SH, or
• and when R1 is
• —X—R2 is not —CH3;
• and when R1 is CH3, —X—R2 is not hydrogen;
• and when X is O, R2 is not hydrogen.