Imidazopyridine and imidazopyrimidine derivatives as antibacterial agents

A method for the treatment of bacterial infections comprising the administration to a patient in need thereof of an effective amount of a compound of the formula

• or a pharmaceutically acceptable salt thereof, wherein:
• X1 is CH2, NH, or O;
• X2 is absent, or is
• (CH2)x′, NH, O, or
• wherein
• are points of attachment, or
• is a tether 2, 3 or 4 atoms in length, selected from
• wherein R is H or (C1-C6)alkyl, and wherein
• are points of attachment and x′ is an integer from 1 to 3;
• Y is N, C—H, C—F, or C-OMe;
• R1 is H or halo;
• R2 is (C3-C6)cycloalkyl,
• (CH2)x-aryl,
• (CH2)x-heterocyclo, or
• (CH2)x-heteroaryl,
• wherein x is 0, 1, or 2;
• R3 is H,
• (C1-C6)alkyl,
• (C3-C6)cycloalkyl,
• aryl,
• heterocyclo,
• heteroaryl,
• C(O)NRaRb,
• C(O)Ra,
• CO2Ra,
• C(O)C(O)NRaRb,
• NO2,
• SO2Ra,
• SO2NRaRb,
• C(Rc)═NORa,
• C(Rc)═NRa,
• wherein
• indicates the point of attachment,
• wherein
• indicates the point of attachment, and wherein
• Ra is H,
• (C1-C6)alkyl,
• (C3-C6)cycloalkyl,
• (CH2)y-aryl,
• (CH2)y-heterocyclo, or
• (CH2)y-heteroaryl,
• wherein y is 0, 1, or 2;
• Rb is H,
• (C1-C6)alkyl,
• (C3-C6)cycloalkyl,
• aryl,
• heterocyclo, or
• heteroaryl;
• Rc is H,
• (C1-C6)alkyl,
• (C3-C6)cycloalkyl,
• aryl,
• heterocyclo, or
• heteroaryl;
• and
• R4 is (C1-C6)alkyl, (C1-C6alkyl)-O—(C1-C6alkyl), cyclopropyl, CH2-cyclopropyl, or cyclobutyl.