Beta-lactamase inhibitor compounds

A compound according to formula (Ia):

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is —CONR′R″, —CN, or an C1-C3 alkyl substituted with C1-C3 alkoxy, —OH, —CN, —NR′R″, or —CONR′R″;
• R2 and R3 are independently selected from H, halo, —CN, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C6 cycloalkyl, C1-C6 alkoxy, —CONR′R″, or C(O)2R′;
• wherein the alkyl, alkenyl, cycloalkyl, and alkoxy represented by R2 or R3 are independently and optionally substituted by one or more halo, —CN, —OH, C1-C3 alkyl, C1-C3 haloalkyl, C3-C6 cycloalkyl, C1-C3 alkoxy, C1-C3 haloalkoxy, —NR′R″, 5-7 membered heterocycle, —C(O)NR′R″ or —NR′C(O)R″;
• and
• each R′ and R″ are independently selected from hydrogen, C1-C6 alkyl, C3-C6 cycloalkyl, phenyl, 5 to 6 membered heterocyclyl or a 5 to 6 membered heteroaryl;
• wherein each alkyl, cycloalkyl, phenyl, heterocyclyl and heteroaryl is optionally and independently substituted with one or more halo, —CN, —OH, C1-C3 alkyl, C1-C3 haloalkyl, C3-C6 cycloalkyl, C1-C3 alkoxy, C1-C3 haloalkoxy, —C(O)(C1-C6 alkyl), —C(O)(C1-C6 alkoxy), —NH2, —NH(C1-C3 alkyl), —N(C1-C3 alkyl)2, a 5-7 membered heterocyclyl or a 5-7 membered heteroaryl;
• provided that R2 and R3 are not both hydrogen;
• and when R1 is —C(O)NR′R″, then neither of R2 or R3 is —C(O)NR′R″.