A compound of formula (Ia): or a salt thereof, wherein: R 1 and R 2 are each independently hydrogen or C 1-6 alkyl, or R 1 and R 2 together with the carbon to which they are attached is a C 3-7 carbocyclyl; Z 1 is -CH-, -CR 3 -, or N (nitrogen); Z 2 is -CH- or -CR 3 -; Z 3 is -CH-, -CR 3 -, or N (nitrogen); Z 4 is -CH- or -CR 3 -; each R 3 is independently selected from the group consisting of halo, cyano, nitro, oxo, -C(=O)OR 3A, -NR 3A (CH 2) p OR 3B, -NR 3A (CH 2) p R 3B, -(CH 2) q OR 3B, -(CH 2) q R 3B, -C(=O)R 3A, halo(C 1 -C 6)alkyl, halo(C 1 -C 6)alkoxy, (C 1 -C 6)alkylC(=O)-, (C 1 -C 6)alkylOC(=O)-, (C 1 -C 6)alkylC(=O)O-, -C(=O)NR 3A R 3B, -NR 3A C(=O)R 3B, and R 3C; each R 3A is independently selected from the group consisting of hydrogen, halo, cyano, -(CH 2) q R 3AA, -(CH 2) q N(R 3AA) 2, (C 1 -C 6)alkyl, C 3-7 carbocyclyl, (C 1 -C 6)alkoxy, halo(C 1 -C 6)alkyl, halo(C 1 -C 6)alkoxy, (C 1 -C 6)alkylC(=O)-, (C 1 -C 6)alkylOC(=O)-, (C 1 -C 6)alkylC(=O)O-, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and heteroaryl(C 1 -C 6)alkyl; each R 3B is independently selected from the group consisting of hydrogen, halo, cyano, -(CH 2) q R 3BB, -(CH 2) q N(R 3BB) 2, (C 1 -C 6)alkyl, C 3-7 carbocyclyl, (C 1 -C 6)alkoxy, halo(C 1 -C 6)alkyl, halo(C 1 -C 6)alkoxy, (C 1 -C 6)alkylC(=O)-, (C 1 -C 6)alkylOC(=O)-, (C 1 -C 6)alkylC(=O)O-, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and heteroaryl(C 1 -C 6)alkyl; each R 3C is independently selected from the group consisting of (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, heteroaryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl, each optionally substituted with one or more R 3CC; each R 3AA is independently selected from the group consisting of (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl, each optionally substituted with one or more R 3CC; each R 3BB is independently selected from the group consisting of (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl, each optionally substituted with one or more R 3CC; each R 3CC is independently selected from the group consisting of halo, cyano, (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl; each p is independently an integer selected from 1, 2, and 3; and each q is independently an integer selected from 0, 1, 2 and 3. R 1 and R 2 are each independently hydrogen or C 1-6 alkyl, or R 1 and R 2 together with the carbon to which they are attached is a C 3-7 carbocyclyl; Z 1 is -CH-, -CR 3 -, or N (nitrogen); Z 2 is -CH- or -CR 3 -; Z 3 is -CH-, -CR 3 -, or N (nitrogen); Z 4 is -CH- or -CR 3 -; each R 3 is independently selected from the group consisting of halo, cyano, nitro, oxo, -C(=O)OR 3A, -NR 3A (CH 2) p OR 3B, -NR 3A (CH 2) p R 3B, -(CH 2) q OR 3B, -(CH 2) q R 3B, -C(=O)R 3A, halo(C 1 -C 6)alkyl, halo(C 1 -C 6)alkoxy, (C 1 -C 6)alkylC(=O)-, (C 1 -C 6)alkylOC(=O)-, (C 1 -C 6)alkylC(=O)O-, -C(=O)NR 3A R 3B, -NR 3A C(=O)R 3B, and R 3C; each R 3A is independently selected from the group consisting of hydrogen, halo, cyano, -(CH 2) q R 3AA, -(CH 2) q N(R 3AA) 2, (C 1 -C 6)alkyl, C 3-7 carbocyclyl, (C 1 -C 6)alkoxy, halo(C 1 -C 6)alkyl, halo(C 1 -C 6)alkoxy, (C 1 -C 6)alkylC(=O)-, (C 1 -C 6)alkylOC(=O)-, (C 1 -C 6)alkylC(=O)O-, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and heteroaryl(C 1 -C 6)alkyl; each R 3B is independently selected from the group consisting of hydrogen, halo, cyano, -(CH 2) q R 3BB, -(CH 2) q N(R 3BB) 2, (C 1 -C 6)alkyl, C 3-7 carbocyclyl, (C 1 -C 6)alkoxy, halo(C 1 -C 6)alkyl, halo(C 1 -C 6)alkoxy, (C 1 -C 6)alkylC(=O)-, (C 1 -C 6)alkylOC(=O)-, (C 1 -C 6)alkylC(=O)O-, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and heteroaryl(C 1 -C 6)alkyl; each R 3C is independently selected from the group consisting of (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, heteroaryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl, each optionally substituted with one or more R 3CC; each R 3AA is independently selected from the group consisting of (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl, each optionally substituted with one or more R 3CC; each R 3BB is independently selected from the group consisting of (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl, each optionally substituted with one or more R 3CC; each R 3CC is independently selected from the group consisting of halo, cyano, (C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, heterocycle, aryl, heteroaryl, heterocycle(C 1 -C 6)alkyl, aryl(C 1 -C 6)alkyl, and C 3-7 carbocyclyl; each p is independently an integer selected from 1, 2, and 3; and each q is independently an integer selected from 0, 1, 2 and 3.