A compound of Formula I and pharmaceutically acceptable salts thereof: wherein R 1 is an aromatic or heteroaromatic ring system optionally substituted with one or two substituents selected from the group consisting of C 1-4 alkyl-Y 1 -, C 2-4 alkenyl-Y 1 -, C 2-4 alkynyl-Y 1 -, C 1-4 alkyl-Y 1 - substituted with halo, such as fluoro, C 2-4 alkenyl-Y 1 - substituted with halo, C 2-4 alkynyl-Y 1 substituted with halo, HO-C 1-4 alkanediyl-Y 1 -, HO-C 2-4 alkenediyl-Y 1 -, HO-C 2-4 alkynediyl-Y 1 -, HO-C 1-4 alkanediyl-, HO-C 2-4 alkenediyl-, HO-C 2-4 alkynediyl-, C 1-4 alkyl- C 2-4 alkenyl-, C 2-4 alkynyl-, C 1-4 alkyl substituted with halo, C 2-4 alkenyl- substituted with halo, C 2-4 alkynyl-substituted with halo, and halogen, wherein the heteroaromatic ring system is a fully or partially aromatic carbocyclic ring system where one or more of the carbon atoms have been replaced with nitrogen, sulphur, and/or oxygen atoms; Y 1 is selected from the group consisting of O, S, NH, C, C O, C NH, O and NHC; X 1 is NH, O, or CH 2; n1 is 0 or 1; X 3 is absent or NR y; R x and R y are independently C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl, or H, such as CH 3 or H; L is O, S, S, S z, NH, C, or CH 2; Z 1, Z 2, and Z 3 are independently selected from N and CH; R 3 is selected from the group consisting of H, halo, C NR 2a R 2b, C OR 2a, OR 2a, NR 2a R 2b, OC R 2a, NR 2a C R 2b, C 1-4 alkyl optionally substituted with one or more halo, C 2-4 alkenyl optionally substituted with one or more halo, and C 2-4 alkynyl optionally substituted with one or more halo, wherein R 2a and R 2b are independently selected from the group consisting of H, C 1-4 alkyl, C 2-4 alkenyl, and C 2-4 alkynyl. R 1 is an aromatic or heteroaromatic ring system optionally substituted with one or two substituents selected from the group consisting of C 1-4 alkyl-Y 1 -, C 2-4 alkenyl-Y 1 -, C 2-4 alkynyl-Y 1 -, C 1-4 alkyl-Y 1 - substituted with halo, such as fluoro, C 2-4 alkenyl-Y 1 - substituted with halo, C 2-4 alkynyl-Y 1 substituted with halo, HO-C 1-4 alkanediyl-Y 1 -, HO-C 2-4 alkenediyl-Y 1 -, HO-C 2-4 alkynediyl-Y 1 -, HO-C 1-4 alkanediyl-, HO-C 2-4 alkenediyl-, HO-C 2-4 alkynediyl-, C 1-4 alkyl- C 2-4 alkenyl-, C 2-4 alkynyl-, C 1-4 alkyl substituted with halo, C 2-4 alkenyl- substituted with halo, C 2-4 alkynyl-substituted with halo, and halogen, wherein the heteroaromatic ring system is a fully or partially aromatic carbocyclic ring system where one or more of the carbon atoms have been replaced with nitrogen, sulphur, and/or oxygen atoms; Y 1 is selected from the group consisting of O, S, NH, C, C O, C NH, O and NHC; X 1 is NH, O, or CH 2; n1 is 0 or 1; X 3 is absent or NR y; R x and R y are independently C 1-4 alkyl, C 2-4 alkenyl, C 2-4 alkynyl, or H, such as CH 3 or H; L is O, S, S, S z, NH, C, or CH 2; Z 1, Z 2, and Z 3 are independently selected from N and CH; R 3 is selected from the group consisting of H, halo, C NR 2a R 2b, C OR 2a, OR 2a, NR 2a R 2b, OC R 2a, NR 2a C R 2b, C 1-4 alkyl optionally substituted with one or more halo, C 2-4 alkenyl optionally substituted with one or more halo, and C 2-4 alkynyl optionally substituted with one or more halo, wherein R 2a and R 2b are independently selected from the group consisting of H, C 1-4 alkyl, C 2-4 alkenyl, and C 2-4 alkynyl.