A compound having structural Formula I: or a pharmaceutically acceptable salt thereof wherein C* indicates a potential chiral carbon atom; R 1 is hydrogen (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-O-, halo(C 1-6)alkyl-O-, (C 1-6)alkyl-NH-, halo(C 1-6)alkyl-NH-, -(C 1-3)alkyl-(C 3-7)cycloalkyl, -(C 1-3)alkyl-aryl, wherein aryl is unsubstituted or substituted by one, two, or three R 7, aryl unsubstituted or substituted by one, two, or three R 7, (C 3-7)cycloalkyl, or -(C 1-3)alkyl-heteroaryl wherein the heteroaryl is a 5- or 6-membered ring containing one, two, or three heteroatoms independently selected from the group consisting of N, O, and S, and wherein heteroaryl is unsubstituted or substituted by one, two, or three R 7; R 2 is (C 1-3)alkyl, or (C 3-7)cycloalkyl; R 3 is aryl unsubstituted or substituted by one, two, or three R 6, five- or six-membered heteroaryl containing one, two, or three heteroatoms independently selected from N, O and S, wherein heteroaryl is unsubstituted or substituted by one, two, or three R 6, (C 1-3)alkyl, or (C 3-7)cycloalkyl; R 4 is hydrogen, (C 1-3)alkyl, halo(C 1-3)alkyl, or (C 3-7)cycloalkyl; R 5 is hydrogen, hydroxy, -N(R 8a)(R 8b), -COOH, -C NH 2, (C 1-3)alkyl, (C 3-7)cycloalkyl, or four- to six-membered monocyclic heterocyclyl containing 1 N heteroatom, wherein the heterocyclyl is unsubstituted or substituted by one to two R 9; each R 6 is independently (C 1-3)alkyl, halo(C 1-3)alkyl, (C 1-3)alkoxy, halo(C 1-3)alkoxy, (C 3-7)cycloalkyl, unsubstituted or substituted by halo, halo, cyano, hydroxy, -NH 2, -(C 1-3)alkyl-COOH, or -(C 1-3)alkyl-COO(C 1-4)alkyl; each R 7 is independently (C 1-3)alkoxy, halo, hydroxy, or (C 1-3)alkyl; R 8a and R 8b are independently hydrogen, (C 1-3)alkyl,or (C 3-7)cycloalkyl; and R 9 is (C 1-3)alkyl, halo(C 1-3)alkyl, or hydroxy. C* indicates a potential chiral carbon atom; R 1 is hydrogen (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-O-, halo(C 1-6)alkyl-O-, (C 1-6)alkyl-NH-, halo(C 1-6)alkyl-NH-, -(C 1-3)alkyl-(C 3-7)cycloalkyl, -(C 1-3)alkyl-aryl, wherein aryl is unsubstituted or substituted by one, two, or three R 7, aryl unsubstituted or substituted by one, two, or three R 7, (C 3-7)cycloalkyl, or -(C 1-3)alkyl-heteroaryl wherein the heteroaryl is a 5- or 6-membered ring containing one, two, or three heteroatoms independently selected from the group consisting of N, O, and S, and wherein heteroaryl is unsubstituted or substituted by one, two, or three R 7; hydrogen (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-O-, halo(C 1-6)alkyl-O-, (C 1-6)alkyl-NH-, halo(C 1-6)alkyl-NH-, -(C 1-3)alkyl-(C 3-7)cycloalkyl, -(C 1-3)alkyl-aryl, wherein aryl is unsubstituted or substituted by one, two, or three R 7, aryl unsubstituted or substituted by one, two, or three R 7, (C 3-7)cycloalkyl, or -(C 1-3)alkyl-heteroaryl wherein the heteroaryl is a 5- or 6-membered ring containing one, two, or three heteroatoms independently selected from the group consisting of N, O, and S, and wherein heteroaryl is unsubstituted or substituted by one, two, or three R 7; R 2 is (C 1-3)alkyl, or (C 3-7)cycloalkyl; (C 1-3)alkyl, or (C 3-7)cycloalkyl; R 3 is aryl unsubstituted or substituted by one, two, or three R 6, five- or six-membered heteroaryl containing one, two, or three heteroatoms independently selected from N, O and S, wherein heteroaryl is unsubstituted or substituted by one, two, or three R 6, (C 1-3)alkyl, or (C 3-7)cycloalkyl; aryl unsubstituted or substituted by one, two, or three R 6, five- or six-membered heteroaryl containing one, two, or three heteroatoms independently selected from N, O and S, wherein heteroaryl is unsubstituted or substituted by one, two, or three R 6, (C 1-3)alkyl, or (C 3-7)cycloalkyl; R 4 is hydrogen, (C 1-3)alkyl, halo(C 1-3)alkyl, or (C 3-7)cycloalkyl; hydrogen, (C 1-3)alkyl, halo(C 1-3)alkyl, or (C 3-7)cycloalkyl; R 5 is hydrogen, hydroxy, -N(R 8a)(R 8b), -COOH, -C NH 2, (C 1-3)alkyl, (C 3-7)cycloalkyl, or four- to six-membered monocyclic heterocyclyl containing 1 N heteroatom, wherein the heterocyclyl is unsubstituted or substituted by one to two R 9; hydrogen, hydroxy, -N(R 8a)(R 8b), -COOH, -C NH 2, (C 1-3)alkyl, (C 3-7)cycloalkyl, or four- to six-membered monocyclic heterocyclyl containing 1 N heteroatom, wherein the heterocyclyl is unsubstituted or substituted by one to two R 9; each R 6 is independently (C 1-3)alkyl, halo(C 1-3)alkyl, (C 1-3)alkoxy, halo(C 1-3)alkoxy, (C 3-7)cycloalkyl, unsubstituted or substituted by halo, halo, cyano, hydroxy, -NH 2, -(C 1-3)alkyl-COOH, or -(C 1-3)alkyl-COO(C 1-4)alkyl; (C 1-3)alkyl, halo(C 1-3)alkyl, (C 1-3)alkoxy, halo(C 1-3)alkoxy, (C 3-7)cycloalkyl, unsubstituted or substituted by halo, halo, cyano, hydroxy, -NH 2, -(C 1-3)alkyl-COOH, or -(C 1-3)alkyl-COO(C 1-4)alkyl; each R 7 is independently (C 1-3)alkoxy, halo, hydroxy, or (C 1-3)alkyl; (C 1-3)alkoxy, halo, hydroxy, or (C 1-3)alkyl; R 8a and R 8b are independently hydrogen, (C 1-3)alkyl,or (C 3-7)cycloalkyl; and hydrogen, (C 1-3)alkyl,or (C 3-7)cycloalkyl; and R 9 is (C 1-3)alkyl, halo(C 1-3)alkyl, or hydroxy. (C 1-3)alkyl, halo(C 1-3)alkyl, or hydroxy.