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-(C 3-7)cycloalkyl, (C 1-6)alkyl-aryl, wherein aryl is unsubstituted or substituted by cyano, (C 3-6)cycloalkyl, (C 1-6)alkoxy, or one to three halo, aryl unsubstituted or substituted by cyano, (C 3-6)cycloalkyl, (C 1-6)alkoxy, or one to three halo, or (C 3-6)cycloalkyl; R 2 is (C 1-6)alkyl, (C 1-6)alkoxy, or (C 3-7)cycloalkyl; R 3 is (C 1-6)alkyl, (C 3-6)cycloalkyl, CO 2 (C 1-6)alkyl, CONR 6a R 6b, -N C (C 1-6)alkyl, -N (C 1-6)alkyl, aryl unsubstituted or substituted by (C 1-6)alkyl, halo(C 1-3)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, (C 3-6)cycloalkyl, CO 2 (C 1-6)alkyl, CONR 6a R 6b, or one to three halo, five- or six-membered heteroaryl containing one to three N, O or S heteroatoms, wherein heteroaryl is unsubstituted or substituted by one to two (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, (C 3-6)cycloalkyl or halo, or (C 2-6)alkynyl, R 4 is hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, halo(C 1-6)alkoxy, (C 1-6)alkoxy, (C 3-7)cycloalkyl, or cyano; R 5 is hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, halo, amino, (C 1-3)alkyl-aryl, (C 1-3)alkyl-(C 3-6)cycloalkyl, or cyano; each R 6a and R 6b are independently hydrogen, (C 1-3)alkyl, or (C 3-6)cycloalkyl; R 8a and R 8b are independently hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-C -O-(C 1-6)alkyl, (C 3-6)cycloalkyl, unsubstituted or substituted by halo, or (C 1-3)alkyl-(C 3-6)cycloalkyl; or R 8a and R 8b along with the nitrogen atom to which they are attached cyclize to form a 4- to 6-membered heterocyclyl containing one or two heteroatoms independently selected from N, O and S, wherein the heterocyclyl is unsubstituted or substituted by one to three R 9; and R 9 is (C 1-3)alkyl, halo, halo(C 1-3)alkyl, (C 3-6)cycloalkyl, or -S 2 -(C 1-3)alkyl. C* indicates a potential chiral carbon atom; R 1 is hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-(C 3-7)cycloalkyl, (C 1-6)alkyl-aryl, wherein aryl is unsubstituted or substituted by cyano, (C 3-6)cycloalkyl, (C 1-6)alkoxy, or one to three halo, aryl unsubstituted or substituted by cyano, (C 3-6)cycloalkyl, (C 1-6)alkoxy, or one to three halo, or (C 3-6)cycloalkyl; hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-(C 3-7)cycloalkyl, (C 1-6)alkyl-aryl, wherein aryl is unsubstituted or substituted by cyano, (C 3-6)cycloalkyl, (C 1-6)alkoxy, or one to three halo, aryl unsubstituted or substituted by cyano, (C 3-6)cycloalkyl, (C 1-6)alkoxy, or one to three halo, or (C 3-6)cycloalkyl; R 2 is (C 1-6)alkyl, (C 1-6)alkoxy, or (C 3-7)cycloalkyl; (C 1-6)alkyl, (C 1-6)alkoxy, or (C 3-7)cycloalkyl; R 3 is (C 1-6)alkyl, (C 3-6)cycloalkyl, CO 2 (C 1-6)alkyl, CONR 6a R 6b, -N C (C 1-6)alkyl, -N (C 1-6)alkyl, aryl unsubstituted or substituted by (C 1-6)alkyl, halo(C 1-3)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, (C 3-6)cycloalkyl, CO 2 (C 1-6)alkyl, CONR 6a R 6b, or one to three halo, five- or six-membered heteroaryl containing one to three N, O or S heteroatoms, wherein heteroaryl is unsubstituted or substituted by one to two (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, (C 3-6)cycloalkyl or halo, or (C 2-6)alkynyl, (C 1-6)alkyl, (C 3-6)cycloalkyl, CO 2 (C 1-6)alkyl, CONR 6a R 6b, -N C (C 1-6)alkyl, -N (C 1-6)alkyl, aryl unsubstituted or substituted by (C 1-6)alkyl, halo(C 1-3)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, (C 3-6)cycloalkyl, CO 2 (C 1-6)alkyl, CONR 6a R 6b, or one to three halo, five- or six-membered heteroaryl containing one to three N, O or S heteroatoms, wherein heteroaryl is unsubstituted or substituted by one to two (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, (C 3-6)cycloalkyl or halo, or (C 2-6)alkynyl, R 4 is hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, halo(C 1-6)alkoxy, (C 1-6)alkoxy, (C 3-7)cycloalkyl, or cyano; hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, halo(C 1-6)alkoxy, (C 1-6)alkoxy, (C 3-7)cycloalkyl, or cyano; R 5 is hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, halo, amino, (C 1-3)alkyl-aryl, (C 1-3)alkyl-(C 3-6)cycloalkyl, or cyano; hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, halo, amino, (C 1-3)alkyl-aryl, (C 1-3)alkyl-(C 3-6)cycloalkyl, or cyano; each R 6a and R 6b are independently hydrogen, (C 1-3)alkyl, or (C 3-6)cycloalkyl; hydrogen, (C 1-3)alkyl, or (C 3-6)cycloalkyl; R 8a and R 8b are independently hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-C -O-(C 1-6)alkyl, (C 3-6)cycloalkyl, unsubstituted or substituted by halo, or (C 1-3)alkyl-(C 3-6)cycloalkyl; hydrogen, (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkyl-C -O-(C 1-6)alkyl, (C 3-6)cycloalkyl, unsubstituted or substituted by halo, or (C 1-3)alkyl-(C 3-6)cycloalkyl; R 9 is (C 1-3)alkyl, halo, halo(C 1-3)alkyl, (C 3-6)cycloalkyl, or -S 2 -(C 1-3)alkyl. (C 1-3)alkyl, halo, halo(C 1-3)alkyl, (C 3-6)cycloalkyl, or -S 2 -(C 1-3)alkyl.