A compound represented by Formula Ia or a pharmaceutically acceptable salt thereof, wherein R 1 is -X-Y; or -W-R 7 -X-Y; R 2 is H, C 1 -C 8 alkyl optionally substituted by one or more halogen atoms, C 1 -C 4 alkyl, OH, or OR'; R 2a is hydrogen; or 10 R 2 and R 2a taken together are oxo; R 3 is H, C 1 -C 4 alkoxy, OH, -NR 19 R 21, CN, halogen, C 3 -C 7 cycloalkyl or C 1 -C 4 alkyl optionally substituted by one or more halogen atoms; R 4 is H, C 1 -C 4 alkoxy, OH, -NR 19 R 21, CN, halogen, C 3 -C 7 cycloalkyl or C 1 -C 4 alkyl optionally substituted by one or more halogen atoms; R 5 is C 1 -C 8 alkyl optionally substituted by one or more halogen atoms, C 1 -C 4 alkyl, OH, OR', -NR 19 R 21, CN or C 3 -C 7 cycloalkyl; C 1 -C 8 alkoxy optionally substituted by one or more halogen atoms; C 6 -C 14 aryl; -(C 0 -C 4 alkyl)-4 to 14 membered heteroaryl, or-(C 0 -C 4 alkyl)-3 to 14 membered heterocyclyl wherein the heteroaryl and heterocyclyl contain at least one heteroatom selected from N, O and S, wherein the aryl, heteroaryl and heterocyclyl are each optionally substituted by one or more Z substituents; R 6 is C 6 -C 14 aryl; -(C 0 -C 4 alkyl)-4 to 14 membered heteroaryl, -(C 0 -C 4 alkyl)-3 to 14 membered heterocyclyl wherein the heteroaryl and heterocyclyl contain at least one heteroatom selected from N, O and S, wherein the aryl, heteroaryl and heterocyclyl are each optionally substituted by one or more Z substituents; W is C 1 -C 6 alkylene optionally substituted by hydroxy, halogens or C 1 -C 4 alkyl; X is C 1 -C 6 alkylene optionally substituted by hydroxy, halogens or C 1 -C 4 alkyl; Y is -C OH, -C OR x, tetrazolyl, carbamoyl, monoalkylcarbamoyl, dialkylcarbamoyl, or -CONH-S q -R x, wherein R x is -C 1 -C 4 alkyl; Z is independently OH, aryl, O-aryl, benzyl, O-benzyl, C 1 -C 6 alkyl optionally substituted by one or more OH groups or NH 2 groups, C 1 -C 6 alkyl optionally substituted by one or more halogen atoms, C 1 -C 6 alkoxy optionally substituted by one or more OH groups, C 1 -C 6 alkoxy optionally substituted by one or more halogen, C 1 -C 6 alkoxy optionally substituted by C 1 -C 4 alkoxy, NR 18 (SO 2)R 21, (SO 2)NR 19 R 21, (SO 2)R 21, NR 18 C R 21, C NR 19 R 21, NR 18 C NR 19 R 21, NR 18 C OR 19, NR 19 R 21, C OR 19, C R 19, SR 19, OR 19, oxo, CN, NO 2, halogen or a 3 to 14 membered heterocyclyl, wherein the heterocyclyl contains at least one heteroatom selected from N, O and S; q is 2; R' is H, C 1 -C 4 alkyl optionally substituted by one or more halogen atoms; R 7 is a divalent moiety represented by -C 6 -C 14 aryl-D-; -3 to 14 membered heterocyclyl-D-, wherein the heterocyclyl contains at least one heteroatom selected from N, O and S, wherein D is O; R 18 is independently H or C 1 -C 6 alkyl; and R 19 and R 21 are each independently H; C 1 -C 8 alkyl. R 1 is -X-Y; or -W-R 7 -X-Y; R 2 is H, C 1 -C 8 alkyl optionally substituted by one or more halogen atoms, C 1 -C 4 alkyl, OH, or OR'; R 2a is hydrogen; or 10 R 2 and R 2a taken together are oxo; R 3 is H, C 1 -C 4 alkoxy, OH, -NR 19 R 21, CN, halogen, C 3 -C 7 cycloalkyl or C 1 -C 4 alkyl optionally substituted by one or more halogen atoms; R 4 is H, C 1 -C 4 alkoxy, OH, -NR 19 R 21, CN, halogen, C 3 -C 7 cycloalkyl or C 1 -C 4 alkyl optionally substituted by one or more halogen atoms; R 5 is C 1 -C 8 alkyl optionally substituted by one or more halogen atoms, C 1 -C 4 alkyl, OH, OR', -NR 19 R 21, CN or C 3 -C 7 cycloalkyl; C 1 -C 8 alkoxy optionally substituted by one or more halogen atoms; C 6 -C 14 aryl; -(C 0 -C 4 alkyl)-4 to 14 membered heteroaryl, or-(C 0 -C 4 alkyl)-3 to 14 membered heterocyclyl wherein the heteroaryl and heterocyclyl contain at least one heteroatom selected from N, O and S, wherein the aryl, heteroaryl and heterocyclyl are each optionally substituted by one or more Z substituents; R 6 is C 6 -C 14 aryl; -(C 0 -C 4 alkyl)-4 to 14 membered heteroaryl, -(C 0 -C 4 alkyl)-3 to 14 membered heterocyclyl wherein the heteroaryl and heterocyclyl contain at least one heteroatom selected from N, O and S, wherein the aryl, heteroaryl and heterocyclyl are each optionally substituted by one or more Z substituents; W is C 1 -C 6 alkylene optionally substituted by hydroxy, halogens or C 1 -C 4 alkyl; X is C 1 -C 6 alkylene optionally substituted by hydroxy, halogens or C 1 -C 4 alkyl; Y is -C OH, -C OR x, tetrazolyl, carbamoyl, monoalkylcarbamoyl, dialkylcarbamoyl, or -CONH-S q -R x, wherein R x is -C 1 -C 4 alkyl; Z is independently OH, aryl, O-aryl, benzyl, O-benzyl, C 1 -C 6 alkyl optionally substituted by one or more OH groups or NH 2 groups, C 1 -C 6 alkyl optionally substituted by one or more halogen atoms, C 1 -C 6 alkoxy optionally substituted by one or more OH groups, C 1 -C 6 alkoxy optionally substituted by one or more halogen, C 1 -C 6 alkoxy optionally substituted by C 1 -C 4 alkoxy, NR 18 (SO 2)R 21, (SO 2)NR 19 R 21, (SO 2)R 21, NR 18 C R 21, C NR 19 R 21, NR 18 C NR 19 R 21, NR 18 C OR 19, NR 19 R 21, C OR 19, C R 19, SR 19, OR 19, oxo, CN, NO 2, halogen or a 3 to 14 membered heterocyclyl, wherein the heterocyclyl contains at least one heteroatom selected from N, O and S; q is 2; R' is H, C 1 -C 4 alkyl optionally substituted by one or more halogen atoms; R 7 is a divalent moiety represented by -C 6 -C 14 aryl-D-; -3 to 14 membered heterocyclyl-D-, wherein the heterocyclyl contains at least one heteroatom selected from N, O and S, wherein D is O; R 18 is independently H or C 1 -C 6 alkyl; and R 19 and R 21 are each independently H; C 1 -C 8 alkyl.