Patent ID: 8772293

Claim:
A compound of formula (I): or a pharmaceutically acceptable salt thereof, wherein: R 1 is a ‘C-linked’ 5- or 6-membered heteroaryl comprising one or two nitrogen atoms, wherein said heteroaryl is optionally substituted on a ring carbon atom by F or CI; or R 1 is a ‘C-linked’ 5-membered heteroaryl comprising one or two nitrogen atoms and one sulphur atom, wherein said heteroaryl is optionally substituted on a ring carbon atom by F or CI; R 2 , R 3 and R 4 are independently H, F, CI or —OCH 3 ; R 5 is CN, F, CI or R 6 ; R a is phenyl optionally substituted by one to three substituents that are independently F, CI, CN, H 2 N(C 1 -C 4 )alkylene-, (C 1 -C 4 )alkylNH(C 1 -C 4 )alkylene-, (C 3 -C 8 )cycloalkyl or R 6 ; or R a is a ‘C-linked’ 5- or 6-membered heteroaryl comprising one or two nitrogen atoms, wherein said heteroaryl is optionally substituted by R 7 or R 8 , or both R 7 and R 8 ; R b is H, F, CI, CN or R 6 ; R 6 is (C 1 -C 4 )alkyl or (C 1 -C 4 )alkyloxy, each optionally substituted by one to eight F; Z 1 is phenyl optionally substituted by one to three substituents that are independently F, CI or R 6 ; or Z 1 is a ‘C-linked’ 5- or 6-membered heteroaryl comprising one or two nitrogen atoms, wherein said heteroaryl is optionally substituted by R 7 or R 8 , or both R 7 and R 8 ; R 7 is attached to a Z 1 ring carbon and is F, CI, NR 9 R 10 , R 6 , (C 3 -C 8 )cycloalkyl or Het'; R 8 is attached to a Z 1 ring nitrogen and is (C 1 -C 4 )alkyl or (C 3 -C 8 )cycloalkyl, each optionally substituted by, one to three F; or R 8 is attached to a Z 1 ring nitrogen and is a ‘C-linked’ Het 1 ; Het 1 ‘is a 3- to 8-membered saturated monoheterocycloalkyl comprising one or two ring members selected from —N(R 11 )— and —O—, wherein said monoheterocycloalkyl is optionally substituted on a ring carbon atom by one to three substituents that are independently F, (C 1 -C 6 )alkyl, (C 1 -C 4 )alkyloxy(C o -C 4 )alkylene or (C 3 -C 8 )cycloalky; and . R 9 , R 10 and R 11 are independently H, (C 1 -C 6 )alkyl or (C 3 -C 8 )cycloalkyl; or, when Het 1 is ‘N-linked’, R 11 is absent from that nitrogen atom.