A compound of formula I: wherein: A 2 is selected from: (i) where R 5 is selected from H, Br, F, methyl, OMe, carboxy, C 1-4 alkyl ester, carboxamide, C 5-7 N-containing heteroaryl group, which is optionally substituted by a C 1-4 alkyl group; (ii) where one of X 1 and X 2 is N, and the other is CH; (iii) a C 5 heteroarylene group, containing 2 or 3 ring heteroatoms, where the bonds to L1 and the core are β to one another; L 1 is selected from: (i) A1 -O-CH 2 - A2; (ii) A1 -CH 2 -O- A2; (iii) A1 -C(=O)-NH- A2; (iv) A1 -CH - A2; (v) A1 -CH 2 -NH-C(=O)- A2; (vi) A1 -S-CH 2 - A2; (vii) A1 -CH 2 -S- A2; (viii) A1 -CH 2 - A2; and (ix) A1 -CH(CH 3)-O- A2; A 1 is phenyl, optionally substituted by F or CF 3; (a) one of R 1, R 2 and R 3 is L 2 -A 3, where L 2 is selected from the group consisting of: a single bond, CH 2, O, NH, NMe, NH-CH 2, and NMe-CH 2; and A 3 is selected from: (i) a C 5-10 N-containing heterocyclic group, which is optionally substituted by one or two groups selected from OH, NH 2, CH 2 N(R 6) 2, C 1-4 alkyl, C 1-4 alkylacyl, C 1-4 alkyl ester, oxo and C 1-4 alkyl sulfonyl, where each R 6 is independently selected from H, C 1-4 alkyl, C 1-4 alkylacyl and C 1-4 alkyl ester; (ii) a C 5-7 N-containing heteroaryl group, which is optionally substituted by a C 1-4 alkyl group; (iii) a C 5-7 non-N-containing heterocyclic group; (b) another of R 1, R 2 and R 3 is selected from: (i) H; (ii) Halo; (iii) NH 2; (iv) NMe 2; (iv) Me; (v) OMe; (vi) OCF 3; (vii) CF 3; (viii) CN; (c) the other one of R 1, R 2 and R 3 is H. A 2 is selected from: (i) where R 5 is selected from H, Br, F, methyl, OMe, carboxy, C 1-4 alkyl ester, carboxamide, C 5-7 N-containing heteroaryl group, which is optionally substituted by a C 1-4 alkyl group; (ii) where one of X 1 and X 2 is N, and the other is CH; (iii) a C 5 heteroarylene group, containing 2 or 3 ring heteroatoms, where the bonds to L1 and the core are β to one another; (i) where R 5 is selected from H, Br, F, methyl, OMe, carboxy, C 1-4 alkyl ester, carboxamide, C 5-7 N-containing heteroaryl group, which is optionally substituted by a C 1-4 alkyl group; (ii) where one of X 1 and X 2 is N, and the other is CH; (iii) a C 5 heteroarylene group, containing 2 or 3 ring heteroatoms, where the bonds to L1 and the core are β to one another; L 1 is selected from: (i) A1 -O-CH 2 - A2; (ii) A1 -CH 2 -O- A2; (iii) A1 -C(=O)-NH- A2; (iv) A1 -CH - A2; (v) A1 -CH 2 -NH-C(=O)- A2; (vi) A1 -S-CH 2 - A2; (vii) A1 -CH 2 -S- A2; (viii) A1 -CH 2 - A2; and (ix) A1 -CH(CH 3)-O- A2; (i) A1 -O-CH 2 - A2; (ii) A1 -CH 2 -O- A2; (iii) A1 -C(=O)-NH- A2; (iv) A1 -CH - A2; (v) A1 -CH 2 -NH-C(=O)- A2; (vi) A1 -S-CH 2 - A2; (vii) A1 -CH 2 -S- A2; (viii) A1 -CH 2 - A2; and (ix) A1 -CH(CH 3)-O- A2; A 1 is phenyl, optionally substituted by F or CF 3; (a) one of R 1, R 2 and R 3 is L 2 -A 3, where L 2 is selected from the group consisting of: a single bond, CH 2, O, NH, NMe, NH-CH 2, and NMe-CH 2; and A 3 is selected from: (i) a C 5-10 N-containing heterocyclic group, which is optionally substituted by one or two groups selected from OH, NH 2, CH 2 N(R 6) 2, C 1-4 alkyl, C 1-4 alkylacyl, C 1-4 alkyl ester, oxo and C 1-4 alkyl sulfonyl, where each R 6 is independently selected from H, C 1-4 alkyl, C 1-4 alkylacyl and C 1-4 alkyl ester; (ii) a C 5-7 N-containing heteroaryl group, which is optionally substituted by a C 1-4 alkyl group; (iii) a C 5-7 non-N-containing heterocyclic group; (b) another of R 1, R 2 and R 3 is selected from: (i) H; (ii) Halo; (iii) NH 2; (iv) NMe 2; (iv) Me; (v) OMe; (vi) OCF 3; (vii) CF 3; (viii) CN; (c) the other one of R 1, R 2 and R 3 is H. (a) one of R 1, R 2 and R 3 is L 2 -A 3, where L 2 is selected from the group consisting of: a single bond, CH 2, O, NH, NMe, NH-CH 2, and NMe-CH 2; and A 3 is selected from: (i) a C 5-10 N-containing heterocyclic group, which is optionally substituted by one or two groups selected from OH, NH 2, CH 2 N(R 6) 2, C 1-4 alkyl, C 1-4 alkylacyl, C 1-4 alkyl ester, oxo and C 1-4 alkyl sulfonyl, where each R 6 is independently selected from H, C 1-4 alkyl, C 1-4 alkylacyl and C 1-4 alkyl ester; (ii) a C 5-7 N-containing heteroaryl group, which is optionally substituted by a C 1-4 alkyl group; (iii) a C 5-7 non-N-containing heterocyclic group; (i) a C 5-10 N-containing heterocyclic group, which is optionally substituted by one or two groups selected from OH, NH 2, CH 2 N(R 6) 2, C 1-4 alkyl, C 1-4 alkylacyl, C 1-4 alkyl ester, oxo and C 1-4 alkyl sulfonyl, where each R 6 is independently selected from H, C 1-4 alkyl, C 1-4 alkylacyl and C 1-4 alkyl ester; (ii) a C 5-7 N-containing heteroaryl group, which is optionally substituted by a C 1-4 alkyl group; (iii) a C 5-7 non-N-containing heterocyclic group; (b) another of R 1, R 2 and R 3 is selected from: (i) H; (ii) Halo; (iii) NH 2; (iv) NMe 2; (iv) Me; (v) OMe; (vi) OCF 3; (vii) CF 3; (viii) CN; (i) H; (ii) Halo; (iii) NH 2; (iv) NMe 2; (iv) Me; (v) OMe; (vi) OCF 3; (vii) CF 3; (viii) CN; (c) the other one of R 1, R 2 and R 3 is H.