A compound of formula I, wherein: R 1 represents a cyclic group selected from phenyl, heteroaryl 1, heterocyclyl 1 and C 3-6 cycloalkyl; wherein each cyclic group is optionally substituted with from 1 to 3 substituents selected from halo, C 1-6 alkyl optionally substituted with 1-3 halogen atoms, phenyl, C 1-6 alkoxy optionally substituted with 1-3 halogen atoms, cyano, heteroaryl 1a and heterocyclyl 1a; and wherein each cyclic group is optionally fused to a benzene ring or a 5- or 6-membered heteroaromatic or heterocyclic ring each containing from 1 to 3 heteroatoms (selected from N, O and S); and when the group is substituted the substitution may occur anywhere on the optionally fused ring system as a whole; and wherein heterocyclyl 1 and heterocyclyl 1a may additionally be substituted with =O; X represents a bond or C 1-6 alkylene (which may be straight or branched); R 2 represents H or C 1-6 alkyl; R 3 represents H or C 1-6 alkyl; Y represents CH(CH 2 CH 2 OH); R 4 represents a cyclic group selected from phenyl, heteroaryl 4, heterocyclyl 4 and C 3-6 cycloalkyl; wherein each cyclic group is optionally substituted with from 1 to 3 substituents selected from halo, C 1-6 alkyl optionally substituted with 1-3 halogen atoms, phenyl, C 1-6 alkyl substituted with phenyl, C 1-6 alkoxy optionally substituted with 1-3 halogen atoms, cyano, heteroaryl 4a and heterocyclyl 4a; and wherein each cyclic group is optionally fused to benzene ring or a 5- or 6-membered heteroaromatic or heterocyclic ring each containing from 1 to 3 heteroatoms (selected from N, O and S); and when the group is substituted the substitution may occur anywhere on the optionally fused ring system as a whole; and wherein heterocyclyl 4 and heterocyclyl 4a may additionally be substituted with =O; heteroaryl 1, heteroaryl 1a, heteroaryl 4 and heteroaryl 4a independently represent a 5- or 6-membered heteroaryl group containing from 1 to 3 heteroatoms (selected from N, O and S); and heterocyclyl 1, heterocyclyl 1a, heterocyclyl 4 and heterocyclyl 4a independently represent a 5- or 6-membered heterocyclyl group containing from 1 to 3 heteroatoms (selected from N, O and S); and pharmaceutically acceptable salts and solvates thereof. R 1 represents a cyclic group selected from phenyl, heteroaryl 1, heterocyclyl 1 and C 3-6 cycloalkyl; wherein each cyclic group is optionally substituted with from 1 to 3 substituents selected from halo, C 1-6 alkyl optionally substituted with 1-3 halogen atoms, phenyl, C 1-6 alkoxy optionally substituted with 1-3 halogen atoms, cyano, heteroaryl 1a and heterocyclyl 1a; and wherein each cyclic group is optionally fused to a benzene ring or a 5- or 6-membered heteroaromatic or heterocyclic ring each containing from 1 to 3 heteroatoms (selected from N, O and S); and when the group is substituted the substitution may occur anywhere on the optionally fused ring system as a whole; and wherein heterocyclyl 1 and heterocyclyl 1a may additionally be substituted with =O; X represents a bond or C 1-6 alkylene (which may be straight or branched); R 2 represents H or C 1-6 alkyl; R 3 represents H or C 1-6 alkyl; Y represents CH(CH 2 CH 2 OH); R 4 represents a cyclic group selected from phenyl, heteroaryl 4, heterocyclyl 4 and C 3-6 cycloalkyl; wherein each cyclic group is optionally substituted with from 1 to 3 substituents selected from halo, C 1-6 alkyl optionally substituted with 1-3 halogen atoms, phenyl, C 1-6 alkyl substituted with phenyl, C 1-6 alkoxy optionally substituted with 1-3 halogen atoms, cyano, heteroaryl 4a and heterocyclyl 4a; and wherein each cyclic group is optionally fused to benzene ring or a 5- or 6-membered heteroaromatic or heterocyclic ring each containing from 1 to 3 heteroatoms (selected from N, O and S); and when the group is substituted the substitution may occur anywhere on the optionally fused ring system as a whole; and wherein heterocyclyl 4 and heterocyclyl 4a may additionally be substituted with =O; heteroaryl 1, heteroaryl 1a, heteroaryl 4 and heteroaryl 4a independently represent a 5- or 6-membered heteroaryl group containing from 1 to 3 heteroatoms (selected from N, O and S); and heterocyclyl 1, heterocyclyl 1a, heterocyclyl 4 and heterocyclyl 4a independently represent a 5- or 6-membered heterocyclyl group containing from 1 to 3 heteroatoms (selected from N, O and S); and pharmaceutically acceptable salts and solvates thereof.