The invention provides compounds of formula I, (I) wherein: R represents a cyclic group selected from phenyl, heteroaryl, heterocyclyl and C 3-6 cycloalkyl； 10 wherein each cyclic group is optionally substituted with from 1 to 3 substituents selected from halo, C -6 alkyl optionally substituted with 1-3 halogen atoms, phenyl, C -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 16-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 and heterocyclyl 1a may additionally be substituted with ═O； 20 X represents a bond or C -6 alkylene (which may be straight or branched)； R 2 represents H or C -6 alkyl； R 3 represents H or C -6 alkyl； Y represents a bond or C -6 alkylene (which may be straight or branched, and optionally substituted with OH or CF 3)； 2 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 -6 alkyl optionally substituted with 1-3 halogen atoms, TET01063WO 4 phenyl, C -6 alkyl substituted with phenyl, C -6 alkoxy optionally substituted with -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, heteroaryl 1a, heteroaryl 4 and heteroaryl 4a independently represent a 5- or 6-m
