Compound of formula I, ** Formula ** where: R 1 represents a cyclic group selected from phenyl, heteroaryl 1, heterocyclyl 1 and C 3-6 cycloalkyl； where each cyclic group is optionally substituted by 1 to 3 substituents selected from halo, C1-6 alkyl optionally substituted by 1-3 halogen atoms, phenyl, C1-6 alkoxy optionally substituted by 1-3 halogen atoms, cyano , heteroaryl1a and heterocyclyl1a； and where each cyclic group is optionally fused with a benzene ring or a 5- or 6-membered heteroaromatic or heterocyclic ring containing between 1 and 3 heteroatoms (selected from N, O and S)； and when the group is replaced, the replacement can occur anywhere in the optionally fused ring system together； and where heterocyclyl1 and heterocyclyl1a can be substituted, additionally, by>； = O； X represents a bond or C1-6 alkylene (which can be straight or branched)； R2 represents H or C1-6 alkyl； R3 represents H or C1-6 alkyl； Y represents CH (CH2CH2OH)； R4 represents a cyclic group selected from phenyl, heteroaryl4, heterocyclyl4 and C3-6 cycloalkyl； where each cyclic group is optionally substituted by 1 to 3 substituents selected from halo, C1-6 alkyl optionally substituted by 1-3 halogen atoms, phenyl, C1-6 alkyl substituted by phenyl, C1-6 alkoxy optionally substituted by 1-3 halogen, cyano, heteroaryl4a and heterocyclyl4a atoms； and where each cyclic group is optionally fused with a benzene ring or a 5- or 6-membered heteroaromatic or heterocyclic ring containing between 1 and 3 heteroatoms (selected from N, O and S)； and when the group is substituted, the substitution can occur anywhere in the optionally fused ring system together: and where heterocyclyl4 and heterocyclyl4a can, additionally, be substituted by>； = O； heteroaryl1, heteroaryl1a, heteroaryl4 and heteroaryl4a independently represent a 5- or 6-membered heteroaryl group containing between 1 and 3 heteroatoms (selected from N, O and S)； and heterocyclyl1, heterocyclyl1a, heterocyclyl4 and heterocyclyl4a in
