Abstract: A compound having formula (I), wherein A is selected from the group consisting of: (i) phenyl, wherein said phenyl is optionally substituted by one or more halogen atoms, C1-6alkyl, C1-3alkoxy, C1-3fluoroalkoxy, nitrile, or —NR7R8 where R7 and R8 are independently hydrogen or C1-3alkyl; (ii) a 5- or 6-membered hetrocyclic group containing at least one heteroatom selected from oxygen, nitrogen and sulfur; and (iii) a fused bicyclic ring (a), wherein ring C represents a heterocyclic group as defined in point (ii) above, which bicyclic ring is attached to group B via a ring atom of ring C; B is selected from the group consisting of: (iv) C1-6alkylene; (v) —MC1-6alkylene or C1-6alkyleneMC1-6alkylene, wherein M is O, S, or —NR2 wherein R2 represents hydrogen or C1-3alkyl; (vi) a 5- or 6-membered heterocyclic group containing at least one nitrogen heteroatom and optionally at least one further heteroatom selected from oxygen, nitrogen and sulfur and optionally substituted by C1-3alkyl; and (vii) H