| abstract |
A compound, or a solvate or a salt thereof, of formula (I), wherein, Ar is an optionally substituted aryl or a C5-7 cycloalkdienyl group, or an optionally substituted single or fused ring aromatic heterocyclic group; R, R1, R2 and R3 are as defined in the description; a process for the preparation of such a compound, a pharmaceutical composition containing such a compound or composition in medicine. |