| abstract |
The present invention provides a compound of the formula: <IMAGE> (I) or a pharmaceutically acceptable salt or in vivo hydrolysable ester thereof wherein: A is a group of the formula (IA) or (IB): <IMAGE> (IA) <IMAGE> (IB) R1 is 1-hydroxyethyl, 1-fluoroethyl or hydroxymethyl; R2 is hydrogen or C1-4alkyl; R3 and R4 are the same or different and are a variety of substituents X is alkanediyl containing 1-6 carbon atoms optionally interrupted by O, S(O)x (wherein x is zero, one or two), -CONR5- or -NR5- or wherein R5 is hydrogen or C1-4alkyl; or X is alkenediyl containing 1-6 carbon atoms optionally interrupted by O, S(O)x or -NR5-. |