| 摘要 |
A compound of formula (I) or a pharmaceutically acceptable salt or in vivo hydrolysable ester thereof: <IMAGE> (I) wherein R is phenyl, 4-hydroxy phenyl, or a 5- or 6-membered heterocyclic ring containing up to three heteroatoms selected from oxygen, sulphur or nitrogen, optionally substituted with hydroxy, amino, halogen or C1-6 alkoxy; R1 represents hydrogen or C1-6 alkyl; R2 and R3 are the same or different and represent hydrogen, C1-6 alkyl, halogen, amino, hydroxy, or C1-6 alkoxy. Their preparation and use is described.
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