| 摘要 |
<p>This invention provides the compounds of the formula (II) <CHEM> and pharmaceutically acceptable salts and esters thereof, wherein A is an oxygen or sulphur atom or is a group NR5, wherein R5 is a hydrogen atom or a C1-6 alkyl, C1-6 alkanoyl, C1-6 alkoxycarbonyl, arylcarbonyl or aralkylcarbonyl group, any of such groups being optionally substituted by C1-3 alkyl, C1-3 alkoxy, hydroxy, C1-3 alkanoyloxy, or esterified or salified carboxy; or R5 is a group of the sub-formula (i): <CHEM> wherein X is a bond or a -CH2- moiety; R6 is hydrogen, fluorine, chlorine, bromine, C1-3 alkyl, C1-3 alkoxy or hydroxy; R7 is hydrogen or C1-3 alkyl, and R8 is hydrogen or C1-3 alkyl; and R3 and R4 are independently hydrogen or C1-6 alkyl; these compounds are useful as antibacterial agents and as beta -lactamase inhibitors. Their preparation and use are described.</p> |
