| 摘要 |
The compounds of the formula (I): <IMAGE> (I) and salts and esters thereof wherein R1 is a hydrogen atom or a lower alkyl, aryl or aralkyl group, R2 and R3 are independently hydrogen, aryl, aralkyl, lower alkyl or substituted lower alkyl, or R3 is joined to R1 to form a 5- or 6- membered ring and X is S, SO or SO2; have been found to be beta -lactamase inhibitors and antibacterial agents. Their preparation and use is described. |
