| 摘要 |
<p>Antibacterial agents have the formula (Ia) or are pharmaceutically acceptable salts or in vivo hydrolysable esters thereof: <CHEM> wherein R<1> is an acyl group, in particular that of an antibacterially active cephalosporin; R<2> is hydrogen, methoxy, or formamido; Y is S, SO, SO2, O or CH2; X is oxygen, sulphur, or -NH- and R<4> is a group of the formula CO Z R<5> wherein Z is -CH=CH-, -(CH2)n- or -NH-; n is 0, 1 or 2; and R<5> is: <CHEM> wherein R<6> and R<7> are the same or different, each representing hydroxy or protected hydroxy and R<8> is hydroxy, amino, halogen or carboxy. The use of the compounds of formula (Ia) and intermediates for their preparation are also disclosed.</p> |
