| 摘要 |
A cephalosporin derivative of the formula I: <IMAGE> I in which X is S, O, CH2 or SO, R1 is (optionally-substituted)imidazol-2-yl or one of the C-7 acyl groups known in the cephalosporin art, R2 is hydrogen or methoxy, R3 is carboxy or a biodegradable ester thereof and -R4 is of the formula XII, XIII or XIV: <IMAGE> +TR <IMAGE> in which R32-R40 inclusive are as defined in the specification; and the salts thereof. Pharmaceutical compositions, methods of manufacture and intermediates are also described. |
