| 摘要 |
A compound of formula (I) or a salt thereof: <IMAGE> (I) wherein R1 is an amino group, an azido group, or an acylamino group as found in antibacterially active penicillins or cephalosporins; R2 is a hydrogen atom or a C1-4 alkyl group; R3 is a hydrogen atom, or a C1-4 alkyl group optionally substituted by a carboxyl, carboxylic ester, hydroxy, C1-4 alkyloxy, acyloxy or heterocyclylthio group; and R4 is hydrogen or a readily removable carboxyl protecting group. The compounds wherein R1 is an acylamino group are found in known antibacterially active penicillins and cephalosporins and wherein R4 is a hydrogen, a pharmaceutically acceptable salting ion or an in vivo hydrolyzable ester forming radical may be formulated in pharmaceutical compositions. Processes for the preparation of the compound (I) are also described. |
