The compounds of the formula (II): ##STR1## or pharmaceutically acceptable salts or esters thereof wherein A is a hydrogen atom or an esterifying radical; X is an alkyl group of 1-12 carbon atoms optionally substituted by a hydroxy, amino, acylamino of C.sub.1-6 alkoxy group, which substituents are not on the carbon atom adjacent to the nitrogen atom; or a C.sub.5-7 cycloalkyl group; or a phenylalkyl group wherein the carbon atom content of the alkyl part is 1-6 and the phenyl part is optionally substituted with a fluorine, bromine, chlorine, C.sub.1-6 alkyl, or C.sub.1-6 alkoxy; with the proviso that when X represents an optionally substituted phenylalkyl group and A represents C.sub.1-3 alkyl, then the --CO.sub.2 A group is attached to the alkyl part of the phenylalkyl group; have been found to be .beta.-lactamase inhibitors and antibacterial agents. Their preparation and use is described.
化学式为(II)的化合物:##STR1## 或其药学上可接受的盐或酯,其中A是氢原子或酯化基团;X是1-12碳原子的烷基,可选择地被氢氧基,
氨基,C.sub.1-6酰胺基或C.sub.1-6烷氧基取代,这些取代基不在与氮原子相邻的碳原子上;或是C.sub.5-7环烷基;或是苯基烷基,其中烷基部分的碳原子含量为1-6,苯基部分可选择地被
氟,
溴,
氯,C.sub.1-6烷基或C.sub.1-6烷氧基取代;但是当X代表可选择地被取代的苯基烷基且A代表C.sub.1-3烷基时,--CO.sub.2 A基团附着在苯基烷基的烷基部分上;这些化合物被发现是β-内酰胺酶抑制剂和抗菌剂。它们的制备和使用被描述。