The compounds of the formulaes (IV), (V) and (VI): ##STR1## and salts and esters thereof where X is a bromine or chlorine atom, and n is 0 or 1; are antibacterial agents. Their preparation and use is described.
                            化学式为(IV)、(V)和(VI)的化合物:##STR1## 以及它们的盐和酯,其中X是
溴或
氯原子,n为0或1; 是抗菌剂。它们的制备和使用被描述。