Compounds of the formula ##STR1## wherein R.sup.1 is hydrogen or a conventional amino-protecting group, and R.sup.2 is a straight or branched chain alkyl group containing from 1 to 4 carbon atoms, allyl, 2-butenyl or 3-butenyl, and nontoxic pharmaceutically acceptable salts and solvates thereof, as well as processes for their preparation, are disclosed. The compounds in which R.sup.1 is hydrogen are potent antibacterial agents.
                            该公式化合物的化合物中,其中R.sup.1是氢或传统的
氨基保护基团,而R.sup.2是含有1至4个碳原子的直链或支链烷基基团,烯丙基,
2-丁烯基或3-
丁烯基,以及其无毒的药用可接受盐和溶剂,以及它们的制备方法。其中R.sup.1为氢时的化合物是有效的抗菌剂。