Zidebactam is a novel extended spectrum beta-lactamase inhibitor (ESBLI). It's combination with cefepime (WCK 5222) is in phase III clinical studies. Five process impurities were found in zidebactam (1) drug substance using process development through reverse phase high performance liquid chromatography (HPLC) method. To give access to the reference standards for the impurity profile of the drug substance as well as the final product, these process impurities of compound 1, have been synthesized and characterized. [GRAPHICS] .