The present invention provides a process of synthesizing 1-(((Z)-(1-(2-aminothiazol-4-yl)-2-oxo-2-(((3S,4R)-2-oxo-4-((2-oxooxazolidin-3-yl)methyl)-1-sulfoazetidin-3 yl)amino)ethylidene)amino)oxy)cyclopropanecarboxylic acid (referred to herein as Compound X), or a salt thereof, or a solvate including hydrate thereof, and/or intermediates thereof, and the use of intermediates for preparing Compound X. In particular, the process relates to the preparation of Compound X using dynamic kinetic resolution (DKR) and asymmetric catalytic reduction, thereby providing an improved route to 1-(((Z)-(1-(2-aminothiazol-4-yl)-2-oxo-2-(((3S,4R)-2-oxo-4-((2-oxooxazolidin-3-yl)methyl)-1-sulfoazetidin-3 yl)amino)ethylidene)amino)oxy)cyclopropanecarboxylic acid (Compound X) and compositions containing said compound, including the arginine salt, sodium salt and hydrated solid forms of Compound X.
