Abstract: The present invention is directed to a new process of preparing highly pure Florfenicol. The invention is further directed to new oxazolidine derivatives useful in making Florfenicol and processes of making these derivatives. Examples of such intermediates include (4R,5R)-3-acetyl-2,2-dimethyl-4-hydroxymethyl-5-[4-(methylsulfonyl)phenyl]-1,3-oxazolidine; and (4S,5R)-3-acetyl-2,2-dimethyl-4-fluoromethyl-5-[4-(methylsulfonyl)phenyl]-1,3-oxazolidine.

Abstract: A novel process is disclosed for the preparation of Cefepime, a cephalosporin antibiotic, using novel new intermediates of the general Formula, where X represents Bromine or Chlorine atom This process comprises the step of cyclizing the bromo or chloro intermediate with thiourea to produce Cefepime of high purity. A process to prepare bromo or chloro intermediate comprising the acylation of 7-Amino-3-[(1-methyl-1-pyrrolidinium) methyl]-3-cephem-4-carboxylate with 4-halo-2-methoxyimino-3-oxobutyric acid halide is also described.