METHOD OF PREPARING CEPHALEXINE OR SALTS THEREOF

摘要

The antibacterial agent cephalexin is prepared from readily available hetacillin by the consecutive steps of nitrosation or formylation to give N-nitroso- or N-formyl-hetacillin, oxidation as with NaIO4 below pH 5 to give the corresponding sulfoxide, rearrangement by heat, preferably with acid present, to give N-nitroso- or N-formylhetacephalexin and finally cleavage to give cephalexin as by zinc and acetic acid or Raney nickel and hydrogen or, preferably, hydrogen chloride in dioxane.