Verfahren zur Herstellung von 1,1-Dioxo-cephem-4-ketonen

摘要

There is provided a process for preparing a compound of formula I, endowed with antielastase activity: wherein R 1 , R 2 , R 3 , R 4 and R 5 are appropriate organic residues or hydrogen or halogen atoms. The process starts from the corresponding cephem esters and comprises the steps of acylating, oxidation and carboxylate removal.