PROCESS FOR PREPARING NEW ALPHA-AMINO-/5,6-DIHYDRO-1,4-OXATHIIN-2-YL- AND -1,4-DITHIIN-2-YL/-ACETIC ACIDS

摘要

New oxathiino- and dithiino-aminoacetic acids of the formula: in which A represents oxygen or sulphur, together with their racemic forms, their optically active forms and mixtures thereof, their reactive derivatives and their acid addition salts, are valuable intermediates for the preparation of therapeutically active derivatives, in particular cephalosporin derivatives of the formula: where R is hydrogen or acetoxy.