Cephalosporin derivatives.

摘要

A cephalosporin derivative of the formula :-
in which R⁰ is a hydrogen atom or a methyl radical; R' is any one of the C-3 substituents from antibacterially-active cephalosporins known in the art; R² is any one of the C-4 substituents from antibacterially-active cephalosporins known in the art; R³ is a hydrogen atom or a 1-6C alkoxy or 1-6C alkylthio radical; X¹ is a sulphur or oxygen atom, a CH₂ radical or a radical of the formula NR⁷ in which R⁷ is a hydrogen atom, a 1-6C alkyl, formyl or benzyl radical; X² is a nitrogen atom or a radical of the formula

R⁴ and R⁷, and R⁵ and R⁶ are a variety of substituents which are described in the specification; and the pharmaceutically-acceptable acid- or base- addition salts thereof. Pharmaceutical compositions, manufacturing processes and intermediates are also described.