PROCEDIMIENTO PARA LA PREPARACION DE DERIVADOS DE CEFALOSPORINAS

LA PRESENTE INVENCION SE REFIERE A NUEVOS DERIVADOS DE CEFALOSPOLINAS DE FORMULA DESCRITA EN LA INVENCION. SE REFIERE IGUALMENTE A UN PROCEDIMIENTO PARA SU PREPARACION Y COMPOSICIONES FARMACEUTICAS QUE LOS CONTIENEN E INTERMEDIARIOS DE SINTESIS. DICHOS DERIVADOS PRESENTAN PROPIEDADES FARMACEUTICAS MEJORADAS. New cephalosporin derivatives of formula: in which: - each of R1, R2 and R3 denotes a hydrogen atom or each of R1 and R2 denotes a hydrogen atom or a methyl group and R3 denotes a carboxyl group, or R1 and R2 taken together with the carbon atom to which they are linked form a cyclobutyl nucleus and R3 denotes a carboxyl group, - the 2 groups A are different: one denotes a hydroxyl group and the other denotes a -NH-SO2-Alk-NH2 group in which Alk denotes a C2-C4 lower alkylene group, and the pharmaceutically acceptable salts and esters of the said derivatives. The invention also relates to a process for their preparation, pharmaceutical compositions containing them and synthesis intermediates. The said derivatives exhibit improved pharmacokinetic properties.