Studies on orally active cephalosporin esters

The synthesis and the biological properties of orally active cephalosporin esters are described. 3-Methoxymethyl cephem derivatives having a 2-(2-aminothiazol-4-yl)-(Z)-2-methoxyiminoacetamide function at C-7 (1) showed good activity against a wide variety of bacteria including some beta-lactamase producing species. The prodrug type esters of 1 exhibited a good urinary recovery after oral administration to mice and 1-(isopropoxycarbonyloxy)ethyl ester (2a, CS-807) has been pre-clinically tested as an orally active cephem prodrug.