Abstract: New esters of cephalosporins of the formula ##EQU1## wherein R.sup.1 is a substituted or unsubstituted alkyl, cycloalkyl, aryl or heterocyclic group, R.sup.2 is S--R.sup.4 wherein R.sup.4 is a methyl, ethyl, benzyl or heterocyclic group, a xanthate, dithiocarbamate, thiouronium, azido, alkoxy, hydrogen, substituted or unsubstituted alkanoyloxy, carbonyloxy or 1-pyridinium group, R.sup.3 is ##EQU2## wherein R.sup.5 is hydrogen, methyl or ethyl, X.sup.2 is O or NH, R.sup.6 is a basic group, R.sup.7 is a substituted or unsubstituted alkyl, cycloalkyl, aryl, aralkyl or heterocyclic group, X.sup.1 is O or S, Y.sup.1 is hydrogen, a hydroxy, alkyloxycarbonyl, halogen, azido, a substituted or unsubstituted amino group, a carboxyl group, the group --COOR.sup.3, or a nitrite group, n is 0 or 1 and m is 0 or 1, useful as active ingredients of pharmaceutical preparations; processes for their preparation; and methods for the treatment of infectious diseases.

Abstract: Penicillin esters of the formula ##EQU1## wherein R.sup.1 is alkyl containing from one to eight carbon atoms, phenyl, thienyl, furyl, or phenyl substituted with one or more members of the group consisting of halogen, hydroxy, and amino, R.sup.2 is selected from the group consisting of --SO.sub.3 H, tetrazolyl, --NHSO.sub.2 R.sup.4, ##EQU2## and AND WHEREIN R.sup.3 is selected from the group consisting of ##EQU3## The radicals R.sup.4 -R.sup.10, X.sup.1 and X.sub.2 are defined in the specification. The esters are well resorbed at oral administration.