Aminoalkyl esters of penicillins

A compound of formula (I) or a pharmaceutically acceptable acid-addition salt thereof which contains a basic nitrogen atom:

• ##SPC13##
• wherein
• Y is alkyl of one to six carbon atoms, phenyl, benzyl, alkoxy of one to six carbon atoms, or benzyloxy;
• Z is alkyl of one to six carbon atoms, phenylbenzyl, alkoxy of one to six carbon atoms, cyclopentyl, cyclohexyl and phenyl, or Y+Z taken together are a 3-benzoxazolidine ring;
• R is phenylacetamido, 2- or 3-thienylacetamido, phenoxyacetamido, .alpha.-amino-phenylacetamido, .alpha.-amino-2- or 3-thienylacetamido, .alpha.-carboxyphenylacetamido, .alpha.-sulphophenyl-acetamido, .alpha.-azidophenylacetamido, .alpha.-guanidino-phenylacetamido, or N-tetrazolylacetamido, provided that:
• when Z is hydrogen, Y is alkoxy of one to six carbon atoms then R is not a group of formula (IV):
• ##EQU11## in which R.sub.1 is C.sub.2.sub.-7 alkyl, phenyl, or furyl.