Erythromycin compounds

A compound of the formula ##STR27## wherein R is ##STR28## or --(CH.sub.2).sub.n --Ar, n is an integer from 3 to 5, Ar is an optionally substituted heterocyclic selected from the group consisting of ##STR29## the optional substituents are at least one member selected from the group consisting of a free, salified, esterified and amidified carboxyl, hydroxyl, halogen, --NO.sub.2, --CN, alkyl, cycloalkyl, alkenyl, alkynyl, O-alkyl, O-alkenyl, O-alkynyl, S-alkyl, S-alkenyl, S-alkynyl, N-alkyl, N-alkenyl and N-alkynyl of up to 12 carbon atoms optionally substituted by one or more halogens, ##STR30## R.sub.1 and R.sub.2 are individually hydrogen or alkyl of up to 12 carbon atoms, ##STR31## R.sub.3 is alkyl of up to 12 carbon atoms, and d) an optionally substituted carbocyclic O-aryl and S-aryl and heterocyclic aryl, O-aryl and S-aryl and Z is hydrogen or an acid remainder or its non-toxic, pharmaceutically acceptable acid addition salts.