Aromatic esters and thioesters of the formula ##STR1## are useful in human and veterinary medicine and in cosmetic formulations. In the formula, X represents oxygen or sulfur, r' and 4" represent hydrogen, lower alkyl, monohydroxyalkyl, polyhydroxyalkyl, aryl or benzyl optionally substituted, the residue of an amino acid or aminated sugar, or taken together form a heterocycle, R.sub.2 represents .alpha., .alpha.'- dissubstituted alkyl having 4-12 carbon atoms or mono- or polycyclic cycloalkyl having 5-12 carbon atoms whose carbon linking carbon is trisubstituted and R.sub.3 and R.sub.4 represent hydrogen or lower alkyl.