Compounds possessing pharmaceutical activity as substances able to lower the level of fatty substances in the blood possess the following general formula: ##STR1## wherein R represents hydrogen, halogen, hydroxy or alkyl or alkoxy containing from 1 to 4 carbon atoms;A.sup.1 and A.sup.2 which can be the same or different are hydrogen or alkyl containing from 1 to 9 carbon atoms such that A.sup.1 and A.sup.2 contain together not more than 10 carbon atoms,Y is oxygen, in which case X is benzyl, benzyloxy or benzylthio or benzyl, benzyloxy or benzylthio substituted by R and Z is amine, azacyclohydrocarbyloxy cycloalkoxy containing from 3 to 6 ring carbon atoms or tertiary aminoalkoxy or pivaloyloxyalkoxy in which the alkoxy group contains from 1 to 3 carbon atoms, or X is hydrogen and Z is pivaloyloxyalkoxy in which the alkoxy group contains from 1 to 3 carbon atoms, orY is oxygen, X is benzyl, benzyloxy or benzylthio or benzyl, benzyloxy or benzylthio substituted by R and Z is alkoxy containing from 1 to 4 carbon atoms, hydroxy or O.sup.- M.sup.+, M being a metal cation of Main Groups I, II or III of the Periodic System of the Elements or an organic base cation or ammonium ion, A.sup.1 and A.sup.2 being the same and being as aforesaid or being different with one of A.sup.1 and A.sup.2 being hydrogen or both being hydrogen and X being a para substituent with respect to Y in the benzene ring in the same general formula,Y is oxygen, X is hydrogen and Z is amine, azacyclohydrocarbyloxy or pivaloyloxyalkoxy in which the alkoxy group contains from 1 to 3 carbon atoms,Or Y is sulphur, in which case X is hydrogen, benzyl, benzyloxy or benzylthio or benzyl, benzyloxy or benzylthio substituted by R and Z is amine, azacyclohydrocarbyloxy, alkoxy containing from 1 to 4 carbon atoms, hydroxy, O.sup.- M.sup.+ wherein M is a metal cation of Main Groups I, II or III of the Periodic System of The Elements or an organic base cation or ammonium ion, cycloalkoxy containing from 3 to 6 ring carbon atoms or tertiaryaminoalkoxy, pivaloyloxyalkoxy or pyridyl-C-alkoxy in which the alkoxy group contains from 1 to 3 carbon atoms, and pharmacologically acceptable acid addition and quaternary ammonium salts of compounds containing basic groups, and optical isomers of said compounds when A.sup.1 and A.sup.2 are different.