The present invention provides compounds of the general formula: ##STR1## wherein Ar is a phenyl radical optionally substituted by alkyl, alkenyl, alkoxy, alkylthio, alkanoyl, hydroxyl, hydroxyalkyl, carboxyl, alkoxycarbonyl, carbamoyl, nitro, amino or halogen, A is a straight-chained or branched, saturated or unsaturated C.sub.1 -C.sub.8 aliphatic hydrocarbon radical which is optionally substituted by a hydroxyl group, n is 0, 1 or 2, B is a straight-chained or branched, saturated or unsaturated C.sub.1 -C.sub.8 -aliphatic hydrocarbon radical and R is 5-(1H)-tetrazolyl, --CO--NH-tetrazolyl, ##STR2## CN, SCN, OH, halogen, 5-(1H)-tetrazolylthio, ##STR3## or CO--O--NH--R.sub.1, wherein R.sub.1 is a hydrogen atom, an alkyl radical optionally substituted by cycloalkyl or an alkenyl, cycloalkyl, aralkyl or aryl radical, wherein the aromatic moiety can be substituted by alkyl, alkenyl, alkoxy, alkylthio, alkanoyl, hydroxyl, hydroxyalkyl, carboxyl, alkoxycarbonyl, carbamoyl, nitro, amino or halogen; and the pharmacologically acceptable salts thereof. The present invention also provides processes for preparing these compounds and pharmaceutical compositions containing them for combating allergic diseases.