Compounds of formula I and a method for their preparation are described: where R1, R2 and R3 are the same or different and signify hydrogens, halogens, alkyl, nitro, amino, alkylcarbonylamino, alkylamino or dialkylamino group； R4 signifies -alkyl-aryl or -alkyl-heteroaryl； X signifies CH2, oxygen atom or sulphur atom； n is 2 or 3； including the individual (R)- and (S)-enantiomers or mixtures of enantiomers thereof； and including pharmaceutically acceptable salts and esters thereof. The compounds have potentially valuable pharmaceutical properties for the treatment of cardiovascular disorders such as hypertension and chronic heart failure.
