The invention concerns compounds of general formula (I) wherein: the group X represents a --NR4, --CH.dbd.N or --CHR5-NR4-group; the group Y represents an oxygen or sulphur atom or a NR, --CR5, --CHR5-, --CR5=CR6- or --CHR5-CHR6 group provided that when group X represents the --CH.dbd.N-- or --CHR5-NR4-group, group Y represents an oxygen or a sulphur atom or a Nr, --CR5 or --CHR group; the group R represents a hydrogen atom or an alkyl, aryl or aralkyl group; the groups R1, R5 and R6, identical or different, represent each a hydrogen or halogen atom or an alkyl or alkoxy group; the group R2 represents a hydrogen atom or an alkyl group; the group R3 represents an aryl group; and the group R4 represents a hydrogen atom, an alkyl, aryl, aralkyl, alkylsulphonamide, arylsulphonamide or aralkylsulphonamide group; and their salt with a pharmaceutically acceptable acid, in the form of a racemic mixture and their optically pure isomer. The invention also concerns their preparation, pharmaceutical compositions containing them and their use as CaSR activity modulator and as medicine for preferably treating diseases or physiological disorders involving the intervention of CaSR activity modulation. ##STR00001##