Compounds having the general formula ##STR1## or pharmaceutically acceptable salts thereof, in which formula R.sup.1 and R.sup.2 are the same or different and each represents a hydrogen atom, a lower alkyl group or a halogen atom, R.sup.3 represents a lower alkyl group or a benzyl group, R.sup.4 represents a hydrogen atom, a lower alkyl group, a benzyl group or a CH.sub.2 CH.sub.2 CH.sub.2 --bridge connected to the phenyl ring in ortho-position relative to the N-substituent, R.sup.5 represents a hydrogen atom or a methyl group and R.sup.6 represents a lower alkyl group, provided that R.sup.1 and/or R.sup.2 represents a lower alkyl group or a halogen atom when R.sup.3 represents a methyl group, R.sup.4 represents a methyl group and R.sup.5 represents a hydrogen atom; methods for the preparation thereof; intermediates useful for their preparation; pharmaceutical preparations containing at least one of these compounds; and the use thereof in the treatment of depressive states and alleviating anxiety.