The present invention relates to pharmaceutical compositions containing, as active ingredient, a compound of formula: ##STR00001## in which R.sub.1 represents a radical --NHCOR.sub.4 or --N(R.sub.5)--Y--R.sub.6, Y is CO or SO.sub.2, R.sub.4 represents a radical -alk-SO.sub.2--R.sub.11, -alk-SO.sub.2--CH.dbd.CH--R.sub.11 or Het substituted with --SO.sub.2--R.sub.11 or a phenyl radical substituted with --SO.sub.2--R.sub.11 or -alk-SO.sub.2--R.sub.11, R.sub.5 represents a hydrogen atom or an alkyl radical, R.sub.6 represents a phenylalkyl, Het or Ar radical, to the novel derivatives of formula (I) and to their preparation, as well s to their use in treating various disorders of the nervous system.