Compounds of the formula: ##STR1## in which - R.sub.1 denotes a polyfluoroalkoxy or polyfluoroalkyl radical, and - R.sub.2 denoteseither a chain --CH.sub.2 --(CH(R.sub.4)).sub.n --R.sub.3, in which R.sub.3 denotes a dialkylamino, piperidino, 1-pyrrolidinyl, mercapto, acylthio, alkylthio, alkylsulphinyl or alkylsulphonyl radical, R.sub.4 denotes a hydrogen atom or an alkyl radical and n is equal to 0 or 1,or a residue of formula: ##STR2## the said alkyl and alkoxy radicals and portions containing 1 to 4 carbon atoms each in a straight or branched chain and said the acyl portions containing 2 to 4 carbon atoms each, and the salts of these compounds, are useful in the treatment of diseases in which glutamate is implicated.