Abstract: A compound of formula (II): ##STR1## in which R is a hydrogen atom or a carboxy, alkoxycarbonyl, --CO--NR.sub.4 R.sub.5, --PO.sub.3 H.sub.2 or --CH.sub.2 OH radical, and R.sub.1 is an -alk-NH.sub.2, -alk-NH--CO--R.sub.3, -alk-COOR.sub.4, -alk-CO--NR.sub.5 R.sub.6 or --CO--NH--R.sub.7 radical. The compounds of formula (II) can be used to prepare compounds of formula (I): ##STR2## in which R and R.sub.1 have the same meanings as above. The compounds of formula (I) have valuable pharmacological properties and are antagonists of the .alpha.-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor, also known as the quisqualate receptor. The compounds of formula (I) are also non-competitive antagonists of the N-methyl-D-aspartate (NMDA) receptor and more specifically are ligands for NMDA receptor glycine modulator sites.