Compounds of formula (I), wherein R is a hydrogen atom or a -COOH, -alk-COOH, -PO3H2, -CH2-PO3H2, or -CH=CH-COOH radical, or a phenyl radical substituted by a carboxy radical, R1 is an alk-CN, -alk-COOH, -alk-Het, alk-PO3H2 or -alk-CO-NH-SO2R2 radical, R2 is an alkyl or phenyl radical, alk is an alkyl radical, Het is a saturated or unsaturated mono- or polycyclic heterocyclic ring containing 1-9 carbon atoms and one or more heteroatoms selected from O, S and N, said heterocyclic ring optionally being substituted by one or more alkyl, phenyl or phenylalkyl radicals, with the proviso that when R is a hydrogen atom or a -COOH or -PO3H2 radical, R1 cannot be -alk-COOH, isomers, racemic mixtures, enantiomers and diastereoisomers thereof, salts thereof, the preparation thereof, intermediates thereof and drugs containing said compounds, are disclosed. The compounds of formula (I) have valuable pharmacological properties and are antagonists of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor also known as the quisqualate receptor. Furthermore, the compounds of formula (I) are non-competitive antagonists of the N-methyl-D-aspartate (NMDA) receptor, and specifically ligands for NMDA receptor glycine modulator sites.