Abstract: Compounds of formula in which R1 represents H, an alkyl or a substituted alkyl, R2 represents H or alkyl and R3 represents an optionally substituted cycloalkyl or an optionally substituted aromatic group, which can be a phenyl or a heterocyclic group comprising one or more hetero-atoms chosen from O, S and N, or R2 and R3 considered together represent the group which is optionally substituted on the phenyl ring, and Z represents a heterocycle comprising one or more heteroatoms chosen from O, S and N, fused with an aromatic ring which can comprise a hetero-atom and can be substituted, the said heterocycle being optionally substituted on N, when it comprises such an atom, by an alkyl or a substituted alkyl group, and the salts of these compounds with acids or bases. Use of these compounds as medicaments. No figure.