| abstract |
Compounds of formula (I) in which R1 and R2, identical or different, each represent a hydrogen or halogen atom, or an alkyl, alkoxy, alkylthio, acyl, alkoxycarbonyl, carboxy, hydroxy, hydroxyalkyl, cyano, nitro group, amino, substituted or non-substituted aminocarbonyl, aminosulfonyl, alkylsulfonylaminoalkyl, N-hydroxycarboximidamide or benzyloxy, R3 represents a hydrogen atom or an alkyl, cycloalkyl or cioalkylalkyl group, R4 represents a hydrogen atom or a substituted or non-substituted alkyl group. |