Compounds of the formula (la): ** Formula ** in which: Ra represents a hydrogen atom or an alkyl radical； R1 a represents a hydrogen atom or a methyl radical； R2a represents a hydrogen atom or a fluorine atom； R3a represents a hydrogen atom or a halogen atom； R4a represents a hydrogen atom, a halogen atom or a hydroxyl, alkyl or alkoxy radical, the alkyl radicals being optionally substituted by one or more identical or different radicals selected from the halogen atoms and the hydroxyl radical, the alkoxy radicals being optionally replaced by one or more halogen atoms； R5a and R5'a, identical or different, represent a hydrogen atom or an alkyl radical； R6a represents a hydrogen atom or an alkyl radical optionally substituted by one or more identical or different radicals selected from the halogen atoms and the hydroxyl radical； R7a represents a halogen atom； said compounds of the formula (la) being in any of the possible racemic, enantiomeric and diastereoisomeric isomeric forms, as well as the addition salts with the mineral and organic acids or with the mineral and organic bases of said compounds of the formula (la) .Compuestos de la fórmula (la): **Fórmula** en la que: Ra representa un átomo de hidrógeno o un radical alquilo； R1 a representa un átomo de hidrógeno o un radical metilo； R2a representa un átomo de hidrógeno o un átomo de flúor； R3a representa un átomo de hidrógeno o un átomo de halógeno； R4a representa un átomo de hidrógeno, un átomo de halógeno o un radical hidroxilo, alquilo o alcoxi, estando los radicales alquilo eventualmente sustituidos por uno o varios radicales idénticos o diferentes seleccionados entre los átomos de halógeno y el radical hidroxilo, estando los radicales alcoxi eventualmente sustituidos por uno o varios átomos de halógeno； R5a y R5'a, idénticos o diferentes, representa un átomo de hidrógeno o un radical alquilo； R6a representa un átomo de hidrógeno o un radical alquilo eventualmente sustituido por uno o varios radicales idénti
