Compounds of the formula (Ia): ** Formula ** in which: R 1a represents a linear or branched alkyl, alkenyl or alkynyl radical, a cycloalkyl radical or a heterocycloalkyl radical, containing from 1 to 7 carbon atoms, being all these radicals optionally substituted by one or several identical or different radicals chosen between the halogen atoms and the radicals R7a, -S (O) xa-R7a with xa representing the integer 0, 1 or 2, -SO2NR5aR7a, -CN, -OR5a, -NR5aR6a, -NR5a- COR7a, - NR5a-CO2-R7a, -NR5a-SO2-R7a, -NHCONR5aR6a, -COR7a, -CO2R5a and -CONR5aR6a； R2a represents a hydrogen atom, an alkyl radical containing from 1 to 10 carbon atoms or a cycloalkyl radical containing from 3 to 10 carbon atoms； R3a represents an alkyl radical containing from 1 to 10 carbon atoms, a cycloalkyl radical containing from 3 to 10 carbon or phenyl atoms optionally substituted with one or several identical or different radicals, chosen between the halogen atoms and the radicals - OR5a and -NR5aR6a； R2a and R3a can optionally form with the carbon atom to which a cyclic radical chosen from a carbocyclic radical and a heterocyclic radical is attached, and which contains 3 to 10 links and optionally one or more heteroatoms more chosen from O, S and -NR5a, this cyclic radical being optionally substituted with one or more identical or different radicals chosen from the halogen atoms, the radicals oxo, R5a, -OR5a and -NR5aR6a； R4a represents a hydrogen atom, an alkyl radical containing from 1 to 10 carbon atoms, a halogen atom or a -CN radical； with R5a and R6a identical or different representing a hydrogen atom or an alkyl radical containing from 1 to 10 carbon atoms, cycloalkyl containing from 3 to 10 carbon atoms or heterocycloalkyl where the heterocycloalkyl radical designates a monocyclic or bicyclic carbocyclic radical , which contains 3 to 10 links, interrupted by one or several heteroatoms, identical or different, chosen from the oxygen, nitrogen or sulfur atoms； and R7a, identical or differe
