Compositions for dyeing keratinous fibers comprising pyrazoloazoles; their use in dyeing as oxidation base and dyeing process; and novel pyrazoloazoles

A compound of formula (I′a) chosen from the compound of the following formula (I′a):

• in which:
• R′1 represents:
• a hydrogen atom, a linear or branched C1-C20 alkyl radical, optionally substituted by 1 or 2 radicals R chosen from a halogen atom, a nitro radical, a cyano radical, a hydroxyl radical, an alkoxy radical, an aryloxy radical, an amino radical, an alkylamino radical, an acylamino radical, a carbamoyl radical, a sulphonamido radical, a sulphamoyl radical, an imido radical, an alkylthio radical, an arylthio radical, an aryl radical, a (C1-C4)alkoxy-carbonyl radical and an acyl radical;
• an aryl radical optionally substituted by 1 or 2 radicals R as defined above:
• a 5- or 6-membered heterocycle containing at least one nitrogen, oxygen, or sulphur atom wherein said heterocycle is optionally substituted by 1 or 2 radicals R as defined above;
• when R′1 denotes a C1-C4 alkyl radical, an aryl radical or a 5- or 6-membered heterocycle, it can be connected to the carbon atom of the pyrazole via an oxygen, nitrogen, or sulphur atom;
• or R′1 can, additionally, denote a halogen atom;
• an acyl radical;
• a sulphonyl radical;
• a sulphinyl radical;
• a phosphonyl radical;
• a carbamoyl radical;
• a sulphamoyl radical;
• a cyano radical;
• a siloxy radical, an amino radical;
• an acylamino radical;
• an acyloxy radical;
• a carbamoyloxy radical;
• a sulphonamide radical;
• an imide radical;
• a ureido radical;
• a sulphamoylamino radical;
• a (C1-C4)alkoxy-carbonylamino radical;
• an aryloxycarbonylamino radical;
• a (C1-C4)alkoxy-carbonyl radical;
• an aryloxycarbonyl radical;
• a carboxyl radical;
• or a hydroxyl radical;
• R′2 is a hydrogen atom;
• a C1-C4 alkyl radical;
• a C1-C4 monohydroxyalkyl radical;
• a C2-C4 polyhydroxyalkyl radical, a C1-C4 aminoalkyl radical;
• a (CH2)p—X—(CH2)gOR′ radical in which p and q are identical or different integers ranging from 1 to 3, R′ represents a hydrogen atom or a methyl radical, and X denotes an oxygen atom or an NR″ group in which R″ represents a hydrogen atom or a methyl radical;
• a (C1-C_)alkoxy(C2-C4)alkyl radical;
• or a di(C1-C4)alkylamino(C1-C4)alkyl radical;
• R′3 has the same meanings as those indicated above for R′1.