Method of dyeing and lightening keratin materials in the presence of a reducing agent comprising a fluorescent disulphide dye

A method for dyeing human keratin fibers comprising applying to the fibers at least one fluorescent disulphide entity chosen from those of formula (V):

• wherein:
• G and G′, which are identical or different, each represent a group —NRcRd, —NR′cR′d or optionally substituted C1-C6 alkoxy;
• Rc, R′c, Rd and R′d, which are identical or different, each represent a hydrogen atom, an aryl(C1-C4)alkyl group, C1-C6 alkoxy or a C1-C6 alkyl group which is optionally substituted;
• or two adjacent radicals Rc and Rd or R′c and R′d which are carried by the same nitrogen atom together form a heterocyclic or heteroaryl group;
• Rg, R′g, R″g, R′″g, Rh, R′h, R″h and R′″h, which are identical or different, each represent a hydrogen atom, a halogen atom, an amino, C1-C4 alkylamino, C1-C4 dialkylamino, cyano, carboxyl, hydroxyl or trifluoromethyl group, an acylamino, C1-C4 alkoxy, C2-C4 (poly)hydroxyalkoxy, alkylcarbonyloxy, alkoxycarbonyl or alkylcarbonylamino radical, an acylamino, carbamoyl or alkylsulphonylamino radical, an aminosulphonyl radical, or a C1-C16 alkyl radical optionally substituted by a group selected from C1-C12 alkoxy, hydroxyl, cyano, carboxyl, amino, C1-C4 alkylamino and C1-C4 dialkylamino, or the two alkyl radicals carried by the nitrogen atom of the amino group form a heterocycle containing 5 to 7 members and optionally comprising another heteroatom which is identical to or different from that of the nitrogen atom;
• or two groups Rg and R′g;
• R″g and R′″g;
• Rh and R′h;
• or R″h and R′″h, carried by two adjacent carbon atoms, together form a benzo or indeno ring or a fused heteroaryl or fused heterocycloalkyl group, the benzo, indeno, heterocycloalkyl or heteroaryl ring being optionally substituted by a halogen atom, an amino, C1-C4 alkylamino, C1-C4 dialkylamino, nitro, cyano, carboxyl, hydroxyl or trifluoromethyl group, an acylamino, C1-C4 alkoxy, C2-C4 (poly)hydroxyalkoxy, alkylcarbonyloxy, alkoxycarbonyl, or alkylcarbonylamino radical, an acylamino, carbamoyl or alkylsulphonylamino radical, an aminosulphonyl radical, or a C1-C16 alkyl radical which is optionally substituted by a group selected from C1-C12 alkoxy, hydroxyl, cyano, carboxyl, amino, C1-C4 alkylamino and C1-C4 dialkylamino;
• or the two alkyl radicals carried by the nitrogen atom of the amino group form a heterocycle containing 5 to 7 members and optionally comprising another heteroatom identical to or different from that of the nitrogen atom;
• or, when G represents —NRcRd and G′ represents —NR′cR′d, two groups Rc and R′g;
• R′c and R″g;
• Rd and Rg;
• or R′d and R′″g together form a saturated heterocycle or heteroaryl which is optionally substituted by a C1-C6 alkyl group;
• R′i, R″i, and R′″i, which are identical or different, each represent a hydrogen atom or a C1-C4 alkyl group;
• R1, R2, R3, R4, R′1, R′2, R′3 and R′4, which are identical or different, each represent a hydrogen atom or a C1-C4 alkyl, C1-C12 alkoxy, hydroxyl, cyano, carboxyl, amino, C1-C4 alkylamino or C1-C4 dialkylamino group, it being possible for said alkyl radicals to form, with the nitrogen atom which carries them, a heterocycle containing 5 to 7 members, optionally comprising another heteroatom different or not different from nitrogen;
• Ta and Tb, which are identical or different, represent:
• i) a covalent a bond;
• ii) at least one radical selected from —SO2—, —O—, —S—, —N+(R)(Ro)—, and —CO—;
• wherein R and Ro, which are identical or different, represent a hydrogen atom or a C1-C4 alkyl or C1-C4 hydroxyalkyl radical, or an aryl(C1-C4) alkyl;
• or iii) a cationic or non-cationic heteroaryl or heterocycloalkyl radical;
• represents an aryl or heteroaryl group which is fused to the phenyl ring;
• or is absent from the phenyl ring;
• m, m′, n and n′, which are identical or different, represent an integer ranging from 0 to 6, wherein m+n and m′+n′, and which are identical or different, each represents an integer ranging from 1 to 10;
• and
• M′ represents a counterion or an organic or inorganic acid salt.