FR2912141A1 - Fluorescent dyes for lightening dark hair, comprise new pyridinium salts substituted with a chain containing a vinyl group, a benzene ring, a nitrogen heterocycle, various linking groups and a terminal thiol group - Google Patents

Abstract

Fluorescent dyes in the form of pyridinium salts substituted with an organic group comprising an olefinic double bond, a benzene ring, a nitrogen heterocycle, various linking groups and a terminal thiol group are new. Fluorescent dyes of formula (I) are new (and their salts, optical isomers, geometrical isomers or solvates such as hydrates). R aaryl-(1-4C alkyl) or 1-6C alkyl (optionally substituted with OH or amino), 1-4C alkylamino or dialkylamino (optionally with the two alkyl groups and the linking nitrogen forming a 5- to 7-membered ring which may also conatin another hetero-atom); R g, R' g, R h, R' hH, halogen, amino, 1-4C alkylamino, dialkylamino, alkoxy, alkylcarbonyloxy, alkoxycarbonyl, alkylcarbonylamino or alkylsulfonylamino, CN, COOH, OH, trifluoromethyl, acylamino, 2-4C (poly)hydroxyalkoxy, carbamoyl, aminosulfonyl or 1-4C alkyl (optionally substituted with 1-4C alkoxy, OH, CN, COOH, amino, 1-4C alkylamino or 1-4C dialkylamino (in which the two alkyl groups and the linking nitrogen may form a 5- to 7-membered ring which may also contain another hetero-atom)), or two groups R gand R' gand/or R hand R h 91>on two adjacent carbons may form a benzene, indene, fused heterocycloalkyl or fused heteroaryl ring (all optionally substituted with halogen, amino, 1-4C alkylamino etc. (as for R g); R i, R' iH or 1-4C alkyl; R 1-R 4H, 1-4C alkyl, 1-4C alkoxy, OH, CN, COOH, amino or 1-4C (di)alkylamino (optionally with the two alkyl groups forming a ring as above); T : a single covalent bond, or one or more of the following groups or their combinations: -SO 2-, -O-, -S-, -NR-, -NRR 0>- and/or -CO-, or a heterocycloalkyl or heteroaryl group (cationic or not); R, R 0>H, 1-4C alkyl, 1-4C hydroxyalkyl or aryl-(1-4C alkyl); -N(Het)- : an optionally substituted heterocyclic group (cationic or not); m, n : 0-6; (m+n) : 1-10; M : an anion; Y : H, alkali or alkaline earth metal, optionally substituted ammonium or phosphonium, or a protective group for thiol functions. If (I) contains other cationic parts, these will be associated with one or more anions so as to achieve electrical neutrality. Independent claims are also included for (1) coloring compositions containing (I) in a cosmetically-acceptable medium (2) coloring compositions containing (I) and reducing agent(s) in a cosmetically-acceptable medium (3) a method for coloring keratin fibres by treatment with compositions containing (I), possibly in presence of reducing agent capable of reducing disulfide bonds in keratinous materials (4) a multi-compartment device in which one compartment contains a composition containing (I) and a second compartment contains a reducing agent as above. [Image].

Description

DYE COMPOSITION COMPRISING A THIOL A FLUORESCENT COLORANT

  The invention relates to the dyeing of keratin materials using thiol fluorescent dyes comprising a heterocycloalkyl group. BACKGROUND OF THE INVENTION The invention relates to the dyeing of keratin materials using fluorescent thiol dyes comprising a heterocycloalkyl group.

  It is known to dye keratin fibers, especially human fibers, by direct dyeing. The method conventionally used in direct dyeing consists in applying to the keratin fibers direct dyes which are colored and dyeing molecules having an affinity for the fibers, allowing them to diffuse and then rinsing the fibers. The direct dyes which are conventionally used are, for example, dyes of the nitrobenzene type, anthraquinone dyes, nitropyridines, dyes of the azo, xanthene, acridine, azine or triarylmethane type. The colorations which result from the use of direct dyes are temporary or semi-permanent dyes because the nature of the interactions which bind the direct dyes to the keratinous fiber, and their desorption from the surface and / or the core of the fiber are responsible for their low dyeing power and their poor resistance to washes or perspiration. Furthermore, the coloration of keratinous fibers from conventional direct dyes does not make it possible to significantly lighten the keratin fibers. The lightening of the color of keratinous fibers, more particularly dark to lighter shades, possibly modifying the shade thereof, constitutes an important demand. Conventionally, to obtain a lighter coloration is implemented a chemical bleaching process. This process consists of treating keratin materials such as keratin fibers, in particular the hair, with a strong oxidizing system, generally consisting of hydrogen peroxide, whether or not associated with persalts, most often in an alkaline medium. This bleaching system has the drawback of degrading keratin materials, in particular keratinous fibers, especially human fibers such as the hair, and of altering their cosmetic properties. The fibers tend to become rough, more difficult to disentangle and more fragile. Finally, the lightening or the bleaching of keratinous fibers by oxidizing agents is incompatible with the treatments for modifying the shape of said fibers, particularly in the straightening treatments. Another lightening technique consists in applying fluorescent direct dyes to dark hair. This technique described in particular in the documents FR 2830189 (OA 01340) and WO 2004/091473 (OA 03107) makes it possible to respect the quality of the keratinous fiber during the treatment, but the fluorescent dyes employed do not exhibit satisfactory shampoo resistance.

  To increase the tenacity of the direct dyes, it is known to fix direct dyes by covalent bonding to the hair. For example, it is known to react dyes with reactive groups with the residues of cystine or cysteine very numerous in keratin fibers, see for example Journal of the Society of Dyers and Colourists, Guise and Stapleton, 91, 259-264 ( 1975); Journal of Cosmetic Chemistry, 42, 1-17 (1991); CA 2024509; In addition it is known to protect the thiol function (s) contained in a molecule to be grafted to the hair before applying them to said hair WO99 / 51194. However, this application does not mention the use of fluorescent dyes for coloring or lightening hair.

  The object of the present invention is to provide novel systems for dyeing keratin materials, in particular human keratinous fibers, in particular the hair, which do not have the drawbacks of existing bleaching processes. In particular, one of the aims of the present invention is to provide direct dyeing systems which make it possible to obtain lightening effects, in particular on naturally or artificially dark keratin fibers, which are stubborn in the face of successive shampoos, which do not degrade keratin fibers and which do not alter their cosmetic properties.

  This object is achieved with the present invention which relates to a process for dyeing keratin materials, in particular keratinous fibers, in particular human fibers such as the hair, more particularly the dark hair, consisting in applying to the keratin materials a dye composition. comprising, in a suitable cosmetic medium, at least one heterocyclic thiol fluorescent dye chosen from the following dyes of formula (I): their organic or inorganic acid salts, optical isomers, geometric isomers, and solvates such as hydrates ; formula (I) in which: - Ra represents an aryl (C 1 -C 4) alkyl group or a (C 1 -C 6) alkyl group optionally substituted with a hydroxyl or amino (C 1 -C 4) alkylamino (C 1 -C 4) group; dialkylamino, said alkyl radicals being able to form with the nitrogen atom which carries them a 5- to 7-membered heterocyl, optionally comprising another heteroatom different or different from nitrogen; preferably Ra represents a (C 1 -C 3) alkyl group optionally substituted by a hydroxyl group such as methyl or ethyl, or a benzyl group; -Rg, R'g, Rh and R'h, identical or different, represent a hydrogen atom, a halogen atom, an amino group, (C1-C4) alkylamino, (C1-C4) dialkylamino, cyano, carboxy, hydroxy, trifluoromethyl, acylamino, C 1 -C 4 alkoxy, (C 2 -C 4) polycarboxylic hydroxyalkoxy, alkylcarbonyloxyalkoxycarbonyl, alkylcarbonylamino, acylamino, carbamoyl, alkylsulfonylamino, amino-sulfonyl, or (C 1 -C 4) radicals. C4) alkyl optionally substituted with a group chosen from (C1-C4) alkoxy, hydroxy, cyano, carboxy, amino, (C1-C4) alkylamino and (C1-C4) dialkylamino, or else the two alkyl radicals borne by the atom nitrogen of the amino group form a heterocycle comprising from 5 to 7 members and optionally comprising another heteroatom identical to or different from that of the nitrogen atom; particularly Rg, R'g, Rh and R'h represent a hydrogen atom; or two groups Rg and R'g; Rh and R'h carried by two adjacent carbon atoms together form a benzo, indeno ring, a fused heterocycloalkyl or fused heteroaryl group; the benzo, indeno, heterocycloalkyl or heteroaryl ring being optionally substituted by a halogen atom, an amino group, (C1-C4) alkylamino, (C1-C4) dialkylamino, cyano, carboxy, hydroxy, trifluoromethyl, an acylamino, alkoxy radical; C1-C4, (poly) hydroxyalkoxy C2-C4, alkylcarbonyloxy alkoxycarbonyl, alkylcarbonylamino, an acylamino, carbamoyl, alkylsulfonylamino radical, an amino-sulphonyl radical, or a (C1-C4) alkyl radical optionally substituted with: a group chosen from (C1-C4) alkoxy, hydroxy, cyano, carboxy, amino, (C1-C4) alkylamino, (C1-C4) dialkylamino, or the two alkyl radicals carried by the nitrogen atom of the amino group form a heterocycle comprising 5- to 7-membered ring and optionally comprising another heteroatom identical to or different from that of the nitrogen atom; especially Rg and R'g together form a benzo group; - R; and R ', which may be identical or different, represent a hydrogen atom or a (C 1 -C 4) alkyl group; particularly R; and R '; represent a hydrogen atom; - R ,, R2, R3, R4, identical or different, represent a hydrogen atom or a group (C1-C4) alkyl, (C1-C4) alkoxy, hydroxy, cyano, carboxy, amino, (C1-C4) alkylamino, (C1-C4) dialkylamino, said alkyl radicals being capable of forming, with the nitrogen atom which bears them, a 5- to 7-membered heterocyl, optionally comprising another heteroatom which may or may not be different from nitrogen; in particular R 1, R 2, R 3 and R 4 are hydrogen atoms or an amino group; especially R 1, R 2, R 3 and R 4 represent a hydrogen atom; Ta is: i) either a covalent bond a, ii) or one or more radicals or combinations thereof selected from -SO2-, -O2, -O2-, or -N (R) -N + (R) (R) u, -C ( Wherein R and R, which may be identical or different, represent a hydrogen atom, a C1-C4 alkyl, C1-C4 hydroxyalkyl or a (C1-C4) alkyl radical; in particular, Ta represents a covalent link a or a group chosen from N (R) -, C (O) u, C (O) uN (R) u, uN (R) uC (O) u, uC (O) uN (R) ûC (O) û, ûOûC (O) û, ûC (O) ûOû and ûN + (R) (R) û, with R, R being identical or different, representing a hydrogen atom, a C1-C4 alkyl group ; especially Ta represent a bond a; iii) a heterocycloalkyl or heteroaryl radical, cationic or non-cationic, preferably monocyclic, containing one or two heteroatoms, particularly two nitrogen atoms, and especially comprising from 5 to 7 members such as imidazolium, piperazinyl, piperazinium, homopiperazinyl, homopiperazinium; optionally substituted with a (C1-C4) alkyl group such as methyl; Het - N represents a cationic or non-cationic heterocyclic group, optionally substituted; in particular the heterocycle is monocyclic, saturated, and comprises in total one to two nitrogen atoms and 5 to 8 members; m and n, identical or different, represent an integer inclusive between 0 and 6 with m + n represents an integer inclusive between 1 and 10; particularly the sum m + n is an integer inclusive between 2 and 4; preferentially m + n is an integer equal to 2; M 'representing an anionic counterion; and Y represents: i) a hydrogen atom; ii) an alkali metal; iii) an alkaline earth metal; iv) an ammonium group: N + RaRaRYR8 or a phosphonium group: P + RaRaRYR8 with Ra, Ra, R7 and R8, identical or different, representing a hydrogen atom or a (C 1 -C 4) alkyl group; or v) a thiol protecting group;

  it being understood that: - when the compound of formula (I) contains other cationic parts, it is associated with one or more anionic counter-ions making it possible to reach the electroneutrality of formula (I).

  Another subject of the invention is a dye composition comprising, in a suitable cosmetic medium, at least one thiol fluorescent dye comprising a heterocyclic group of formula (I) as defined above, and optionally a reducing agent.

  The invention also relates to new thiol fluorescent dyes of formula (I) as defined above.

  The dyeing process according to the invention makes it possible to visibly stain dark keratin materials, in particular dark human keratin fibers, especially dark hair.

  In addition, the process of the invention makes it possible to obtain a coloration of the keratin materials, in particular human keratinous fibers, in particular the hair, without degrading said material, which is persistent with regard to shampoos, of the current aggressions (sun, perspiration). ), and other hair treatments. The process of the invention also makes it possible to obtain a lightening of keratin materials such as keratinous fibers, particularly dark keratinous fibers and more particularly dark hair.

  For the purposes of the invention, dark keratin material is understood to mean that which has an L * luminescence in the C.I.E. L * a * b *, less than or equal to 45 and preferably less than or equal to 40, knowing moreover that L * = 0 is equivalent to black and L * = 100 to white. For the purposes of the invention, the term naturally or artificially dark hair, hair whose pitch is less than or equal to 6 (dark blonde) and preferably less than or equal to 4 (chestnut). The lightening of the hair is evaluated by the variation in pitch before and after application of the compound of formula (I). The notion of tone is based on the classification of natural nuances, a tone separating each nuance from that which follows it or immediately precedes it. This definition and the classification of natural shades is well known to hair professionals and published in the book Science of hair treatment Charles ZVIAK 1988, Ed Masson, p. 215 and 278. The pitch ranges from 1 (black) to 10 (very light blonde), a unit corresponding to a tone; the higher the number, the clearer the nuance. An artificially colored hair is a hair whose color has been modified by a coloring treatment, for example a coloration with direct dyes or oxidation dyes. Within the meaning of the present invention, and unless a different indication is given: the aryl or heteroaryl radicals or the aryl or heteroaryl part of a radical may be substituted by at least one substituent borne by an atom of carbon, chosen from: • a C1-C16, preferably C1-C8, alkyl radical optionally substituted by one or more radicals chosen from hydroxyl, C1-C2 alkoxy and (C2-C4) poly (-hydroxyalkoxy) radicals; acylamino, amino substituted with two identical or different C1-C4 alkyl radicals, optionally bearing at least one hydroxyl group or, the two radicals being able to form, with the nitrogen atom to which they are attached, a heterocycle comprising 5- to 7-membered, preferably 5 or 6-membered, optionally substituted saturated or unsaturated group optionally comprising another heteroatom identical to or different from nitrogen; A halogen atom such as chlorine, fluorine or bromine; • a hydroxyl group; A C1-C2 alkoxy radical; A C1-C2 alkylthio radical; A C2-C4 (poly) -hydroxyalkoxy radical; An amino radical; A 5- or 6-membered heterocycloalkyl radical; A 5- or 6-membered optionally cationic heteroaryl radical, preferentially imidazolium, and optionally substituted with a (C1-C4) alkyl radical, preferably methyl; An amino radical substituted with one or two identical or different C1-C6 alkyl radicals optionally carrying at least: i) a hydroxyl group; ii) an amino group optionally substituted by one or two C1-C3 alkyl radicals; optionally substituted, said alkyl radicals being able to form, with the nitrogen atom to which they are attached, an optionally substituted 5 to 7-membered heterocyclic ring, saturated or unsaturated, optionally comprising at least one other heteroatom different from or different from nitrogen, an acylamino radical (-NR-COR ') in which the radical R is a hydrogen atom, a C 1 -C 4 alkyl radical optionally bearing at least one hydroxyl group and the radical R' is a C 1 -C 4 alkyl radical; C2; a carbamoyl radical ((R) 2 N-CO-) in which the R radicals, which may be identical or different, represent a hydrogen atom or a C 1 -C 4 alkyl radical optionally carrying at least one hydroxyl group; an alkylsulphonylamino radical (R'SO2-NR-) in which the radical R represents a hydrogen atom, a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the radical R 'represents a C1-alkyl radical; -C4, a phenyl radical; an aminosulphonyl radical ((R) 2 N-SO 2 -) in which the radicals R, which may be identical or different, represent a hydrogen atom, a C 1 -C 4 alkyl radical optionally bearing at least one hydroxyl group, • a carboxylic radical in acid or salified form (preferably with an alkali metal or ammonium, substituted or unsubstituted); • a cyano group; A polyhaloalkyl group comprising from 1 to 6 carbon atoms and from 1 to 6 halogen atoms, which are identical or different, the polyhaloalkyl group is, for example, trifluoromethyl; the cyclic or heterocyclic part of a non-aromatic radical may be substituted by at least one substituent carried by a carbon atom chosen from the following groups: • hydroxy, • C 1 -C 4 alkoxy, • (poly) C 2 -C 4 hydroxyalkoxy, A C1-C2 alkylthio radical; Alkylcarbonylamino (RCO-NR'-) in which the radical R 'is a hydrogen atom, a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the radical R is a C1-C2 alkyl radical; amino substituted with two identical or different C1-C4 alkyl groups optionally bearing at least one hydroxyl group, said alkyl radicals being able to form, with the nitrogen atom to which they are attached, a heterocycle comprising from 5 to 7 members, optionally substituted saturated or unsaturated optionally comprising at least one other heteroatom different or different from nitrogen; Alkylcarbonyloxy (RCO-O-) in which the radical R is a C 1 -C 4 alkyl radical, amino substituted with two identical or different C 1 -C 4 alkyl groups optionally carrying at least one hydroxyl group, said alkyl radicals being able to form with the nitrogen atom to which they are attached, an optionally substituted saturated or unsaturated 5- to 7-membered heterocyclic ring optionally comprising at least one other heteroatom different from or different from nitrogen; Alkoxycarbonyl (RO-CO-) in which the radical R is a C 1 -C 4 alkyl radical, amino substituted with two identical or different C 1 -C 4 alkyl groups optionally bearing at least one hydroxyl group, said alkyl radicals being able to form with the nitrogen atom to which they are attached, an optionally substituted saturated or unsaturated 5- to 7-membered heterocyclic ring optionally comprising at least one other heteroatom different from or different from nitrogen; a cyclic, heterocyclic radical or a non-aromatic part of an aryl or heteroaryl radical may also be substituted with one or more oxo or thioxo groups; an aryl radical represents a mono or polycyclic group, condensed or not, comprising from 6 to 22 carbon atoms, and of which at least one ring is aromatic; preferably the aryl radical is a phenyl, biphenyl, naphthyl, indenyl, anthracenyl, or tetrahydronaphthyl; a diarylalkyl radical represents a group comprising, on the same carbon atom of an alkyl group, two identical or different aryl groups, such as diphenylmethyl or 1,1-diphenylethyl; a heteroaryl radical represents a mono- or polycyclic group, fused or otherwise, optionally cationic, comprising from 5 to 22 members, from 1 to 6 heteroatoms chosen from nitrogen, oxygen, sulfur and selenium, and at least one cycle is aromatic; preferably heteroaryl is selected from acridinyl, benzimidazolyl, benzobistriazolyl, benzopyrazolyl, benzopyridazinyle, benzoquinolyl, benzothiazolyl, benzotriazolyl, benzoxazolyl, pyridinyl, tetrazolyl, dihydrothiazolyl, imidazopyridinyl, imidazolyl, indolyl, isoquinolyl, naphthoimidazolyle, naphthooxazolyle, naphthopyrazolyle, oxadiazolyl, oxazolyl, oxazolopyridyl phenazinyl, phenoxazolyl, pyrazinyl, pyrazolyl, pyrilyl, pyrazoyltriazyl, pyridyl, pyridinoimidazolyl, pyrrolyl, quinolyl, tetrazolyl, thiadiazolyl, thiazolyl, thiazolopyridinyl, thiazoylimidazolyl, thiopyrylyl, triazolyl, xanthylyl and its ammonium salt; a diheteroarylalkyl radical represents a group comprising, on the same carbon atom of an alkyl group, two heteroaryl groups, which are identical or different, such as difurylmethyl, 1,1-difurylethyl, dipyrrolylmethyl and dithienylmethyl; a cyclic radical is a non-aromatic cycloalkyl radical, mono- or polycyclic, condensed or otherwise, containing from 5 to 22 carbon atoms, which can comprise from 1 to several unsaturations; particularly the cyclic radical is cyclohexyl; - A sterically hindered cyclic radical is a cyclic radical, aromatic or not, substituted or unsubstituted, hindered by steric effect or constraint, comprising from 6 to 14 members, which can be bridged, as sterically hindered radicals include bicyclo [1.1]. Butane, mesylates such as 1,3,5-trimethylphenyl, 1,3,5-triterbutylphenyl, 1,3,5-isobutylphenyl, 1,3,5-trimethylsilylphenyl and adamantyl; a heterocyclic radical is a non-aromatic mono or polycyclic radical, condensed or otherwise, containing from 5 to 22 members, comprising from 1 to 6 heteroatoms chosen from nitrogen, oxygen, sulfur and selenium; an alkyl radical is a C1-C16 hydrocarbon radical, linear or branched, preferably C1-C8;

  the optionally substituted expression attributed to the alkyl radical, that is to say that said alkyl radical may be substituted by one or more radicals chosen from i) hydroxyl, ii) C 1 -C 4 alkoxy, iii) acylamino, iv) amino optionally substituted by one or two identical or different C 1 -C 4 alkyl radicals, said alkyl radicals being capable of forming, with the nitrogen atom bearing them, a 5- to 7-membered heterocyl, optionally comprising another heteroatom different from or different from nitrogen; v) or a quaternary ammonium group -N R'R "R" ', M for which R', R ", R" ', identical or different, represent a + hydrogen atom, or a C 1 -C 4 alkyl group, or else -N R'R "R" 'form

  a heteroaryl such as imidazolium optionally substituted with a C1-C4 alkyl group, and M represents the counterion of the organic acid, mineral or the corresponding halide; an alkylene chain represents a divalent C1-C18 chain; especially C1-C6, more particularly C1-C2 when the chain is linear; optionally substituted with one or more, identical or different, halogen atoms or groups selected from hydroxy, alkoxy, (di) (C1-C4) (alkyl) amino, Ra-Za-C (Zb) - with Za, Zb, identical or different, representing an oxygen atom, sulfur, or a group NRa ', and Ra, representing an alkali metal, a hydrogen atom, or an alkyl group and Ra' representing a hydrogen atom or a grouping alkyl;

  an alkoxy radical is an alkyl-oxy or alkyl-O- radical for which the alkyl radical is a hydrocarbon radical, linear or branched, C1-C16, preferably C1-C8;

  an alkylthio radical is an alkyl-S- radical for which the alkyl radical is a hydrocarbon radical, linear or branched, C1-C16 preferably C1-C8; when the alkylthio group is optionally substituted, this implies that the alkyl group is optionally substituted as defined above; the boundaries delimiting the range of a range of values lie within this range of values;

  an organic or inorganic acid salt is more particularly chosen from a salt derived from i) hydrochloric acid HCl, ii) hydrobromic acid HBr, iii) sulfuric acid H 2 SO 4, iv) alkylsulphonic acids: Alk- S (O) 2OH such as methylsulfonic acid and ethylsulfonic acid; v) arylsulfonic acids: Ar-S (O) 2OH such as benzene sulfonic acid and toluene sulfonic acid; (vi) citric acid; vii) succinic acid; viii) tartaric acid; ix) lactic acid, x) alkoxysulfinic acids: Alk-O-S (O) OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H3PO4; xiii) acetic acid CH3COOH; xiv) triflic acid CF3SO3H and xv) tetrafluoroboric acid HBF4; an anionic counterion is an anion or an anionic group associated with the cationic charge of the dye; more particularly the anionic counterion is selected from i) halides such as chloride, bromide; ii) nitrates; iii) sulphonates, including C1-C6 alkylsulphonates: Alk-S (O) 2O- such as methylsulphonate or mesylate and ethylsulphonate; iv) arylsulfonates: Ar-S (O) 20-such as benzenesulfonate and toluenesulphonate or tosylate; v) citrate; vi) succinate; (vii) tartrate; viii) lactate; ix) alkyl sulphates: Alk-O-S (O) O- such as methysulfate and ethylsulfate; x) arylsulfates: Ar-O-S (O) O-such as benzenesulphate and toluenesulphate; xi) alkoxysulfates: Alk-O-S (O) 2O- such as methoxy sulfate and ethoxysulfate; xii) aryloxysulfates: Ar-O-S (O) 2 O-, xiii) phosphate; (xiv) acetate; xv) triflate; and xvi) borates such as tetrafluoroborate.

  The heterocyclic thiols fluorescent dyes of formula (I) are compounds capable of absorbing in UV or visible radiation at an Xabs wavelength between 250 and 800 nm and capable of reemitting in the visible range to a length emission wave Xem between 400 and 800 nm.

  Preferably, the heterocyclic thiol-containing fluorescent compounds of the invention are dyes capable of absorbing in the visible Xabs between 400 and 800 nm and reemitting in the visible Xem between 400 and 800 nm. More preferably, thiols fluorescent dyes having a heterocyclic group of formula (I) are dyes capable of absorbing at an Xabs between 420 nm and 550 nm and reemitting in the visible at an Xem of between 470 and 600 nm.

  One particular embodiment of the invention relates to thiols fluorescent dyes having a heterocyclic group of formula (I) in which m is 0.

  According to a particular embodiment of the invention, the heterocyclic thiol fluorescent dyes of formula (I), the heterocycle Hét N- represents a heterocyclic group, cationic or otherwise, optionally substituted; in particular the heterocycle is monocyclic, saturated, and comprises in total two nitrogen atoms and is formed from 5 to 8 members. In particular, the heterocyclic is chosen from piperazinyl, homopiperazinyl, hexahydro-1,4-diazepinyl, and piperazinium, homopiperazinium or hexahydro-1,4-diazepinium optionally substituted with a (C 1 -C 4) alkyl group.

  According to another embodiment, heterocyclic thiol-containing fluorescent dyes of formula (I) in which the heterocycle Het represents a heterocyclic N-N group; monocyclic, saturated, comprising in total a single nitrogen atom and formed from 5 to 7 members. In particular, the heterocyclic is chosen from pyrrolidinyl, piperidyl and azepanyl. The fluorescent compounds of the invention contain a SY function which may be in the covalent -S-Y or ion -S-Y + form depending on the nature of Y and the pH of the medium.

  One particular embodiment relates to thiols fluorescent dyes having a heterocyclic group of formula (I) with SY function where Y represents a hydrogen atom, or an alkali metal. Advantageously, Y represents a hydrogen atom.

  According to another particular embodiment of the invention, in formula (I) above, Y is a protective group known to those skilled in the art such as those described in the books Protective Groups in Organic Synthesis, TW Greene, John Willey & Sons ed., NY, 1981, pp.193-217; Protecting Groups, P. Kocienski, Thieme, 3rd ed., 2005, chap. 5. Especially when Y represents a protective group of the

  thiol function, Y is chosen from the following radicals:

(C1-C4) alkylcarbonyl;

(C 1 -C 4) alkylthiocarbonyl;

  (C1-C4) alkoxycarbonyl; (C1-C4) alkoxythiocarbonyl;

C 1 -C 4 alkylthio thiocarbonyl;

  ^ (di) (C1-C4) (alkyl) aminocarbonyl; ^ (di) (C1-C4) (alkyl) aminothiocarbonyl; arylcarbonyl as phenylcarbonyl; aryloxycarbonyl; aryl (C1-C4) alkoxycarbonyl; (di) (C1-C4) (alkyl) aminocarbonyl as dimethylaminocarbonyl; (C 1 -C 4) (alkyl) arylaminocarbonyl; carboxy; SO3; M + with M + representing an alkali metal such as sodium or potassium, or else M 'of the formula (I) and M + are absent; optionally substituted aryl such as phenyl, dibenzosuberyl, or 1,3,5-cycloheptatrienyl, optionally substituted heteroaryl; including in particular cationic or non-cationic heteroaryl, comprising from 1 to 4 following heteroatoms: i) monocyclic with 5, 6 or 7 members such as furanyl or furyl, pyrrolyl or pyrryl, thiophenyl or thienyl, pyrazolyl, oxazolyl, oxazolium, isoxazolyl, isoxazolium thiazolyl, thiazolium, isothiazolyl, isothiazolium, 1,2,4-triazolyl, 1,2,4-triazolium, 1,2,3-triazolyl, 1,2,3-triazolium, 1,2,4-oxazolyl, 1 2,4-oxazolium 1,2,4-thiadiazolyl 1,2,4-thiadiazolium pyrylium thiopyridyl pyridinium pyrimidinyl pyrimidinium pyrazinyl pyrazinium pyridazinyl pyridazinium triazinyl triazinium tetrazinyl tetrazinium azepine azepinium, oxazepinyl, oxazepinium, thiepinyl, thiepinium, imidazolyl, imidazolium; ii) 8 to 11-membered bicyclic compounds such as indolyl, indolinium, benzoimidazolyl, benzoimidazolium, benzoxazolyl, benzoxazolium, dihydrobenzoxazolinyl, benzothiazolyl, benzothiazolium, pyridoimidazolyl, pyridoimidazolium, thienocycloheptadienyl, these mono or bicyclic groups being optionally substituted by one or more groups such as C 1 -C 4) alkyl as methyl, or polyhalo (C 1 -C 4) alkyl as trifluoromethyl; iii) or tricyclic ABC according to: wherein the two rings A, C optionally comprise a heteroatom, and the ring B is a 5-, 6- or 7-membered particularly 6-membered ring and contains at least one heteroatom such as pyperidyl, pyranyl; Optionally substituted heterocycloalkyl, optionally cationic, the heterocycloalkyl group especially represents a saturated or partially saturated 5-, 6- or 7-membered monocyclic group comprising from 1 to 4 heteroatoms selected from oxygen, sulfur and nitrogen, such as di / tetrahydrofuranyl, di / tetrahydrothiophenyl, di / tetrahydropyrrolyl, di / tetrahydropyranyl, di / tetra / hexahydrothiopyranyl, dihydropyridyl, piperazinyl, piperidinyl, tetramethylpiperidinyl, morpholinyl, di / tetra / hexahydroazepinyl, di / tetrahydropyrimidinyl these groups being optionally substituted with one or more groups such as (C1-C4) alkyl, oxo or thioxo; or the heterocycle represents the following group: ## STR1 ## wherein R ', R'd, R'e, R'f , R'g and R '", which are identical or different, represent a hydrogen atom or a (C1-C4) alkyl group, or else two R'g groups with R'", and / or R'e with R'f form an oxo or thioxo group, or else R'g with R'e together form a cycloalkyl, and v represents an integer inclusive between 1 and 3, preferably R 'to R' "represent a hydrogen atom; and An represents a counterion; isothiouronium -C (NR 'R'd) = N + R'eR'f; An with R ', R'd, R'e and R'f, identical or different, represent a hydrogen atom or a (C 1 -C 4) alkyl group; preferentially R 'to R' f represent a hydrogen atom; and An- represents a counterion; isothiourea -C (NR 'R'd) = NR'e with R'd and R'e as defined above; optionally substituted di (aryl) (C 1 -C 4) alkyl, such as 9-anthracenylmethyl, phenylmethyl or diphenylmethyl, optionally substituted by one or more groups chosen in particular from (C 1 -C 4) alkyl, (C 1 -C 4) alkoxy, such as methoxy, hydroxy, (C1-C4) alkylcarbonyl, and (di) (C1-C4) (alkyl) amino such as dimethylamino; optionally substituted heteroaryl (C 1 -C 4) alkyl, the heteroaryl group is in particular, cationic or non-monocyclic, comprising 5 or 6 members and 1 to 4 heteroatoms chosen from nitrogen, oxygen and sulfur; , such as pyrrolyl, furanyl, thiophenyl, pyridyl, pyridyl N-oxide such as 4-pyridyl or 2-pyridyl-N-oxide, pyrylium, pyridinium, triazinyl, optionally substituted with one or more group such as alkyl particularly methyl preferably (di) heteroaryl (C 1 -C 4) alkyl is (di) heteroarylmethyl or (di) heteroarylethyl; CR'R 2 R 3 with R ', R 2 and R 3, which may be identical or different, representing a halogen atom or a group chosen from: - (C 1 -C 4) alkyl; - (C1-C4) alkoxy; optionally substituted aryl such as phenyl optionally substituted by one or more groups such as (C 1 -C 4) alkyl, (C 1 -C 4) alkoxy, hydroxy; - optionally substituted heteroaryl such as thiophenyl, furanyl, pyrrolyl, pyranyl, pyridyl, optionally substituted with a (C1-C4) alkyl group; -P (Z ') R''R'2R'3 with R'1, and R'2 identical or different represent a hydroxyl group, (C1-C4) alkoxy or alkyl, R'3 represents a hydroxyl group or ( C 1 -C 4) alkoxy, and Z 'represents an oxygen or sulfur atom; sterically hindered cyclic such as adamantyl group; and optionally substituted (C 1 -C 4) alkoxyalkyl such as methoxymethyl (MOM), ethoxyethyl (EOM) and isobutoxymethyl.

  According to a particular embodiment, the protected heterocyclic thiol protected fluorescent dyes of formula (I) comprise a cationic aromatic 5- or 6-membered monocyclic moiety Y i) heteroaryl comprising from 1 to 4 heteroatoms selected from oxygen, sulfur and nitrogen, such as oxazolium, isoxazolium, thiazolium, isothiazolium, 1,2,4-triazolium, 1,2,3-triazolium, 1,2,4-oxazolium, 1,2,4-thiadiazolium, pyrylium, pyridinium pyrimidinium, pyrazinyl, pyrazinium, pyridazinium, triazinium, tetrazinium, oxazepinium, thiepinyl, thiepinium, imidazolium; ii) cationic 8 to 11-membered bicyclic heteroaryl such as indolinium, benzoimidazolium, benzoxazolium, benzothiazolium, these mono or bicyclic heteroaryl groups being optionally substituted with one or more groups such as alkyl as methyl, or polyhalo (C 1 -C 4) alkyl as trifluoromethyl; iii) or heterocyclic according to: R '\ N + N R'd An in which R' and R'd, identical or different, represent a hydrogen atom or a (C 1 -C 4) alkyl group; preferentially R 'to R'd represent a (C 1 -C 4) alkyl group such as methyl; and An represents a counterion.

  Especially Y represents a group chosen from oxazolium, isoxazolium, thiazolium, isothiazolium, 1,2,4-triazolium, 1,2,3-triazolium, 1,2,4-oxazolium, 1,2,4-thiadiazolium, pyrylium, pyridinium , pyrimidinium, pyrazinium, pyridazinium, triazinium and imidazolium, benzoimidazolium, benzoxazolium, benzothiazolium, these groups being optionally substituted by one or more (C1-C4) alkyl groups including methyl.

  In particular Y represents an alkali metal or a protective group such as: - (C 1 -C 4) alkylcarbonyl such as methylcarbonyl or ethylcarbonyl; arylcarbonyl, such as phenylcarbonyl; - (C1-C4) alkoxycarbonyl; -aryloxycarbonyl; aryl (C1-C4) alkoxycarbonyl; - (di) (C1-C4) (alkyl) aminocarbonyl such as dimethylaminocarbonyl; - (C1-C4) (alkyl) arylaminocarbonyl; optionally substituted aryl such as phenyl; 5- or 6-membered monocyclic heteroaryl such as imidazolyl or pyridyl; 5- to 6-membered cationic monocyclic heteroaryl such as pyrylium, pyridinium, pyrimidinium, pyrazinium, pyridazinium, triazinium, imidazolium; these groups being optionally substituted by one or more, identical or different, (C 1 -C 4) alkyl groups such as methyl; - 8 to 11-membered cationic bicyclic heteroaryl such as benzoimidazolium, or benzoxazolium; these groups being optionally substituted by one or more, identical or different, (C 1 -C 4) alkyl groups such as methyl; cationic heterocycle of the following formula: Me N +

  N-Me-Isothiouronium -C (NH2) = N + H2; An; - isothiourea -C (NH 2) = NH; -SO3, W.

  According to one particular embodiment of the invention, the dyes of the invention belong to the formula (I), contain the ethylene group connecting the pyridinium portion to the phenyl in the ortho or para position, or in the 4-4 ', 2-2' positions. , 4-2 'or 2-4'.

  By way of example of thiol fluorescent dyes, mention may be made in particular of the following compounds: ## STR1 ## ùN O 2An 2An- \ / N / H Name \ \ N \ O SH An- 0 NH 1 HS An- / HS S \ / \\ NH +, / ùN ùN + \ CN H ù An 2An- / / N \ HH \> \ / \ O SH O SH An- An- ùN + An- ~~ o / SH SH o ~ 2An \ N + ~ ~ \ I / IN ~~ \ N + JNO ~ o ~ SH An- N 3An- ~ \ NN SH N ~ / \ ^ An An- v \ oo ~ s So3- An- 2An- 2An- OSH An- SH 2An-W Year- SO3 2An- SH ~ N 1, D ~ S \ N Name / 2An - HS. N + / / NI I. \ \ / N \ \ 2An- SH 2An o \ N + 'SN o Where SH N An- / \ / ùN An-HS NN ~ p' `- \ o S Y N Y - 2An- An O Ni ~ N 3An \ N ~~ I \ N ~~ 1. Y N N Y Y N Y N N N O N N N HZN "-N + ~ N -N + NN HS An / ~ N + 2An -N ~ \ N + ~ N ~ SH An HS 2An With An-, identical or different, representing an anionic counterion, and M + representing an alkali metal.

  The protected thiol dyes of formula (I ") can be synthesized in two steps: the first step of preparing the unprotected thiol dye (I ') according to the methods known to those skilled in the art, for example Thiols and organic Sulfides, Thiocyanates and Isothiocyanates, organic, Ullmann's Encyclopedia, Wiley-VCH, Weinheim, 2005. And the second step of protecting the thiol function according to conventional methods known to those skilled in the art to lead to protected thiol dyes of formula (I). "). By way of example, to protect the thiol function of the thiol dye, the methods of Protectin Groups in Organic Synthesis, T.W. Greene, John Willey & Sons, Ed., NY, 1981, pp.193-217; Protecting Groups, P. Kocienski, Thieme, 3rd ed., 2005, chap. 5.

  We can illustrate this method by the method consisting of i) generating heterocyclic thiols fluorescent dyes of formula (I ') by reduction of a heterocyclic, two-chromophore fluorescent dye bearing a disulfide -SS- function such as (A) and ii) to protect, according to conventional methods, said thiol function of (I ') to access the protected thiol fluorescent dyes of formula (Ia): Tai Tai (CRiRZ) n, (CR3R4) n (CR3R4) n (CR, R2) n, (A) M '(CR 1 R 2) n Ta (CR 3 R 4) n (I ") (CRIR 2) 7, Ta (CR R) H ii) 22 -HR with R 1, R 2, R 3, R 4, Ra, R 6 , R'g, Rh, R'h, R, R ', m, n, Het and M' are as defined above; Y 'represents a protective group of thiol function; and R represents a leaving group nucleofuge, For example, mesylate, tosylate, triflate or halide may be reacted Alternatively, a protected thiol compound may be reacted with a protecting group Y 'as defined above prepared according to one of the procedures described in the works cited above, said protected thiol compound comprising at least one nucleophilic function with a sufficient, preferably equimolar, amount of a "reactive fluorescent chromophore" or a compound comprising such a "reactive fluorescent chromophore" j . In other words, it comprises an electrophilic function to form a covalent bond E as can be schematized below: (CRIR2) n. ## STR5 ## where R 1, R 2, R 3, R 4, R a, R 6, R 6, R 6, R 6, R 6 , R ', R', m, n, Het, Y 'and M' are as defined above; ~ u represents a nucleophilic group; E represents an electrophilic group; and E the bond generated after nucleophilic attack on the electrophile.

  By way of example, the covalent bonds E that can be generated are listed in the table below from the condensation of electrophiles with nucleophiles: Electrophiles E Nucleophiles Wu Covalent bonds E Esters activated * Amines Carboxamides Acyl azides ** Amines Carboxamides Acyl halides Amines Carboxamides Acyl halides Alcohols Esters Acyl cyanides Alcohols Esters Acyl cyanides Amines Carboxamides Alkyl halides Amines Alkylamines Alkali halides Carboxylic acids Esters Alkyl halides Thiols Thioesters Alkyl halides Alcohols Ethers Sulphonic acids and their thiols Thioethers salts Sulphonic acids and their carboxylic acids Esters salts Sulphonic acids and their alcohols Ethers salts Anhydrides Alcohols Esters Anhydrides Amines Carboxamides 5 10 Aryl halides Thiols Thioethers Aryl halides Amines Arylamines Aziridines Thiols Thioethers Carboxylic acids Amines Carboxamid Carboxylic acids Alcohols Esters Carbodiimides Carboxylic acids N-acyl ureas or anhydrides Diazoalkanes Carboxylic acids Esters Epoxides Thiols Thioethers Haloacetamides Thiols Thioethers Esters imides Amines Amidines Isocyanates Amines Ureas Isocyanates Alcohols Urethanes Isothiocyanates Amines Thioureas Maleimides Thiols Thioethers Sulphonic esters Amines Alkylamines Sulphonic esters Thiols Thioethers Esters sulphonic Acids carboxylic esters Esters Sulphonic esters Alcohols Ethers Sulfonyl halides Amines Sulfonamides * Activated esters of the general formula ûCO-Part with Part representing a leaving group such as oxysuccinimidyl, oxybenzotriazolyl, optionally substituted aryloxy;

  The acyl azides can rearrange to give the isocyanates.

  An alternative to this process is to use a fluorescent chromophore having an electrophilic acrylate function (-OCO-C = C-) on which an addition reaction is carried out which will generate an L bond.

  It is also possible to use a thiol reagent Y'-SH comprising a group Y 'as defined previously, the nucleophilic function SH of which can react on the carbon atom in alpha of the halogen atom borne by the fluorescent chromophore jj to conduct with the protected thiol fluorescent dye of formula (I "): HS-Y '(CR1R2) m T ~ (CR3R4) n Hal (1") with R1, R2, R3, R4, Ra, Rg, R'g, Rh , R'h, Ta, R, R ', m, n, Het, Y', (I ") and M 'are as defined above, and Hal represents a nucleofugal halogen atom such as bromine, iodine or chlorine.

  More particularly, it will be possible to substitute a nucleofugal leaving group with a thiourea group (S = C (NRR) NRR) to generate the isothiouroniums. For example, if the thiourea group is a thioimidazolium ([3), the reaction scheme is as follows: ## STR1 ## ## STR2 ## (c) (III) - H Hal with Ra, R'g, R'd, Rg, R'g, Rh, R'h, R, R ', m, n, Het, Hal, An- and M 'are as defined previously. An alternative is to use in place of the halide comprising the fluorescent chromophore a chromophore comprising another type of nucleofuge such as tosylate, mesylate.

  According to another possibility, certain protected heterocyclic thiols (I "') fluorescent dyes can be obtained by reacting a protected thiol compound with a compound carrying two carboxylic acid functions activated by conventional methods (for example reaction with a carbodiimide or with thionyl chloride) The resulting product is then reacted with a heterocyclic fluorescent chromophore carrying a nucleophilic function, for example of primary or secondary amine type, or of aliphatic or aromatic alcohol type such as phenol (CR1R2). ), n r r r + E- (CR 3 R 4) SY '(1 ") g R' 9 M 'with R 1, R 2, R 3, R 4, R a, R 8, R' 8, Rh, R ', R', R ';, Het, Ta, Y', m, n, M ', E, Wu and (I "') as defined above. [Conformément Conformément] According to another possibility, the protected heterocyclic thiols fluorescent dyes of formula (I ') can be obtained by reaction of a compound comprising a thiol group protected by a group Y ', and a hydroxyl group activated beforehand in leaving group nucleofuge LU, for example mesylate, tosylate, triflate or halide with a fluorescent chromophore f bearing a nucleophilic amino function on the heterocyclic part of Hét. ## STR5 ## wherein R 1 g, Rh, Rh, R, R ', Het, Ta, Y', n, M ', E and E are as defined above.

  By way of example, a compound containing a protected thiol group contains a leaving group R, such as, for example, mesylate, tosylate, or triflate which may undergo the nucleophilic attack of the amine carried by the styryl fluorescent chromophore: OR - ROH Another alternative comes from the use of halides as nucleofugal leaving group on a thiol compound which may be substituted by a primary amine function, for example carried by a styryl fluorescent chromophore: Hal ~~ SY 'Hét According to another possibility, the protected thiol fluorescent dyes of formula (I) according to the invention may be obtained by reaction of a compound comprising a thiol group Y as defined above and an electrophilic group Lfl with a compound comprising a For example, an aldehyde or ketone may be condensed when G represents an oxygen atom with a activated methylene such as alkylpyridinium to generate an ethylene bond> C = C <. This reaction is commonly known as Knoevenagel condensation. By activated methylenes, for example those mentioned in the patent DE19951134, 1,2-dialkylpyridinium and in particular 1,2-dimethylpyridinium: ## STR2 ##

  + ~ -Q (1) - H2G with R1, R2, R3, R4, Ra, Rg, R'g, Rh, R'h, R, R ', Het, Ta, m, n, Y and M 'as defined above and G representing an oxygen atom, sulfur or a group N (R) with R representing a hydrogen atom or a group (C 1 -C 4) alkyl. An alternative to this process is to provide: (i) a Knoevenagel condensation of an aldehyde or ketone comprising a hetero ring Het with a nucleophilic amino group with an activated methylene such as alkylpyridinium to lead to Styryl-Heterocyclic Intermediate If. The latter can then ii) react on a cyclic monomer containing at least one thiolactam function, to conduct after ring opening to the heterocyclic fluorescent dye thiol (I '): Hét NH i) gG - H2G With R ,, R2, R3, R4 , Ra, Rg, R'g, Rh, R'h, R, R ', Het, n and M' as defined above, G and G ', which may be identical or different, or a group N (R) with R representing a hydrogen atom or a (C 1 -C 4) alkyl group.

  Alternatively, when the reagent (g ') has an exocyclic amino group Het, the fluorescent dye amide, thioamide, guanidine or amidine group is obtained ii) S (R3R4C), G'Het N -Iu (CR3R4) n ## STR2 ## wherein R 1, R 2, R 3, R 4, R 6, R 6, R 6, R 6, R 6, R 4, R 6 , M ', G and G' as defined above and R 'represents a hydrogen atom, or an alkyl group. It being understood that the amine of the heterocycle of the reagent (9 ') can be protected and then deprotected

  We can refer to the book Advanced Organic Chemistry, J. March, 4th Ed, John Willey & Sons, 1992 or TW Greene Protective Groups in Organic Synthesis, for more details on the operating conditions used for the mentioned processes above. The thiol fluorescent dyes formed can be converted to thiol protected fluorescent dyestuffs by the protection of the thiol by using conventional protecting groups. The protected thiol dyes can be deprotected by conventional routes.

  The composition of the invention contains at least one heterocyclic thiol fluorescent dye of formula (I). In addition to the presence of at least one fluorescent dye of formula (I), the composition of the invention may also contain a reducing agent.

  This reducing agent may be chosen from thiols, for example cysteine, homocysteine, thiolactic acid, the salts of these thiols, phosphines, bisulfite, sulphites, thioglycolic acid and its esters, especially the glycerol monothioglycolate, and thioglycerol. This reducing agent may also be chosen from borohydrides and their derivatives, such as, for example, borohydride, cyanoborohydride, triacetoxyborohydride or trimethoxyborohydride salts: sodium, lithium, potassium, calcium, quaternary ammonium salts (tetramethylammonium, tetraethylammonium, tetra butylammonium, benzyltriethylammonium); catechol borane. The dye composition useful in the invention generally contains an amount of heterocyclic thiol fluorescent dye of formula (I) of between 0.001 and 50% relative to the total weight of the composition. Preferably, this amount is between 0.005 and 20% by weight and even more preferably between 0.01 and 5% by weight relative to the total weight of the composition. The dye composition may further contain additional direct dyes. These direct dyes are, for example, chosen from neutral, acidic or cationic nitro-benzene direct dyes, neutral azo, acid or cationic direct dyes, tetraazapentamethine dyes, neutral or acidic or cationic quinone dyes, in particular neutral anthraquinone dyes and direct azine dyes. , triarylmethane direct dyes, indoamine direct dyes and natural direct dyes.

  Among the natural direct dyes that may be mentioned are lawsone, juglone, alizarin, purpurin, carminic acid, kermesic acid, purpurogalline, protocatechaldehyde, indigo, isatin, curcumin, spinulosin, apigenidine. It is also possible to use the extracts or decoctions containing these natural dyes, and in particular poultices or extracts made from henna.

  The dye composition may contain one or more oxidation bases and / or one or more couplers conventionally used for dyeing keratinous fibers. Among the oxidation bases, mention may be made of para-phenylenediamines, bis-phenylalkylenediamines, para-aminophenols, bis-para-aminophenols, ortho-aminophenols, heterocyclic bases and their addition salts. Among these couplers, there may be mentioned meta-phenylenediamines, meta-aminophenols, meta-diphenols, naphthalenic couplers, heterocyclic couplers and their addition salts. The coupler or couplers are each generally present in an amount of between 0.001 and 10% by weight of the total weight of the dye composition, preferably between 0.005 and 6%. The oxidation base (s) present in the dyeing composition are in general each present in an amount of between 0.001% and 10% by weight relative to the total weight of the dyeing composition, preferably between 0.005% and 6% by weight.

  In general, the addition salts of the oxidation bases and couplers that can be used in the context of the invention are chosen especially from the addition salts with an acid such as hydrochlorides, hydrobromides, sulphates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, phosphates and acetates and addition salts with a base such as alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, ammonia, amines or alkanolamines.

  The medium suitable for dyeing, also called dyeing medium, is a cosmetic medium generally consisting of water or a mixture of water and at least one organic solvent. As organic solvent, there may be mentioned for example lower alkanols C1-C4, such as ethanol and isopropanol; polyols and polyol ethers such as 2-butoxyethanol, propylene glycol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether and monomethyl ether, as well as aromatic alcohols such as benzyl alcohol or phenoxyethanol, and mixtures thereof. The solvents when present are preferably present in proportions preferably of between 1 and 40% by weight approximately relative to the total weight of the dye composition, and even more preferably between 5 and 30% by weight approximately. According to one variant, the invention contains a reducing agent capable of reducing the disulfide bonds of keratin. This reducing agent is as defined above.

  The dye composition may also contain various adjuvants conventionally used in compositions for dyeing hair, such as anionic, cationic, nonionic, amphoteric, zwitterionic surfactants or mixtures thereof, anionic, cationic, nonionic, amphoteric and zwitterionic polymers. or mixtures thereof, inorganic or organic thickeners, and in particular anionic, cationic, nonionic and amphoteric polymeric associative thickeners, antioxidants, penetrating agents, sequestering agents, perfumes, buffers, dispersing agents, conditioning agents such as, for example, volatile or non-volatile silicones, modified or otherwise, such as aminosilicones, film-forming agents, ceramides, preserving agents, opacifying agents, conductive polymers. The adjuvants above are generally present in an amount for each of them between 0.01 and 20% by weight relative to the weight of the composition. Of course, one skilled in the art will take care to choose this or these optional additional compounds in such a way that the advantageous properties intrinsically attached to the dyeing composition according to the invention are not, or not substantially, impaired by the or the additions envisaged. The pH of the dyeing composition is generally between 3 and 14 approximately, and preferably between 5 and 11 approximately. It can be adjusted to the desired value by means of acidifying or alkalizing agents usually used for dyeing keratin fibers or else using conventional buffer systems.

  Among the acidifying agents, mention may be made, by way of example, of mineral or organic acids such as hydrochloric acid, orthophosphoric acid, sulfuric acid, carboxylic acids such as acetic acid, tartaric acid, citric acid, lactic acid, sulphonic acids.

  Among the alkalinizing agents that may be mentioned, by way of example, are ammonia, alkaline carbonates, alkanolamines such as mono-, di- and triethanolamines and their derivatives, sodium or potassium hydroxides and following formula (y):

  R 1 / Rat / N Wa N Ra 4 R 1 (Y) in which Wa is a propylene residue optionally substituted with a hydroxyl group or a C 1 -C 4 alkyl radical; Ra1, Ra2, Ra3 and Ra4, which may be identical or different, represent a hydrogen atom, a C1-C4 alkyl radical or a C1-C4 hydroxyalkyl radical. The dye composition may be in various forms,

  such as in the form of liquid, cream, gel, or in any other form suitable for dyeing keratinous fibers, and especially hair. According to a particular embodiment in the process of the invention, a reducing agent may be applied pre-treatment before application of the composition containing at least one heterocyclic thiol fluorescent dye of formula (I).

  This reducing agent may be chosen from thiols, for example cysteine, homocysteine, thiolactic acid, the salts of these thiols, phosphines, bisulfite,

  sulphites, thioglycolic acid, and its esters, in particular glycerol monothioglycolate, and thioglycerol. This reducing agent may also be chosen from borohydrides and their derivatives, such as, for example, borohydride, cyanoborohydride, triacetoxyborohydride or trimethoxyborohydride salts: sodium, lithium, potassium, calcium, quaternary ammonium salts (tetramethylammonium, tetraethylammonium, tetra butylammonium, benzyltriethylammonium); catecholborane. This pretreatment may be of short duration, in particular from 0.1 second to 30 minutes, preferably from 1 minute to 15 minutes with a reducing agent as mentioned above.

  When the heterocyclic thiol fluorescent dye (I) comprises a group Y protecting the thiol function, the method of the invention may be preceded by a deprotection step aimed at rendering the SH function in situ. By way of example, it is possible to deprotect the SY function with the protective group by adjusting the pH as follows: Y: alkylcarbonyl deprotection protecting group, pH> 9 arylcarbonyl, pH> 9 alkoxycarbonyl, pH> 9 aryloxycarbonyl, pH> 9 arylalkoxycarbonyl pH> 9 (di) (alkyl) aminocarbonyl, pH> 9 (alkyl) arylaminocarbonyl pH> 9 aryl optionally substituted such pH> 9 as phenyl, monocyclic heteroaryl with 5, 6 or 7 pH> 9 members such as oxazolium; 8 to 11-membered 9-membered bicyclic heteroaryl such as benzoimidazolium or benzoxazolium The deprotection step may also be carried out in the course of a hair pretreatment step such as, for example, the hair reduction pretreatment. According to one variant, the reducing agent is added to the dye composition containing at least one heterocyclic thiol fluorescent dye (I) at the time of use. According to another method, the composition comprising at least one heterocyclic thiol fluorescent dye of formula (I) also contains at least one reducing agent as defined above. This composition is then applied to the hair. According to another variant, the reducing agent is applied in post-treatment, after the application of the composition containing at least one thiol fluorescent dye (I). The duration of the post-treatment with the reducing agent may be short, for example from 0.1 second to 30 minutes, preferably from 1 minute to 15 minutes, with a reducing agent as described above. According to a particular embodiment, the reducing agent is a thiol or borohydride type agent as described above. A particular embodiment of the invention relates to a method in which the thiol fluorescent dye can be applied directly to hair without reducing agents, free of pre- or post-treatment reducers.

  A treatment with an oxidizing agent may optionally be associated. Any type of conventional oxidizing agent may be used in the art. Thus, it may be chosen from hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulphates, as well as the enzymes among which may be mentioned peroxidases, oxides, 2-electron reductases such as uricases and 4-electron oxygenases such as laccases. The use of hydrogen peroxide is particularly preferred. This oxidizing agent may be applied to the fibers before or after the application of the composition containing at least one thiol fluorescent dye of formula (I).

  The application of the dye composition according to the invention is generally carried out at room temperature. It can however be carried out at temperatures ranging from 20 to 180 C.

  The invention also relates to a multi-compartment device or "kit" of dyeing in which a first compartment contains a dye composition comprising at least one heterocyclic thiol fluorescent dye of formula (I) and a second compartment contains a reducing agent capable of reduce the disulfide functions of keratin materials. One of these compartments may further contain one or more other dyes of direct dye type or oxidation dye. It also relates to a multi-compartment device in which a first compartment contains a dye composition comprising at least one heterocyclic thiol fluorescent dye of formula (I); a second compartment contains a reducing agent capable of reducing the disulfide bond of the keratin materials; a third compartment contains an oxidizing agent. Alternatively, the dyeing device contains a first compartment containing a dye composition which comprises at least one protected thiol fluorescent dye of formula (I) and a second compartment containing an agent capable of deprotecting the protected thiol to release the thiol. Each of the devices mentioned above can be equipped with a means for delivering the desired mixture onto the hair, for example such as the devices described in patent FR 2 586 913.

  The examples which follow serve to illustrate the invention without, however, being limiting in nature. The thiol fluorescent dyes of the examples below have been fully characterized by conventional spectroscopic and spectrometric methods.

EXAMPLES

  SYNTHESIS EXAMPLE Synthesis of 1-methyl-4 - ((E) -2- {4- [4- (2-sulfanyl-ethyl) piperazin-1-yl] phenyl} vinyl) pyridinium methylsulfate [1] / - ## STR5 ## wherein: ## STR2 ## is a synthesis scheme ## STR1 ## wherein: ## STR1 ## ## STR2 ## HO O HO O HOO EtOH O HO + OH [1] Operating Mode

Step 1: Synthesis of 4,4 '- [disulfanediylbis (ethane-2,1-diylpiperazine-4,1-5 diyl)] dibenzaldehyde

  2.5 g of 4-piperazin-1-yl-benzaldehyde, 1.37 g of 1-bromo-2 - [(2-bromoethyl) disulfanyl] ethane, 7.3 g of potassium carbonate (K 2 CO 3), and mL of N-methylpyrrolidinone (NMP) are mixed at 75 C for 55 h. The product is purified by chromatography on silica gel (eluent: acetone / heptane 80/20 then dichlormethane / methanol 90/10). 469 mg of yellow oil are collected. The analyzes indicate that the product is compliant.

  Step 2: Synthesis of 4,4 '- {disulfanediylbis [ethane-2,1-diylpiperazin-4,1-diyl-4,1-phenylene (E) ethen-2,1-diyl]} bis (1-dimethylsulfate) methylpyridinium) [the]

469 mg of 4,4 '- [disulfanediylbis (ethane-2,1-diylpiperazine-4,1-diyl)] dibenzaldehyde, 5 mL of isopropanol (iPrOH), 415 mg of 1,4-dimethylpyridinium methylsulfate, 80 mg pyrrolidine, 56 mg of acetic acid and 5 ml of dichloromethane are mixed at room temperature for 24 h and then at 40 ° C. for 24 h. After cooling the mixture, 20 ml of acetone are added, the precipitate obtained is filtered, washed with 10 ml of isopropanol, then with 3 times 25 ml of acetone, and dried. 610 mg of red powder are collected. The analyzes indicate that the product is compliant and pure. 1 H NMR (400 MHz, MeOH-d4) 2.68 (m, 8H), 2.78 (t, 4H), 2.95 (t, 4H), 3.37 (m, 8H), 3.68 (s, 6H). , 4.24 (s, 6H), 7 (d, 4H), 7.16 (d, 2H), 7.62 (d, 4H), 7.82 (d, 2H), 8.01 (d, 4H), 8.56 (d, 4H) Step 3: Synthesis of 1-methyl-4 - ((E) -2- {4- [4- (2-sulfanylethyl) piperazin-1-yl] phenyl} vinyl) pyridinium salt [1]

  16 mg of the compound [la] are dissolved in 10 ml of water / ethanol mixture (v / v: 1/1); 60 mg (2 eq) of 3- [bis (2-carboxyethyl) phosphino] propanoic acid hydrochloride hydrate in solution in 1 mL of water and 21 mg (4 eq) of sodium bicarbonate in solution in 1 mL of water are added to the mixture. After stirring for 30 minutes at 40 ° C. under an inert atmosphere, the analyzes indicate that the mixture contains most of the expected product [1].

  LC-MS analysis: LC-DAD (400-700 nm) Column: Waters XTerra MS C18 5pm (4.6 x 50) mm Mobile phase: A: Water + formic acid 0.1% / B: acetonitrile Linear gradient: T (min) A % / B%: 0 min 95/5; 8 min 0/100 Flow rate: 1 ml / min.

  Detection: UV Diode array at = 400-700nm Retention time t = 3.0 min. Relative purity> 90% MS (ESI +) mlz = 285 corresponds to the peak mass of the expected product monocation [1] EXAMPLE OF COLORING Staining process

  10 ml of fresh solution of the compound [1] of the synthetic example obtained in step 3 are applied to a lock of 1 g of hair of pitch 4 arranged at the bottom of the same bowl for 30 minutes at room temperature (the locks are returned and re-impregnated after 15 minutes). The locks are then rinsed with running water and dried. After staining, the pitch wick 4 became visually brighter than untreated control wicks.

  Persistence with respect to successive shampoos: The wicks thus treated are divided in two, one half is subjected to 5 successive shampoos in a cycle which comprises wetting the locks with water, washing with a conventional shampoo, rinsing with water followed by drying.

  25 Visual Observations During shampoos, there is no visible bleeding, shampoo foam and rinsing water are not colored The observed color is preserved and the lightening effect remains visible on the hair of height of your 4 so treated. Results in the L * a * b system * The color of the locks before and after the 5 washes was evaluated in the L * a * b * system using a KONICA MINOLTA CM 2600 spectrophotometer, (Illuminant D65). In this system L * a * b *, L * represents the intensity of the color, a * indicates the green / red color axis and b * the blue / yellow color axis. The higher the value of L, the lighter or less intense the color. Conversely, the lower the value of L, the darker or more intense the color. The higher the value of a * the higher the shade is red and the higher the value of b * the hue is yellow.

  The variation of the coloration between the locks of HT4 hair, stained and washed is measured by (AE) according to the following equation:

  In this equation, L *, a * and b * represent the values measured before staining and Lo *, ao. * and bo * represent the values measured after staining or after staining and shampooing. The higher the value of AE, the greater the difference in color between the HT4 locks and the colored locks. AE AE Wick HT4 after application of the compound (1) 4.22 according to the invention AE Wick HT4 after application of the compound (1) 5.22 according to the invention and 5 successive shampoos The results of the table shows that it There is no significant difference in color variation even after 5 shampoos. Thus the coloration and the lightening effect on the hair remain virtually unchanged which shows a very good resistance to shampoos dyes of the invention. Results of Reflectance The lightening of the compositions in accordance with the invention and their persistence with respect to successive shampoos were also expressed as a function of the reflectance of the hair. These reflectances are compared to the reflectance of a lock of untreated HT4 pitch hair. The reflectance is measured using a KONIKAMINOLTA spectrophotocolorimeter, CM 2600d and after irradiation of the hair with visible light in the wavelength range of 400 to 700 nanometers.

  It is firstly noted that the reflectance of a lock of hair treated with a composition according to the invention is greater than that of untreated hair. The treated locks therefore appear visually clearer.

  In addition, the results show that the reflectance of the locks of hair of pitch 4 treated with the composition of the invention evolve very little after shampooing. Thus the coloration and the lightening effect on the hair remain virtually unchanged which shows a very good resistance to shampoos dyes of the invention. Reflectance of wicks treated with compound 1 at application and after 5 shampoos t). t). t). Wavelength (nm) reference Compound 1

  Compound 1 - 5 shampoos 6-5-4-3-2-1-0

Claims (25)

  1. Fluorescent dye of the following formula (I): ## STR1 ## its organic or inorganic acid salts, optical isomers, geometric isomers, and solvates such as hydrates; formula (I) in which: - Ra represents an aryl (C 1 -C 4) alkyl group or a (C 1 -C 6) alkyl group optionally substituted with a hydroxyl or amino (C 1 -C 4) alkylamino (C 1 -C 4) group; dialkylamino, said alkyl radicals being able to form with the nitrogen atom which carries them a 5- to 7-membered heterocyl, optionally comprising another heteroatom different or different from nitrogen; - Rg, R'g, Rh and R'h, identical or different, represent a hydrogen atom, a halogen atom, an amino group, (C1-C4) alkylamino, (C1-C4) dialkylamino, cyano, carboxy, hydroxy, trifluoromethyl, acylamino, C 1 -C 4 alkoxy, (C 2 -C 4) polycarboxylic hydroxyalkoxy, alkylcarbonyloxyalkoxycarbonyl, alkylcarbonylamino, acylamino, carbamoyl, alkylsulfonylamino, amino-sulfonyl, or (C 1 -C 4) radicals. C4) alkyl optionally substituted with a group chosen from (C1-C4) alkoxy, hydroxy, cyano, carboxy, amino, (C1-C4) alkylamino and (C1-C4) dialkylamino, or else the two alkyl radicals borne by the atom nitrogen of the amino group form a heterocycle comprising from 5 to 7 members and optionally comprising another heteroatom identical to or different from that of the nitrogen atom; or two groups Rg and R'g; Rh and R'h carried by two adjacent carbon atoms together form a benzo, indeno ring, a fused heterocycloalkyl or fused heteroaryl group; the benzo, indeno, heterocycloalkyl or heteroaryl ring being optionally substituted by a halogen atom, an amino group, (C1-C4) alkylamino, (C1-C4) dialkylamino, cyano, carboxy, hydroxy, trifluoromethyl, an acylamino, alkoxy radical; C1-C4, (poly) hydroxyalkoxy C2-C4, alkylcarbonyloxy alkoxycarbonyl, alkylcarbonylamino, an acylamino, carbamoyl, alkylsulfonylamino radical, an amino-sulphonyl radical, or a (C1-C4) alkyl radical optionally substituted with: a group chosen from (C1-C4) alkoxy, hydroxy, cyano, carboxy, amino, (C1-C4) alkylamino, (C1-C4) dialkylamino, or the two alkyl radicals carried by the nitrogen atom of the amino group form a heterocycle comprising 5- to 7-membered ring and optionally comprising another heteroatom identical to or different from that of the nitrogen atom; - R; and R ', which may be identical or different, represent a hydrogen atom or a (C 1 -C 4) alkyl group; - R ,, R2, R3, R4, identical or different, represent a hydrogen atom or a group (C1-C4) alkyl, (C1-C4) alkoxy, hydroxy, cyano, carboxy, amino, (C1-C4) alkylamino, (C1-C4) dialkylamino, said alkyl radicals being capable of forming, with the nitrogen atom which bears them, a 5- to 7-membered heterocyl, optionally comprising another heteroatom which may or may not be different from nitrogen; Ta is: i) either a covalent bond a, ii) or one or more radicals or combinations thereof selected from -SO2-, -06, -Siu, ùN (R) ù, ùN + (R) (R) ù, ùC ( Wherein R and R, which may be identical or different, represent a hydrogen atom, a C 1 -C 4 alkyl, C 1 -C 4 hydroxyalkyl or aryl (C 1 -C 4) alkyl radical; iii) a heterocycloalkyl or heteroaryl radical, cationic or non-cationic; Het - N represents a cationic or non-cationic heterocyclic group, optionally substituted; -m and n, identical or different, represent an integer inclusive between 0 and 6 with m + n represents an integer inclusive between 1 and 10; M 'representing an anionic counterion; and Y represents: i) a hydrogen atom; ii) an alkali metal; iii) an alkaline earth metal; iv) an ammonium group: N + RaRaRYR8 or a phosphonium group: P + RaRaRYR8 with Ra, Ra, R7 and R8, identical or different, representing a hydrogen atom or a (C 1 -C 4) alkyl group; or v) a protecting group of thiol function, it being understood that: when the compound of formula (I) contains other cationic parts, it is associated with one or more anionic counter-ions making it possible to reach the electroneutrality of formula (I).   2. Fluorescent dye of formula (I) according to claim 1 wherein m is zero.   3. Fluorescent dye of formula (I) according to any one of the preceding claims wherein the heterocycle Het represents the Hét N-N heterocyclic group N ~, cationic or nor, optionally substituted; in particular the heterocycle is monocyclic, saturated, and comprises in total two nitrogen atoms and is formed from 5 to 8 members. 15   4. Fluorescent dye of formula (I) according to any one of claims 1 or 2 wherein the heterocycle Hét represents the heterocyclic group N; monocyclic, saturated, comprising a total of one nitrogen atom and 5 to 7 members.   5. Fluorescent dye of formula (I) according to any one of the preceding claims wherein Y represents a hydrogen atom, or an alkali metal.   6. Fluorescent dye of formula (I) according to any one of claims 1 to 4 wherein Y represents a hydrogen atom, or an alkali metal.   7. Fluorescent dye of formula (I) according to claim 30 wherein Y represents a protective group selected from the following radicals: (C1-C4) alkylcarbonyl; (C 1 -C 4) alkylthiocarbonyl; (C1-C4) alkoxycarbonyl; (C1-C4) alkoxythiocarbonyl; (C 1 -C 4) alkylthio thiocarbonyl; • (di) (C1-C4) (alkyl) aminocarbonyl; (Di) (C1-C4) (alkyl) aminothiocarbonyl; Arylcarbonyl; Aryloxycarbonyl; • aryl (C 1 -C 4) alkoxycarbonyl; • (di) (C1-C4) (alkyl) aminocarbonyl; (C1-C4) (alkyl) arylaminocarbonyl; • carboxy; • SO3; M + with M + representing an alkali metal or M 'of the formula (I) and M + are absent; Optionally substituted aryl; optionally substituted heteroaryl; • isothiouronium -C (NR 'R'd) = N + R'eR'f; An with R ', R'd, R'e and R'f, identical or different, represent a hydrogen atom or a (C 1 -C 4) alkyl group; preferentially R 'to R' f represent a hydrogen atom; and An represents a counterion; isothiourea -C (NR 'R'd) = NR'e with R', R'd and R'e as defined above; (di) aryl (C1-C4) alkyl optionally substituted; Optionally substituted (di) heteroaryl (C 1 -C 4) alkyl; • CR'R2R3 with R ', R2 and R3 identical or different, representing a halogen atom or a group selected from i) (C1-C4) alkyl; ii) (C1-C4) alkoxy; iii) optionally substituted aryl; Optionally substituted heteroaryl; and P (Z ') R''R'2R'3 with R'1, and R'2, which may be identical or different, represent a hydroxy, (C 1 -C 4) alkoxy or alkyl group, R' 3 represents a hydroxyl group or (C 1 -C 4) alkoxy, and Z 'represents an oxygen or sulfur atom; Cyclic sterically hindered; and • optionally substituted (C.sub.1 -C.sub.4) alkyloxy.   8. Fluorescent dye of formula (I) according to any one of the preceding claims wherein Y represents an alkali metal or a protective group chosen from: - (C1-C4) alkylcarbonyl; -arylcarbonyl; - (C1-C4) alkoxycarbonyl; aryloxycarbonyl; -aryl (C1-C4) alkoxycarbonyl; - (di) (C1-C4) (alkyl) aminocarbonyl • (C1-C4) (alkyl) arylaminocarbonyl; optionally substituted aryl; 5- or 6-membered cationic monocyclic heteroaryl; cationic bicyclic 8 to 11-membered heteroaryl; Cationic heterocycle of the following formula: Me N + N ~ Me An - isothiouronium -C (NH2) = N + H2; An; -isothiourea -C (NH2) = NH; and - S03; W.   9. Fluorescent dye of formula (I) according to any one of the preceding claims which comprises the ethylene group connecting the pyridinium moiety to the phenyl ortho or para position or 4-4 'positions, 2-2', or 2-4 . 15   10. Fluorescent dye of formula (I) according to any one of the preceding claims, chosen from the dyes: NNNOOO ~~ SH An SO An- N / N + / N / \ ùSH 3An- 102An- 2An- NNI, SH N \ ~ INI ~ SH 2An- NN 2An- ùN O 2An - \ ~ \ N ~. Name \ NH N \ OHOS ~ N \ SH An- An- / HS S \ / NH lN H ùN + / o ù An ùN + 2An- N \ \ OH An- H An- / \ O> / \ O SH O SH 2An- N / NJ An- ~~ SH \ N + / o / SH o ~ 3An- NN ~~ \ I / O SH An- ~ I ~ O ~ \ N + J ~~ O ~ N + ~ NN- SH An- \ oo ~ s, Anso3-An- 2An- 2AnOSH An- SH 2An- WAn- Year SO3 2An- SH ~ N 1, D ~ S \ N Name / 2An- HS. N + / / NI I. \ \ / N \ \ 2An- SH 2An o \ N + 'SN o Where SH N An- / \ / ùN An-HS NN ~ p' `- \ o S Y N Y - 2An-An O Ni ~ N 3An \ N ~~ I \ N ~~ ~. Y Y N N Y Y Y N Y N N O Y N N HZN "-N + ~ N -N + NN HS Y / N + 2An -N ~ \ N + ~ N ~ SH An HS 2Anwith An-, identical or different, representing a anionic counterion, and M + representing an alkali metal.   11. A dye composition comprising in a suitable cosmetic medium, a heterocyclic thiol fluorescent dye of formula (I) as defined in any one of claims 1 to 10.   12. dye composition comprising in a suitable cosmetic medium, at least one heterocyclic thiol fluorescent dye of formula (I) as defined in any one of claims 1 to 10 and at least one reducing agent.   13. Dyeing composition according to the preceding claim wherein the reducing agent is chosen from: cysteine, homocysteine, thiolactic acid, the salts of these thiols, phosphines, bisulfite, sulfites, thioglycolic acid, as well as its esters, borohydrides and their derivatives, the sodium, lithium, potassium, calcium and quaternary ammonium salts; catecholborane.   14. Composition according to any one of claims 11 to 13, wherein the heterocyclic thiol fluorescent dye of formula (I) is present in an amount of between 0.001 and 50% by weight relative to the total weight of the composition.   15. A method for dyeing keratin materials, wherein a dye composition as defined in any one of claims 11 to 14, comprising, in a suitable cosmetic medium, at least one heterocyclic thiol fluorescent dye of formula (I ) as defined in any one of claims 1 to 10, optionally in the presence of a reducing agent capable of reducing the disulfide bonds of keratin materials.   16. The method of dyeing according to the preceding claim wherein when the heterocyclic thiol fluorescent dye of formula (I) comprises a protection Y group, the application is preceded by a deprotection step.   17. A method of dyeing keratin materials according to the preceding claim characterized in that the keratin materials are dark keratinous fibers having a pitch of less than or equal to 6, preferably less than or equal to 4.   18. A method according to any one of claims 15 to 17 wherein the reducing agent is applied before or after the application of thiol fluorescent dye.   The process of any one of claims 15 to 18, wherein the composition comprises an oxidizing agent.   20. A method according to any one of claims 15 to 19 comprising a further step of applying to the keratin fibers an oxidizing agent.   21. A multi-compartment device in which a first compartment contains a dye composition comprising a fluorescent dye thiol as defined in claims 1 to 10 and a second compartment contains a reducing agent capable of reducing the disulfide bonds of keratin materials.   22. Device according to the preceding claim comprising a third compartment which contains an oxidizing agent.   23. Use of heterocyclic thiols fluorescent dyes as defined in claims 1 to 10 for dyeing dark human keratin fibers.   24. Use according to claim 23 for lightening dark keratin fibers.   25. Use according to claims 23 and 24 characterized in that the keratinous fibers have a pitch of less than 6.30