WO2018115093A1

WO2018115093A1 - Acidic composition comprising thiolactones and process for treating keratin materials using same

Info

Publication number: WO2018115093A1
Application number: PCT/EP2017/083761
Authority: WO
Inventors: Christian Blaise
Original assignee: L'oreal
Priority date: 2016-12-21
Filing date: 2017-12-20
Publication date: 2018-06-28
Also published as: FR3060345A1; FR3060345B1

Abstract

The present invention relates to i) a process for treating keratin materials, especially human keratin fibres, comprising the application of an acidic aqueous composition comprising at least one particular thiolactone, in particular for shaping keratin fibres and/or straightening/relaxing, ii) an acidic aqueous composition comprising the particular thiolactone(s), iii) and novel thiolactones, iv) a process for preparing the novel thiolactones, and v) the use of said thiolactones for treating keratin fibres.

Description

ACIDIC COMPOSITION COMPRISING THIOLACTONES AND PROCESS FOR TREATING KERATIN MATERIALS USING SAME

In the hair field, consumers wish to have available compositions which make it possible to introduce a temporary change to their head of hair, while targeting good shape retention of the effect produced. In general, it is desired for the change to withstand shampooing for at least fifteen days or even more, depending on the nature of said change.

Heat treatments are generally used to modify the shape of the head of hair in a long-lasting manner. These treatments allow a visual modification of the appearance of the hairstyle, combining a decrease in the degree of frizziness, a reduction in overall volume of the head of hair, a decrease in little curls, a gain in manageability, a straighter overall appearance, a substantial gain in sheen, and a resistance to humidity and to heat in order to maintain the hairstyle throughout the day.

Moreover, this type of treatment has the advantage of facilitating the daily maintenance of the head of hair, with the use of fewer care products, in particular rinse- out care products such as hair conditioners or masks, or leave-in care products such as sera, care creams or balms, or taming mousses. Drying of the hair is facilitated, with a much shortened blow-drying time and a decrease in the daily use of flat irons, in terms both of time and intensity. This thus makes it possible to limit the risks of damaging the hair through combined factors of mechanical and thermal stress.

Several techniques are combined with these heat treatments. A first technique is based on the use of compositions based on thiol-based reducing agents. These techniques require strict adherence to the application conditions recommended by the suppliers, in particular in terms of amount and leave-in time. In addition, they may be contraindicated on hair that is too sensitized and may not be compatible with same-day application of other treatments, such as dyeing or bleaching operations. Moreover, they have an unpleasant smell.

Another technique is based on the use of compositions based on formol (or formaldehyde) and derivatives thereof. These treatments have the particular feature of being robust, perfectly compatible with all the other conventional hair treatments, such as the thiol-based straightening operations previously mentioned, alkaline relaxing operations, dyeing or bleaching operations of all types, performed before or after. They provide the hair with excellent manageability, a very bright sheen and easy daily care. However, in the event of repeated applications, further damage to the hair occurs, which can lead to breaking of the hairs. Furthermore, for toxicological reasons, the use of some of these compounds is now prohibited and/or regulated. It is therefore increasingly sought to avoid the use of such substances, which may prove to be aggressive to the hair and other keratin materials.

Another technique is based on the use of compositions based on acids, and most particularly on the use of glyoxylic acid. Patent application WO 201 1 /104 282 thus proposed a novel process for semi-permanently straightening the hair, which consists in applying an a-keto acid solution to the hair for 15 to 120 minutes, then drying and, finally, straightening the head of hair with an iron at a temperature of about 200 'Ό. The a-keto acid employed is preferably glyoxylic acid. However, it has been noted that glyoxylic acid may not be well tolerated, in particular when the scalp is sensitive and/or irritated. Its volatility, amplified by the use of heat from the iron, can also be a problem. Furthermore, the compositions of the prior art may adversely affect the hair and/or adversely affect its colour. Treatments using a composition comprising a base combined with a heat treatment have also been proposed for straightening the hair. Such treatments make it possible to obtain good relaxing of curls, but can lead to impairment of the hair fibre. EP 1837010 especially describes a straightening/relaxing process using a composition comprising sodium hydroxide and a heat treatment. WO 2007/144707 describes a straightening/relaxing process using a composition comprising a non-hydroxylated base such as monoethanolamine or ethylenediamine, combined with a heat treatment. WO 2009/1 17344 also describes a straightening/relaxing process using a composition comprising a non-hydroxylated base and a protein-denaturing agent, combined with a heat treatment. In order to limit hair fibre impairment, it has also been proposed to use compositions comprising weak acids at alkaline pH, combined with a heat treatment. WO 2010/049434 describes, for example, a straightening/relaxing process in which a composition comprising a dicarboxylic acid, such as maleic acid, and a heat treatment are applied.

There is still a need to develop a process for treating keratin materials, in particular keratin fibres such as the hair, more particularly a process for shaping or straightening/relaxing keratin fibres in a way that is efficient and long-lasting, while at the same time limiting degradation of the hair, in particular in a way that is persistent with respect to successive shampoo washes.

This or these aims are achieved by the use of an aqueous composition comprising at least one compound of formula (I) below:

(I)

and also the organic or mineral acid or base salts thereof, the optical isomers thereof, the geometrical isomers thereof, the tautomers thereof, and the solvates thereof such as hydrates;

in which formula (I):

• Y represents an oxygen or sulfur atom or a group NR with R representing a hydrogen atom or a (CrC₆)alkyl or hydroxy(CrC₆)alkyl group; preferably, Y represents an oxygen atom;

^• Ri, R₂, R3, R₄, R5 and R₆, which may be identical or different, represent:

i) a hydrogen atom;

ii) hydroxyl;

iii) amino -NR'R", with R' and R", which may be identical or different, representing a hydrogen atom or a (CrC₆)alkyl or hydroxy(CrC₆)alkyl group;

iv) cyano;

v) -(Y')p-C(Y")-(Y"')_q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , preferably with p+q = 0 or 1 , Y', Y" and Y'", which may be identical or different, representing an oxygen or sulfur atom, or NR with R as defined previously, preferably Y', Y" and Y'" represent an oxygen atom;

vi) optionally substituted (CrC₆)alkyl;

vii) optionally substituted (C₂-C₆)alkenyl;

viii) optionally substituted (CrC₆)alkoxy;

preferably, said alkyl, alkenyl or alkoxy groups being optionally substituted with one or more groups chosen from hydroxyl and -(0)_t-C(0)-R₈ with t being equal to 0 or 1 , R₈ represents a) a hydrogen atom, b) a hydroxyl group, c) (Ci-

C₆)alkyl, d) (CrC₆)alkoxy, e) (di)(Ci-C₆)(alkyl)amino, f) (di)hydroxy(d- C₆)alkylamino;

or alternatively:

ix) Ri and R₃ together form a covalent bond;

x) Ri and R₂, and/or R₃ and R₄, and/or R₅ and R₆ form, together with the carbon atom that bears them, a double bond oxo =0 or

with R₉ and R10 representing a) a hydrogen atom or a group chosen from b) hydroxyl, c) (Ci- C₆)alkyl optionally substituted with one or more hydroxyl groups, and d) (C₂- C₆)alkenyl, e) -(Y')p-C(Y")-(Y"')_q-R₇ with Y', Y", Y'", p, q and R₇ being as defined previously;

• n represents an integer between 0 and 6 inclusive, particularly between 0 and 4 inclusive, more particularly between 0 and 3 inclusive, and, preferably, n is equal to 1 ;

it being understood that:

- when n is greater than or equal to 2, then the contiguous groups C(R₅)-R6 may be identical or different; and

- said composition is at acidic pH.

Another subject of the invention is a process for treating keratin materials, in particular keratin fibres, especially human keratin fibres such as the hair, for shaping keratin fibres and/or straightening/relaxing said materials, using the compound(s) of formula (I) as defined previously.

Another subject of the invention is the compounds of formula (I) as defined previously.

Another subject of the invention is a process for preparing the compounds of formula (I) as defined previously.

Another subject of the invention is the cosmetic use of the compounds of formula

(I) as defined previously for treating keratin fibres, especially human keratin fibres such as the hair, preferably for shaping keratin fibres and/or straightening/relaxing said fibres.

The compounds of formula (I) of the invention, as defined previously, make it possible in particular to obtain good relaxing of curls, that is long-lasting in particular with respect to shampooing operations, while at the same time limiting degradation of the hair.

Other characteristics and advantages of the invention will emerge more clearly on reading the description and the examples that follow.

In the following text, unless indicated otherwise:

^■ the term "organic or mineral acid salt means cosmetically acceptable organic or mineral acid salts, more particularly the salts chosen from a salt derived from i) hydrochloric acid HCI, ii) hydrobromic acid HBr, iii) sulfuric acid H2SO4, iv) alkylsulfonic acids: Alk-S(0)₂OH such as methanesulfonic acid and ethanesulfonic acid; v) arylsulfonic acids: Ar-S(0)₂OH such as benzenesulfonic acid and toluenesulfonic acid; vi) citric acid; vii) succinic acid; viii) tartaric acid; ix) lactic acid; x) alkoxysulfinic acids: Alk-0-S(0)OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H₃P0₄; xiii) acetic acid CH₃C(0)OH; xiv) triflic acid CF3SO3H; and xv) tetrafluoroboric acid HBF₄;

^■ the term "alkyl" means a linear or branched hydrocarbon-based radical containing from 1 to 8 carbon atoms, in particular from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, for example methyl, ethyl, n- propyl, isopropyl, butyl, n-pentyl, n-hexyl, preferably methyl ;

^■ the term "alkenyl" means a linear or branched hydrocarbon-based radical containing from 2 to 8 carbon atoms, in particular from 2 to 6 carbon atoms, preferably from 2 to 4 carbon atoms, and comprising at least one or more conjugated or non-conjugated unsaturations, such as ethylenyl, n-propylenyl, isopropylenyl, butylenyl, n-pentylenyl, n-hexylenyl ;

^■ the term "alkoxy" means an alkyl oxy group with "alkyl' or "alkenyl' as defined previously;

^■ the term "optionally substituted' preceding alkyl, alkenyl or alkoxy groups means that said groups may be substituted on the hydrocarbon -based radical with one or more groups, which may be identical or different, chosen from i) hydroxyl, ii) thiol, iii) halogen, iv) (Ci-C₄)alkoxy, v) hydroxy(C₂-C )alkoxy; vi) (di)hydroxy(Ci-C )(alkyl)amino, vii) cyano, viii) nitro(so), ix) R_a-Z_a-C(Zb)-Z_c- and x) Ra-Za-S(0)t-Zc- with Z_b representing an oxygen or sulfur atom or a group NR_a', Z_a and Z_c, which may be identical or different, representing a bond, an oxygen or sulfur atom or a group NR_a; R_a representing a hydrogen atom or a (Cr C )alkyl group and R_a' representing a hydrogen atom or an alkyl group and t being 1 or 2;

^■ moreover, the addition salts that may be used in the context of the invention are especially chosen from salts of addition with a cosmetically acceptable base such as the basifying agents as defined below, for instance alkali metal hydroxides such as sodium hydroxide or potassium hydroxide, aqueous ammonia, amines or alkanolamines;

^■ the term "relaxincf' includes, according to the invention, the relaxing, straightening or uncurling of Caucasian or African hair. The term "to relax" includes, according to the invention, the act of relaxing, straightening or uncurling of Caucasian or African hair;

^■ the expression "at least one" is equivalent to "one or more"; and

^■ the expression "inclusive" ^ a range of concentrations means that the limits of the range are included in the defined range.

The thiolactone(s) of formula (I) According to a particular embodiment of the invention, the compound(s) of formula (I) are such that n is zero, and preferably of formula (la):

(la)

in which formula (la):

• Ri, R₂, R3 and R₄ are as defined previously, in particular

identical or different, representing:

i) a hydrogen atom,

ii) -(0)_p-C(0)-(0)q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , with p+q = 0 or 1 ,

iii) (CrC₆)alkyl optionally substituted with one or more hydroxyl groups,

iv) (C₂-C₆)alkenyl,

or alternatively:

v) Ri and R₂, and/or R₃ and R₄, preferably R₃ and R₄, form, together with the carbon atom that bears them, a double bond oxo =0 or

with R₉ and R10 representing a hydrogen atom or a (CrC₆)alkyl group.

According to a particular embodiment of the invention, the compound(s) of formula (I) are such that n is 1 or 2, and referably of formula (lb):

(lb)

in which formula (lb):

• Ri, R₂, R3, R₄, R5 and R₆, which may be identical or different, represent: i) a hydrogen atom,

ii) hydroxyl,

iii) cyano,

iv) amino -NR'R", with R' and R", which may be identical or different, representing a hydrogen atom or a (CrC₆)alkyl or hydroxy(CrC₆)alkyl group;

v) -(Y')p-C(0)-(Y")q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , with Y' and Y", which may be identical or different, representing an oxygen atom or NR with R as defined previously, preferably with p+q = 0 or 1 ,

vi) (CrC₆)alkyl optionally substituted with one or more groups chosen from hydroxyl and -C(0)-R₈ with R₈ representing a) a hydrogen atom, b) a hydroxyl group, c) (CrC₆)alkoxy,

vii) (C₂-C₆)alkenyl,

viii) (CrC₆)alkoxy,

or alternatively:

ix) Ri and R₂, and/or R₃ and R₄, and/or R₅ and R₆ form, together with the carbon atom that bears them, a double bond oxo =0 or

with R₉ and Rio representing a) a hydrogen atom or a group chosen from b) hydroxyl, c) (Ci- C₆)alkyl.

According to a particular embodiment of the invention, the compound(s) of formula (I) are such that n is 1 , and preferably of formula (I'b):

(I'b)

in which formula (I'b):

• Ri, R₂, R3, R₄, R5 and R₆, which may be identical or different, are as defined previously, and in particular represent:

i) a hydrogen atom,

ii) hydroxyl,

iii) cyano, iv) amino -NR'R", with R' and R", which may be identical or different, representing a hydrogen atom or a (CrC₆)alkyl or hydroxy(CrC₆)alkyl group,

v) -(Y')p-C(0)-(0)q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, and Y' representing an oxygen atom or NR with R as defined previously, p and q, which may be identical or different, being equal to 0 or 1 , with p+q = 0 or 1 ,

vi) optionally substituted (CrC₆)alkyl,

vii) (C₂-C₆)alkenyl,

viii) (CrC₆)alkoxy,

said alkyl groups being optionally substituted with one or more groups chosen from hydroxyl and -(0)_t-C(0)-R₈ with t being equal to 0 or 1 , R₈ representing a) a hydrogen atom, b) a hydroxyl group, c) (CrC₆)alkyl, d) (CrC₆)alkoxy, e) (di)(Ci-C₆)(alkyl)amino, f) (di)hydroxy(Ci-C₆)alkylamino;

or alternatively:

with R₉ and Rio representing i) a hydrogen atom or a group chosen from ii) hydroxyl, iii) (Cr C₆)alkyl optionally substituted with one or more hydroxyl groups, in particular, R₃ and R₄ form, together with the oxygen atom, an oxo group and/or in particular, Ri and R₂ represent, together with the carbon atom,

According to another particular embodiment of the invention, the compound(s) of formula (I) are such that n is 2, and preferably of formula (l"b):

(l"b)

in which formula (l"b):

• Ri, R₂, R3, R₄, R5, Re, R'5 and R'₆, which may be identical or different, represent: i) a hydrogen atom,

ii) cyano,

iii) -C(0)-(0)_q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , vi) (CrC₆)alkyl optionally substituted with one or more groups chosen from hydroxyl and -C(0)-R₈ with R₈ representing a) a hydrogen atom, b) a hydroxyl group, c) (CrC₆)alkoxy,

or alternatively:

v) Ri and R₂, and/or R₃ and R₄, and/or R₅ and R₆ and/or R'₅ and R'₆ form, together with the carbon atom that bears them, a double bond oxo =0; in particular, R₃ and R₄, or R₅ and R₆ or R'₅ and R'₆ form, together with the carbon atom that bears them, a double bond oxo =0.

According to a particular embodiment of the invention, the compound(s) of formula (I) are such that n is 1 or 2, and is of formula (lc):

(lc)

in which formula (lc):

• R₂, R₄, R5 and R₆, which may be identical or different, represent:

i) a hydrogen atom,

ii) hydroxyl,

iii) cyano,

iv) amino -NR'R", with R' and R", which may be identical or different, representing a hydrogen atom or a (CrC₆)alkyl or hydroxy(CrC₆)alkyl group,

v) -(Y')p-C(0)-(0)q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , with Y representing an oxygen atom or NR with R as defined previously, with p+q = 0 or 1 ,

vii) (C₂-C₆)alkenyl,

viii) (CrC₆)alkoxy,

or alternatively: ix) R₅ and R₆ form, together with the carbon atom that bears them, a double bond oxo =0 or

with R₉ and Rio representing a hydrogen atom or a (Ci- C₆)alkyl group.

According to a more particular embodiment of the invention, the compounds of formula (I) are of formula (lc) and n is 1 .

According to another particular embodiment of the invention, the compound(s) of formula (I) are such that n is 2, and preferably of formula (I'c):

(I'c)

in which formula (I'c):

• R₂, R₄, R5, Re, '5 and R'₆, which may be identical or different, represent:

i) a hydrogen atom,

ii) hydroxyl,

iii) -(0)_p-C(0)-(0)q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , with p+q = 0 or 1 ,

iv) (CrC₆)alkyl,

v) (CrC₆)alkoxy.

More preferentially, the thiolactones of the invention are chosen from the following compounds:

1 2 3 4

5 6 7 8

265 266 267 and also the organic or mineral acid or base salts thereof, the optical isomers thereof, the geometrical isomers thereof, the tautomers thereof, and the solvates thereof such as hydrates.

Another subject of the invention is the compounds of formula (l"c):

o o

(l"c)

in which formula (l"c):

Rii and R12, which may be identical or different, represent a hydrogen atom or a (Cr C₆)alkyl group, such as methyl or ethyl.

More particularly, the compound(s) of formula (I) are chosen from the following thiolactones:

11 8

120 121 122

and also the organic or mineral base salts, the optical isomers, and the solvates such as hydrates.

More preferentially, the compound is of formula 116. Process for preparing the thiolactone(s)

Another subject of the invention is a process for preparing the compound of formula (l"c) as defined according to the following synthetic scheme:

which consists in reacting in step i) 3-butene-1 ,2,3-tricarboxylic acid (A) with at least one molar equivalent of thioacetic acid in particular in an aprotic organic solvent which is preferably halogenated, such as dichloromethane, or an ether such as THF, more particularly by heating the reaction medium to the reflux point of the solvent, preferably to a temperature of between 40 ^ and 80°C, to give compound (B); in step ii), compound (B) reacts with a strong organic or mineral acid such as hydrochloric acid, in particular in a polar protic solvent such as water, more particularly by heating to the reflux point of the solvent, preferably to a temperature of between 60 and 90 °C, to give the thiolactone (C); in steps iii) and v), compound (C) reacts with at least one equivalent of an alcohol R'n-OH or, respectively, R'12-OH, with R'n and R'12, which may be identical or different, representing a (CrC₆)alkyl group, in particular in a polar organic solvent such as ethyl acetate, preferably at low temperature such as O 'C, to give the monoesters (D) and (E), which can also, in the presence of alcohol, be esterified on the second carboxyl group in steps iv) and vi) to give the diester (F), compounds (D), (E) and (F) being able to be purified by chromatography, for example on a column of silica. Compounds (C), (D), (E) and (F) constitute all of the compounds of formula (l"c).

The composition of the invention:

The composition of the invention comprises one or more compounds of formula (I) as defined previously.

According to a particular embodiment, the composition comprises one or more compounds of formula (I) as defined previously, in an amount inclusively between 0.01 % and 50% by weight relative to the total weight of the composition, in particular between 0.1 % and 30%, more particularly between 1 % and 20%, preferentially between 2% and 15%, more preferentially between 5% and 10% by weight relative to the total weight of the composition.

According to a particular embodiment of the invention, the composition of the invention does not comprise any thiol-based reducing agent such as thiolactic acid; preferably, the composition does not comprise any reducing agent.

According to one embodiment of the invention, the composition does not comprise any alkaline agent.

The pH of the composition used in the process of the invention is greater than or equal to 1 or less than or equal to 6.9. Preferably, the pH of the composition ranges from 2. to 6 and more preferably from 3 to 5. The compositions

The composition(s) of the invention are cosmetic, i.e. they contain a physiologically acceptable medium, that is to say a medium that is compatible with human keratin materials such as the skin (of the body, face, around the eyes or the scalp), the hair, the eyelashes, the eyebrows, bodily hair, the nails or the lips.

The physiologically acceptable medium of the composition(s) used in the process according to the invention is advantageously an aqueous medium. It may be constituted, for example, of water or of a mixture of water and of at least one cosmetically acceptable organic solvent. Examples of organic solvents that may be mentioned include C₂-C₄ lower alcohols, such as ethanol and isopropanol; polyols, especially those containing from 2 to 6 carbon atoms, for instance glycerol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, dipropylene glycol or diethylene glycol; polyol ethers, for instance 2-butoxyethanol, propylene glycol monomethyl ether and diethylene glycol monomethyl ether or monoethyl ether; and mixtures thereof.

The cosmetic compositions of the invention are preferably aqueous and then comprise water at a concentration ranging from 10% to 99.5%, better still from 30% to 95% and even better still from 50% to 90% by weight relative to the total weight of the composition.

The composition used according to the invention may also contain one or more cosmetic additives chosen from nonionic, anionic, cationic and amphoteric surfactants, vitamins and provitamins, including panthenol, sunscreens, fillers, colorants, nacreous agents, opacifiers, sequestrants, film-forming polymers, cationic, anionic or neutral polymers, associative polymers, plasticizers, silicones, thickeners, oils, antioxidants, antifoams, moisturizers, emollients, penetrants, fragrances and preserving agents; preferably one or more nonionic, anionic, cationic or amphoteric surfactants, cationic, anionic or neutral polymers, or associative polymers.

Depending on their nature and the purpose of the composition, the usual cosmetic ingredients may be present in usual amounts, which can be readily determined by a person skilled in the art and which may be, for each ingredient, between 0.01 % and 80% by weight. A person skilled in the art will take care to select the ingredients included in the composition, and also the amounts thereof, so that they do not harm the properties of the compositions of the present invention.

The compositions used in the process according to the invention may be in any formulation form conventionally used, and especially in the form of an aqueous, alcoholic or aqueous-alcoholic, or oily, solution or suspension; a solution or a dispersion of the lotion or serum type; an emulsion, in particular of liquid or semi-liquid consistency, of the O/W, W/O or multiple type; a suspension or emulsion of soft consistency of cream (O/W) or (W/O) type; an aqueous or anhydrous gel, or any other cosmetic form. These compositions may be packaged in pump-action bottles or in aerosol containers, so as to apply the composition in vaporized (lacquer) form or in the form of a mousse. Such packaging forms are indicated, for example, when it is desired to obtain a spray or a mousse, for treating the hair. In these cases, the composition preferably comprises at least one propellant. pH of the composition(s):

The composition which comprises the thiolactone(s) of formula (I) as defined previously is at acidic pH, i.e. less than 7, in particular inclusively between 0.5 and 6.8 and more particularly between 1 and 6.5. According to a particular embodiment of the invention, the composition which comprises the thiolactone(s) of formula (I) as defined previously is aqueous and its pH is between 2 and 6, preferentially between 3 and 5.

The pH values may be adjusted with an organic or mineral acid, or with an alkaline agent chosen from mineral or organic or hybrid alkaline agents or mixtures thereof.

The term "organic acid" means an acid, i.e. a compound that is capable of releasing a cation or proton H⁺ or H₃0⁺, in aqueous medium, which comprises at least one optionally unsaturated, linear or branched C1-C20 hydrocarbon-based chain, a (hetero)cycloalkyl or (hetero)aryl group and at least one acidic chemical function chosen in particular from carboxyl C(0)OH, sulfuric S0₃H, S0₂H, and phosphoric P0₃H₂, P0₄H₂.

More particularly, the acids used are chosen from hydrochloric acid HCI, hydrobromic acid HBr, sulfuric acid H₂S0₄, alkylsulfonic acids: (Ci-C₆)Alk-S(0)₂OH such as methanesulfonic acid and ethanesulfonic acid; arylsulfonic acids: Ar-S(0)₂OH such as benzenesulfonic acid and toluenesulfonic acid; (CrC₆)alkoxysulfinic acids: Alk- 0-S(0)OH such as methoxysulfinic acid and ethoxysulfinic acid; aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; phosphoric acid H₃P0₄; triflic acid CF3SO3H and tetrafluoroboric acid HBF₄, and carboxylic acid(s) of formula (K) below:

in which formula (K) or a salt thereof:

A represents a saturated or unsaturated, cyclic or non-cyclic, and aromatic or non- aromatic hydrocarbon-based group, which is monovalent when t is 0 or polyvalent when t is greater than or equal to 1 , comprising from 1 to 50 carbon atoms, which is optionally interrupted with one or more heteroatoms and/or optionally substituted, especially with one or more hydroxyl groups; preferably, A represents a monovalent (CrC₆)alkyl group or a polyvalent (CrC₆)alkylene group optionally substituted with one or more hydroxyl groups.

Particularly, the carboxylic acid(s) of formula (K) as defined previously, and preferably the acid(s) used, are an alpha-hydroxy acid such as lactic acids, glycolic acids, tartaric acids or citric acids.

The mineral alkaline agent(s) are preferably chosen from aqueous ammonia, alkaline carbonates or bicarbonates such as sodium or potassium carbonates and sodium or potassium bicarbonates, sodium hydroxide or potassium hydroxide, or mixtures thereof.

According to an advantageous embodiment of the invention, the alkaline agent(s) are organic amines, i.e. they contain at least one substituted or unsubstituted amino group.

The organic alkaline agent(s) are more preferentially chosen from organic amines with a pK_b at 25^qC of less than 12, preferably of less than 10 and even more advantageously of less than 6. It should be noted that it concerns the pK_b corresponding to the function having the highest basicity.

Hybrid compounds that may be mentioned include the salts of the amines mentioned previously with acids such as carbonic acid or hydrochloric acid.

The organic alkaline agent(s) are chosen, for example, from alkanolamines, oxyethylenated and/or oxypropylenated ethylenediamines, amino acids and the compounds of formula (L) below:

N - W - N

R R _(L)

in which formula (L):

· W is a divalent CrC₆ alkylene radical optionally substituted with a hydroxyl group or a CrC₆ alkyl radical, and/or optionally interrupted with one or more heteroatoms such as oxygen or NR^U;

R^x, R^y, R^z, R* and R^u, which may be identical or different, represent a hydrogen atom or a CrC₆ alkyl, d-Ce hydroxyalkyl or CrC₆ aminoalkyl radical.

Preferably, the alkanolamine is ethanolamine (or monoethanolamine).

In one variant of the invention, the composition comprises, as alkaline agent, one or more alkanolamines (preferably ethanolamine) and aqueous ammonia. In this variant, the alkanolamine(s) are present in a predominant amount relative to the aqueous ammonia. More preferentially, the pH is adjusted so that the pH is between 2.5 and 9.5 inclusive, or between 1 and 6 inclusive, more particularly between 2 and 5 and preferably between 3 and 4, by means of NH₄OH or citrate buffer. Process for treating keratin fibres

Thus, one subject of the present invention is a process for treating keratin materials, in particular keratin fibres, especially human keratin fibres such as the hair, comprising:

a) the application to said keratin materials of an acidic aqueous composition containing at least one thiolactone chosen from those of formula (I) as defined previously, and also the organic or mineral acid or base salt forms thereof, the optical isomers thereof, and the solvates thereof such as hydrates.

According to a particular embodiment of the invention, the process is a process for treating keratin materials, especially human keratin fibres such as the hair, comprising:

a) the application to said keratin materials of an acidic aqueous composition containing at least one thiolactone chosen from those of formula (I) as defined previously, and also the organic or mineral acid or base salt forms thereof, the optical isomers thereof, and the solvates thereof such as hydrates,

b) followed by step of straightening/relaxing said keratin materials by means of a straightening iron at a temperature of at least 100°C or a step of shaping the keratin fibres.

The straightening iron is used at a temperature of at least 100 °C, preferably at a temperature between, limits included, 100°C and 300 ^, preferably between 120°C and 280 °C, more preferably between 150 ^<€ and 250 °C, and better still between 200 and 250 ^<€.

The composition of the invention may be applied to dry or wet keratin materials, preferably to dry or wet hair, preferably to dry hair.

The bath ratio of the applied composition may range from 0.1 to 10, more particularly from 0.2 to 5 and preferably between 0.5 and 3. The term "bath ratio" means the ratio between the total weight of the applied composition and the total weight of keratin materials to be treated.

The process of the invention may comprise other intermediate steps aimed at improving the straightening of the keratin fibres.

In particular, the step of applying the composition may be followed by a leave-on time. The leave-on time, namely the time of contact of the composition on the hair, is preferably at least 5 minutes, preferably between 10 and 60 minutes and preferably between 15 and 45 minutes.

Rinsing of the hair may optionally be envisaged after the application of the composition and optionally the leave-on time.

The hair may then optionally be wrung dry, preferably wrung dry.

A step of drying with a hairdryer, optionally combined with straightening with a brush (blow-drying) may be envisaged before the step of straightening using a straightening iron.

According to a particular embodiment, the straightening with the straightening iron is performed in several passes on the hair, in general 3 to 10 passes.

According to a particular embodiment, the process of the invention comprising the steps of applying the composition according to the invention to the hair, then of straightening with an iron, is performed one or more times, optionally separated by one or more cosmetic treatments, preferably shampoo washes, until the desired shape or shape intensity is obtained.

According to a particular embodiment of the invention, the process for treating keratin materials of the invention does not include any thiol-based reducing agent such as thiolactic acid; preferably, the process does not include any reducing agent.

According to a particular embodiment, the process for treating keratin materials does not include a lanthionization step. Preferably, the process for treating keratin fibres does not include an alkaline agent.

The examples that follow serve to illustrate the invention without, however, being limiting in nature.

EXAMPLES

I) General synthetic process for the novel compounds of the invention Thioacetic acid is added to the double bond of 3-butene-1 ,2,3-tricarboxylic acid in an apolar solvent such as dichloromethane or tetrahydrofuran at a temperature of between 40 ^ and 80 'Ό to give the triacid (B). This compound is then reacted in a strong acid as reagent and solvent such as 6N hydrochloric acid at a temperature of between ΘΟ'Ό and 90^ to give the thiolactone (116). This compound may then be reacted under standard peptide coupling conditions (for instance DCC, temperature of 0°C, ethyl acetate) in the presence of the desired alcohol. Depending on the number of equivalents of peptide coupling agent and of alcohol reacted together, compounds (117) to (122) may be obtained after purification on a column of silica.

esterification

- 117 to 122

Compound (B):

1st step: Synthesis of 4-(acetylsulfanyl)butane-1 ,2,3-tricarboxylic acid (B)

(B)

Procedure:

18.8 g of 3-butene-1 ,2,3-tricarboxylic acid (0.1 mol) were placed in 300 ml of tetrahydrofuran in a 500 ml three-necked flask equipped with a thermometer, a condenser, an argon inlet, a bubbler, a dropping funnel and a magnetic stirrer. The medium was cooled to between 0 and δ'Ό with an ice bath. A solution containing 8.6 ml of thioacetic acid (0.12 mol) in 100 ml of tetrahydrofuran was then added dropwise while keeping the temperature below δ'Ό. The reaction medium, with stirring, was left to return to room temperature and then refluxed for 4 hours while monitoring the reaction progress by thin-layer chromatography. The reaction medium was left at room temperature for 8 hours and then concentrated under reduced pressure. The residue thus obtained was taken up in cold ethyl ether to crystallize the expected compound. The precipitate obtained was then filtered on a sinter funnel and dried under vacuum in the presence of P₂0₅ to constant weight. A white powder, compliant on NMR, was thus obtained.

2nd step: Synthesis of 4-(carboxymethyl)-5-oxotetrahvdrothiophene-3-carboxylic acid

Procedure:

12 g of 4-(acetylsulfanyl)butane-1 ,2,3-tricarboxylic acid (0.045 mol) (compound (B)) were placed in 200 ml of 6N hydrochloric acid (1 .2 mol HCI) in a 250 ml three-necked flask equipped with a condenser, a thermometer and a magnetic stirrer. The reaction medium was stirred for 15 minutes at room temperature and then maintained at 90 'Ό for 4 hours. The reaction progress was monitored by thin-layer chromatography. The mixture was allowed to return to room temperature and then evaporated under reduced pressure. The powder thus obtained was then taken up in ethyl ether, filtered on a sinter funnel and then dried under vacuum in the presence of P2O5 to constant weight. A white powder, compliant with the expected product on NMR, was thus obtained.

Application examples (straightening):

ΙΠ-1 - Application protocol: Before applying the active agents, the hair is washed according to the following protocol:

Step 1 : Application of cleansing shampoo (so as to obtain clean hair):

1 . Weigh out 0.4 ml of cleansing shampoo per gram of hair in a watch glass. 2. Wet the lock with tap water, passing the lock between the fingers for 5 seconds.

3. Drain the lock of hair dry between two fingers.

4. Apply the cleansing shampoo along the lock of hair (from the root to the end homogeneously).

5. Massage the lock gently between two fingers along its length (so as to work the shampoo into a lather) for 15 seconds from top to bottom (without making knots).

6. Rinse under tap water for 10 seconds, passing the lock between the fingers.

7. Drain the lock dry between two fingers.

8. Comb the lock.

9. Dry the lock with a hairdryer.

Protocol for applying the active agents of the invention:

Step 2: Application of the test product of the invention:

1 . Prepare the solution of the active agent at 10% w/w in water or an aqueous- alcoholic solution containing no more than 30% alcohol.

2. Place a 2.7 g lock in a chute.

3. Apply the solution of the test product along the lock of hair (from the root to the end homogeneously).

4. Leave it on for 30 minutes.

5. Drain the lock dry between two fingers.

6. Blow dry 20 times.

7. Pass the straightening iron through 10 times at 230 ^ over the course of 30 seconds.

The locks are then shampooed according to the following protocol, which may be repeated according to the number of shampoo washes performed:

Step 3: Application of Shampoo (Persistence):

1 . Weigh out 0.4 ml of DOP camomile shampoo per gram of hair in a watch glass.

2. Wet the lock with tap water, passing the lock between the fingers for 5 seconds. 3. Drain the lock of hair dry between two fingers.

6. Rinse under tap water for 10 seconds, passing the lock between the fingers.

7. Drain the lock dry between two fingers.

8. Comb the lock.

9. Repeat steps 4 to 8 as many times as there are shampoo washes to be performed (1 to 10 shampoo washes).

10. Dry the lock under a hood.

Example (1 ) of application with gamma-thiobutyrolactone at 10% by weight in water and 30% by weight of ethanol, sponta = 5.4.

Example (2) of application with thiophen-2(5H)-one at 10% by weight in water and 30% by weight of ethanol, spontaneou

Example (3) of application with 4-hydroxythiophen-2(5H)-one at 10% by weight in water and 30% by weight of ethanol, spontaneous pH = 2.1 .

From photos 1 to 4, it is seen from the above results that the locks treated with the thiolactones of the invention make it possible to obtain straightening that persists even after 10 shampoo washes. There is indeed durability of the straightening effect.

Study of the visualization of thiol with ABDF on sections of treated hair

It is known from the literature that the visualization of thiols on sections of keratin fibres such as the hair may be performed using 4-(aminosulfonyl)-7-fluoro-2,1 ,3- benzoxadiazole, also known as ABD-F, which is a specific marker for thiols. Reaction:

A comparative study is performed to differentiate the formation of thiol as a function of the treatments performed. The following bibliographic reference is relied on to do this: Journal of Textile Research, David J. Evans, 1989, 59, pages 569-576 - A Method for Determining the Penetration of Reducing Agents into Wool Using Fluorescence Microscopy

Protocol for treatment of keratin fibres followed by visualization with ABDF:

1 . Preparation of the ABDF solution:

Chemical products:

- EDTA (disodium salt) or disodium salt of ethylenediaminetetraacetic acid dihydrate [6381 -92-6]

- Sodium dodecyl sulfate (or sodium lauryl sulfate). [151 -21 -3]

- Sodium tetraborate decahydrate (or borax). [1303-96-4]

- 37% hydrochloric acid [7647-01 -0]

- 4-(Aminosulfonyl)-7-fluoro-2,1 ,3-benzoxadiazole [91366-65-3] ABD-F

Preparation of the borate buffer:

Weigh out 37.2 mg of EDTA.

Weigh out 576.8 mg of sodium lauryl sulfate.

Weigh out 954.5 mg of borax

Place the three weighed products in a 100 ml beaker and then add 50 ml of water. Adjust the pH to 8 with hydrochloric acid. Make up to 100 g with the required amount of water.

The borate buffer solution thus prepared may be stored in a refrigerator.

Preparation of the ABD-F solution:

Weigh out 2.16 mg of ABD-F in a 5 ml beaker.

Make up to 5 ml with the borate buffer.

Maintain magnetic stirring until dissolution of the ABD-F is complete.

2. Protocols for sections of hair/visualization with ABDF:

Production of the 10 urn sections of hair

The treated hair is divided into 40 fibres and then coated with PTFE for inclusion as rapidly as possible into an LR white resin (medium-grade acrylic resin) and its accelerator in proportions of 2 g of resin per 2 drops of accelerator.

Using these inclusions, dried for a minimum of 1 hour, 10 μηι cross sections are produced using a Leica RM 2265 microtome equipped with knives. The sections are then deposited on a microscope slide (10 sections)

Revelation with ABDF on the hair sections is then performed according to the following protocol:

- place one drop of ABDF solution prepared beforehand onto the sections

- leave to act for 30 seconds

- dab with a paper towel

- rinse with distilled water three times, dabbing each time.

The preparations are then dried and included in Dako balm between a microscope slide and a cover glass.

The slides are then observed with a Leica CTR6000 microscope with filter D; given that in the case of theoretical ABD-F: excitation wavelength AE_xc = 378 nm, emission wavelength Asm = 502 nm, filters A, A4 and D may be used.

3. Hair treatment protocol:

The hair treated is natural Caucasian hair containing 90% white hairs (90% NW). blank Protocol :

A 1 g lock of hair was placed in a chute at room temperature, and 1 0 ml of a 70%/30% water/ethanol mixture adjusted to pH 5.7 with hydrochloric acid solution were then added. The lock was left for 30 minutes at room temperature and was then wrung dry and rinsed with distilled water for 3 x20 seconds with osmosed water (1 50 ml, 200 ml, 200 ml). The treatment with LR resin was then performed as indicated above. qamma-Thiobutyrolactone protocol without heat:

A 1 g lock of hair was placed in a chute at room temperature, and 1 0 ml of a 1 M solution of gamma-thiobutyrolactone at pH 5.7 (spontaneous pH) were then added. The lock was left for 30 minutes at room temperature and was then wrung dry and rinsed with distilled water for 3 x20 seconds with osmosed water (1 50 ml, 200 ml, 200 ml). The treatment with LR resin was then performed as indicated above: the sections were produced and the localization of the SH functions was visualized by microscope with ABDF.

qamma-Thiobutyrolactone protocol with heat:

A 1 g lock of hair was placed in a chute at room temperature, and 1 0 ml of a 1 M solution of gamma-thiobutyrolactone at pH 5.7 (spontaneous pH) were then added. The lock was left for 30 minutes at room temperature and was then wrung dry and rinsed with distilled water for 3 x20 seconds with osmosed water (1 50 ml, 200 ml, 200 ml). Blow-drying was then performed ( 1 0 passes), followed by straightening with a straightening iron (1 0 passes). The treatment with LR resin was then performed as indicated above: the sections were produced and the localization of the SH functions was visualized by microscope with ABDF.

Thioqlvcolic acid protocol at pH:

A 1 g lock of hair was placed in a chute at room temperature, and 10 ml of a 1 M solution of thioglycolic acid adjusted to pH 9 with aqueous ammonia were then added. The lock was left in contact with the solution (1 minute, 2 minutes, 5 minutes) at room temperature and was then wrung dry and rinsed with distilled water for 3x20 seconds with osmosed water (150 ml, 200 ml, 200 ml). The treatment with LR resin was then performed as indicated above: the sections were produced and the localization of the SH functions was visualized by microscope with ABDF.

Results

It is seen from photographs 5 to 12 that, at an equivalent concentration, the gamma-thiobutyrolactone of the invention at acidic pH with an application of heat makes it possible to straighten the keratin fibres in an identical manner to that of thioglycolic acid at pH 9, without proceeding via penetration into the core of said fibres.

Claims

1. Aqueous composition comprising one or more compounds of formula (I) below:

(I)

in which formula (I):

· Y represents an oxygen or sulfur atom or a group NR with R representing a hydrogen atom or a (CrC₆)alkyl or hydroxy(CrC₆)alkyl group; preferably, Y represents an oxygen atom;

• Ri, R₂, R3, R₄, R5 and R₆, which may be identical or different, represent:

i) a hydrogen atom,

ii) hydroxyl,

iv) cyano,

v) -(Y')p-C(Y")-(Y"')q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , Y', Y" and Y'", which may be identical or different, representing an oxygen or sulfur atom, or NR with R as defined previously, preferably Y', Y" and Y'" represent an oxygen atom,

vi) optionally substituted (CrC₆)alkyl,

vii) optionally substituted (C₂-C₆)alkenyl,

viii) optionally substituted (CrC₆)alkoxy,

preferably, said alkyl, alkenyl or alkoxy groups being optionally substituted with one or more groups chosen from hydroxyl and -(0)_t-C(0)-R₈ with t being equal to 0 or 1 , R₈ represents a) a hydrogen atom, b) a hydroxyl group, c) (Ci- C₆)alkyl, d) (CrC₆)alkoxy, e) (di)(Ci-C₆)(alkyl)amino, f) (di)hydroxy(d- C₆)alkylamino;

or alternatively:

x) Ri and R₃ together form a covalent bond; xi) Ri and R₂, and/or R₃ and R₄, and/or R₅ and R₆ form, together with the carbon atom that bears them, a double bond oxo =0 or

with R₉ and Rio representing a) a hydrogen atom or a group chosen from b) hydroxyl, c) (Ci- C₆)alkyl optionally substituted with one or more hydroxyl groups, and d) (C₂- C₆)alkenyl, e) -(Y')p-C(Y")-(Y"')_q-R₇ with Y', Y", Y'", p, q and R₇ being as defined previously;

• n represents an integer between 0 and 6 inclusive, particularly between 0 and 4 inclusive, more particularly between 0 and 3 inclusive, and, preferably, n is equal to 0, 1 or 2;

it being understood that:

- said composition is at acidic pH.

2. Composition according to the preceding claim, in which the compound(s) of formula (I) are such that n is zero, and preferably of formula (la):

(la)

in which formula (la):

• Ri, R₂, R3 and R₄ are as defined previously, in particular

identical or different, representing:

i) a hydrogen atom,

iii) (CrC₆)alkyl optionally substituted with one or more hydroxyl groups,

iv) (C₂-C₆)alkenyl,

or alternatively:

with R₉ and R₁0 representing a hydrogen atom or a (CrC₆)alkyl group.

3. Composition according to Claim 1 , in which the compound(s) of formula (I) are such that n is 1 or 2, and preferably of formula (lb):

(lb)

in which formula (lb):

i) a hydrogen atom,

ii) hydroxyl,

iii) cyano,

iv) -(Y')p-C(0)-(Y")q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , with Y' and Y", which may be identical or different, representing an oxygen atom or NR with R as defined previously, preferably with p+q = 0 or 1 ,

v) (CrC₆)alkyl optionally substituted with one or more groups chosen from hydroxyl and -C(0)-R₈ with R₈ representing a) a hydrogen atom, b) a hydroxyl group, c) (CrC₆)alkoxy,

vi) (C₂-C₆)alkenyl,

vii) (CrC₆)alkoxy,

or alternatively:

viii) Ri and R₂, and/or R₃ and R₄, and/or R₅ and R₆ form, together with the carbon atom that bears them, a double bond oxo =0 or

with R₉ and R10 representing a) a hydrogen atom or a group chosen from b) hydroxyl, c) (Ci- C₆)alkyl.

4. Composition according to either of Claims 1 and 3, in which compound(s) of formula (I) are such that n is 1 , and of formula (I'b):

(I'b)

in which formula (I'b):

^• Ri, R₂, R3, R₄, R5 and R₆, which may be identical or different, are as defined in Claim 1 , and in particular represent:

i) a hydrogen atom,

ii) hydroxyl,

iii) cyano,

iv) -(0)_p-C(0)-(0)q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , with p+q = 0 or 1 ,

v) optionally substituted (CrC₆)alkyl,

vi) (C₂-C₆)alkenyl,

vii) (CrC₆)alkoxy,

said alkyl groups being optionally substituted with one or more groups chosen from hydroxyl and -(0)_t-C(0)-R₈ with t being equal to 0 or 1 , R₈ representing a) a hydrogen atom, b) a hydroxyl group, c) (CrC₆)alkyl, d) (CrC₆)alkoxy, e) (di)(CrC₆)(alkyl)amino, f) (di)hydroxy(CrC₆)alkylamino;

or alternatively:

with R₉ and R10 representing i) a hydrogen atom or a group chosen from ii) hydroxyl, iii) (Ci- C₆)alkyl optionally substituted with one or more hydroxyl groups, in particular,

R₃ and R₄ form, together with the carbon atom, an oxo group and/or in particular, Ri and R₂ represent, together with the carbon atom,

5. Composition according to any one of Claims 1 , 3 and 4, in which the compound(s) of formula (I) are such that n is 1 , and of formula (l"c):

in which formula (l"c):

Rii and R12, which may be identical or different, represent a hydrogen atom or a (Cr C₆)alkyl group, such as methyl or ethyl, preferably a hydrogen atom.

6. Composition according to either of Claims 1 and

compound(s) of formula (I) are such that n is 2, and of formula (l"b)

in which formula (l"b):

• Ri , R₂, R3, R₄, R5, Re, R'5 and R'₆, which may be identical or different, represent: i) a hydrogen atom,

ii) cyano,

iii) -C(0)-(0)_q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 ,

iv) (CrC₆)alkyl optionally substituted with one or more groups chosen from hydroxyl and -C(0)-R₈ with R₈ representing a) a hydrogen atom, b) a hydroxyl group, c) (CrC₆)alkoxy,

or alternatively:

7. Composition according to Claim 1 , in which the compound(s) of formula (I) are such that n is 1 or 2, and of formula lc):

(lc)

in which formula (lc):

• R₂, R₄, R5 and R₆, which may be identical or different, represent:

i) a hydrogen atom,

ii) hydroxyl,

iv) cyano,

v) -(0)_p-C(0)-(0)q-R₇ with R₇ representing a hydrogen atom or a (CrC₆)alkyl group, p and q, which may be identical or different, being equal to 0 or 1 , with p+q = 0 or 1 ,

vii) (C₂-C₆)alkenyl,

viii) (CrC₆)alkoxy,

or alternatively:

x) R₅ and R₆ form, together with the carbon atom that bears them, a double bond oxo =0 or

with R₉ and R10 representing a hydrogen atom or a (Ci- C₆)alkyl group.

8. Composition according to the preceding claim, in which the compound(s) of formula (I) are of formula (lc) and n is 1 .

9. Composition according to either of Claims 1 and 7, in which the compound(s) of formula (I) are such that n is 2, and of formula (I'c):

(I'c)

in which formula (I'c):

i) a hydrogen atom,

ii) hydroxyl,

iv) (CrC₆)alkyl, or

v) (CrC₆)alkoxy. 10. Composition according to any one of the preceding claims, in which the compounds of formula I are chosen from the followin com ounds:

10 11 12

11. Composition according to any one of the preceding claims, the pH of which is inclusively between 0.5 and 6.8, in particular between 1 and 6.5, more particularly at a pH of between 2 and 6 and preferentially between 3 and 5.

12. Composition according to any one of the preceding claims, in which the compound(s) of formula (I) are in an amount inclusively between 0.01 % and 50% by weight relative to the total weight of the composition, in particular between 0.1 % and 30%, more particularly between 1 % and 20%, preferentially between 2% and 15%, more preferentially between 5% and 10% by weight relative to the total weight of the composition.

13. Composition according to any one of the preceding claims, which does not comprise any thiol-based reducing agents such as thiolactic acid, and preferably does not comprise any reducing agent.

14. Compound chosen from those of formula (l"c) as defined in Claim 5; preferentially, the compounds are chosen from those of formulae 116, 117, 118, 119, 120, 121 and 122:

11 8

120 121 122

and also the organic or mineral acid or base salts thereof, the optical isomers thereof, and the solvates thereof such as hydrates.

15. Process for preparing the compounds of formula (l"c) as defined in the preceding claim, according to the following synthetic scheme:

which consists in reacting in step i) 3-butene-1 ,2,3-tricarboxylic acid (A) with at least one molar equivalent of thioacetic acid in particular in an aprotic organic solvent which is preferably halogenated, such as dichloromethane, or an ether such as THF, more particularly by heating the reaction medium to the reflux point of the solvent, preferably to a temperature of between 40 ^ and eO'C, to give compound (B); in step ii), compound (B) reacts with a strong organic or mineral acid such as hydrochloric acid, in particular in a polar protic solvent such as water, more particularly by heating to the reflux point of the solvent, preferably to a temperature of between 60 and 90 °C, to give the thiolactone (C); in steps iii) and v), compound (C) reacts with at least one equivalent of an alcohol R'n-OH or, respectively, R'12-OH, with R'n and R'12, which may be identical or different, representing a (CrC₆)alkyl group, in particular in a polar organic solvent such as ethyl acetate, preferably at low temperature such as O'C, to give the monoesters (D) and (E), which can also, in the presence of alcohol, be esterified on the second carboxyl group in steps iv) and vi) to give the diester (F), compounds (D), (E) and (F) being able to be purified by chromatography, for example on a column of silica; compounds (C), (D), (E) and (F) constituting all of the compounds of formula (l"c).

16. Cosmetic use of one or more compounds of formulae (la), (l"c), (l"b), (lc) and (I'c) as defined in any one of Claims 2 and 5 to 10, for treating keratin fibres, especially human keratin fibres such as the hair, preferably for shaping keratin fibres and/or straightening/relaxing said fibres.

17. Process for treating keratin materials, especially human keratin fibres such as the hair, comprising:

a) the application to said keratin materials of a composition as defined in any one of Claims 1 to 13.

18. Process according to the preceding claim, comprising, after step a), followed by a step b) of straightening/relaxing said keratin materials by means of a straightening iron at a temperature of at least 100 °C, or a step of shaping said keratin materials, preferably at a temperature of between, limits included, Ι ΟΟ'Ό and 300 °C, preferably between 120°C and 280 ^<€, more preferably between 150°C and 250 ^<€, and even better still between 200 and 250 °C.

19. Process according to either of Claims 17 and 18, which does not comprise any thiol-based reducing agent such as thiolactic acid, and preferably does not comprise any reducing agent.