Photochromic molecules usable as portion of a cosmetic ingredient, coloured cosmetic ingredients for cosmetic products changing colour when irradiated with ultraviolet light, and method for the preparation thereof

Abstract

Photochromic molecules denominated FC-YNAPHT or FC-RNAPHT usable as portions of a cosmetic ingredient, coloured cosmetic ingredients for cosmetic products changing colour when irradiated by ultraviolet light (UV, preferably UV-A). (Fomula AA & Formula BB) (AA) (BB) Method for the synthesis of said photochromic molecules. Monosubstituted and disubstituted transesterification product between FC-YNAPHT or FC-RNAPHT and a polymer or cosmetic oil having the aim to increase the molecular weight of the photochromic molecule. (Fomula CC & Formula DD) (CC) (DD) Method for the transesterification. Cosmetic compositions for make-up containing said photochromic transesterification products, capable of changing colour both per se and when applied to the skin when they are exposed to UV radiation.

Description

“Photochromic molecules usable as portion of a cosmetic ingredient, coloured cosmetic ingredients for cosmetic products changing colour when irradiated with ultraviolet light, and method for the preparation thereof’.* * * *

[0001] The present invention relates to photochromic molecules usable as portion of a cosmetic ingredient, coloured cosmetic ingredients for cosmetic products changing colour when irradiated through ultraviolet light (UV, preferably UV-A) and method for the preparation thereof.

[0002] There are various colorants used in the cosmetic field and their properties, like gloss, have been improved over time, following the trends of the moment and customer requirements. The continuous development of new trends on the cosmetic market of specific and diversified requirements for cosmetic products is an index of the constant need to create new and more sophisticated formulations providing new benefits and special effects.

[0003] It is to be noted that a make-up realized under artificial lighting appears lighter in natural light, while a make-up realized under sunlight appears darker in an artificially lighted environment.

[0004] With the aim of meeting customers’ new needs, the possibility of breaking the static nature of colours in formulations through the exploitation of photochromism, a known chemical phenomenon, was envisaged, in order to obtain an innovative, exclusive product capable of amazing.

[0005] The term photochromism derives from the Greek words “phos” (light) and “chroma” (colour) and means “the transformation of something's colour due to exposure to light”. The molecules capable of undergoing this phenomenon are called photochromic. Typically, such molecules change colour when irradiated by a given wavelength, and then go back to their initial colour, or to a colour very similar to the initial one, once irradiation is stopped.

[0006] Photochromism is a physical phenomenon based on a reversible reaction transforming a molecule from a state A to a state Bfollowing the absorption of an electromagnetic radiation. The two states A and B are isomers, in that the photochemical excitation causes a rearrangement of the electronic and nuclear structure of the molecule. Such structures differ mainly for their absorption spectra. The initial stable state A absorbs in the spectral region of ultraviolet, and for such reason is generally colourless, while state B, having a higher energy, absorbs in the visible spectrum and is strongly coloured.

[0007] Photochromic molecules can find application in industrial fields if they meet requirements like: rapid activation of colour changing (also called “switch”), high efficiency and solubility in the matrix inside which such molecules are incorporated.

[0008] In the art, there are known photochromic molecules like spiropyrans, spirooxazines and naphtopyrans, changing colour through UV- A radiation (400 - 315 nm), which is the most accessible wavelength of the solar spectrum. The high efficiency of such chemical agents and their markedly rapid switch speed allowed their use for producing photochromic lenses.

[0009] These three categories of molecules are defined “T-type”: their aromatic structure is reversibly opened through UV irradiation, with consequent colouring of the compound, and closing of the structure through interruption of the exposition to UV radiation or heating.

[0010] WO 2009 / 109546 Al describes a naphtopyran having a structural formula different from those according to the present invention. The proposed use for such naphtopyran is all kinds of optical devices andelements, such as ophthalmic elements and devices, display elements and devices, windows or mirrors.

[0011] WO2021165207A1 of the same applicant describes a spiropyran provided with photochromic properties, that in visible light is transparent, while when irradiated through UV-A radiations assumes a blue colour.

[0012] Patent FR2845910B1 describes a cosmetic composition containing at least an oil phase and at least a naphtopyran provided with photochromic properties, that is soluble in said oil phase.

[0013] Photochromic molecules spiropyrans, spirooxazines and naphtopyrans as such cannot be used in the cosmetic field, as chemical agent having a low molecular weight could be absorbed through the skin.

[0014] Aim of the present invention is providing photochromic cosmetic ingredients for producing cosmetic products capable of changing colour when stimulated by ultraviolet light.

[0015] According to the invention, molecules provided with photochromic properties were synthetized as defined in the claims:- a spirooxazine (FC-SPOX) which, when irradiated with UV-A has a blue-violet colour;- two different naphtopyrans (FC-YNAPHT and FC-RNAPHT) which, when irradiated with UV-A, become strongly yellow and red, respectively.

[0016] Concerning the synthesis of such molecules, FC-SPOX is synthetized in three steps:- nitrosation of 2,7- dihydroxynaphthalene with nitrous acid, carrying out the reaction in water under an air atmosphere, so obtaining l-nitroso-2,7-diidroxyinaphtalene;- condensation of l-nitroso-2,7-diidroxyinaphtalene and 1,3,3- trimethyl-2-methyleneindoline, so obtaining spiro[2H-indole-2,3'- [3H]napht[2,l-b][l,4]ossazin]-9'-ole;- nucleophile substitution between ethyl 2-bromoacetate and spiro[2H-indole-2,3'-[3H]napht[2,l-b][l,4]ossazin]-9'-ole, so obtaining the spirooxazine FC-SPOX.

[0017] For the synthesis of yellow FC-YNAPHT and red FC- RNAPHT naphtopyrans, there are provided four steps:- condensation of 7-bromo-2-naphtol and l,l-diphenyl-2-propyn-l- ol or l,l-bis(4-methoxyphenyl)propyn-2-in-l-ol in order to obtain 9-bromo-3,3-dipheyil-3H-naphto[2,l-b]pyran or 9-bromo-3,3- bis(4’-methoxyphenyl)-3H-naphto[2, l-b]pyran, respectively, with acid catalysis in the presence of a dehydrating agent;- transformation of the brome group into acetyl through a first Sonogashira reaction using (triisopropyl silyl)acetylene in micellar catalysis;- removal of the silyl portion to obtain the terminal acetylene using tetrabutylammonium fluoride;- condensation through a second Sonogashira reaction in micellar catalysis between the product obtained in the preceding step and ethyl 4-bromobenzoate in micellar catalysis.

[0018] As above explained, the photochromic molecules belonging to known chemical categories have a molecular weight that is too low, so generating toxicological concerns when applied to the human body. Therefore, at the end of the synthesis of each photochromic molecule according to the invention, there is provided a step of transesterification of the photochromic molecule, so as to obtain photochromic cosmetic ingredients that do not cause unwanted toxicological effects.

[0019] All of the three photochromic molecules, FC-SPOX, FC- YNAPHT or FC-RNAPHT are hence transesterified in order to increase their molecular weight, using a polymer / cosmetic oil chosen from the group consisting in: cosmetic oils chosen from the group consisting inpolysiloxanes; bis-hydroxyethoxypropyl dimethicone being preferred;- cosmetic oils of natural origin like: hydrogenated dilinoylel alcohol and castor oil;- polyesters with at least one hydroxy function having a high molecular weight, at least higher than 500 Dalton, having a carbon chain with a number or carbon atoms higher than 20; the most suitable comprise oils derived from linoleic acid like the polyester having INCI name Dimer Dilinoleyl Dimer Dilinoleate; castor oil and hydrogenated castor oil; Dimer Dilinoleyl Dimer Dilinoleate being particularly preferred;- esters of polyglycerols with a number of carbon atoms higher than 20, e.g. poliglyceryl 3 - caprylate or polyglyceryl-3 diisostearate;- cosmetic polymers chosen from the group of polyurethanes, e.g. INCI: polyurethane- 102 or IPDI / Di-C12-13 Alkyl Tartrate / Bis-Hydroxy ethoxypropyl Dimethicone Copolymer.

[0020] In particular, FC-SPOX has a molecular weight of 430.5 g / mol; when transesterified with Dimer Dilinoleyl Dimer Dilinoleate (molecular weight 1589 g / mol) the monosubstituted transesterified molecule has a molecular weight of 1989.5 g / mol, while the disubstituted transesterified molecule has a molecular weight of 2390 g / mol.

[0021] FC-YNAPHT has a molecular weight of 506.6 g / mol; when transesterified with Dimer Dilinoleyl Dimer Dilinoleate the monosubstituted transesterified molecule has a molecular weight of 2065.6 g / mol, while the disubstituted transesterified molecule has a molecular weight of 2543.2 g / mol.

[0022] FC-RNAPHT has a molecular weight of 566.7 g / mol; when transesterified with Dimer Dilinoleyl Dimer Dilinoleate the monosubstituted transesterified molecule has a molecular weight of 2125.7 g / mol, while the disubstituted transesterified molecule has a molecular weight 2603.3 g / mol.

[0023] Preferably, the transesterified molecule / s, i.e. the cosmetic ingredient, is / are inserted into a cosmetic product diluted in the same polymer / cosmetic oil used for the transesterification reaction.

[0024] The cosmetic products containing the transesterified photochromic molecules according to the present invention can be applied to labial mucosa, skin, eyelashes, hair, nails, and can be, e.g. lipstick, lip gloss, foundation, blush or rouge, face powder, products for eye make-up, hair products, nail polish, etc. It should be noted that the photochromic colorants change colour when exposed to UV radiation, both when they are exposed as such (e.g. the stick of a lipstick) and when they are applied to the skin. In an indicative way, the percentage in weight of transesterified photochromic colorant inside the cosmetic product according to the present invention ranges about 0.1% - 30%, preferably 2 -29%.

[0025] A first advantage of the present invention is providing new cosmetic ingredients provided with photochromic effect, capable of providing an incentive to buy cosmetic products due to their novelty (surprise effect, WOW effect).

[0026] A second advantage of the present invention is that the cosmetic ingredients according to the present invention are photochromic molecules functionalized with cosmetic polyesters, hence they are provided with a high molecular weight and do not raise toxicological concerns.

[0027] A third advantage of the present invention is that the cosmetic ingredients according to the present invention can be diluted directly in the same cosmetic polyester used for the functionalization of said photochromic molecules: this simplifies the formulation of the final cosmetic products.

[0028] A fourth advantage of the present invention is the automatic adjustment of make-up to moment-to-moment lighting conditions, as it is known that a make-up realized under artificial lighting appears lighter in natural light, while a make-up realized under sunlight appears darker in an artificially lighted environment. As a consequence, with the cosmeticproducts according to the present invention there is prevented the “non-natural whiteness” that occurs in a person that was made up in artificial light and then is exposed to natural light.

[0029] A fifth advantage of the present invention is that overall three molecules were synthetized, of which, in UV-A light, one becomes blue, one yellow and one red, i.e. substantially the three primary colours are provided, which can be mixed in order to obtain a complete colour palette.

[0030] The features and the advantages according to the present invention will be made more evident by the following detailed description of an embodiment thereof shown by way of non-limiting example in the accompanying drawings, in which: figure 1 shows the 1H-NMR spectrum of compound 4 in Scheme 1; figure 2 shows the 13C-NMR spectrum of compound 4 in Scheme 1; figure 3 shows the 1H-NMR spectrum of FC-SPOX molecule; figure 4 shows the 13C-NMR spectrum of FC-SPOX molecule; figure 5 shows the UV characterization of FC-SPOX, comparing the closed form and the open form of the molecule, obtained by irradiating the sample with X=370 nm; figure 6 shows a comparison between the IR spectrum of compound 4 and of FC-SPOX; figure 7 shows the 1H-NMR spectrum of compound 7 in Scheme 2; figure 8 shows the 1H-NMR spectrum of compound 8 in Scheme 2; figure 9 shows the 1H-NMR spectrum of compound 9 in Scheme 2; figure 10 shows the 1H-NMR spectrum of FC-YNAPHT; figure 11 shows the UV characterization of FC-YNAPHT, comparing the closed form and the open form of the molecule, obtained by irradiating the sample with X=370 nm; figure 12 shows the IR spectrum of FC-YNAPHT; figure 13 shows the 1H-NMR spectrum of compound 11 in Scheme 3; figure 14 shows NMR spectra, comparing the non- functionalizedcosmetic polymer (RR-Lusplan 5), FC-SPOX photochromic molecule (EI-16bis) and the transesterification product (RR-02); figure 15 shows the comparison between the IR spectra of the nonfunctionalized cosmetic polymer RR-Lusplan 5 and functionalized with FC-SPOX; figure 16 shows the thermogravimetric analysis, comparing the nonfunctionalized cosmetic polyester, the functionalized polyester and FC-SPOX; figure 17 shows the NMR spectra comparing the non- functionalized polymer (indicated as EI-REM798.1), FC-YNAPHT molecule (indicated as EI-161-fondo), while the transesterification product is EI-164-4h; figure 18 shows the comparison between the IR spectra of the nonfunctionalized cosmetic polymer and functionalized with FCYNAPHT; figure 19A shows pre-UV FC-SPOX while figure 19B shows FC- SPOX when irradiated with UV-A; figure 20 shows transesterified FC-SPOX in mass (on the left) and on a thin layer (on the right) pre-irradiation (top) and post-irradiation (bottom) with a 370 nm torch; figure 21A shows a comparison between the FC-YNAPHT functionalized polymer in mass diluted to 1 :2, while figure 22B shows the comparison of FC-YNAPHT functionalized polymer in mass diluted to 1 :5 in non- functionalized polyester, pre-irradiation and postirradiation with a UV torch (excitation at 370 nm); figure 22 A shows pre-irradiation transesterified FC-RNAPHT while figure 22B shows FC-RNAPHT irradiated with UV-A; figures 23 show FC-YNAPHT X = H) e FC-RNAPHT (X = CH3O-) naphtopyrans according to the present invention transesterified with a polymer / cosmetic oil provided with two hydroxy groups at its ends;figure 23 A shows a disubstituted molecule, while figure 23B shows a monosubstituted molecule.Spirooxazine: FC-SPOX

[0031] The first molecule according to the present invention is a spirooxazine provided with photochromic properties; for the sake of brevity, in the following this molecule will be indicated as FC-SPOX. FC-SPOX is provided with a markedly rapid opening and closing kinetics (switch), much more rapid than the spiropyran described in WO2021165207A1. This kinetics is due to the site chosen for the transesterification, which is on the naphthalene ring and not on the nitrogen of the indolenine portion, which, being sterically not bulky, allows such kinetic.

[0032] In the following, there is shown the general formulation of spirooxazines, wherein the generic functional group X represents the functionalization site. As can be observed, irradiation or heat cause the opening of the pyran ring, which closes as soon as irradiation is stopped.

[0033] FC-SPOX spirooxazine was prepared according to the procedure shown in Scheme 1.Scheme 1: synthesis of FC-SPOXSynthesis of FC-SPOX

[0034] 2,7- dihydroxynaphthalene (CAS 582-17-2), indicated with 1 in Scheme 1, is nitrosed with nitrous acid, prepared in situ, by using sodium nitrite (CAS 7632-00-0) and a strong acid (98% concentrated sulphuric acid, CAS 7664-93-9). The reaction is carried out in water under an air atmosphere, in which NaOH (0.6M) and compound 1 are dissolved, then NaNCh is dispersed, maintaining such dispersion for 2h at 60°C. Stoichiometric ratios are 1 : 1.04 between compound 1 and sodium nitrite, and 1 : 1 between compound 1 and NaOH. Successively the dispersion is brought to 0°C and a solution of 35% sulphuric acid V / V is dripped slowly (in about one hour). The sulphuric acid is about 2.4 times in moles with respect to 2,7- dihydroxynaphthalene.

[0035] The dispersion is stirred overnight, letting the temperature go from 0°C to room temperature. Successively, the precipitate is filtered through a Buchner funnel, so obtaining a violaceus solid. The conversion rate is always 87-92%; no purification of 1 -nitroso 2,7- dihydroxynaphthalene (indicated with 2 in Scheme 1) is provided, as this molecule does not cause any problem in the following synthesis steps, and is completely removed during the last reaction step.

[0036] The successive reaction comprises the condensation between 1 -nitroso 2,7- dihydroxynaphthalene 2 and l,3,3-trimethyl-2- methylenindoline (CAS 118-12-7), indicated with 3 in Scheme 1, with the aim of obtaining spiro[2H-indole-2,3'-[3H]napht[2,l-b][l,4]ossazin]-9'-ole, indicated with 4 in Scheme 1. The reaction is carried out under nitrogen at 60°C in dry ethanol (placed on molecular sieves 3 A - pore diameter 3 A) and degassed. Carrying out the reaction in non-treated ethanol is anyway possible, but such precaution is preferable as the oxygen present in the solvent increases the production of collateral reactions that decrease the yield and often do not lead to the total conversion of the reagent into the product (See Table 1).

[0037] The reaction procedure provides the dispersion in ethanol ofcompound 2 for 15 minutes at 60°C; the solid previously underwent three cycles of vacuum / nitrogen. Weighing about 10% in weight in excess of the reagent is necessary due to the impurity in compound 1. The dispersion is between 10% and 12% in mass on ethanol volume. Successively, a 1-1.2M solution of compound 3 in ethanol is slowly dripped at room temperature on the dispersion, maintained at a temperature of 60°C (the mole ratio between compounds 2 and 3 is 1 : 1.1). The time provided for the reaction is 17 to 48 hours. In the case the reaction is carried out in inert conditions with dry and degassed ethanol, the compound is purified through washing in heptane, so obtaining a violet solid through filtration. If it is chosen to operate under air or under nitrogen but using non-degassed anhydrous ethanol, due to the noncomplete conversion of the reagents, all the precipitate must be dissolved in chloroform (after the heptane washing). The solid residue in chloroform so obtained is the mixture of non-reacted compounds 1 and 2. By removing the solvent under vacuum, the product FC-SPOX is obtained.

[0038] In optimal conditions, the reaction yield is 70-95%. Fusion temperature 215-217°C.Table 1: Second synthesis step, variation of the solvent conditions;* means no; means yes.

[0039] Table 1 allows to appreciate the improvement of the reaction yield according to the applied experimental conditions. As said, the best yield is obtained by passing ethanol on molecular sieves, degassing it, operatingunder an inert atmosphere, washing the final product with heptane; these precautions allow to prevent the extraction with chloroform.

[0040] The last synthesis step comprises the nucleophile substitution between ethyl 2-bromoacetate (CAS 105-36-2) and the compound indicated with 4 in Scheme 1, so obtaining FC-SPOX. In this case, too, the reaction must be carried out in anhydrous conditions under an inert atmosphere. The reaction is carried out in anhydrous and inert tetrahydrofuran (THF), but it can also be carried out in anhydrous conditions and under an inert atmosphere. Compound 4 and potassium tert-butilate (tBuOK, CAS 865-47-4) are placed in a round-bottomed flask and are dissolved in the chosen solvent (0.05M - 0.1M, mole ratio 1: 1.2 between compound 4 and base); as base, NaOH or potassium carbonate can be used, too, as long as they are water-free. The formation of the aromatic anion is observed through the solution colour changing from violaceous brown to green. It is stirred for about 30 minutes at room temperature. Successively, 2.5 equivalents in volume of ethyl 2- bromoacetate are added and the disappearance of the anion is observed. The reaction is totally carried out at room temperature, under a nitrogen inert atmosphere. Reaction time around 24 h. A complete conversion of the molecule is observed. The compound is purified after having removed the solvent under vacuum, washing with isopropanol. FC-SPOX appears as a grey precipitate that is obtained by filtering through Buchner funnel and washing with water in order to remove KBr. Yield 80-88%. Melting point 147-150°C.Characterization of FC-SPOXNMR characterization

[0041] Figure 1 shows the 1H-NMR spectrum of compound 4 in Scheme 1.

[0042] Figure 2 shows the 13C-NMR spectrum of compound 4 in Scheme 1.

[0043] Figure 3 shows the 1H-NMR spectrum of FC-SPOX molecule.

[0044] Figure 4 shows the 13 C-NMR spectrum of FC-SPOX molecule.UV-vis characterization of FC-SPOX

[0045] Figure 5 shows the UV characterization of FC-SPOX, comparing the closed form and the open form of the molecule, obtained by irradiating the sample with X=370 nm.IR characterization of FC-SPOX

[0046] Figure 6 shows the comparison between the IR spectrum of compound 4 and FC-SPOX. The disappearance of the vibrational stretching at 3400 cm’1of the hydroxy group with the appearance of the peak at 1758 cm’1confirms the formation of the ester and the correct functionalization of the molecule through nucleophile substitution.Naphtopyrans: FC-YNAPHT and FC-RNAPHT

[0047] Naphtopyrans are photochromic compounds capable of absorbing at wavelengths lower than spirooxazine when they are in their open form, and indeed they are yellow-red in colour.

[0048] Naphtopyrans are characterized by a naphthalene portion and two aromatic rings bonded to the spiro position. Suitably functionalizing the para position, the absorption spectrum of the molecule can be modified, hence its colour in the open form. The general structure of naphtopyrans is as follows:f functionalization for transesterification, X is the functionalization site for modifying the absorption spectrum of the molecule, and hence its colour.

[0049] The two naphtopyrans according to the present invention are denominated FC-YNAPHT (yellow) and FC-RNAPHT (red).On the left, the structure of FC-YNAPHT (yellow), on the right, the structure ofFC-RNAPHT (red).

[0050] In the following, the method of synthesis of the two molecules according to the present invention are described (Scheme 2 for yellow naphtopyran and Scheme 3 for red naphtopyran). The difference between red and yellow naphtopyran is the presence of methoxy groups in para on the two terminal phenyl rings (compare Scheme 2 and Scheme 3).Synthesis of the yellow naphtopyran FC-YNAPHT

[0051] The second photochromic molecule according to the present invention is the yellow naphtopyran FC-YNAPHT, prepared according to Scheme 2.Scheme 2: synthesis of the yellow naphtopyran FC-YNAPHT

[0052] The first step of synthesis is the condensation between 7- bromo-2-naphtol (CAS 116230-30-9), indicated with 5 in Scheme 2 and 1,1- diphenyl-2-propyn-l-ol (CAS 3923-52-2), indicated with 6 in Scheme 2, in order to obtain 9-bromo-3,3-diphenyl-3H-naphto[2,l-b]pyran, indicated with 7 in Scheme 2. The reflux reaction is carried out in 1,2 dichloroethane (1,2- DCE) under a nitrogen inert atmosphere, concentration of compound 5 in 1,2-DCE 0.5M. As it is a condensation, it is necessary to introduce a dehydrating agent, like triethyl orthoformate (CAS 122-51-0); alternatively, trimethyl orthoformate (CAS 149-73-5) can be used, too. The mole ratio between 7- bromo-2-naphtol and the dehydrating agent is 1 :2, while between 7-bromo-2- naphtol and l,l-diphenyl-2-propyn-l-ol is 1 : 1.1. The reaction is catalysed through pyridinium p-toluenesulfonate (CAS 24057-28-1), at 9% in moles of 7-bromo-2-naphtol. Reaction time is about 6 - 20 hours. After having evaporated the solvent under vacuum, the mixture so obtained is extracted in water / dichloromethane. After the removal of the solvent from the organic fraction under vacuum, the crude so obtained is washed in heptane: for 10 g of theoretic yield of product 20 mL of heptane are sufficient. A white crystalline solid is obtained. The solid so obtained is not photochromic in mass, but is photochromic only when dissolved in common organic solvents. The reaction yield is 80 - 90%.

[0053] The brome atom bonded to the indolenine portion is crucial for functionalizing the molecule in order to obtain the site of catalytic transesterification. The three following reactions are carried out one after the other and the overall yield is calculated starting from compound 7 in order to obtain FC-YNAPHT.

[0054] The second step is the transformation of the brome group into acetyl through a Sonogashira reaction. The reaction occurs in micellar catalysis between compound 7 and (triisopropyl silyl)acetylene (CAS 89343- 06-6) in water under an air atmosphere, in the presence of Kolliphor ELP (CAS 61791-12-6) as surfactant at 2% in weight, dissolved in the reaction medium. The reaction is catalysed through palladium acetate (CAS 3375-31- 3) and XPhos (2-dicyclogexylphosphino-2',4',6'-triisopropylbiphenyl, CAS 564483-18-7), in presence of triethylamine (CAS 121-44-8). Reaction time 5 days at 80°C. The conversion is 100%. In order to obtain the compound indicated with 8 in Scheme 2, the organic phase is extracted in dichloromethane (DCM), and successively the organic fraction is filtered onsilica to remove palladium, so obtaining an ochre-brown oil, once the solvent was removed under vacuum. The stoichiometric ratios provide: 1 equivalent of compound 7, 1.6 equivalents of (triisopropyl silyl)acetylene, 0.0075 equivalents of palladium catalyser, 0.019 equivalents of XPhos and 6 equivalents of triethylamine. The concentration of compound 7 in water is IM.

[0055] In order to deprotect the silyl portion and obtain the terminal acetylene (compound 9 in Scheme 2), the obtained oil, indicated with 8 in Scheme 2, is dissolved in a 0.3M tetrahydrofuran (THF) solution, always under an air atmosphere, and a tetrabutylammonium fluoride solution (TBAF, CAS 429-41-4) IM in THF is slowly dripped, TBAF being in excess with respect to compound 9, and is equal to 1.2 equivalents. The deprotecting reaction occurs at room temperature, over a time between 30 minutes and 90 minutes. The conversion is complete. The purification to remove excess TBAF anew provides an extraction in water / dichloromethane. By removing DCM from the organic phase a brown solid is obtained, photochromic only when dissolved in an organic solvent. Inside triisopropyl silyl fluoride remains as a by-product of the deprotecting reaction, which is easily removed with the purification of the last reaction step.

[0056] The last reaction step provides a Sonogashira reaction, carried out in micellar catalysis, between the deprotected product 9 and ethyl 4- bromobenzoate (CAS 5798-75-4), in water under an air atmosphere, in the presence of Kolliphor ELP (CAS 61791-12-6) as surfactant at 2% in weight, dissolved in the reaction medium. The reaction is catalysed by palladium acetate (CAS 3375-31-3) and XPhos (2-dicyclogexylphosphino-2',4',6'- triisopropylbiphenyl, CAS 564483-18-7), in the presence of triethlylamine (CAS 121-44-8). Reaction time 3 days at 80°C. The stoichiometric ratios are as follows: 1 equivalent of compound 9, 1.6 equivalents of (triisopropyl silyl)acetylene, 0.0075 equivalents palladium catalyser, 0.019 equivalents of XPhos and 6 equivalents of triethylamine. The concentrationof compound 9 in water is IM. Extraction with water / chloromethane; palladium and surfactant are removed through filtration on silica of the organic phase, and successively the solvent is removed in order to obtain a dark oil. By washing with ethanol said oil, yellow naphtopyran FC-YNAPHT is obtained as a yellow solid, photochromic only when dissolved in a solvent.The overall yield over the reaction steps one after the other is about 30%.Characterization of FC-YNAPHTNMR characterization

[0057] Figure 7 shows the 1H-NMR spectrum of compound 7 of Scheme 2.

[0058] Figure 8 shows the 1H-NMR spectrum of compound 8 of Scheme 2.

[0059] Figure 9 shows the 1H-NMR spectrum of compound 9 of Scheme 2.

[0060] Figure 10 shows the 1H-NMR spectrum of FC-YNAPHT.UV-vis characterization of FC-YNAPHT

[0061] Figure 11 shows the UV characterization of FC-YNAPHT, comparing the closed form and the open form of the molecule, obtained through irradiation of the sample with UV-A radiations.IR characterization of FC-YNAPHT

[0062] Figure 13 shows the IR spectrum of FC-YNAPHT. The peak at 1711 cm’1is characteristic of the ester.Synthesis of the red naphtopyran FC-RNAPHT

[0063] The third photochromic molecule according to the present invention is the naphtopyran FC-RNAPHT, prepared according to Scheme 3.Scheme 3: synthesis of red naphtopyran FC-RNAPHT

[0064] The first step of the synthesis is the condensation between 7- bromo-2-naphtol (CAS 116230-30-9), indicated with 5 in Scheme 3, and 1,1- Bis(4-methoxyphenyl)prop-2-yn-l-ol (CAS 101597-25-5), indicated with 10 in Scheme 3, to obtain 9-bromo-3,3-bis(4’- methoxyphenyl)-3H-naphto[2,l- b]pyran, indicated with 11 in Scheme 3. The reflux reaction is carried out in 1,2 dichloroethane (1,2-DCE) under a nitrogen inert atmosphere, concentration of 7-bromo-2-naphtol in 1,2-DCE 0.5M. As it is a condensation, it is necessary to introduce a dehydrating agent, like triethyl orthoformate (CAS 122-51-0); alternatively, trimethyl orthoformate (CAS 149-73-5) can be used, too. The mole ratio between compound 5 and the dehydrating agent is 1 :2, while between compounds 5 and 10 is 1 : 1.1. The reaction is catalysed by pyridinium p-toluenesulfonate (CAS 24057-28-1), at 9% in moles of compound 5. Reaction time is about 6 - 20 hours. After having evaporated the solvent under vacuum, the mixture so obtained is extracted in water / dichlorom ethane. After the removal of the solvent from the organic fraction under vacuum, the crude so obtained is washed in heptane at elevated temperature; for 10 g of theoretic yield of product 20 mL of heptane are sufficient. A white-yellowish crystalline solid is obtained. The solid so obtained is not photochromic in mass, but is photochromic only when dissolved in common organic solvents. The reaction yield is 90 to 97%.

[0065] The brome atom bonded to the indolenine portion is crucial for functionalizing the molecule in order to obtain the site of catalytictransesterification.

[0066] The second step is the transformation of the brome group into acetyl through a Sonogashira reaction. The reaction occurs in micellar catalysis between compound 11 and (triisopropyl silyl)acetylene (CAS 89343- 06-6) under air in water, in presence of Kolliphor ELP (CAS 61791-12-6) as surfactant at 2% in weight, dissolved in the reaction medium. The reaction is catalysed by palladium acetate (CAS 3375-31-3) and XPhos (2- dicyclogexylphosphino-2',4',6'-triisopropylbiphenyl, CAS 564483-18-7), in the presence of triethylamine (CAS 121-44-8). Reaction time 5 days at 80°C. The conversion occurs at 100%, in order to obtain the compound indicated with 12 in Scheme 3, the organic phase is extracted in di chloromethane (DCM), and successively the organic fraction is filtered on silica to remove palladium, so obtaining an ochre-brown oil, once the solvent was removed under vacuum. The stoichiometric ratios provide: 1 equivalent of compound 11, 1.6 equivalents of (triisopropylsilyl)acetylene, 0.0075 equivalents of palladium catalyser, 0.019 equivalents of XPhos and 6 equivalents of triethylamine. The concentration of compound 11 in water is IM.

[0067] In order to deprotect the silyl portion and obtain the terminal acetylene (compound indicated with 13 in Scheme 3), the obtained oil, indicated with 12, is dissolved in a 0.3M solution of tetrahydrofuran (THF), always under an air atmosphere, and a IM tetrabutylammonium fluoride solution (TBAF, CAS 429-41-4) in THF is slowly dripped, which is in excess with respect to compound 12, and is equal to 1.2 equivalents. The deprotecting reaction occurs at room temperature, with a reaction time between 30 minutes and 90 minutes. The conversion is complete. Anew, the purification to remove excess TBAF provides an extraction in water / dichloromethane. By removing DCM from the organic phase a brown solid is obtained, photochromic only when dissolved in an organic solvent. Inside triisopropyl silyl fluoride remains as a by-product of the deprotecting reaction, which is easily removed with the purification of the last reaction step.

[0068] The last step of reaction provides s Sonogashira reaction again, carried out in micellar catalysis, between the deprotected product indicated with 13 in Scheme 3 and ethyl 4-bromobenzoate (CAS 5798-75-4), in water under an air atmosphere, in the presence of Kolliphor ELP (CAS 61791-12- 6) as surfactant at 2% in weight, dissolved in the reaction medium. The reaction is catalysed by palladium acetate (CAS 3375-31-3) and XPhos (2- dicyclogexylphosphino-2',4',6'-triisopropylbiphenyl, CAS 564483-18-7), in the presence of triethlyl amine (CAS 121-44-8). Reaction time 3 days at 80°C. The stoichiometric ratios are as follows: 1 equivalent of compound 13, 1.6 equivalents of (triisopropyl silyl)acetylene, 0.0075 equivalents of palladium catalyser, 0.019 equivalents of XPhos and 6 equivalents of tri ethylamine. The concentration of compound 12 in water is IM. Extraction with water / chloromethane, palladium and surfactant are removed through extraction on silica of the organic phase, and successively the solvent is removed in order to obtain a dark oil. By washing with ethanol said oil, red naphtopyran FC-RNAPHT is obtained as a dark orange solid, photochromic only when dissolved in a solvent. The overall yield over the three reaction steps one after the other is about 30%.Characterization of FC-RNAPHTNMR characterization

[0069] Figure 13 shows the 1H-NMR spectrum of compound 11 of Scheme 3.Transesterification of polyester

[0070] The transesterification, shown in Scheme 4, occurs between one of the photochromic molecules FC-SPOX or FC-YNAPHT or FC- RNAPHT and any polymer / oligomer provided with terminal hydroxy groups, and represents the final step to obtain photochromic colorants usable as cosmetic ingredients.

[0071] Said polymer / oligomer having terminal hydroxy groups, one for each end of the molecule, is chosen from the group consisting in:- cosmetic oils chosen from the group consisting in polysiloxanes; bis-hydroxyethoxypropyl dimethicone being preferred;- cosmetic oils of natural origin like: hydrogenated dilinoylel alcohol and castor oil;- polyesters with at least one hydroxy function having a high molecular weight, at least higher than 500 Dalton, having a carbon chain with a number or carbon atoms higher than 20; the most suitable comprise oils derived from linoleic acid like the polyester having INCI name Dimer Dilinoleyl Dimer Dilinoleate; castor oil and hydrogenated castor oil; Dimer Dilinoleyl Dimer Dilinoleate being particularly preferred;- esters of polyglycerols with a number of carbon atoms higher than 20, e.g. poliglyceryl 3 - caprylate or polyglyceryl-3 diisostearate;- cosmetic polymers chosen from the group of polyurethanes, e.g. INCI: polyurethane- 102 or IPDI / Di-C12-13 Alkyl Tartrate / Bis-Hydroxy ethoxypropyl Dimethicone Copolymer.

[0072] The preferred stoichiometric ratios provide 1 photochromic molecule for 4 hydroxy groups. Given the cosmetic use of the product, as catalyser dibutyltin(IV) oxide, CAS 818-08-6 (e.g. Fascat 9101 in beads), is used in a quantity between 0.005 and 0.01% in moles with respect to the photochromic molecule. The catalyser is present in a heterogeneous phase that allows to be filtered at the end of the reaction. In order to anyway avoid thisScheme 4: General reaction of transesterification between the photochromic molecule FC-SPOX and the polymer / cosmetic oil having terminal hydroxy groups on its chain.Scheme 4bis: General reaction of transesterification between the photochromic naphtopyran molecules and the polymer / cosmetic oil having terminal hydroxy groups on its chain.

[0073] The protocol provides the absence of solvent as reaction medium, the solvent being the same polymer / oil that is then partially functionalized. By operating at 140-160°C, the photochromic molecules here shown are all soluble in the reaction medium. In this way, carrying out the reaction under reduced pressure is necessary, so as to distil at the same time the ethanol that develops along with the transesterification. Given the reduced quantities of catalyser, reaction times are quite long. With the catalyser present at 0.01% in moles at 160°C there are needed 6.5h, while with the catalyser at 0.005% in moles up to 24h.

[0074] Generally speaking, the catalyser and the photochromic molecule FC-SPOX or FC-YNAPHT or FC-RNAPHT according to the present invention are dispersed in the polymer / cosmetic oil; while the temperature increases up to 160°C, the suspension becomes more and more fluid, allowing the proper stirring inside the round-bottomed flask. By observing the mixture brought at 160°C a gradual development of gas(ethanol) and a gradual dissolution of the precipitate are observed; in this way, a homogeneous solution is formed. The reaction is monitored through IR and NMR (more accurate method). At the end of the reaction, the resulting oil is cooled to room temperature.

[0075] No purification is provided, as low quantities of metallic catalyser are used.

[0076] The following alternatives are possible:- Stoichiometry of functionalizable OH groups: photochromic molecule: 3:1 to 50: 1, preferably 4: 1 (ratio expressed in equivalents);- Catalyser: in addition to dibutyltin oxide, also Tin(II) oxalate can work analogously;- Temperature: 120 to 180 °C, preferably 140 to 160°C;- Time: 1 to 48 h, preferably 12-20 h.

[0077] Finally, in order to obtain a transparent raw material that becomes coloured under irradiation, the transesterified polymer can be diluted in a further quantity of the same non-functionalized cosmetic polymer used for the transesterification reaction, e.g. using an excess of cosmetic polymer. In particular, Dimer Dilinoleyl Dimer Dilinoleate is a preferred polymer both for transesterification and dilution. Alternatively, the transesterified photochromic molecule can be diluted with another cosmetic oil, compatible with the oil used for the transesterification.Transesterification with FC-SPOX

[0078] The reaction of FC-SPOX with any polymer / oligomer having terminal hydroxy groups as shown in Scheme 4 is monitored through NMR and IR.

[0079] Figure 14 shows NMR comparing non-functionalized cosmetic polymer (RR-Lusplan 5, Dimer Dilinoleyl Dimer Dilinoleate provided by Nippon Fine Chemical), photochromic molecule FC-SPOX (EI-16bis) and transesterification product (RR-02).

[0080] By comparing the NMR spectra, shown in figure 14, there can be observed that the characteristic quartet of CH2 of the ester ethyl at 4.35 ppm is not present anymore in the transesterification product (in figure 14 denoted as RR-02). Conversely, the appearance of a new triplet at 4.25 ppm is noted, due to the correct transesterification, in addition to the peaks of CH2 due to the presence of the esters of the polymer that is undergoing functionalization.

[0081] By working with an excess of OH, the triplet of the CH2 vicinal to OH remains. Through the integration of this peak in comparison to the other, how much polymer has been functionalized can be inferred.

[0082] Figure 15 shows the comparison between the IR spectra of the non-fimctionalized cosmetic polymer RR-Lusplan 5 and functionalized with FC-SPOX.

[0083] The comparison between the IR spectra shown in figure 15 of the polymer terminating with OH to be functionalized and the transesterification product confirms the complete transesterification of the molecule. Indeed, the stretching visible at 3362 cm'1of the terminal hydroxy group decreases with the functionalization, while a new peak, due to the presence of an ester different from the one in the polymer, is observed at 1765 cm'1.

[0084] Figure 16 shows the thermogravimetric analysis (TGA) comparing the non-fimctionalized cosmetic polyester, FC-SPOX molecule and the transesterification product (functionalized polyester) obtained from the reaction between the two. Method: 30-600°C, 10°C / min, N2, 50mL / min. It can be concluded that the transesterification product is stable up to 234°C.Transesterification with FC-YNAPHT

[0085] The reaction of FC-YNAPHT with any polymer / oligomer having terminal hydroxy groups as shown in Scheme 4bis is monitored through NMR and IR.

[0086] Figure 17 shows NMRs in comparison. The non-fimctionalizedcosmetic polymer is indicated here as EI-REM798.1, the molecule FC- YNAPHT is indicated as EI-161-fondo and the transesterification product is EI-164-4h.

[0087] By comparing the NMR spectra, shown in figure 17, there can be observed that the characteristic quartet of the CEE of the ester ethyl at 4.4 ppm is not present anymore in the spectrum of the transesterification product (indicated in figure 18 as EI-161-fondo). Conversely, the appearance of a new triplet at 4.35 ppm is observed, due to the correct transesterification, in addition to the peaks of the CEEs due to the presence of the polymer esters that is undergoing functionalization.

[0088] In this case, the reaction ends in only 4h because the catalyser is at 0.01% in moles with respect to the photochromic molecule.

[0089] By working with an excess of OH, the triplet of the CH2 vicinal to OH remains. Through the integration of this peak in comparison to the other, how much polymer has been functionalized can be inferred.

[0090] Figure 18 shows the comparison between the IR spectra of the non- functionalized cosmetic polymer and functionalized with FC-YNAPHT.

[0091] Also the comparison between the IR spectra shown in figure 18 of the polymer terminating with OH to be functionalized and the transesterification product confirms the complete transesterification of the molecule. Indeed, it can be observed that the stretching visible at 3362 cm’1of the terminal hydroxy group decreases with the functionalization, while a new peak, due to the presence of an ester different from the one in the polymer, is observed at 1719 cm’1.

[0092] The transesterification reaction of FC-RNAPHT is totally analogous to the reaction for FC-YNAPHT. For the sake of brevity, the corresponding graphs are not shown.

[0093] The molecular weights of the described molecules are: FC- SPOX 430.5 g / mol; molecule 4 of the Scheme 1 has a molecular weight of 344.4 g / mol. FC-SPOX transesterified with Dimer Dilinoleyl DimerDilinoleate oil (polyester derived from linoleic acid having a molecular weight of 1589 g / mol): mono substituted 1989.5 g / mol, disubstituted 2390 g / mol. These weights are based on the molecular mass of Dimer Dilinoleyl Dimer Dilinoleate oil used, measured through NMR titration. From the theoretical point of view, the theoretical molecular weight of Dimer Dilinoleyl Dimer Dilinoleate having three repeating units should be 1616.8 g / mol, hence in that case the molecular weight of the monosubstituted molecule should be 2017.3 g / mol, while the molecular weight of the disubstituted molecule should be of 2417.3 g / mol.

[0094] Concerning FC-YNAPHT molecular weights: referring to Scheme 2, molecule 7 has a molecular weight of 413.3 g / mol, molecule 8 has a molecular weight of 514.8 g / mol, molecule 9 has a molecular weight of358.4 g / mol, FC-YNAPHT has a molecular weight of 506.6 g / mol. According to the titration, FC-YNAPHT transesterified with Dimer Dilinoleyl Dimer Dilinoleate oil, when monosubstituted has a molecular weight of 2065.6 g / mol, while disubstituted has a molecular weight of 2543.2 g / mol. The theoretical calculation provides instead 2093.4 g / mol when monosubstituted or 2570 g / mol when di substituted.

[0095] FC-RNAPHT: referring to Scheme 3, molecule 11 has a molecular weight of 473.4 g / mol, molecule 12 has a molecular weight of574.4 g / mol, molecule 13 has a molecular weight of 418.5 g / mol, FC- RNAPHT has a molecular weight of 566.7 g / mol. FC-RNAPHT transesterified with Dimer Dilinoleyl Dimer Dilinoleate oil monosubstituted has a molecular weight of 2125.7 g / mol, disubstituted 2603.3 g / mol. The theoretical calculation provides instead 2153.5 g / mol when monosubstituted, or 2630.1 g / mol when di substituted.

[0096] Figure 19A shows that functionalized FC-SPOX bonded to the Dimer Dilinoleyl Dimer Dilinoleate polymer, and diluted in the same Dimer Dilinoleyl Dimer Dilinoleate has a grey / yellowish colour, while figure 19B shows that functionalized FC-SPOX bonded to Dimer Dilinoleyl DimerDilinoleate polymer and diluted in Dimer Dilinoleyl Dimer Dilinoleate when irradiated with an UV-A radiation becomes blue-violet. In both figures, the percentages indicate the quantity of present functionalized polymer.

[0097] Figure 20 shows a comparison between transesterified FC- SPOX in mass in non-functionalized polyester, pre-irradiation and postirradiation with a UV torch (excitation at 370 nm). Here, too, the polymer used for transesterification and dilution is Dimer Dilinoleyl Dimer Dilinoleate. Here, too, it can be observed that pre-irradiation FC-SPOX is yellow, while when under UV-A radiation it becomes intensely blue- violet.

[0098] Figure 21 A shows pre-irradiation transesterified FC-YNAPHT diluted 1 :2 in mass and under UV irradiation, while figure 2 IB shows pre- irradiation transesterified FC-YNAPHT diluted 1 :5 in mass and under UV-A irradiation. From both figures it can be observed that pre-irradiation FC- YNAPHT shows a weak yellow colour, while under UV-A irradiation the yellow colour is markedly intensified.

[0099] Figure 22A shows pre-irradiation transesterified FC-RNAPHT while figure 22B shows transesterified FC-RNAPHT under UV-A radiation. The comparison between the figures allows to observe that pre-irradiation transesterified FC-RNAPHT appears weakly yellow-orange, while under UV- A radiation its colour becomes red.

[0100] The cosmetic materials or ingredients so synthetized can be inserted into sundry cosmetic compositions. Said cosmetic compositions comprise at least a cosmetic material or ingredient above described in the function of cosmetic oil or film-forming agent in a percentage of 2% to 30% in weight.

[0101] In the following there are provided examples of sundry cosmetic compositions wherein different percentages of cosmetic ingredient / s comprising at least one photochromic molecule are used; such cosmetic compositions have indeed the characteristic of changing colour when under UV light.EXAMPLE 1: EYESHADOW n weightviscosity increasing agent 0.2 skin-conditioning agent 1.9 water 3.0surfactant 2.9colorant 28.0 skin-conditioning agent 6.0 opacifying agent 20.0viscosity increasing agent 19.0 transesterified20.0 skin-conditioning agent 6.0 preservative 1.0EXAMPLE 3: LIP GLOSSEXAMPLE 4: LIP GLOSS

Claims

CLAIMS1. Naphtopyran FC-YNAPHT provided with photochromic properties having the following structural formulation:appearing lightly yellow to visible light and strongly yellow under exposition to UV-A radiation.

2. Naphtopyran FC-RNAPHT provided with photochromic properties, having the following structural formulation, wherein the two terminal phenyl rings have each a para methoxy group:appearing lightly yellow-orange to visible light and red under exposition to UV-A radiation.

3. Yellow FC-YNAPHT naphtopyran according to claim 1 or red FC- RNAPHT naphtopyran according to claim 2, transesterified with a polymer or a cosmetic oil having an OH group at each end, having the following structural formulation for the disubstituted naphtopyran:and the following structural formulation for the monosubstitutednaphtopyran:wherein X stands for H for FC-YNAPHT or for a methoxy group for FC- RNAPHT.

4. Yellow FC-YNAPHT naphtopyran or red FC-RNAPHT naphtopyran transesterified according to claim 3 with a polymer or a cosmetic oil, wherein said polymer or cosmetic oil having an OH group at each end is chosen from the group consisting in:- cosmetic oils chosen from the group of polysiloxanes; bishydroxy ethoxypropyl dimethicone being preferred;- cosmetic oils of natural origin like INCI: hydrogenated dilinoylel alcohol and castor oil;- high molecular weight polyesters with at least one hydroxyl functionality, at least higher than 500 Daltons, having a carbon chain longer than 20 C; oils derived from linoleic acid are preferred, like the polyester INCI: Dimer Dilinoleyl Dimer Dilinoleate; castor oil and hydrogenated castor oil;- esters of polyglycerols with a carbon chain longer than 20 C, like polyglyceryl-3 caprylate or polyglyceryl-3 diisostearate;- cosmetic polymers chosen from the group of polyurethanes, like INCI: polyurethane- 102 or IPDI / Di-C12-13 Alkyl Tartrate / Bis-Hydroxy ethoxypropyl Dimethicone Copolymer.

5. Transesterified naphtopyran according to one or more of claims 3 or 4, wherein the ester used for the transesterification is Dimer Dilinoleyl Dimer Dilinoleate, which preferably is used also for diluting thetransesterified naphtopyran itself.

6. Yellow FC-YNAPHT naphtopyran or red FC-RNAPHT naphtopyran transesterified according to one or more of claims 3-5 for use as cosmetic ingredient for cosmetic compositions capable of changing colour when exposed to UV-A irradiation.

7. Cosmetic composition containing a transesterified naphtopyran according to one or more of claims 3-5, wherein said cosmetic compositions are chosen from the group consisting in lipsticks, lip gloss, foundations, blushes, powders, products for eye make-up, hair products, nail polish.

8. Cosmetic composition according to claim 7, wherein said transesterified yellow FC-YNAPHT naphtopyran and / or red FC-RNAPHT naphtopyran is / are provided in the final cosmetic composition in a percentage of 0.1% - 30% in weight, preferably 2% - 29% in weight.

9. Cosmetic composition according to claim 7 or 8, wherein the transesterified naphtopyrans are combined with other transesterified photochromic molecules, preferably with transesterified spirooxazine, wherein out of three molecules, when exposed to UV-A light one becomes blue, one yellow and one red, i.e. substantially the three primary colours are provided, which can be mixed in order to obtain a complete colour palette.

10. Cosmetic composition according to one or more of claims 7-9, changing colour when exposed to UV-A light, both per se and when applied on the skin of a user.

11. Method for the synthesis of yellow FC-YNAPHT naphtopyran according to claim 1, or of red FC-RNAPHT naphtopyran according to claim 2, comprising the following steps:- condensation of 7-bromo-2-naphthol and l,l-diphenyl-2-propyn- l-ol or l,l-bis(4-methoxyphenyl)prop-2-yn-l-ol in order to obtain 9-brome-3,3- diphenyl -3H-nafto[2,l-b]pyran or 9-bromo-3,3- bis(4’-methxoiphenyl)-3H-nafto[2,l-b]pyran, respectively, underacid catalysis in the presence of a dehydrating agent;- transformation of the bromo group into an acetyl group through a first Sonogashira reaction using (triisopropyl silyl)acetylene in micellar catalysis;- removal of the silyl portion in order to obtain a terminal acetylene using tetrabutylammonium fluoride;- condensation through a second Sonogashira reaction in micellar catalysis of the product of the preceding step with ethyl 4- bromobenzoate in micellar catalysis; after steps of extraction and purification and washing, yellow FC- YNAPHT naphtopyran is obtained as a yellow solid or red FC-RNAPHT naphtopyran is obtained as a dark orange solid.

12. Method according to claim 11, comprising a further step of transesterification of yellow FC-YNAPHT naphtopyran or red FC- RNAPHT naphtopyran in order to obtain said cosmetic ingredient, said step comprising the mixing of said yellow FC-YNAPHT naphtopyran or red FC-RNAPHT naphtopyran with a polymer or cosmetic oil having an OH group at each end, in presence of catalyst without a solvent, the solvent being the same polymer or cosmetic oil used for the transesterification reaction, working at a temperature between 120°C and 180°C, with a ratio of 3: 1 a 50: 1 (equivalent ratio) between OH groups and FC-YNAPHT naphtopyran or red FC-RNAPHT naphtopyran for a time between 1 and 48 hours.

13. Method according to claim 12, wherein the preferred conditions for the transesterification are:- stoichiometry of functionalizable OH group s / photochromic molecule is 4: 1 (equivalent ratio);- the catalyst is dibutyltin oxide or alternatively tin oxalate;- temperature is between 140 and 160°C;- reaction time is 12-20 hours.

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