1 PROCESS FOR PREPARATION OF CHEMICAL COMPOUNDS OF INTEREST BY NUCLEOPHILIC AROMATIC SUBSTITUTION Field of the invention This invention relates to the field of chemical synthesis, and in particular the invention proposes a new process enabling a nucleophilic aromatic substitution to be performed on aromatic carboxylic acid derivatives, in the absence of a catalyst in order, in particular, but not exclusively, to form symmetric or asymmetric biaryls. 5 Prior art Nucleophilic aromatic substitution is a very commonly used chemical reaction, during which an atom attached to an aromatic cycle is substituted by a nucleophilic group. It makes it possible to prepare a wide variety of aromatic 10 compounds, in particular pharmaceutical active principles, for example biphenyls. Nucleophilic aromatic substitution, performed at an industrial level, is usually performed in the presence of catalysts involving precious metals, in particular palladium. However, for increased safety of patients, pharmaceutical regulations have been made considerably stricter in recent years in order to require the 15 pharmaceutical industry to remove the maximum traces of these precious metals in the finished pharmaceutical active principles. As an example, the European Agency for the Evaluation of Medicinal Products (Agence Européenne d'Évaluation des Médicaments, EMEA) indicates for palladium a tolerated daily dose of 100 micrograms if the API is administered orally or 10 micrograms parenterally, i.e. less 20 than 10 ppm and 1 ppm, respectively. In practice, when the synthetic pattern of the active principle requires the use of a precious metal at the end of synthesis and the metal content standards allowed for this active principle are exceeded, it is necessary to find removal processes, which costly both in time and money. The trapping or removal of the residual catalysis metals is, for the 25 pharmaceutical industry, a time-consuming and expensive step, capable of producing polluting residues, and there is a real need to overcome these constraints (see, for example, Königsberger et al, Organic Process Research & Development 2003, 7, 733-742, or Pink et al. Organic Process Research & Development 2008, 12, 589-595). 2 Another known disadvantage of the nucleophilic substitution is the need to protect/unprotect the carboxyl function (CO H), necessary as a carbon anchoring 2 point for subsequent chemical functionalization. It is indeed generally accepted that the CO H function reacts with the organometallic compounds in order to lead to 2 5 ketone derivatives (Jorgenson, M. J. Org. React. 1970, 18, 1. Ahn, T.; Cohen, T. Tetrahedron Lett. 1994, 35, 203). The protective group most commonly used is the oxazoline function, and the reaction is known as the Meyers reaction (Meyers et al., Tetrahedron 2004, 60(20), 4459). According to this reaction, starting with a benzoic acid orthosubsituted by a fluorine atom or an alkoxy group, the carboxyl function is 10 first protected (1→2, diagram 1). The aryloxazoline 2 thus obtained is capable of promoting the movement of the ortho-alkoxy and fluoro groups by nucleophiles ("Nu") (2→3, diagram 1). A step of unprotection of 3 must then be performed in order to release the CO H function and obtain the desired compound 4. The 2 oxazoline can be chiral and the reaction with aryllithians or magnesians leads to 15 optically active biaryls. The Meyers reaction is of great industrial interest, in particular for obtaining these optically active biaryls, but requires these protection/unprotection steps to be performed. Moreover, the Meyers reaction does not make it possible to treat compounds 3 comprising a C6 substituent other than hydrogen: these compounds are 20 totally inert to hydrolysis of the protected carboxyl group and do not lead to 4. 3 O N O N Y X Y Nu Nu X= F, alcoxy 3 2 1) SOCl 2 H+ 2)HNC(CH)CHOH 2 32 2 3) SOCl 2 COOH COOH Y X Y Nu 1 4 Diagram 1 The invention proposes a new process that enables nucleophilic aromatic 5 substitution, on an industrial scale and with a high yield, in an optimized number of steps. The invention has the industrial advantage of not requiring the use of metal catalysts, and therefore makes it possible to avoid all of the current steps of purification/removal of precious metals, in particular palladium. It also has the advantage of not involving the generation of polluting residues. The invention has 10 another advantage, which is that it does not require a protection/unprotection step, for the starting compounds having a carboxyl function, for example but not exclusively benzoic acids, naphthoic acids and derivatives. Thus, the process according to the invention is a one-step process. 15 Definitions In the sense of this invention, the term "aryl" means a mono- or polycyclic system of 5 to 20, and preferably 6 to 12, carbon atoms having one or more aromatic rings (when there are two rings, it is called a biaryl) among which it is possible to cite the phenyl group, the biphenyl group, the 1-naphthyl group, the 2-naphthyl 20 group, the tetrahydronaphthyl group, the indanyl group and the binaphthyl group. 4 The term aryl also means any aromatic ring including at least one heteroatom chosen from an oxygen, nitrogen or sulfur atom. The aryl group can be substituted by 1 to 3 substituents chosen independently of one another, among a hydroxyl group, a linear or branched alkyl group comprising 1, 2, 3 or 4, 5 or 6 carbon atoms, in particular 5 methyl, ethyl, propyl, butyl, an alkoxy group or a halogen atom, in particular bromine, chlorine and iodine. The term "catalyst" refers to any product involved in the reaction for increasing the speed of said reaction, but is regenerated or removed during or at the end of the reaction. 10 By "protecting the carboxyl function (CO H)", we mean adding to said 2 function a group destroying the reactivity of the carboxyl function with regard to the nucleophiles; this group can be an oxazoline; numerous chemical groups other than the oxazoline function have been used to protect the CO H function: 2,6-di-tert- 2 butyl-4-methoxyphenylic ester (Hattori, T.; Satoh, T.; Miyano, S. Synthesis 1996, 15 514. Koshiishi, E.; Hattori, T.; Ichihara, N.; Miyano, S. J. Chem. Soc., Perkin Trans. 1 2002, 377), amide (Kim, D.; Wang, L.; Hale, J. J.; Lynch, C. L.; Budhu, R. J.; MacCoss, M.; Mills, S. G.; Malkowitz, L.; Gould, S. L.; DeMartino, J. A.; Springer, M. S.; Hazuda, D.; Miller, M.; Kessler, J.; Hrin, R. C.; Carver, G.; Carella, A.; Henry, K.; Lineberger, J.; Schleif, W. A.; Emini, E. A. Bioorg. Med. Chem. Lett. 2005, 15(8), 20 2129), alkylamide (Guo, Z.; Schultz, A. G. Tetrahedron Lett. 2001, 42(9), 1603), dialkylamides (Hoarau, C.; Couture, A.; Deniau, E.; Grandclaudon, P. Synthesis 2000), 1-imidazolyles (Figge, A.; Altenbach, H. J.; Brauer, D. J.; Tielmann, P. Tetrahedron: Asymmetry 2002, 13(2), 137), 2-oxazolyles (Cram, D. J.; Bryant, J. A.; Doxsee, K. M. Chem. Lett. 1987, 19), 2-thiazolyles, and so on. 25 By "leaving group" we mean a group that leads the two electrons of the sigma bond connecting it with the aromatic carbon atom during the substitution reaction with the nucleophile; according to the invention, the leaving group can be chiral or non-chiral; according to a preferred embodiment of the invention, the leaving group is chiral; according to the invention, the leaving group can be electroattractive or 30 non-electroattractive. By "alkyl", we mean any saturated linear or branched hydrocarbon chain, with 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl. 5 By "alkoxy", we mean any O-alkyl or O-aryl group, chiral or not. By "alkenyl", we mean any linear or branched hydrocarbon chain having at least one double bond, of 2 to 12 carbon atoms, and preferably 2 to 6 carbon atoms. By "alkynyl", we mean any linear or branched hydrocarbon chain having at 5 least one triple bond, of 2 to 12 carbon atoms, and preferably 2 to 6 carbon atoms. By "amine", we mean any compound derived from ammoniac NH by 3 substitution of one or more hydrogen atoms with an organic radical. According to the invention, a preferred amine is an aniline derivative. By "functional group", we mean a sub-molecular structure including an 10 assembly of atoms conferring a reactivity specific to the molecule that contains it, for example an oxy, carbonyl, carboxy, sulfonyl group, and so on. By "nucleophile", we mean an acyclic or cyclic compound, of which the characteristic is to include at least one atom with a free electron pair, charged or not. According to a preferred embodiment of the invention, by "nucleophile" we mean an 15 acyclic or cyclic compound of which the characteristic is to include at least one atom with a charged free electron pair, preferably negatively charged. By "nucleophile that may be chiral", we mean a nucleophile with at least one asymmetric carbon. By "electroattractive group" we mean a functional group having the ability to 20 attract electrons, in particular if it is substituted for an aromatic group, for example a group in particular of the NO or SO R, in which R is an alkyl, or CN or halogen 2 2 type. The amines and alkoxys are not electroattractive groups. By "heterocycle", we mean a ring with 5 or 6 links containing 1 to 2 heteroatoms chosen from O, S, N, optionally substituted with an alkyl. 25 By "aniline derivatine", we mean a compound of general formula R27 R26 R28 NH R29 R31 R30 in which R26 is a hydrogen atom, an alkyl group, an alkoxy group or an aryl; 6 R27, R28, R29, R30 and R31 are each independently a hydrogen atom, an halogen group, an alkyl group, an aryl, a heterocyclic group, a haloalkyl group, an alkoxy group, a nitro group, a cyano group or -(O) -(CH ) -R32, or -[N(H)] -(CH ) -R32, m 2 n m 2 n or two of these substituants bound to contiguous carbon atoms from an aryl ring, a 5 heteroaryl ring, a heterocyclic group or a cycloalkyl group with 4 to 7 links, or, when R27 is not in a ring with R28 and when neither R26 nor R27 are H, R26 and R27 can be implicated, with the nitrogen atom to which R26 is linked and with the carbon atom contiguous to this nitrogen atom, in a ring with 5 or 6 links, aromatic or dihydroaromatic, with carbon atoms and 1 or 2 nitrogen atoms, 10 with m equal 0 to 1, n equal to 0, 1, 2, 3, or 4, and R32 is an hydrogen atom, a hydroxyl group, -COOH or a disubstituted amine. According to the invention, alkylamines and dialkylamines are not aniline derivatives. By "MNu", we mean a reactant in which M is a metal and Nu is an independent nucleophile or a substituent of the aromatic ring of the benzoic acid 15 derivative of general formula (II), in which said substituent is capable – or having a functional group capable - of reacting in the presence of a base and a metal to form MNu. When Nu is a substituent of the aromatic ring of (II), the nucleophilic aromatic substitution reaction occurs intramolecularly between the MNu function formed on the substituent and the leaving group in the ortho position of the carboxylic acid 20 function. General description Thus, the invention relates to a process for preparing aromatic carboxylic acid derivatives, preferably benzoic acids, by nucleophilic aromatic substitution, in which 25 the following are reacted: an aromatic carboxylic acid derivative with a carboxyl function and a single one, or one of the salts thereof, preferably a lithium, sodium, potassium salt or a zinc salt, preferably a benzoic acid derivative or one of the salts thereof, in which said carboxylic acid derivative has, in the ortho position of the carboxyl function, a 30 leaving group, which is preferably a fluorine or chlorine atom or a chiral or non- chiral alkoxy group, and in this last case, a methoxy group is preferred; said aromatic carboxylic acid derivative being not substituted: • by another electroattractive group than the leaving group if any, 7 • by a phenyl group, substituted in para position, especially by a benzyloxy in para position, when the leaving group is a fluorine or chlorine atom; with a MNu reactant, in which M is a metal and Nu is a chiral or non-chiral 5 nucleophile, said nucleophilic aromatic substitution reaction being performed without a catalyst and without a step of protection/unprotection of the acid function of the starting compound. Preferably, the aromatic carboxylic acid derivative, starting product of the 10 reaction, is a benzoic acid derivative with the general formula (II) R1 R6 R2 R5 R3 R4 (II) in which 15 R1 is CO H, and R2 is a fluorine or chlorine atom or an alkoxy group, chiral 2 or not, preferably OCH 3; or R1 is a fluorine or chlorine atom or an alkoxy group, chiral or not, preferably OCH and R2 is CO H 3 2 20 R3 is a hydrogen atom, an alkyl group, and alkoxy group, an aryl or an amine substituted or not by one or two alkyl groups, or R3 forms with R4 an aromatic ring or not, or a heterocycle, optionally substituted, in particular by a functional group; or is a substituent capable of reacting in the presence of a base and a metal to form MNu; 25 R4 is a hydrogen atom, an alkyl group, an alkoxy group, preferably OCH , an 3 aryl or an amine substituted or not by one or two alkyl groups, or R4 forms with R3 an aromatic ring or not, or a heterocycle, optionally substituted, in particular by a functional group, or R4 forms with R5 an aromatic ring or not, or a heterocycle, 8 optionally substituted, in particular by a functional group; or is a substituent capable of reacting in the presence of a base and a metal to form MNu; R5 is a hydrogen atom, an alkyl group, an alkoxy group, an aryl or an amine substituted or not by one or two alkyl groups or R5 forms with R4 an aromatic ring 5 or not, or a heterocycle, optionally substituted, in particular by a functional group, or R5 forms with R6 an aromatic ring or not, or a heterocycle, optionally substituted, in particular by a functional group; or is a substituent capable of reacting in the presence of a base and a metal to form MNu; R6 is a hydrogen atom, an alkyl group, an alkoxy group, an aryl or an amine 10 substituted or not by one or two alkyl groups, or R6 forms with R5 and aromatic ring or not, or a heterocycle, optionally substituted, in particular by a functional group; or is a substituent capable of reacting in the presence of a base and a metal to form MNu; which reacts with 15 a compound (III) of general formula NuM in which Nu is a nucleophile, and M is a metal, preferably Li, Mg, Zn, Cu or an organomagnesian MgX in which X is a halogen atom or an alkoxy group, chiral or not, preferably OCH , 3 said nucleophilic aromatic substitution reaction being performed without a catalyst and without a step of protection/unprotection of the acid function of the 20 compound (II), in order to obtain a compound of general formula (I), which corresponds to the general formula (II) in which the R1 or R2 that is not CO H has 2 been substituted by Nu. Procedure 25 Advantageously, the reaction is performed at between -78°C and the solvent reflux. Preferably, the reaction is performed in a polar aprotic solvent, preferably anhydrous THF (tetrahydrofuran) or diethyl ether, benzene, toluene or a hydrocarbon such as pentane, hexane, heptane or octane. Advantageously, the NuM compound is preferably added drop by drop, at a 30 temperature between -78°C and the solvent reflux. Preferably, the solution is stirred, then hydrolyzed with water. Advantageously, the hydrolysis is performed at low temperature. The pH is adjusted to 1 with an aqueous hydrochloric acid solution (2N) and the solution is extracted 9 with an appropriate solvent, for example ethyl acetate. The organic phase is then dried and concentrated in a vacuum. The raw product is recrystallized or chromatographed. According to an embodiment of the invention, at least one NuM equivalent is 5 used for one equivalent of starting aromatic carboxylic acid derivative. Advantageously, in addition to this equivalent, one NuM equivalent per leaving group of the starting molecule to be substituted is added. According to another embodiment of the invention, at least one equivalent of a metal base, preferably butyllithium, sodium hydride, potassium hydride or lithium 10 hydride is used for an equivalent of starting aromatic carboxylic acid derivative in order to form the metal salt corresponding to the acid function of the aromatic carboxylic acid derivative, and at least one NuM equivalent is added for each leaving group of the staring molecule to be substituted. According to an embodiment of the invention, if the starting compound is a 15 salt of aromatic carboxylic acid, at least one NuM equivalent is used for one equivalent of salt of starting aromatic carboxylic acid derivative in order to form the metal salt corresponding to the acid function and at least one equivalent of NuM is added per leaving group of the starting molecule to be substituted is added. According to another embodiment of the invention, if the starting compound 20 is a salt of aromatic carboxylic acid, at least one equivalent of a metal base, preferably butyllithium, sodium hydride, potassium hydride or lithium hydride is used for an equivalent of salt of starting aromatic carboxylic acid derivative in order to form the metal salt corresponding to the acid function of the aromatic carboxylic acid derivative, and at least one NuM equivalent is added for each leaving group of 25 the staring molecule to be substituted. The yields expected for the reaction process according to the invention are between 40 and 100%, preferably 45 to 90%, and more preferably 60 to 90%. Specific cases 30 According to a first preferred embodiment, R1 is CO H, R2 is an alkoxy, 2 preferably OCH , and R3 to R6 are as defined above. 3 According to a second preferred embodiment, if R2 is CO H, R1 is an alkoxy, 2 preferably OCH and R3 to R6 are as defined above. 3 10 According to another embodiment, a hydrogen atom is in the para position of the acid function. According to a first embodiment, if R1 is Co H, R4 is a hydrogen 2 atom and R2, R3, R5 and R6 are as defined above. According to a second embodiment, if R2 is CO H, R5 is a hydrogen atom and R1, R3, R4 and R6 are as 2 5 defined above. According to a specific embodiment of the process according to the invention, the compound of general formula (II) is such that R1 is CO H, R2 is a halogen atom, 2 preferably fluorine or an alkoxy group, chiral or not, preferably methoxy, and R3 to R6 are as defined above and are preferably each a hydrogen atom. 10 According to another specific embodiment of the process according to the invention, the compound of general formula (II) is such that R1 is CO H, R2 is a 2 halogen atom, preferably fluorine, or an alkoxy group, chiral or not, preferably methoxy, R3 and R4, or R4 and R5, or R5 and R6 form together a ring, optionally substituted, such that the starting aromatic carboxylic acid derivative is a naphthalene 15 derivative with the general formulae (IIa, IIb or IIc) below, in which R7, R8, R9 and R10 are each independently a hydrogen atom, an alkyl group, an alkoxy group, an aryl or an amine substituted or not by one or two alkyl groups; and substituants R3, R4, R5 and R6 non-implied in the ring are as defined above. R10 COOH COOH COOH R9 R2 R6 R2 R6 R2 R10 R7 R8 R3 R3 R5 R7 R4 R9 R7 R10 R8 R8 R9 20 (IIa) (IIb) (IIc) According to a prefered embodiment, when the leaving group is a fluorine, MNu is not sBuLi or tBuLi or PhLi. 25 According to another prefered embodiment, when the leaving group is a methoxy, MNu is not sBuLi. Presence of an asymmetric carbon