PROCESSES FOR PRODUCING ALKYL ACRYLATE DIMERS

Abstract

The present invention relates to a process for producing an alkyl acrylate dimer. Furthermore, the present invention relates to a process for producing a hydrogenated alkyl acrylate dimer obtained by the dimerization process according to the present invention. Moreover, the present invention relates to a process of producing a hydrolyzed alkyl acrylate dimer obtained by the dimerization process according to the present invention.

Description

1 / 45 PROCESSES FOR PRODUCING ALKYL ACRYLATE DIMERS

[0001] This application claims priority over the application filed in 13-04-2023 in Europe with number 23167673.5, all the content of this application being incorporated into this document by way of reference for any purpose. Field of invention

[0002] The present invention relates to a process for producing an alkyl acrylate dimer. Furthermore, the present invention relates to a process for producing a hydrogenated alkyl acrylate dimer obtained by the dimerization process according to the present invention. Additionally, the present invention relates to a process for producing a hydrolyzed alkyl acrylate dimer obtained by the dimerization process according to the present invention. Background of the art

[0003] The use of specific phosphines as catalysts for the dimerization of alkyl acrylates via the Rauhut-Currier reaction has already been described in the state of the art.

[0004] US 3074999 A describes an alkyl acrylate dimerization reaction catalyzed by tertiary phosphines having three alkyl groups, three alicyclic groups, or three aryl groups, such as tributylphosphine or triphenylphosphine. However, these catalysts exhibit low activity in the dimerization reaction. Regarding the disclosed process, moderate yields are reported, which are serious disadvantages for commercial production.

[0005] US 3227745 A describes a tertiary phosphine-catalyzed alkyl acrylate dimerization reaction in the presence of large amounts of tert-butyl alcohol as solvent. The tertiary phosphines disclosed are trialkyphosphines. However, with the described process, only a low acrylate conversion of less than 50% is achieved. Petition 870250080389, dated 08 / 09 / 2025, page 6 / 68 2 / 45 which is not suitable for industrial production processes.

[0006] US 3342853 A describes the triamine phosphine-catalyzed acrylate dimerization that can be generated prior to the dimerization reaction from PCl3. Yields of 70 to 80% of methylene glutarate ester dimers are reported when the reaction is conducted at 60 to 65 °C, however significant amounts of byproduct are also generated. Furthermore, triamine phosphines are generally toxic and CMR (carcinogenic, mutagenic, and toxic to reproduction) reagents, and when the catalyst is generated in situ, PCb is used as the precursor, which is a very hazardous chemical. These are serious disadvantages for the commercialization and industrialization of this process.

[0007] US 3342854 A describes acrylate dimerization reactions catalyzed by monoaminophosphines or bis-aminophosphines. However, the low activity of diphenylaminophosphines for acrylate dimerization requires the use of high phosphine charges, which is a serious disadvantage for commercial production. This is shown by two examples in this patent application using an in situ generated dibutylaminodiphenylphosphine catalyst or a diethylaminodiphenylphosphine catalyst that results in dimer yields equal to or less than 10%. Furthermore, using the process according to US 3342854 A, a significant amount of byproduct is obtained.

[0008] Weiping Su et al. describe in P(RNCH2CH2)3N: Catalysts for the Head-to-Tail Dimerization of Methyl Acrylate” J. Org. Chem. 2003, 68, 9499-9501, the dimerization of methyl acrylate in THF or dioxane as solvents at room temperature using proazaphosphatranes as phosphine catalysts. With a catalyst loading of 1 mol%, a yield of up to 82% is obtained. However, the catalysts described in this article are quite complex and difficult to synthesize, resulting in expensive overall catalyst costs, which is a serious disadvantage for potential industrialization. Petition 870250080389, dated 08 / 09 / 2025, page 7 / 68 3 / 45 Furthermore, with the use of low catalyst loads (1 mol%), the reaction kinetics are slow at room temperature, resulting in long reaction times (up to 24 hours), which is also a disadvantage for industrial production. Summary of the invention

[0009] A problem of the present invention is to provide an efficient process for the production of an alkyl acrylate dimer using a highly active, robust, reusable, inexpensive and readily available catalyst, wherein the catalyst has relatively low toxicity, can be used with relatively low catalyst loadings and provides excellent selectivity.

[0010] Specifically, a problem of the present invention is to provide a process for preparing an alkyl acrylate dimer in which the use of large quantities of tertiary alcohols as solvents and relatively high catalyst loadings can be avoided. More specifically, a problem of the present invention is to provide an efficient process for preparing a hydrogenated alkyl acrylate dimer and an efficient process for preparing a hydrolyzed alkyl acrylate dimer.

[0011] It has now been found that these and other problems can be solved by the process of the present invention. The present invention relates to a process for producing a dimer according to formula (II), characterized in that it comprises a step i) of dimerizing alkyl acrylates according to formula (I) to obtain a dimer according to formula (II) using a catalyst according to formula (III), according to the following reaction scheme: (I) (II) Petition 870250080389, dated 09 / 08 / 2025, p. 8 / 68 4 / 45 R12Âp / RaR Ç (III) where Réum alkyl group; R1 and R2, which are identical or different, are aliphatic groups or together with the N atom form a heteroaliphatic ring; Rae is a hydrocarbyl group; Rb is an aliphatic group or NR3R4, with R3 and R4 being identical or different and being aliphatic groups or forming a heteroaliphatic ring together with the N atom; wherein said dimerization step i) is carried out in the presence of a compound A which is a tertiary alcohol or a silanol; and wherein an acid is added during said step i).

[0012] Furthermore, the present invention relates to a process as defined above, which further comprises an initial step (0) of preparing the catalyst according to formula (III) by reacting a compound according to formula (IV) X Rc I Ra (iv) in which X is a chloride, a bromide, or an iodide, preferably a chloride; Raé as defined above; Rc is X (in the case of catalysts of formula (III) in which Rb is NR3R4 as defined above) or Rb (in the case of catalysts of formula (III) in which Rb is an aliphatic group); with Petition 870250080389, dated 08 / 09 / 2025, page 9 / 68 5 / 45 - an amine of formula (V): R1R2NH (V), with Ri and R2 being as defined above when Rc is Rb or - both an amine of formula (V) and an amine of formula (V): R3R4NH (V), with R3 and R4 being as defined above when Rcé X.

[0013] Furthermore, the present invention provides a process for producing a compound according to formula (VI), comprising the process as defined above, followed by a step ii) of hydrogenation of the dimer according to formula (II) obtained in the dimerization step using H2 and a hydrogenation catalyst, such as Pd-based catalysts, for example, Pd / C, Pd / AbOs, Pd / SiO2, Ru-based catalysts, for example, Ru / C, Pt-based catalysts, such as Pt / C, Ni-based catalysts, such as supported nickel catalysts or Raney nickel, Co-based catalyst, such as supported cobalt or Raney cobalt, Rh-based catalyst, such as Rh / C, Ir-based catalyst, such as Ir / C, preferably Pd / C or Raney nickel, preferably Pd / C, to obtain a compound according to formula (VI) 0 (VI) where R is as defined above.

[0014] The present invention also relates to a process for producing a compound according to formula (VII') oo (VII') and comprising a further step iii) of reacting the compound of formula (VI) with an amine of formula HNR5R5, wherein R5 and R6 are identical or different, and are each selected from groups based on saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic, optionally substituted hydrocarbons. Petition 870250080389, dated 09 / 08 / 2025, p. 10 / 68 6 / 45 which has an average number of carbon atoms in the range of 1 to 36, provided that R5 and R6 can optionally form together a ring member, which is optionally substituted and / or which optionally contains a heteroatom.

[0015] The R5 and R6 groups, which are identical or different, may specifically be groups chosen from C1-C12 alkyl, aryl, alkaryl or arylalkyl or the phenyl group. The R5 and R6 groups may optionally be substituted, in particular by hydroxyl groups.

[0016] The R5 and R6 groups, which are identical or different, may be specially selected from among methyl, ethyl, propyl (n-propyl), isopropyl, n-butyl, isobutyl, n-pentyl, amyl, isoamyl, hexyl, cyclohexyl or 2-hydroxyethyl groups. The R5 and R6 groups may also be such that, together with the nitrogen atom, they form a morpholine, piperazine, pyrrolidine or piperidine group. According to particular embodiments, R5 = R6 = methyl or R5 = R6 = ethyl or R5 = R6 = 2-hydroxyethyl. Satisfactory results are obtained when R5 = R6 = methyl.

[0017] Finally, the present invention relates to a process for producing a compound according to formula (VII), comprising the process as defined above, followed by a step ii') of hydrolysis of the dimer according to formula (II) obtained in the dimerization step using acid catalysts, such as Lewis or Bronsted acids, for example: HCl, H2SO4, para-toluenesulfonic acid, methanesulfonic acid, triflic acid, solid acid catalysts, such as Amberlyst resins or zeolites, Nafion to obtain a compound according to formula (VII)

[0018] The present invention is based on the recognition that it is Petition 870250080389, dated 08 / 09 / 2025, page 11 / 68 7 / 45 provides an efficient process for the production of an alkyl acrylate dimer using a highly active, robust, reusable, inexpensive, and readily available catalyst. The catalyst for the dimerization of alkyl acrylates is a compound according to formula (III) which has relatively low toxicity, is reusable, can be used with relatively low catalyst loadings, and provides excellent selectivity. Furthermore, the present invention provides an efficient process for the preparation of an alkyl acrylate dimer using the compound according to formula (III) as a catalyst, in which the use of large amounts of tertiary alcohols relative to the alkyl acrylate and the use of relatively high catalyst loadings can be avoided. Specifically, the molar amount of tertiary alcohol relative to the alkyl acrylate can be reduced to a ratio of 0.01:1 and the catalyst loading can be reduced to 0.20 mol%.Finally, the present invention provides an efficient process for the preparation of a hydrogenated alkyl acrylate dimer and an efficient process for the preparation of a hydrolyzed alkyl acrylate dimer. Detailed description of the invention

[0019] According to the present invention, the term approximately means ± 10% of the specified numerical value, preferably ± 5% and more preferably ± 2%.

[0020] The present invention relates to a process for producing a dimer according to formula (II), characterized in that it comprises a step i) of dimerizing alkyl acrylates according to formula (I) to obtain a dimer according to formula (II) using a catalyst according to formula (III), according to the following reaction scheme: (I) (II) Petition 870250080389, dated 09 / 08 / 2025, p. 12 / 68 8 / 45 R1 I r^N'I- » R» in which Réum alkyl group; R1 and R2, which are identical or different, are aliphatic groups or together with the N atom form a heteroaliphatic ring; Rae is a hydrocarbyl group; Rb is an aliphatic group or NR3R4, with R3 and R4 being identical or different and being aliphatic groups or forming together with the N atom a heteroaliphatic ring; wherein the aforementioned dimerization step i) is carried out in the presence of a compound A that is a tertiary alcohol or a silanol; and wherein an acid is added during said step i).

[0021] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, compound A is a tertiary alcohol, such as ferc-butanol, ferc-amyl alcohol or pinacol and more preferably ferc-butanol.

[0022] Preferably, in the process for producing a dimer according to formula (II) as defined herein, the molar ratio [compound A] / [alkyl acrylate according to formula (I)] is selected from about 4:1 to about 0.01:1, preferably from about 2:1 to about 0.1:1 and more preferably from about 0.5:1 to about 0.1:1, and notably from about 0.5:1 to about 0.2:1.

[0023] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, R is a C1-C18 alkyl, more preferably C1-C5, even more preferably a C1-C4 alkyl and most preferably a methyl.

[0024] Preferably, in the process to produce a dimer of Petition 870250080389, dated 09 / 08 / 2025, p. 13 / 68 9 / 45 according to formula (II) as defined in this document, R is a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, 2-ethylhexyl group, octyl group, decyl group, dodecyl group, t-dodecyl group, tetradecyl group, hexadecyl group or octadecyl group, more preferably a methyl group, ethyl group, isopropyl group, butyl group or 2-ethylhexyl group, more preferably a methyl group, ethyl group, isopropyl group or butyl group, most preferably a methyl group.

[0025] Preferably, in the process for producing a dimer according to formula (II) as defined herein, Ri and R2 are identical linear or branched alkyl groups comprising from 1 to 6 carbon atoms, more preferably from 1 to 3 carbon atoms, most preferably ethyl.

[0026] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, Ri and R2 together with the N atom form a heteroaliphatic ring comprising 3 to 5 carbon atoms, preferably 4 carbon atoms.

[0027] Preferably, in the process for producing a dimer according to formula (II) as defined herein, Ra is an aromatic or aliphatic group, more preferably an aromatic group, more preferably selected from phenyl, tolyl, xylyl, mesityl, duryl, pentamethylphenyl, 2,6-di-isopropylphenyl, tert-butylphenyl, di tert-butylphenyl, methoxyphenyl, dimethoxyphenyl, methoxytolyl, methylenedioxyphenyl, biphenyl, nitrophenyl, halogen-substituted phenyl, trifluoromethylphenyl, naphthyl, pyridyl, furyl, pyrrolyl, thiophenyl, 2-indolyl, benzofuryl and all their positional isomers.

[0028] Preferably, Rae selected from phenyl; ortho-, meta- or para-tolyl; xylyl including all positional isomers, such as: 2,3 Petition 870250080389, dated 09 / 08 / 2025, p. 14 / 68 10 / 45 dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl and 3,5-dimethylphenyl; 3-methyl-4-methoxyphenyl, 2-methyl-4-methoxyphenyl, 2-methyl-3-methoxyphenyl, 4-methyl-3-methoxyphenyl, 5-methyl-3-methoxyphenyl, 6-methyl-3-methoxyphenyl, 2-methoxy-3-methylphenyl, 2-methoxy-4-methylphenyl, 2-methoxy-5-methylphenyl, 2-methoxy-6-methylphenyl; mesitila including todos os isômeros de position, tais como: 2,3,4-trimetilfenila, 2,3,5-trimetilfenila, 2,3,6-trimetilfenila, 2,4,5-trimetilfenila, 2,4,6-trimetilfenila e 3,4,5-trimetilfenila; durila including todos os isômeros de position, tais como: 2,3,4,5-tetrametilfenila, 2,3,4,6-tetrametilfenila e 2,3,5,6-tetrametilfenila; pentametilfenila, 2,6-di-isopropylfenila; orto -, meta - ou para tert-butilfenila; 2,3-di-tert-butylphenyl, 2,4-di-tert-butylphenyl, 2,5-di-tert-butylphenyl, 2,6-di-tert-butylphenyl, 3,4-di-tert-butylphenyl and 3,5-di-tert-butylphenyl; ortho-, meta- or para-methoxyphenyl; ortho-, meta- or para-chlorophenyl;2,3-dimethoxyphenyl, 2,4-dimethoxyphenyl, 2,5-dimethoxyphenyl, 2,6-dimethoxyphenyl, 3,4-dimethoxyphenyl and 3,5-dimethoxyphenyl; 2,3-methylenedioxyphenyl, 3,4-methylenedioxyphenyl; ortho-, meta- or para-nitrophenyl; ortho-, meta- or para-biphenyl; ortho-, meta- or para-trifluoromethylphenyl, ortho-, meta- or para-fluorophenyl; 1- or 2-naphthyl; 2-pyridyl, 3-pyridyl or 4-pyridyl; 2-furyl, 3-furyl; 1-pyrroyl, 2-pyrroyl or 3-pyrroyl; 2-thiophenyl, 3-thiophenyl; 2-indolyl, 3-indolyl, 2-benzofuryl and 3-benzofuryl; preferably phenyl; ortho-, meta- or para-tolyl; or xylyl and their isomeric positions.

[0029] Preferably, in the process for producing a dimer according to formula (II) as defined herein, Rb is NR3R4, with R3 and R4 being identical or different and being an aliphatic group or forming together with the N atom a heteroaliphatic ring, more preferably R3 and R4 are identical linear or branched alkyl groups comprising from 1 to 6 carbon atoms, more preferably from 1 to 3 carbon atoms, most preferably ethyl.

[0030] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, Raé Petition 870250080389, dated 09 / 08 / 2025, p. 15 / 68 11 / 45 is a phenyl group, R1 and R2 are ethyl groups, and Rb is NR3R4, with R3 and R4 being ethyl groups.

[0031] Preferably, in the process for producing a dimer according to formula (II) as defined herein, the catalyst according to formula (III) is a compound selected from the group consisting of compounds according to formulas (VIII) to (XIV): (IX) (XIV)

[0032] Most preferably, in the process for producing a dimer according to formula (II) as defined in this document, the catalyst according to formula (III) is a compound selected from the group consisting of compounds according to formulas (IX) and (XI) to (XIV), more preferably selected from the group consisting of compounds according to formulas (XI), (XII) and (XIV), more preferably still selected from the group consisting of compounds according to formulas (XI) and (XIV), most preferably the catalyst according to formula (III) is the compound according to formula (XIV). Petition 870250080389, dated 09 / 08 / 2025, p. 16 / 68 12 / 45

[0033] Preferably, in the process for producing a dimer according to formula (II) as defined herein, step i) of dimerization is carried out in an organic solvent, more preferably an aprotic solvent, more preferably selected from tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (MeTHF), toluene, xylene, anisole, diethyl ether, tert-butyl methyl ether (MTBE), dichloromethane (DCM), chloroform, 1,4-dioxane, pentane, cyclopentane, hexane, cyclohexane, methylcyclohexane, benzene and acetonitrile, more preferably MeTHF, anisole and toluene, most preferably MeTHF and anisole.

[0034] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, the dimerization step i) is carried out at a temperature in the range of about 20°C to about 120°C, more preferably about 20°C to about 80°C, more preferably even higher from about 25°C to about 60°C, most preferably from about 30°C to about 60°C.

[0035] Preferably, in the process for producing a dimer according to formula (II) as defined herein, in step i) the catalyst according to formula (III) is used with a catalyst loading of 0.20 mol% to 1.00 mol% relative to the alkyl acrylate according to formula (I), more preferably from about 0.25 mol% to about 0.90 mol%, even more preferably from about 0.30 mol% to about 0.90 mol%, even more preferably from about 0.30 mol% to about 0.80 mol%, even more preferably from about 0.30 mol% to about 0.70 mol%, even more preferably from about 0.30 mol% to about 0.60 mol%, most preferably from about 0.30% in moles at 0.50% by mole.

[0036] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, the step Petition 870250080389, dated 09 / 08 / 2025, p. 17 / 68 13 / 45 of dimerization i) is carried out under anhydrous conditions and in the absence of oxygen.

[0037] The applicant found that better results can be obtained if an acid is added during the dimerization step (i). This acid can be chosen from mineral acids such as HCl, HNO3, H3PO4, H2SO4, H3BO3, HF, HBr, HClO4, HI, NaHSO4, KHSO4, NH4HSO4, NaHSO3, KHSO3, H3PO3, H3PO2 etc... Alternatively, it can be chosen from organic acids such as acetic acid, malic acid, tartaric acid, lactic acid, pyruvic acid, citric acid, formic acid, uric acid, ascorbic acid, gluconic acid, itaconic acid, propanoic acid, butanoic acid, (meth)acrylic acid, terephthalic acid, benzoic acid, toluic acid, levulinic acid, methanesulfonic acid, para-toluenesulfonic acid, triflic acid. It could also be a heterogeneous solid, such as Amberlyst resin, etc...

[0038] Preferably, the process for producing a dimer according to formula (II) as defined herein further comprises an initial step (0) of preparing the catalyst according to formula (III) by reacting a compound according to formula (IV) X Rc Ra (IV) in which X is a chloride, a bromide, or an iodide, preferably a chloride; Ra is a hydrocarbyl group; Rc is X (in the case of catalysts of formula (III) in which Rb is NR3R4 as defined above) or Rb (in the case of catalysts of formula (III) in which Rb is an aliphatic group); with Petition 870250080389, dated 08 / 09 / 2025, page 18 / 68 14 / 45 - an amine of formula (V): R1R2NH (V), with Ri and R2 being as defined herein when Rc is Rb or - both an amine of formula (V) and an amine of formula (V'): R3R4NH (V'), with R3 and R4 being as defined herein when Rc is X.

[0039] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, step 0) and step i) are consecutive steps carried out without isolating the catalyst after step 0).

[0040] Preferably, in the process to produce a dimer according to formula (II) as defined in this document, Rc is X.

[0041] Preferably, in the process for producing a dimer according to formula (II) as defined herein, step 0) is carried out in an organic solvent, more preferably an aprotic solvent, more preferably selected from tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (MeTHF), toluene, xylene, anisole, diethyl ether, tert-butyl methyl ether (MTBE), dichloromethane (DCM), chloroform, dioxane, pentane, cyclopentane, hexane, cyclohexane, methylcyclohexane, benzene and acetonitrile, more preferably MeTHF, anisole and toluene, most preferably MeTHF and anisole.

[0042] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, step 0) is carried out at a temperature in the range of about 20°C to about 100°C, preferably about 20°C to 80°C, more preferably about 25°C to 60°C, most preferably at a temperature of about 40°C.

[0043] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, step 0) is carried out by slowly adding the reagent of formula (IV) to a Petition 870250080389, dated 09 / 08 / 2025, p. 19 / 68 15 / 45 solution of the amine R1R2NH in the aprotic solvent where the amine is used in an amount equal to or greater than 2 equivalents relative to the reagent of formula (IV) when Rc in (IV) is Rb and Rb is an aliphatic group. Step (0) can also be carried out by slowly adding the reagent of formula (IV) to a solution containing both the amine Ri R2NH and R3R4NH in the aprotic solvent where the total amount of amines is equal to or greater than 4 equivalents relative to the reagent for formula (IV) when Rc in (IV) is X.

[0044] Preferably, in the process for producing a dimer according to formula (II) as defined in this document, step 0) is carried out under anhydrous conditions and in the absence of oxygen.

[0045] Preferably, in the process for producing a dimer according to formula (II) as defined herein, step 0) comprises a filtration step to remove ammonium salt byproducts formed before carrying out step i).

[0046] Furthermore, the present invention provides a process for producing a compound according to formula (VI), comprising the process for producing a dimer according to formula (II) as defined herein, followed by a step ii) of hydrogenating the dimer according to formula (II) obtained in the dimerization step using H2 and a hydrogenation catalyst, such as Pd-based catalysts, for example, Pd / C, Pd / AlO3, Pd / SiO2, Ru-based catalysts, for example, Ru / C, Pt-based catalysts, such as Pt / C, Ni-based catalysts, such as supported nickel catalysts or Raney nickel, Co-based catalyst, such as supported cobalt or Raney cobalt, Rh-based catalyst, such as Rh / C, Ir-based catalyst, such as Ir / C, preferably Pd / C or Raney nickel, preferably Pd / C, to obtain a compound according to formula (VI) Petition 870250080389, dated 09 / 08 / 2025, p. 20 / 68 16 / 45 (vi) where R is as defined in this document.

[0047] In a preferred embodiment, the process for producing a compound according to formula (VI) further comprises a step iii') of hydrolysis of the hydrogenated dimer according to formula (VI) obtained in step ii) using acid catalysts, such as Lewis or Bronsted acids, for example: HCl, H2SO4, para-toluenesulfonic acid, methanesulfonic acid, triflic acid, solid acid catalysts, such as Amberlyst resins, zeolites or Nafion to obtain a compound according to formula (XV).

[0048] Finally, the present invention relates to a process for producing a compound according to formula (VII), comprising the process as defined above, followed by a step ii') of hydrolysis of the dimer according to formula (II) obtained in the dimerization step using acid catalysts, such as Lewis or Bronsted acids, for example: HCl, H2SO4, para-toluenesulfonic acid, methanesulfonic acid, triflic acid, solid acid catalysts, such as Amberlyst resins or zeolites, Nafion to obtain a compound according to formula (VII). oo (vii) Petition 870250080389, dated 08 / 09 / 2025, page 21 / 68 17 / 45

[0049] In a preferred embodiment, the process for producing a compound according to formula (VII) further comprises a step iii') of hydrogenating the hydrolyzed dimer according to formula (VII) obtained in step ii') using H2 and a hydrogenation catalyst, such as Pd-based catalysts, for example, Pd / C, Pd / Al2O3, Pd / SiÜ2, Ru-based catalysts, for example, Ru / C, Pt-based catalysts, such as Pt / C, Ni-based catalysts, such as supported nickel catalysts or Raney nickel, Co-based catalyst, such as supported cobalt or Raney cobalt, Rh-based catalyst, such as Rh / C, Ir-based catalyst, such as Ir / C, preferably Pd / C or Raney nickel, preferably Pd / C, to obtain a compound according to formula (XV). HO OH (XV) Examples 1. Aminophosphine-catalyzed dimerization of methyl acrylate General protocols for the phosphine screening study: a) Dimerization catalyzed by symmetrical bis-aminophosphines of dichlorophosphines:

[0050] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophosphines and amines were used in this way.

[0051] In a round-bottomed flask with two 25 ml tubes, the following are added: □ 3 ml of 2-methyltetrahydrofuran Petition 870250080389, dated 08 / 09 / 2025, page 22 / 68 18 / 45 □ Dichlorophosphine precursor (1.8 mmol, 0.01 eq. relative to methyl acrylate).

[0052] In a round-bottomed flask with three 50 ml necks equipped with a magnetic stirring device, the following were added: □ 1 ml of 2-methyltetrahydrofuran □ 4 equivalents relative to the dichlorophosphine precursor of the desired amine (7.2 mmol).

[0053] The dichlorophosphine solution was progressively added to the amine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). After the addition of dichlorophosphine to the amine solution, a white precipitate formed, corresponding to the insoluble ammonium chloride salt byproduct. At the end of the addition, the mixture was then left stirring at room temperature and the progress of the reaction was monitored using 31P NMR (see Table 1 below for the 31P chemical shift results of the investigated aminophosphines).

[0054] After the formation of phosphine was complete (which generally requires 1 hour of stirring at room temperature after the addition of chlorophosphine for unhindered amines and 2 hours for more sterically hindered amines), the mixture was then filtered through a cannula into a 100 ml round-bottom flask with three necks equipped with a magnetic stirrer, a condenser, a heater, and a temperature probe, and containing 32 ml of molten tert-butanol (2:1 v / v relative to methyl acrylate). The mixture was then left stirring at 60 °C. Immediately, 15.95 ml of methyl acrylate (15.15 g, 0.176 mol, 1 eq.) were carefully added over 1 hour (exothermic) to the reactor, and the progress of the reaction was monitored using 1H NMR. The reactions continued until the advance ceased or until 1 day of reaction. The conversion of Petition 870250080389, dated 08 / 09 / 2025, page 23 / 68 19 / 45 methyl acrylate was then estimated by 1H NMR thanks to the integration of methylene protons from the products and methylene protons in the starting methyl acrylate. Product NMR spectrum: 1H NMR (CDCl3, 400 MHz) δ (ppm): 6.03 (s, 1H), 5.46 (s, 1H), 3.60 (s, 3H), 3.51 (s, 3H), 2.48 (t, J = 7.6 Hz, 2H), 2.37 (t, J = 7.6 Hz, 2H). b) Monoaminophosphine-catalyzed dimerization of monochlorophosphines:

[0055] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves and tert-butanol was distilled under argon before each reaction. Monochlorophosphines and amines were used in this manner.

[0056] In a round-bottomed flask with two 25 ml tubes, the following were added: □ 3 ml of 2-methyltetrahydrofuran □ precursor of monochlorophosphine (1.8 mmol, 0.01 eq. relative to methyl acrylate).

[0057] In a round-bottomed flask with three 50 ml necks equipped with a magnetic stirring device, the following were added: □ 1 ml of 2-methyltetrahydrofuran □ 2 equivalents relative to the monochlorophosphine precursor of the desired amine (3.6 mmol).

[0058] The monochlorophosphine solution was progressively added to the amine solution under stirring (1400 rpm) for 1 hour while maintaining the temperature of the reaction medium below 40 °C (exothermic reaction). After the addition of monochlorophosphine to the amine solution, a white precipitate formed, corresponding to the insoluble ammonium chloride salt byproduct. At the end of the addition, the Petition 870250080389, dated 08 / 09 / 2025, page 24 / 68 The 20 / 45 mixture was then left stirring at room temperature and the progress of the reaction was monitored using 31P NMR.

[0059] After the formation of phosphine was complete (which generally requires 1 hour of stirring at room temperature after the addition of monochlorophosphine for unhindered amines and 2 hours for more sterically hindered amines), the mixture was then filtered through a cannula into a 100 ml round-bottom flask with three necks equipped with a magnetic stirrer, a condenser, a heater and a temperature probe and containing 32 ml of molten tert-butanol (2:1 v / v relative to methyl acrylate). The mixture was then left stirring at 60 °C. Immediately, 15.95 ml of methyl acrylate (15.15 g, 0.176 mol, 1 eq.) were carefully added over 1 hour (exothermic) to the reactor and the progress of the reaction was monitored using 1H NMR. The reactions were continued until the progression ceased or until 1 day of reaction.The conversion of methyl acrylate was then estimated by 1H NMR thanks to the integration of methylene protons from the products and the methylene proton in the starting methyl acrylate. c) Asymmetric bis-aminophosphine-catalyzed dimerization of dichlorophosphines, diisopropylamine, and an additional amine:

[0060] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophosphines and amines were used in this way.

[0061] In a round-bottomed flask with two 25 ml tubes, the following were added: □ 3 ml of 2-methyltetrahydrofuran □ dichlorophosphine precursor (1.8 mmol, 0.01 eq. relative to methyl acrylate). Petition 870250080389, dated 08 / 09 / 2025, page 25 / 68 21 / 45

[0062] In a round-bottomed flask with three 50 ml necks equipped with a magnetic stirring device, the following were added: □ 1 ml of 2-methyltetrahydrofuran □ 3 equivalents relative to the dichlorophosphine precursor of diisopropylamine (5.4 mmol).

[0063] The dichlorophosphine solution was progressively added to the amine solution under stirring (1400 rpm) for 1 hour while maintaining the temperature of the reaction medium below 40 °C (exothermic reaction). After the addition of dichlorophosphine to the amine solution, a white precipitate was formed corresponding to the insoluble ammonium chloride salt byproduct (in the case of the invention, diisopropylammonium chloride). The mixture was then left stirring at room temperature and the progress of the reaction was monitored by 31P NMR. The formation of the intermediate chloro(di-isopropylamino)phosphine was confirmed by 31P NMR (for example, for chlorophenyl(di-isopropylamino)phosphine a singlet was observed at +132.5 ppm).

[0064] After the formation of the chloraminophosphine intermediate was complete (which usually requires 1 hour of stirring at room temperature after the addition of dichlorophosphine), 1 equivalent of a second amine (1.8 mmol) was added to the mixture at room temperature under stirring and the reaction mass was left stirring at room temperature for another hour.

[0065] After the bis-aminophosphine was completed, the mixture was then filtered through a cannula into a 100 ml round-bottom flask with three spools equipped with a magnetic stirrer, a condenser, a heater, and a temperature probe, and containing 32 ml of melted tert-butanol (2:1 v / v relative to methyl acrylate). The mixture was then left to stir at 60 °C. Immediately, Petition 870250080389, dated 08 / 09 / 2025, page 26 / 68 22 / 45 15.95 ml of methyl acrylate (15.15 g, 0.176 mol, 1 eq.) were carefully added over 1 hour (exothermic) to the reactor, and the reaction progress was monitored using 1H NMR. The reactions were continued until progress ceased or until 1 day of reaction. The conversion of methyl acrylate was then estimated by 1H NMR by integrating the methylene protons from the products and the methylene proton in the starting methyl acrylate.

[0066] To confirm that the target catalysts were successfully synthesized, the crude reaction medium was analyzed using 31P NMR. Indeed, this parameter (31P NMR chemical shift) was characteristic of the synthesized aminophosphine, and the area under the peak was proportional to the molar concentration of aminophosphine in solution. The 31P NMR spectrum was recorded using a Bruker Avance 400 MHz spectrometer.

[0067] In addition, - the phosphine NMR yield (%), which corresponds to the molar selectivity of the aminophosphine synthesis reaction deduced from the peak areas in the 31P NMR spectra recorded in the Me-THF solution before transfer to the dimerization reactor; - the maximum conversion during acrylate dimerization for some of the tests presented above in Table 1, which corresponds to the maximum conversion rate of methyl acrylate measured from 1H NMR; They were measured.

[0068] The t-BuOH:acrylate ratio in v:v (and in mol / mol) was also provided.

[0069] For Inv 4.4, the reaction was initiated with an initial charge of 0.5 mol% dichlorophenylphosphine followed by the addition of an additional amount of methyl acrylate (0.5 eq. to achieve an initial charge of 0.33 mol% dichlorophenylphosphine) after a reaction time of 20 hours.

[0070] All results are compiled in Table 1 below: Petition 870250080389, dated 08 / 09 / 2025, page 27 / 68 Table 1: Results of the aminophosphine screening study - dimerization process Chlorophosphine Precursor No. Amine 1 Amine 2 31P Shift (ppm) Chlorophosphine Loading (% mol) Phosphine NMR Yield (%) Max. Conversion tBuOH:Acrylate Ratio v:v mol / mol (tBuOH / Me Acrylate) Cp 1 ΛΛ P \= / o H — 37.1 1 41 0 2:1 1.90 Cp 2 „ PH — 46.9 1 83 10 2:1 1.90 Inv. 1 >VCI ò H -- 65 0.5 79 73 2:1 1.90 Inv. 2 CK „CI P ò QHQH 72.7 1 85 55 2:1 1.90 Inv. 3.1 Ckp.CI HH 97.8 1 54 99 2:1 1.90 Inv. 3.2 Ckp.CI HH 97.8 0.5 46 72 2:1 1.90 Inv. 4.1 CKp,CI ò HH 63.8 1 84 88 2:1 1.90 Inv. 4.2 CKp.CI o HH 63.8 0.5 96 76 2:1 1.90 23 / 45 Petition 870250080389, dated 08 / 09 / 2025, page 28 / 68 Chlorophosphine Precursor No. Amine 1 Amine 2 31P Shift (ppm) Chlorophosphine Loading (% mol) Phosphine NMR Yield (%) Max. Conversion tBuOH:Acrylate Ratio v:v mol / mol (tBuOH / Me Acrylate) Inv. 4.3 CKp,CI ò HQH 63.8 0.5 96 84 1:1 0.95 Inv. 4.4 CKp,CI ò HQH 63.8 0.33 98 91 1:4 0.24 Inv. 5 CKp,CI ò H ' 'NH 77.0 0.5 98 — 1:4 0.24 Inv. 6 CKp.CI ò H N'* H 78.4 0.5 95 43 1:4 0.24 Inv. 7 CKpXI ò HH 96.5 0.5 93 47 2:1 1.90 24 / 45 (Cp = Comparative example) All phosphines were synthesized. Petition 870250080389, dated 08 / 09 / 2025, page 29 / 68 25 / 45

[0071] The chlordiphenylphosphine precursor provided only moderate yields of aminophosphine by reaction with diisopropylamine (Comp 1) and did not provide good catalytic activity. The chlordiphenylphosphine precursor reacted with pyrrolidine (Comp 2) and also did not provide good catalytic activity. On the other hand, the aminophosphines according to the invention (Inv 1 to 7) provided relatively good catalytic activities.

[0072] The best performing system was di-isopropylaminopyrrolidinephenylphosphine (Inv 4.1 to 4.4). It was very surprising to observe that, with only 0.33 mol% of the initial charge of dichlorophosphine, an acrylate conversion of 91% was achieved with di-isopropylaminopyrrolidinephenylphosphine (Inv 4.4). Furthermore, it was observed that this phosphine was quite robust, allowing for easier handling and even recycling for multiple batches.

[0073] The presence of tert-butyl alcohol during the dimerization reaction improved the selectivity of the reaction with respect to the expected dimer. Surprisingly, it was still possible to find suitable conditions that allowed the use of t-BuOH with very low amounts of basic aminophosphines without compromising the catalytic activity of phosphine and providing good selectivity. d) Optimization of the dimerization reaction: Bis(diethylamino)phenylphosphine catalyzed (initial precursor of dichlorophenylphosphine at 0.7 mol% relative to methyl acrylate) the dimerization of methyl acrylate in tert-butanol (1:4 v / v of t-BuOH:methyl acrylate = 0.24 mol(t-BuOH) / mol(M-Acrylate)), 45 °C.

[0074] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophenylphosphine and diethylamine were used accordingly. Petition 870250080389, dated 08 / 09 / 2025, page 30 / 68 26 / 45

[0075] In a round-bottomed flask with two 50 ml tubes, the following were added: □ 15 ml of 2-methyltetrahydrofuran □ 4.2 ml of dichlorophenylphosphine (5.57 g, 0.031 mol, 0.007 eq.).

[0076] In a round-bottomed flask with three 100 ml necks equipped with a magnetic stirring device, the following are added: □ 20 ml of 2-methyltetrahydrofuran □ 12.9 ml of diethylamine (9.1 g, 0.124 mol, 0.028 eq.). (4 equivalents relative to dichlorophenylphosphine).

[0077] Dichlorophenylphosphine in 2-methyltetrahydrofuran solution was progressively added to the diethylamine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). After the addition of dichlorophenylphosphine, a white precipitate corresponding to the ammonium chloride salt byproduct (in this case, diethylammonium chloride) was formed. At the end of the addition, the mixture was then left stirring at room temperature and the progress of the reaction was monitored using NMR.

[0078] After completion of the formation of bis-(diethylamino)phenylphosphine, which requires 1 hour of stirring at room temperature after the addition of dichlorophenylphosphine, the mixture was filtered through a cannula into a 500 ml double-jacketed reactor maintained at 45°C and equipped with a temperature probe, a condenser, and a mechanical stirrer (propeller with four inclined diverters) containing: □ 100 ml of distilled tert-butanol (1:4 v / v tert-butanol:methyl acrylate) □ 400 ml of methyl acrylate (380.8 g, 4.42 mol, 1 eq.) Petition 870250080389, dated 09 / 08 / 2025, p. 31 / 68 27 / 45

[0079] The mixture was then left stirring at 45 °C for 19 hours. The progress of the reaction was monitored using 1H NMR. The conversion of methyl acrylate was estimated by 1H NMR by integrating the methylene protons from the products and the methylene protons in the starting methyl acrylate. According to the NMR, the conversion of the initial methyl acrylate was ~92% mol.

[0080] At the end of the reaction, the volatiles (t-BuOH, Me-THF and unconverted methyl acrylate) were removed by distillation, allowing the recovery of 31 g of unreacted methyl acrylate. The desired product (dimethyl 2-methyleneglutarate) was then distilled under vacuum (160 °C, 15 mbar) to give 283 g of analytically pure product (isolated yield = 75%). The high-boiling-point byproducts (methyl acrylate oligomers) that remained in the distillation vessel represented approximately 57 g (15%). 1H NMR (CDCl3, 400 MHz) δ (ppm): 6.03 (s, 1H), 5.46 (s, 1H), 3.60 (s, 3H), 3.51 (s, 3H), 2.48 (t, J = 7.6 Hz, 2H), 2.37 (t, J = 7.6 Hz, 2H). 13C NMR (CDCI3, 101 MHz) δ (ppm): 172.73, 166.75, 138.76, 125.56, 51.59, 51.26, 32.66 and 27.17. e) Bis(diethylamino)phenylphosphine (precursor of dichlorophenylphosphine at 0.7 mol% relative to methyl acrylate) catalyzed the dimerization of methyl acrylate in tert-butanol (1:8 v / v of t-BuOH:methyl acrylate = 0.12 mol(t-BuOH) / mol(M-Acrylate)), 45 °C.

[0081] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophenylphosphine and diethylamine were used accordingly.

[0082] In a round-bottomed bottle with two 50 ml tubes, the following are added: □ 15 ml of 2-methyltetrahydrofuran Petition 870250080389, dated 08 / 09 / 2025, page 32 / 68 28 / 45 □ 4.2 ml of dichlorophenylphosphine (5.57 g, 0.031 mol, 0.007 eq.).

[0083] In a round-bottomed flask with three 100 ml necks equipped with a magnetic stirring device, the following were added: □ 20 ml of 2-methyltetrahydrofuran □ 12.9 ml of diethylamine (9.1 g, 0.124 mol, 0.028 eq.). (4 equivalents relative to dichlorophenylphosphine).

[0084] Dichlorophenylphosphine in 2-methyltetrahydrofuran solution was progressively added to the diethylamine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). After the addition of dichlorophenylphosphine, a white precipitate corresponding to the ammonium chloride salt byproduct (in this case, diethylammonium chloride) was formed. At the end of the dichlorophosphine addition, the mixture was then left stirring at room temperature and the progress of the reaction was monitored using NMR.

[0085] After completion of the formation of bis-(diethylamino)phenylphosphine, which requires 1 hour of stirring at room temperature after the addition of dichlorophenylphosphine, the mixture was filtered through a cannula into a 500 ml double-jacketed reactor maintained at 45°C and equipped with a temperature probe, a condenser, and a mechanical stirrer (propeller with four inclined diverters) containing: □ 50 ml of distilled tert-butanol (1:8 v / v tert-butanol:methyl acrylate) □ 400 ml of methyl acrylate (380.8 g, 4.42 mol, 1 eq.).

[0086] The mixture was then left stirring at 45 °C for 19 hours. The progress of the reaction was monitored using 1H NMR. The conversion of methyl acrylate was estimated by 1H NMR by integrating the methylene protons from the products and the methylene protons in the starting methyl acrylate. According to the NMR, the conversion of Petition 870250080389, dated 09 / 08 / 2025, p. 33 / 68 29 / 45 of the starting methyl acrylate was ~88% by mole. At the end of the reaction, the volatiles (t-BuOH, Me-THF and unconverted methyl acrylate) were removed by distillation, allowing the recovery of 44 g of unreacted methyl acrylate.

[0087] The desired product (dimethyl 2-methyleneglutarate) was then distilled under vacuum (160 °C, 15 mbar) to give 271 g of analytically pure product (isolated yield = 71%). The high-boiling-point byproducts (methyl acrylate oligomers) that remained in the distillation vessel accounted for 59 g (16%). 1H NMR (CDCl3, 400 MHz) δ (ppm): 6.03 (s, 1H), 5.46 (s, 1H), 3.60 (s, 3H), 3.51 (s, 3H), 2.48 (t, J = 7.6 Hz, 2H), 2.37 (t, J = 7.6 Hz, 2H). 13C NMR (CDCI3, 101 MHz) δ (ppm): 172.73, 166.75, 138.76, 125.56, 51.59, 51.26, 32.66 and 27.17. f) Bis(diethylamino)phenylphosphine catalyzed (precursor of dichlorophenylphosphine at 0.7 mol% relative to methyl acrylate) the dimerization of methyl acrylate in tert-butanol (1:8 v / v of t-BuOH:methyl acrylate = 0.12 mol(t-BuOH) / mol(M-Acrylate)), 60 °C, average for 2 batches.

[0088] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophenylphosphine and diethylamine were used accordingly.

[0089] In a round-bottomed flask with two 25 ml tubes, the following were added: □ 8 ml of 2-methyltetrahydrofuran □ 2.1 ml of dichlorophenylphosphine (2.79 g, 0.0155 mol, 0.007 eq.).

[0090] In a round-bottomed flask with three 50 ml necks equipped with a magnetic stirring device, the following were added: Petition 870250080389, dated 08 / 09 / 2025, page 34 / 68 30 / 45 □ 10 ml of 2-methyltetrahydrofuran □ 6.5 ml of diethylamine (4.6 g, 0.062 mol, 0.028 eq.) (4 equivalents with respect to dichlorophenylphosphine).

[0091] Dichlorophenylphosphine in 2-methyltetrahydrofuran solution was progressively added to the diethylamine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). After the addition of dichlorophenylphosphine, a white precipitate corresponding to the diethylammonium chloride salt byproduct was formed. The mixture was then left stirring at room temperature and the progress of the reaction was monitored using NMR.

[0092] After completion of the formation of bis-(diethylamino)phenylphosphine, which requires 1 hour of stirring at room temperature after the addition of dichlorophenylphosphine, the mixture was filtered through a cannula into a 500 ml double-jacketed reactor maintained at 60°C and equipped with a temperature probe, a condenser, and a mechanical stirrer (propeller with four inclined diverters) containing: □ 25 ml of distilled tert-butanol (1:8 v / v tert-butanol:methyl acrylate) □ 200 ml of methyl acrylate (190 g, 2.21 mol, 1 eq.).

[0093] The mixture was then stirred at 60 °C for 20 hours. The progress of the reaction was monitored using 1H NMR. The conversion of methyl acrylate was estimated by 1H NMR by integrating the methylene protons from the products and the methylene protons in the starting methyl acrylate. According to the NMR, the conversion of the starting methyl acrylate was ~95% mol (average of 2 batches). At the end of the reaction, the volatiles (t-BuOH, Me-THF and unconverted methyl acrylate) were removed by distillation.

[0094] The desired product (dimethyl 2-methyleneglutarate) was then distilled under vacuum (140 °C, 5 mbar) to yield 137 g of product. Petition 870250080389, dated 08 / 09 / 2025, page 35 / 68 31 / 45 analytically pure (average of 2 batches, isolated yield = 72%). The high-boiling-point byproducts (mainly methyl acrylate oligomers) that remained in the distillation vessel represented 40 g (21%, average of 2 batches). g) Bis(diethylamino)phenylphosphine (precursor of dichlorophenylphosphine at 0.9 mol% relative to methyl acrylate) catalyzed the dimerization of methyl acrylate in tert-butanol (1:4 v / v of t-BuOH:methyl acrylate = 0.24 mol(t-BuOH) / mol(M-Acrylate)), 30 °C.

[0095] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophenylphosphine and diethylamine were used accordingly.

[0096] In a round-bottomed bottle with two 50 ml tubes, the following are added: □ 20 ml of 2-methyltetrahydrofuran □ 5.43 ml of dichlorophenylphosphine (7.17 g, 0.04 mol, 0.009 eq.).

[0097] In a round-bottomed flask with three 100 ml necks equipped with a magnetic stirring device, the following are added: □ 20 ml of 2-methyltetrahydrofuran □ 16.6 ml of dichlorophenylphosphine (11.7 g, 0.16 mol, 0.036 eq.). (4 equivalents relative to dichlorophenylphosphine).

[0098] Dichlorophenylphosphine in 2-methyltetrahydrofuran solution was progressively added to the diethylamine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). After the addition of dichlorophenylphosphine, a white precipitate corresponding to the diethylammonium chloride salt byproduct was formed. At the end of the addition Petition 870250080389, dated 08 / 09 / 2025, page 36 / 68 32 / 45 of dichlorophosphine, the mixture was then left stirring at room temperature and the progress of the reaction was monitored using NMR.

[0099] After completion of the formation of bis-(diethylamino)phenylphosphine, which requires 1 hour of stirring at room temperature after the addition of dichlorophenylphosphine, the mixture was filtered through a cannula into a 500 ml double-jacketed reactor maintained at 30°C and equipped with a temperature probe, a condenser, and a mechanical stirrer (propeller with four inclined diverters) containing: □ 100 ml of distilled tert-butanol (1:4 v / v tert-butanol:methyl acrylate) □ 400 ml of methyl acrylate (380.8 g, 4.42 mol, 1 eq.).

[0100] The mixture was then stirred at 30 °C for 20 hours. The progress of the reaction was monitored by 1H NMR. At this stage, the conversion level of methyl acrylate was 93%, as estimated by 1H NMR. The volatiles (2-methyltetrahydrofuran, t-BuOH and remaining methyl acrylate) were then removed under vacuum, recovering 27 g of methyl acrylate. Subsequently, the desired dimethyl 2-methyleneglutarate was removed by vacuum distillation (160 °C, 15 mbar) to recover 284 g of analytically pure product, corresponding to a purified isolated yield of 75%. The high-boiling-point byproducts (mainly methyl acrylate oligomers) remaining in the distillation vessel accounted for 49 g (13%). h) Bis(diethylamino)phenylphosphine catalyzed (precursor of dichlorophenylphosphine at 0.9 mol% relative to methyl acrylate) the dimerization of methyl acrylate in tert-butanol (1:4 v / v of t-BuOH:methyl acrylate = 0.24 mol(t-BuOH) / mol(M-Acrylate)), 30 °C, progressive addition of methyl acrylate.

[0101] All reactions were conducted in carefully dried containers under an inert argon atmosphere. Methyl acrylate, Petition 870250080389, dated 09 / 08 / 2025, p. 37 / 68 33 / 45 tert-butanol and diethylamine were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophenylphosphine was used as well.

[0102] In a round-bottomed bottle with two 50 ml tubes, the following are added: □ 20 ml of 2-methyltetrahydrofuran □ 5.43 ml of dichlorophenylphosphine (7.17 g, 0.04 mol, 0.009 eq.).

[0103] In a round-bottomed flask with three 100 ml necks equipped with a magnetic stirring device, the following were added: □ 20 ml of 2-methyltetrahydrofuran □ 16.6 ml of dichlorophenylphosphine (11.7 g, 0.16 mol, 0.036 eq.). (4 equivalents relative to dichlorophenylphosphine).

[0104] Dichlorophenylphosphine in 2-methyltetrahydrofuran solution was progressively added to the diethylamine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). After the addition of dichlorophenylphosphine, a white precipitate corresponding to the diethylammonium chloride salt byproduct was formed. At the end of the dichlorophosphine addition, the mixture was then left stirring at room temperature and the progress of the reaction was monitored using NMR.

[0105] After completion of the formation of bis-(diethylamino)phenylphosphine, which requires 1 hour of stirring at room temperature after the addition of dichlorophenylphosphine, the mixture was filtered through a cannula into a 500 ml double-jacketed reactor maintained at 30°C and equipped with a temperature probe, a condenser, and a mechanical stirrer (propeller with four inclined diverters) containing: □ 100 ml of distilled tert-butanol (1:4 v / v tert-butanol:methyl acrylate) □ 100 ml of methyl acrylate (95.2 g, 1.105 mol, 0.25 eq.). Petition 870250080389, dated 09 / 08 / 2025, p. 38 / 68 34 / 45

[0106] Next, 300 ml of methyl acrylate (285.6 g, 3.315 mol, 0.75 eq.) were progressively added to the reactor over 4 hours. At the end of the addition, the mixture was then left stirring at 30 °C for 16 hours. The progress of the reaction was monitored using 1H NMR. At this stage, the conversion level of methyl acrylate was 92%, as estimated by 1H NMR.

[0107] The volatiles (2-methyltetrahydrofuran, t-BuOH and remaining methyl acrylate) were then removed under vacuum, allowing the recovery of 29 g of methyl acrylate. Subsequently, the desired dimethyl 2-methyleneglutarate was removed by vacuum distillation (160°C, 15 mbar) to recover 288 g of analytically pure product, corresponding to a purified isolated yield of 76%. The high-boiling-point byproducts (methyl acrylate oligomers) that remained in the distillation vessel represented 49 g (13%). i) (Di-isopropylamino)pyrrolidinephenylphosphine catalyzed (precursor of dichlorophenylphosphine at 0.4 mol% relative to methyl acrylate) the dimerization of methyl acrylate in tert-butanol (1:8 v / v of tBuOH:methyl acrylate = 0.12 mol(t-BuOH) / mol(M-Acrylate)), 60 °C with catalyst recycling.

[0108] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate and tert-butanol were dried using 4A molecular sieves, and tert-butanol was distilled under argon before each reaction. Dichlorophenylphosphine, diisopropylamine, and pyrrolidine were used accordingly.

[0109] In a round-bottomed flask with two 50 ml tubes, the following were added: □ 20 ml of 2-methyltetrahydrofuran □ 3.6 ml of dichlorophenylphosphine (4.77 g, 0.027 mol, 0.012 eq.).

[0110] In a round-bottomed flask with three tubing Petition 870250080389, dated 08 / 09 / 2025, page 39 / 68 35 / 45 of 100 ml equipped with a magnetic stirring device were added: □ 20 ml of 2-methyltetrahydrofuran □ 11.15 ml of diisopropylamine (8.05 g, 0.08 mol, 0.036 eq.) (3 equivalents relative to dichlorophenylphosphine).

[0111] Dichlorophenylphosphine in 2-methyltetrahydrofuran solution was progressively added to the diisopropylamine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). The mixture was left stirring at room temperature and 1 equivalent (0.027 mol, 1.92 g) of pyrrolidine was added to the reaction mixture, which was left stirring at room temperature for another hour to complete the formation of bis-(amino)phosphine.

[0112] The reaction mixture was filtered through a cannula into a 500 ml double-jacketed reactor equipped with a temperature probe, a condenser, and a mechanical stirrer (propeller with four inclined diverters) containing: □ 25 ml of distilled tert-butanol (1:8 v / v tert-butanol:methyl acrylate) □ 200 ml of methyl acrylate (190.1 g, 2.2 mol, 1 eq.).

[0113] The mixture was then left stirring at 60 °C for 19 hours. The progress of the reaction was monitored using 1H NMR. According to 1H NMR, the conversion of the starting methyl acrylate was ~ 86% by mole.

[0114] The volatiles (t-BuOH, Me-THF and unconverted methyl acrylate) are removed by distillation allowing the recovery of 20 g of methyl acrylate.

[0115] The desired product (dimethyl 2-methyleneglutarate) is then distilled under vacuum (125 °C, 7 mbar) to provide 103 g of analytically pure product. Petition 870250080389, dated 08 / 09 / 2025, page 40 / 68 36 / 45

[0116] Next, 190 g of methyl acrylate (2.2 mol, 1 eq.) are added to the residue still containing active phosphine catalyst, followed by the addition of 20 g of tert-butanol. The mixture is left stirring at 60 °C for a further 16 hours to convert a second batch of methyl acrylate. The volatiles are removed by distillation allowing the recovery of 37 g of methyl acrylate and the product is distilled under vacuum (125 °C, 8 mbar) to give 126 g of analytically pure product.

[0117] Finally, an additional 190 g of methyl acrylate (2.2 mol, 1 eq.) is added to the residue which still contains active phosphine and the mixture is stirred again at 70 °C for 20 hours. At the end of the reaction, the volatiles are removed under vacuum to recover 44 g of methyl acrylate, and the product is distilled under vacuum to give 91 g of pure product.

[0118] In total, 320 g of dimethyl 2-methyleneglutarate product are recovered, corresponding to an overall purified isolated yield of 56%.

[0119] This is the first example of an aminophosphine catalyst that can be recycled after the acrylate dimerization reaction. j) Influence of the presence / absence of t-BuOH

[0120] All reactions were conducted in carefully dried vessels under an inert argon atmosphere. Methyl acrylate was dried using 4A molecular sieves. Dichlorophosphines and amines were used in the same way.

[0121] In a round-bottomed flask with two 25 ml tubes, the following were added: □ 18 ml of 2-methyltetrahydrofuran □ dichlorophosphine precursor (10.5 mmol, 0.005 eq. relative to methyl acrylate).

[0122] In a round-bottomed flask with three tubing Petition 870250080389, dated 08 / 09 / 2025, page 41 / 68 37 / 45 of 50 ml equipped with a magnetic stirring device were added: □ 6 ml of 2-methyltetrahydrofuran □ 3 equivalents relative to the dichlorophosphine precursor of diisopropylamine (31.4 mmol).

[0123] The dichlorophosphine solution was progressively added to the amine solution under stirring (1400 rpm) for 1 hour while maintaining the reaction medium temperature below 40 °C (exothermic reaction). After the addition of dichlorophosphine to the amine solution, a white precipitate formed, corresponding to the insoluble salt byproduct of diisopropylammonium chloride. The mixture was then left stirring at room temperature and the progress of the reaction was monitored using 31P NMR. The formation of the intermediate chloro(diisopropylamino)phosphine was confirmed by 31P NMR (e.g., for chlorophenyl(diisopropylamino)phosphine a singlet was observed at +132.5 ppm).

[0124] After the formation of the chloraminophosphine intermediate was complete (which usually requires 1 hour of stirring at room temperature after the addition of dichlorophosphine), 1 equivalent of pyrrolidine (10.5 mmol) was added to the mixture at room temperature under stirring and the reaction mass was left stirring at room temperature for another hour.

[0125] After the bis-aminophosphine conversion, the mixture was then filtered through a cannula into a 500 ml double-jacketed reactor equipped with a mechanical stirrer (propeller with four inclined diverters), a condenser, a heater, and a temperature probe, and containing 190 ml of methyl acrylate (180 g, 2.1 mol). The mixture was then left stirring at 60 °C for 20 hours. The conversion of methyl acrylate was then estimated by 1H NMR thanks to the integration of methylene protons from the products and the methylene proton in the acrylate. Petition 870250080389, dated 08 / 09 / 2025, page 42 / 68 38 / 45 of starting methyl. At 66% conversion to methyl acrylate, the selectivity with respect to the dimer, as determined by 1H NMR, was estimated at 78 mol%.

[0126] In comparison, when t-BuOH was present during the reaction (1:1 v / v tert-BuOH:methyl acrylate), initial charge of dichlorophenylphosphine of 0.5 mol%, 60 °C (corresponding to Inv 4.3), at a similar conversion level (66%), the selectivity towards the dimer was 87%, clearly demonstrating the positive impact of t-BuOH on the selectivity of the reaction. k) Impact charge of methyl acrylate dimerization

[0127] The reactions are carried out in carefully dried vessels and under an inert argon atmosphere.

[0128] The solvent tert-butanol was subjected to flash distillation under argon before the reaction and the anisole was dried over activated molecular sieve 4A overnight before the reaction.

[0129] The reagents diethylamine and methyl acrylate were also dried on activated molecular sieve 4A overnight before the reaction. K1) In a 250 ml double-jacketed reactor equipped with a temperature probe, a mechanical stirrer (propeller with 4 inclined deflectors) and baffles are added at room temperature: - 40 g of anisole. - 18.4 ml of diethylamine (12.98 g, 177 mmols)

[0130] A solution of dichlorophenylphosphine (DCPP) in anisole (previously prepared by diluting 6.17 ml of 97% pure DCPP (8.14 g, 44 mmol) in 30 g of anisole) is progressively added under stirring (500 rpm) at room temperature to the diethylamine in anisole solution over 1 hour (exothermic).

[0131] During the addition, a precipitate (NH2Et2Cl) forms, resulting in a gel-like solution. At the end of the addition, a Petition 870250080389, dated 09 / 08 / 2025, p. 43 / 68 39 / 45 An additional 30 g of anisole is added to the mixture to reduce the viscosity of the suspension, and the reaction medium is left stirring at room temperature for 1 hour and 30 minutes. 31P NMR analysis at this stage confirms the complete conversion of DCPP to the desired bis(diethylamino)phenylphosphine.

[0132] The suspension is then easily filtered in an argon filtration cell using a 6 µm filter cloth. The solid is washed with an additional 60 g of anisole. In total, 138.4 g of a clear yellow solution is obtained as the filtrate. Quantitative 31P NMR analysis of the solution using triethyl phosphate as an internal probe allows the determination of the aminophosphine catalyst concentration in the solution: 4.6 wt% corresponding to 6.3 g of catalyst (25 mmol), which corresponds to a catalyst loading of only 0.28 mol% relative to methyl acrylate.

[0133] In a 1.5 l double-jacketed reactor equipped with a condenser, a temperature probe, a mechanical stirrer (propeller with 4 inclined deflectors) and baffles, 157.8 g of tert-butanol (200 ml) are added followed by the addition of the previous catalyst in anisole solution (138.4 g). The solution is then left stirring at 40 °C (500 rpm) and 760 g of methyl acrylate (8.828 mol) are progressively added to the solution over 4 hours (exothermic). At the end of the methyl acrylate addition, the reaction mixture is stirred at 40 °C overnight and the progress of the reaction is monitored by quantitative GC chromatography.

[0134] The conversion of methyl acrylate is monitored over time (as well as the dimer yield) and the kinetic curves are represented in the graphs below (left: methyl acrylate conversion over time; right: dimer yield over time). As can be seen in the graph below (black curves), with only 0.28 mol% catalyst feedstock, a conversion is obtained. Petition 870250080389, dated 08 / 09 / 2025, page 44 / 68 40 / 45 final yield of 66% after 24 hours at 40°C, corresponding to a dimer yield of 58%. K2) In a 250 ml double-jacketed reactor equipped with a temperature probe, a mechanical stirrer (propeller with 4 inclined deflectors) and baffles are added at room temperature: - 40 g of anisole. - 25.7 ml of diethylamine (18.17 g, 247 mmols)

[0135] A solution of dichlorophenylphosphine (DCPP) in anisole (previously prepared by diluting 8.44 ml of 99% pure DCPP (11.13 g, 62 mmol) in 30 g of anisole) is progressively added under stirring (500 rpm) at room temperature to the diethylamine solution over 1 hour (exothermic).

[0136] During the addition, a precipitate (NH2Et2Cl) forms, resulting in a gel-like solution. At the end of the addition, the reaction medium is left stirring at 40 °C for 30 minutes. 31P NMR analysis at this stage confirms the complete conversion of DCPP to the desired bis(diethylamino)phenylphosphine.

[0137] The suspension is then filtered through a cannula into an intermediate flask and the solid is washed with an additional 90 g of anisole. In total, 153.7 g of a clear yellow solution is obtained. Quantitative 31P NMR analysis of the solution using triethyl phosphate as an internal probe allows the determination of the aminophosphine catalyst concentration in the solution: 8.6 wt% corresponding to 13.2 g of catalyst (52 mmol), which corresponds to a catalyst loading of only 0.6 mol% relative to methyl acrylate.

[0138] In a 1.5 L double-jacketed reactor equipped with a condenser, a temperature probe, a mechanical stirrer (propeller with 4 inclined deflectors) and baffles, 157.8 g of tert-butanol (200 mL) are added followed by the addition of the previous catalyst in anisole solution (153.7 g). The solution is then left stirring the Petition 870250080389, dated 08 / 09 / 2025, page 45 / 68 41 / 45 °C (500 rpm) and 760 g of methyl acrylate (8.828 mol) are progressively added to the solution over 4 hours. At the end of the methyl acrylate addition, the reaction mixture is stirred at 40 °C overnight and the reaction progress is monitored using quantitative GC chromatography.

[0139] By monitoring the conversion of methyl acrylate over time (as well as the dimer yield) and the kinetic curves, it is found that, with a catalyst loading of only 0.6 mol%, a final conversion > 99% is obtained after 25 hours at 40 °C, corresponding to a dimer yield of 82%. K3) In a 250 ml double-jacketed reactor equipped with a temperature probe, a mechanical stirrer (propeller with 4 inclined deflectors) and baffles are added at room temperature: - 40 g of anisole. - 25.7 ml of diethylamine (18.17 g, 247 mmols)

[0140] A solution of dichlorophenylphosphine (DCPP) in anisole (previously prepared by diluting 8.44 ml of 99% pure DCPP (11.13 g, 62 mmol) in 30 g of anisole) is progressively added under stirring (500 rpm) at room temperature to the diethylamine solution over 1 hour (exothermic).

[0141] During the addition, a precipitate (NH2Et2Cl) forms, resulting in a gel-like solution. At the end of the addition, the reaction medium is left stirring at 40 °C for 30 minutes. 31P NMR analysis at this stage confirms the complete conversion of DCPP to the desired bis(diethylamino)phenylphosphine.

[0142] The suspension is then filtered through a cannula into an intermediate flask and the solid is washed with an additional 90 g of anisole. In total, 142.0 g of a light yellow solution is obtained. Quantitative 31P NMR analysis of the solution using triethyl phosphate as an internal probe allows the determination of the catalyst concentration of Petition 870250080389, dated 08 / 09 / 2025, page 46 / 68 42 / 45 aminophosphine in solution: 7.2% by weight corresponding to 10.22 g of catalyst (41 mmol), which corresponds to a catalyst loading of only 0.46 mol% relative to methyl acrylate.

[0143] In a 1.5 l double-jacketed reactor equipped with a condenser, a temperature probe, a mechanical stirrer (propeller with 4 inclined deflectors) and baffles, 157.8 g of tert-butanol (200 ml) are added followed by the addition of 760 g of methyl acrylate (8.828 mol). The catalyst previously prepared in anisole solution (142.0 g) is then added to the solution under stirring (500 rpm, exothermic). The solution is then left stirring at 40°C overnight and the progress of the reaction is monitored by quantitative GC chromatography.

[0144] The conversion of methyl acrylate is monitored over time (as well as the dimer yield) and the kinetic curves are showing that, with a catalyst loading of only 0.46 mol%, a final conversion of 87% is obtained after 48 hours at 40 °C, corresponding to a dimer yield of 76%. 2. Catalytic hydrogenation of dimethyl 2-methyleneglutarate to dimethyl 2-methylglutarate

[0145] The substrate 2-methyleneglutarate dimethyl (50 g, 0.29 mol) obtained according to the dimerization reaction described above (Inv 4.4) was first added to a 100 ml autoclave reactor equipped with a mechanical stirrer (Rushton turbine) followed by the addition of the Pd / C catalyst (3%) (powder, 51% moisture content, 1 g wet corresponding to 0.49 g dry, 1% by weight relative to the substrate). The reactor was then hermetically sealed and purged 3 times with 20 bar of nitrogen followed by 3 times with 5 bar of hydrogen. The reaction mixture was left stirring at 1400 rpm and the temperature of the reaction mixture was then adjusted to 40 °C. The reaction medium was then left stirring at 40 °C, 5 bar hydrogen pressure (1400 rpm). Petition 870250080389, dated 08 / 09 / 2025, page 47 / 68 43 / 45 for 6 hours and hydrogen consumption was monitored over time.

[0146] At the end of the reaction, which was confirmed by the absence of hydrogen consumption, the reaction mixture was allowed to cool to room temperature, stirring was stopped, and the autoclave was depressurized. The reactor was purged with nitrogen, the crude product was removed from the reactor, and the catalyst was removed by filtration. The product 2-methyldimethylglutarate was obtained after filtration of the catalyst as a clear liquid (50 g corresponding to a 99% yield) and was used as is. 3. Synthesis of 2-methylenepentanedioic acid from dimethyl 2-methylenepentanedioate O 0 0 O Ό'γ +2 H2O H0 íl H2SO4(cat.) -2MeOH

[0147] In a 2 l double-jacketed reactor equipped with a mechanical stirrer (propeller with four inclined deflectors), baffles, a temperature probe and a distillation column connected to a receiver, the following are added: - 700 g (4.07 mol, 1 eq.) of dimethyl 2-methylenepentanedioate. - 879 ml of water (48.8 mol, 12 eq). - 95% sulfuric acid (9 ml, 16.6 g, 0.163 mol, 4 mol% relative to dimethyl 2-methylenepentanedioate) is added dropwise to the reaction mixture at room temperature using an addition funnel.

[0148] The mixture is then stirred at 120 °C and the progress of the reaction is monitored by 1H NMR analysis. Throughout the reaction, the generated methanol is distilled from the reaction medium to shift the reaction equilibrium towards the desired methyleneglutaric acid. Petition 870250080389, dated 08 / 09 / 2025, pages 48 / 68 44 / 45

[0149] After 2 hours and 30 minutes of stirring at 120 °C, 1H NMR analysis indicates a slow conversion of the diester to the diacid, therefore an additional amount of sulfuric acid is added to the reaction mixture to accelerate the kinetics: 2.26 ml (0.04 mol, 1 mol%) and the temperature of the mixture is increased to 130 °C.

[0150] However, after 2 hours of further stirring at 130 °C, the diester conversion is still very slow, therefore 2.26 ml (0.04 mol, 1 mol%) of H2SO4 are added again to the reaction mass.

[0151] After 11 hours and 30 minutes of stirring at 130 °C, 1060 ml of a water / MeOH mixture were removed by distillation and 50 ml of fresh water are added to the reaction vessel.

[0152] After 16 hours and 30 minutes of stirring at 130 °C, 1H NMR analysis indicates approximately 10 mol% of remaining unhydrolyzed ester functions and significant formation of polymeric byproducts.

[0153] At this stage, the mass of distillate recovered is 1195 g containing 6 g of insoluble starting diester.

[0154] The temperature of the reaction medium is reduced to 80 °C and 36 ml of a 35% by weight aqueous NaOH solution (2 eq. relative to H2SO4) are slowly added to the vessel to neutralize the catalyst (exothermic).

[0155] The contents of the reactor, maintained at 80 °C, are drained into a beaker while being constantly stirred, and the mixture solidifies into a white paste that becomes increasingly firm as it cools.

[0156] 147 ml of water are added to the paste to obtain a filterable liquid paste and the mixture is allowed to cool to room temperature to complete the precipitation of the diacid product.

[0157] The product is then filtered through a sintered filter and a very viscous filtrate is obtained.

[0158] The cake is washed 4 times with 80 ml of water and then 6 times with 70 ml of water, shaking the mixture well before each filtration. Petition 870250080389, dated 09 / 08 / 2025, p. 49 / 68 45 / 45

[0159] The resulting aqueous filtrate that precipitated at room temperature overnight is filtered and washed again 10 times with 20 ml of water to collect additional product.

[0160] The solid fractions are combined and the product is dried under vacuum at 50 °C (10 mbar) for 2 hours to provide 286 g of a white powder with more than 98% by weight organic purity and containing 3% by weight water corresponding to a 48% isolated yield. NMR Spectra: 1H NMR (MeOD-d4, 400 MHz) δ (ppm): 6.16 (s, 1H), 5.63 (s, 1H), 2.62.56 (t, J = 7.6 Hz, 2H), 2.51-2.47 (t, J = 7.6 Hz, 2H), 13C NMR (MeOD-d4, 101 MHz) δ (ppm): 176.7, 170.12, 141.16, 126.38, 34.07, 28.52. Petition 870250080389, dated 09 / 08 / 2025, pp. 50 / 68

Claims

1 / 5 CLAIMS 1. Process for producing a dimer according to formula (II) characterized in that it comprises a step i) of dimerization of alkyl acrylates according to formula (I) to obtain a dimer according to formula (II) using a catalyst according to formula (III), according to the following reaction scheme: wherein R is an alkyl group; R1 and R2, which are identical or different, are aliphatic groups or together with the N atom form a heteroaliphatic ring; R1 is a hydrocarbyl group; Rb is an aliphatic group or NR3R4, with R3 and R4 being identical or different and being aliphatic groups or together with the N atom form a heteroaliphatic ring; wherein said dimerization step i) is carried out in the presence of a compound A which is a tertiary alcohol or a silanol; and wherein an acid is added during said dimerization step i).

2. Process according to claim 1, characterized in that compound A is a tertiary alcohol, such as tert-butanol, ferc-amyl alcohol or pinacol, and more preferably ferc-butanol.

3. Process, according to claim 1 or 2, characterized Petition 870250080389, dated 08 / 09 / 2025, page 51 / 68 2 / 5 by the fact that the molar ratio [compound A] / [alkyl acrylate according to formula (I)] is selected from about 4:1 to about 0.01:1, preferably from about 2:1 to about 0.1:1 and most preferably from about 0.5:1 to about 0.1:

1.

4. Process, according to any one of claims 1 to 3, characterized in that R is a C1-C18 alkyl, preferably C1-C8, more preferably a C1-C4 alkyl and most preferably a methyl.

5. Process, according to any one of claims 1 to 4, characterized in that R1 and R2 are identical linear or branched alkyl groups comprising from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, most preferably ethyl.

6. Process, according to any one of claims 1 to 4, characterized in that R1 and R2 together with the N atom form a heteroaliphatic ring comprising 3 to 5 carbon atoms, preferably 4 carbon atoms.

7. Process, according to any one of claims 1 to 6, characterized in that Ra is an aromatic or aliphatic group, preferably an aromatic group, most preferably selected from phenyl, tolyl, xylyl, mesityl, duryl, pentamethylphenyl, 2,6-diisopropylphenyl, tert-butylphenyl, di-tert-butylphenyl, methoxyphenyl, dimethoxyphenyl, methoxytolyl, methylenedioxyphenyl, biphenyl, nitrophenyl, halogen-substituted phenyl, trifluoromethylphenyl, naphthyl, pyridyl, furyl, pyrrolyl, thiophenyl, 2-indolyl, benzofuryl and all their positional isomers.

8. Process, according to any one of claims 1 to 7, characterized in that Rb is NR3R4, with R3 and R4 being identical or different and being an aliphatic group or forming together with the N atom a heteroaliphatic ring, preferably Petition 870250080389, dated 08 / 09 / 2025, page 52 / 68 3 / 5 Ra and R4 are identical linear or branched alkyl groups comprising from 1 to 6 carbon atoms, more preferably from 1 to 3 carbon atoms, most preferably ethyl.

9. Process, according to any one of claims 1 to 8, characterized in that Ra is a phenyl group, Ri and R2 are ethyl groups, and Rb is NR3R4, with R3 and R4 being ethyl groups.

10. Process, according to any one of claims 1 to 9, characterized in that step i) of dimerization is carried out in an organic solvent, preferably an aprotic solvent, most preferably selected from tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (MeTHF), toluene, xylene, anisole, diethyl ether, tert-butyl methyl ether (MTBE), dichloromethane (DCM), chloroform, dioxane, pentane, cyclopentane, hexane, cyclohexane, methylcyclohexane, benzene and acetonitrile, most preferably MeTHF and toluene.

11. Process, according to any one of claims 1 to 10, characterized in that the dimerization step i) is carried out at a temperature in the range of about 20°C to about 120°C, preferably from about 20°C to about 80°C, more preferably from about 25°C to about 60°C.

12. Process, according to any one of claims 1 to 11, characterized in that it further comprises an initial step (0) of preparing the catalyst according to formula (III) by reacting a compound according to formula (IV) X Rc Ra (IV) wherein X is a chloride, a bromide or an iodide, preferably chloride; Ra is as defined in claim 1, 7 or 9; Petition 870250080389, dated 08 / 09 / 2025, page 53 / 68 4 / 5 Rc is X or Rb, wherein Rb is as defined in claim 1, 8 or 9; with - an amine of formula V: R1R2NH (V), with Ri and R2 being as defined in claims 1, 5, 6 or 9, where Rc is Rb or - either an amine of formula (V) or an amine of formula (V'): R3R4NH (V'), with R3 and R4 being as defined in claims 1, 8 or 9, where Rc is X.

13. Process according to claim 12, characterized in that step 0) and step i) are consecutive steps performed without isolating the catalyst after step 0).

14. Process for producing a compound according to formula (VI) characterized in that it comprises the process as defined in any one of claims 1 to 13, followed by a step ii) of hydrogenation of the dimer according to formula (II) obtained in the dimerization step using H2 and a hydrogenation catalyst, such as Pd-based catalysts, Ru-based catalysts, Pt-based catalysts, Co-based catalysts, Rh-based catalysts, Ir-based catalysts and Ni-based catalysts, to obtain a compound of formula (VI) oo (vi) where R is as defined in claim 1 or 4.

15. Process for producing a compound according to formula (VII) characterized in that it comprises the process as defined in any one of claims 1 to 13, followed by a step ii') of hydrolysis of the dimer according to formula (II) obtained in the dimerization step using acid catalysts, such as Lewis or Bronsted acids, to obtain a compound of formula (VII) oo (vii) 16. Process for producing a compound according to formula (VII'), (VII'), characterized in that it comprises the process, as defined in claim 14, followed by a step iii) of reacting the compound of formula (VI) with an amine of formula HNR5R6, wherein R5 and R6 are identical or different, and are each selected from saturated or unsaturated, linear or branched, optionally cyclic, optionally aromatic, optionally substituted hydrocarbon-based groups having an average number of carbon atoms in the range of 1 to 36, provided that R5 and R6 may optionally form together a ring member, which is optionally substituted and / or which optionally contains a heteroatom; preferably, R5 = R6 = methyl. Petition 870250080389, dated 09 / 08 / 2025, p. 55 / 68