Synthesis process of functionalized mercaptans under H2S pressure

Abstract

The present invention relates to a method for the preparation of a compound of the formula R2-XC in the presence of at least one enzyme selected from sulfhydrylases. * H(NR1R7)-(CH2) n - a process for the synthesis of functionalized mercaptans, comprising reacting a compound of formula G(II) with H2S; The reaction is carried out in a reactor, the H2S partial pressure in the gas headspace of the reactor being between 0.01 bar and 4 bar, preferably between 0.1 bar and 3 bar, for example between 0.1 bar and 2.5 bar, more preferentially between 0.25 bar and 2 bar at the reaction temperature.

Description

[Technical Field]

[0001] The present invention relates to a process for synthesizing functionalized mercaptans, and more particularly to a composition that enables this process to be carried out. [Background technology]

[0002] Mercaptans are used in many industrial fields, and many synthesis methods are known, including sulfidation of alcohols, catalytic or photochemical addition of hydrogen sulfide to unsaturated organic compounds, or substitution of halides, epoxides, or organic carbonates with hydrogen sulfide.

[0003] However, these processes have many drawbacks and are not necessarily suitable for the synthesis of functionalized mercaptans, i.e., mercaptans containing at least one functional group other than a thiol group (-SH). This type of mercaptan constitutes a chemical family with great potential, particularly amino acids and derivatives with thiol function, especially homocysteine. They can be used, for example, as synthetic intermediates in the cosmetics industry. However, currently, there is no effective synthetic method suitable for the production of these functionalized mercaptans that is industrially viable, especially for applications in the field of general-purpose chemicals.

[0004] For example, in conventional chemical methods, substitution using hydrogen sulfide often requires high temperature and pressure, resulting in the formation of undesirable by-products of the olefin, ether, sulfide, and / or polysulfide types. Catalytic or photochemical addition of hydrogen sulfide to unsaturated compounds generally occurs under slightly milder conditions, but as with the above, many by-products are formed by isomerization of the starting materials, non-regioselective addition, or double addition, leading to the formation of sulfides and / or polysulfides.

[0005] Therefore, such conventional synthesis methods require overly stringent operating conditions for compounds such as functionalized mercaptans, and as a result, large amounts of sulfides and / or polysulfides that are difficult to upgrade are co-produced.

[0006] The synthesis of functionalized mercaptans by biological pathways is a known means alternative to chemical pathways. For example, cysteine is currently produced biologically by fermentation pathways (Maier T., 2003. Nature Biotechnology, 21:422 - 427). Such biological pathways are milder and more suitable for multifunctional molecules. However, these biological pathways often have low yields and / or are not easily or impossible to set up on an industrial scale. Furthermore, here too, the production of the target mercaptan is accompanied by polysulfides such as the corresponding sulfides and / or disulfides (see, for example, International Publication No. WO2012 / 053777).

[0007] Therefore, there is a need for an improved process for synthesizing functionalized mercaptans, particularly by biological pathways.

[0008] In particular, there is a need for a process for synthesizing functionalized mercaptans that enables obtaining a good yield, that is, a yield of at least 20%, preferably at least 60%, more preferably at least 80%, and even more preferentially at least 90%.

[0009] There is also a need for a process for synthesizing functionalized mercaptans that can be carried out on an industrial scale under mild operating conditions. Summary of the Invention Problems to be Solved by the Invention

[0010] One object of the present invention is to provide an improved process for synthesizing functionalized mercaptans having particularly improved yields, namely at least 20%, preferably at least 60%, more preferably at least 80%, and even more preferably at least 90%.

[0011] Another object of the present invention is to provide an industrial process with operating conditions suitable for the synthesis of mild, polyfunctional mercaptans.

[0012] Another object of the present invention is to avoid the use of hydrosulfide salts and / or sulfide salts as reagents, and therefore to provide a more environmentally friendly process.

[0013] The present invention achieves the above objectives completely or partially. [Means for solving the problem]

[0014] According to the present invention, the functionalized mercaptan of formula (I), as defined below, particularly L-homocysteine, is favorably synthesized by the reaction of the compound of formula (II) with H2S in the presence of a sulfhydrylase enzyme under a specific range of H2S partial pressure in the reactor where the reaction takes place. In particular, the H2S partial pressure is 0.01 bar to 4 bar, for example 0.01 bar to 3 bar, preferably 0.1 bar to 3 bar, for example 0.1 bar to 2.5 bar, and more preferably 0.25 bar to 2 bar.

[0015] Thus, the inventors found that the conversion rate of the compound of formula (II) to the functionalized mercaptan of formula (I) is strongly dependent on the partial pressure of H2S in the reactor. Surprisingly, the inventors found that within a specific range of partial pressure of H2S in the reactor, a conversion rate and / or yield of at least 20%, preferably at least 60%, more preferably at least 80%, and more preferably at least 90% could be obtained. For example, the conversion rate and / or yield was 80% to 100%, or even 90% to 100%. In particular, the conversion rate and / or yield was 100%.

[0016] In reality, contrary to expectations, increasing the H2S partial pressure in the reactor beyond a certain limit does not improve the conversion rate and / or yield of the reaction; rather, it may limit or inhibit the latter. It is expected that as the H2S partial pressure in the reactor increases, the amount of H2S in the reaction medium increases (especially in dissolved form in liquid reaction mediums), thus accelerating the reaction. However, in practice, excessively high H2S partial pressure is detrimental to the reaction.

[0017] Furthermore, the specific range of H2S partial pressure in the reactor according to the present invention enables fast reaction kinetics. For example, a 100% yield can be achieved in 1 hour. Therefore, the reaction time may be 0.15 hours to 10 hours, for example, 0.25 hours to 4 hours, preferably 0.5 hours to 1 hour.

[0018] It has also been observed that the process according to the present invention can yield better yields than processes using hydrosulfide salts and / or sulfide salts as reagents. Therefore, the use of hydrogen sulfide can limit or even simplify the process of purifying and managing wastewater that is required when the above-mentioned salts are used. Thus, the process according to the present invention is more environmentally friendly.

[0019] The present invention therefore relates to a process for synthesizing at least one functionalized mercaptan of the following general formula (I): R2-XC * H(NR1R7)-(CH2) n -SH (I) In the formula, - R1 and R7 are the same as or different from each other, and are a hydrogen atom, or an aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms which may have one or more heteroatoms; - X is selected from -C(=O)-, -CH2- and -CN; - R2 is: (i) absent when X represents -CN (ii) or a hydrogen atom (iii) or -OR3, where R3 is a hydrogen atom, or an aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms which may have one or more heteroatoms (iv) or -NR4R5, where R4 and R5 are the same as or different from each other, and are a hydrogen atom, or an aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms which may have one or more heteroatoms; n is 1 or 2; * represents an asymmetric carbon; The process includes the following stages: a) Providing at least one compound of the following general formula (II): R2-X-C * H(NR1R7)-(CH2) n -G (II) In the formula, * , R1, R2, R7, X and n are as defined for formula (I), G represents any one of (i) R6-C(O)-O-, or (ii) (R7O)(R8O)-P(O)-O-, or (iii) R9O-SO2-O-; R6 is a hydrogen atom, or a linear, branched or cyclic, saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms which may have one or more aromatic groups, -OR 10 , (=O), -C(O)OR 11 , -NR 12 R 13 and is optionally substituted by one or more groups selected from; R10 , R 11 , R 12 and R 13 Each of these is independently selected from the following: H, or linear, branched, or cyclic, saturated or unsaturated hydrocarbon chains having 1 to 20 carbon atoms; R7 and R8 are either identical or different from each other, and are protons, alkali metals, alkaline earth metals, or ammonium; R9 is selected from protons, alkali metals, alkaline earth metals, and ammonium; b) Provision of H2S; c) Reaction of at least one of the compounds of formula (II) with H2S in the presence of at least one enzyme selected from sulfhydrases, preferably sulfhydrases associated with the compounds of formula (II); The reaction takes place in a reactor, and the partial pressure of H2S in the gas headspace of the reactor is 0.01 bar to 4 bar, for example 0.01 bar to 3 bar, preferably 0.1 bar to 3 bar, for example 0.1 bar to 2.5 bar, and more preferably 0.25 bar to 2 bar at the reaction temperature; d) Obtain at least one functionalized mercaptan of formula (I); e) Selective separation of at least one functionalized mercaptan of formula (I) obtained in stage d); and f) Optional additional functionalization and / or optional deprotection of the functionalized mercaptan of formula (I) obtained in stage d) or e); Stages a) and b) are performed simultaneously by choice.

[0020] Unless otherwise specified, the expression "X~X" includes the limit value mentioned.

[0021] An unsaturated hydrocarbon chain is understood to be a hydrocarbon chain having at least one double or triple bond between two carbon atoms.

[0022] Heteroatoms are understood to be atoms selected from O, N, S, P, and halogens in particular.

[0023] The inert gas is understood to be any gas that is little to no reactive, particularly in the context of the process according to the present invention. Examples include dinitrogen, argon, or methane, preferably dinitrogen.

[0024] The reaction medium (or mixture) is understood to be a medium comprising, in particular, at least one compound of formula (II), H2S, and the at least one sulfhydrylase.

[0025] Therefore, the reaction medium is - At least one compound of formula (II) as defined below, - H2S, - At least one sulfhydrase as defined below, - By choice, the cofactor defined below, - Optionally, the bases defined below, and - Optionally, a solvent, preferably water, may be included.

[0026] Preferably, the reaction medium is in the form of a liquid, such as an aqueous solution, especially under the temperature and pressure conditions of stage c).

[0027] H2S is in gaseous form, particularly under the temperature and pressure conditions of stage c). Specifically, it is understood that some of the H2S is dissolved in the reaction medium to carry out the reaction in stage c), while the other portion is in gaseous form in the gas headspace of the reactor under the aforementioned partial pressures.

[0028] "Gas headspace" is understood to mean the space within the reactor located above the reaction medium, preferably above the liquid reaction medium. More specifically, "gas headspace" is understood to mean the space located between the surface of the liquid reaction medium and above the reactor (or above the reactor containing the gas phase if the lower part of the reactor contains the liquid phase). The gas headspace particularly contains the gas phase containing H2S at the aforementioned partial pressure.

[0029] The reaction medium and H2S are introduced into the reactor in such quantities that the gas headspace is located above the reaction medium contained in the reactor.

[0030] Alternatively, stage c) can be explained as follows: c) Reaction of at least one compound of formula (II) with H2S in the presence of at least one enzyme selected from sulfhydrylases, preferably sulfhydrylases associated with the compound of formula (II); The reaction is carried out in a reactor, and the partial pressure of H2S above the reaction medium is 0.01 bar to 4 bar at the reaction temperature, for example, 0.01 bar to 3 bar, preferably 0.1 bar to 3 bar, for example, 0.1 bar to 2.5 bar, and more preferably 0.25 bar to 2 bar.

[0031] According to one embodiment, the partial pressure of H2S corresponds to the total pressure of the gas phase present in the gas headspace (i.e., only H2S is present in the gas headspace of the reactor).

[0032] According to one embodiment, the H2S partial pressure can be kept constant throughout the entire duration of stage c). This can be achieved by continuously introducing H2S into the reactor during stage c), or by adding H2S to the reactor regularly or irregularly and isolatedly. In fact, since H2S is consumed during the reaction, the decrease in H2S partial pressure can be compensated for.

[0033] According to another embodiment, the H2S partial pressure can be achieved before or during stage c), after which the introduction of H2S into the reactor is stopped. Thus, the H2S partial pressure decreases during stage c), preferably until the reaction is stopped.

[0034] The partial pressure of H2S can be controlled through stage c) by any known technique, for example, using a pressure gauge. H2S can be added in the reactor to reach equilibrium between the liquid phase (reaction medium) and the gas phase (containing H2S at the partial pressure).

[0035] Preferably, the total pressure of the gas phase in the gas headspace (for example, the pressure of H2S if the latter is the sole gas, or the total pressure of a mixture of H2S and an inert gas) is roughly equivalent to atmospheric pressure (approximately 1.01325 bar). Alternatively, depending on the desired operating conditions, it may be possible to operate at a pressure lower or higher than atmospheric pressure.

[0036] For example, the following methods can be cited.

[0037] According to one embodiment, a vacuum is created in the reactor, and then H2S is introduced at the partial pressure according to the present invention. For example, the vacuum is reduced to -1 bar, and then an H2S pressure of 0.25 bar is applied.

[0038] According to another embodiment, the following stages are performed: - Purge the reactor headspace with an inert gas such as N2; then, - Create a partial vacuum; then, - H2S is introduced at the partial pressure according to the present invention. For example, after purging the reactor headspace with N2, a vacuum is created to -0.25 bar, and then 0.25 bar of H2S is added.

[0039] According to another embodiment, a mixture of an inert gas such as N2 and H2S at the partial pressure according to the present invention can be introduced into the reactor. For example, a mixture of 0.25 bar H2S and 0.75 bar N2 can be introduced.

[0040] In another embodiment, an inert gas such as N2 can be introduced into the reactor (purging the gas headspace), and then H2S can be added at the partial pressure according to the present invention. For example, N2 can be added at a pressure of 1 bar, and then H2S can be added at a pressure of 0.25 bar.

[0041] The temperature during stage c) can be 10°C to 60°C, preferably 20°C to 40°C, more specifically 25°C to 40°C.

[0042] The reactor used in stage c) can be of any type. Preferably, it is selected from a plug-flow reactor or a continuous reactor, preferably agitated and / or performing gas phase recirculation and / or liquid phase recirculation. Preferably, the reactor allows for the recirculation (or recycling) of the gas phase present in the gas headspace.

[0043] Stages a) and b) can be performed simultaneously or in any order.

[0044] The reaction medium can be prepared by adding the compound of formula (II), sulfhydrylase, and its cofactors in any order of choice. Next, it is preferable to introduce H2S. This makes it easier to control the H2S pressure introduced into the reactor.

[0045] Preferably, the compound of formula (II) and / or sulfhydrase is in the form of a solution, and more preferably in the form of an aqueous solution.

[0046] H2S can be introduced into the reactor by any known method, particularly by bubbling into the reaction medium, preferably from the bottom of the reactor. Bubbling can be carried out by mixing H2S with an inert gas, such as dinitrogen, argon, or methane, preferably dinitrogen. Preferably, H2S is introduced purely (without mixing with other gases). Alternatively, H2S may be introduced through the reactor headspace and then equilibrated with the reaction medium, for example. It is preferable to stir the reaction medium at this time.

[0047] Preferably, during stage c), and more preferably throughout stage c), H2S is in excess, preferably molar excess, of the compound of formula (II). Therefore, preferably, during stage c), and more preferably throughout stage c), H2S may be in a hyperstoichiometric amount relative to the amount of the compound of formula (II).

[0048] In particular, the molar ratio of H2S / formula (II) is preferably 1.1 to 20, preferably 1.1 to 10, preferably 2 to 8, for example 3.5 to 8, and even more preferably 3.5 to 5, during the period of stage c), and more preferably throughout the entire period of stage c). The ratio may be kept constant throughout the entire period of stage c).

[0049] Stage c) can be carried out in a solution, particularly an aqueous solution. For example, the solution contains 50% to 99% by weight of water, preferably 75% to 97% by weight, based on the total weight of the solution.

[0050] The pH of the reaction medium in stage c) can be 4 to 9, for example 5 to 8, preferably 6 to 7.5, more specifically 6.2 to 7.2, especially if the reaction medium is an aqueous solution.

[0051] The pH can be adjusted to the above range, in particular, according to the operating optimum conditions of the selected sulfhydrylase. The pH can be measured by conventionally known methods, such as using a pH probe. The pH can be adjusted, in particular, by adding a base, preferably through the reaction in stage c). Any type of base can be used, but a base containing a sulfur atom is preferred. The base is understood to be a compound or mixture of compounds having a pH greater than 7, preferably 8 to 14.

[0052] The base can be selected from hydrosulfide salts and / or sulfide salts, sodium hydroxide, potassium hydroxide, or ammonia. The preferred base is ammonium hydrosulfide (NH4SH).

[0053] The hydrosulfide salt and / or sulfide salt can be selected from the group consisting of ammonium hydrosulfide, alkali metal hydrosulfides, alkaline earth metal hydrosulfides, alkali metal sulfides, and alkaline earth metal sulfides.

[0054] Alkali metals are understood to be lithium, sodium, potassium, rubidium, and cesium, preferably sodium and potassium.

[0055] Alkaline earth metals are understood to be beryllium, magnesium, calcium, strontium, and barium, with calcium being preferred.

[0056] In particular, the hydrosulfide salt and / or sulfide salt can be selected from the group consisting of the following: Ammonium hydroxide (NH4SH), sodium hydroxide (NaSH), potassium hydroxide (KSH), calcium hydroxide (Ca(SH)2), sodium sulfide (Na2S), ammonium hydroxide (NH4)2S, potassium sulfide (K2S), and calcium sulfide (CaS). The preferred hydroxide is ammonium hydroxide (NH4SH).

[0057] The base can be added at a concentration of 0.1 M to 10 M, preferably 0.5 M to 10 M, and more preferably 0.5 M to 5 M. Concentrated base is particularly used to limit the dilution of the reaction medium when adding the base.

[0058] Stage c) can be executed in batch, semi-continuous, or continuous manner.

[0059] Stage c) Essentially performed in the absence of oxygen:

[0060] Oxygen is understood to specifically refer to dioxygen (O2).

[0061] Preferably, stage c) is carried out essentially in the absence of oxygen, or in the absence of oxygen. When stage c) is carried out essentially in the absence of oxygen (or in the absence of oxygen O2), it is possible to limit (or prevent) the co-production of undesirable by-products such as sulfides and / or polysulfides, particularly disulfides, as necessary (see French Patent Application No. FR2007577).

[0062] More specifically, "essentially in the absence of oxygen" is understood to mean that a certain amount of oxygen may remain in the reaction medium and / or gas phase (contained in the gas headspace of the reactor) such that the amount of sulfides and / or polysulfides produced is 5% by weight or less of the total weight of the compound of formula (I) produced.

[0063] For example, "essentially in the absence of oxygen" is understood to mean that the reaction medium contains less than 0.0015% by weight (preferably less than 0.0015% by weight) of oxygen relative to the total weight of the reaction medium, and / or that the gas phase (contained in the gas headspace) contains less than 21% by volume (preferably less than 21% by volume) of oxygen relative to the total volume of the gas phase.

[0064] Therefore, the reaction medium may contain 0% to 0.0015% by weight (preferably less than 0.0015% by weight) of oxygen relative to the total weight of the reaction medium, and / or the gas phase (contained in the gas headspace) may contain 0% to 21% by volume (preferably less than 21% by volume) of oxygen relative to the total volume of the gas phase. In particular, the amount of oxygen in the reaction medium and / or the gas phase (contained in the gas headspace) is such that the amount of sulfide and / or polysulfide produced is 5% by weight or less relative to the total weight of the compound of formula (I) produced.

[0065] For example, stage c) can be carried out in a sealed reactor (i.e., without supplying oxygen from air).

[0066] Preferably, the gas phase (contained in the gas headspace) is oxygen-free. Preferably, the gas phase (contained in the gas headspace) is oxygen-free, and the reaction mixture contains 0% to 0.0015% by weight (preferably less than 0.0015% by weight) of oxygen relative to the total weight of the reaction mixture. This is because an O2 / H2S mixture can be explosive, which clearly poses a risk to operator safety.

[0067] More specifically, if stage c) is carried out in the absence of oxygen (or in the absence of oxygen), L-homocysteine ​​can be produced as needed, while limiting (or preventing) the co-production of the undesirable by-product L-homocysteine ​​and / or L-homocysteine ​​sulfide (also known as 4,4'-sulfandiylbis(2-aminobutanoic acid) / L-homolantihonine).

[0068] L-homocysteine ​​sulfide has the following formula: [ka]

[0069] L-homocystin has the following formula: [ka]

[0070] Conventional methods can be used to perform stage c) in the absence of oxygen, or in the absence of oxygen.

[0071] According to one embodiment, before stage c), oxygen is removed from the reaction medium, for example, by degassing.

[0072] According to another embodiment, before stage c), oxygen is removed individually from each component or from a mixture of at least two components forming the reaction medium. For example, each of the solutions containing the compound of formula (II), sulfhydrylase, and optionally the solvent is degassed.

[0073] Oxygen can also be removed from the gas phase of the reactor headspace, preferably by degassing.

[0074] The reactor can also be deactivated with an inert gas such as dinitrogen, argon, or methane, preferably dinitrogen.

[0075] Various technologies can be combined.

[0076] Preferably, the substantial or complete absence of oxygen is achieved in the following way: - The reactor is deactivated with an inert gas such as dinitrogen, argon, or methane, preferably dinitrogen. - The solution containing the compound of formula (II), sulfhydrylase, and the solvent is degassed as an option. Industrial degassing methods are well known, and examples include the following: - Reduced pressure (vacuum degassing) - Temperature control (increase the temperature of the aqueous solvent and decrease the temperature of the organic solvent) - Membrane degassing - Degassing by repeating the freeze-degass-thaw cycle. - Degassing by spraying with an inert gas (e.g., argon, dinitrogen, or methane). According to one embodiment, in stage c), oxygen is not present in either a dissolved form in the liquid (particularly in the reaction medium) or in a gaseous form (particularly in the gas phase).

[0077] The separation stage e) can be carried out according to any technique known to those skilled in the art. In particular, if the final product is solid: - By extraction and / or decantation using a solvent that is immiscible with the reaction medium, followed by evaporation of the solvent; - By precipitation (by partially evaporating the solvent or by adding a solvent in which the target compound is poorly soluble). This precipitation is followed by a filtration stage according to any method generally known to those skilled in the art. The final product can then be dried; or - By selective precipitation achieved by adjusting the pH as a function of the solubility of various compounds.

[0078] Homocysteine ​​can be recovered, particularly in solid form.

[0079] If the final product is in liquid form, separation can be carried out by distillation, or by liquid / liquid extraction followed by distillation or evaporation.

[0080] Stage f) of additional functionalization and / or optional deprotection allows for the acquisition of additional chemical functions and / or deprotection of specific chemical functions by conventional methods. For example, if X-R2 represents a carboxyl functional group, the latter can be esterified, reduced to an aldehyde, reduced to an alcohol, and then esterified, amidated, nitrified, etc. All functional groups can be acquired and / or deprotected by those skilled in the art, depending on the intended end use of the functionalized mercaptan of formula (I).

[0081] Therefore, the functionalized mercaptan of formula (I) obtained at the end of stage d) or e) may be subjected to one or more additional chemical reactions to obtain one or more mercaptan derivatives having different functionalities, where the chemical reactions are well known.

[0082] Functionalized mercaptans of general formula (I): The process according to the present invention aims to obtain a functionalized mercaptan of the following general formula (I): R2-XC * H(NR1R7)-(CH2) n -SH (I) During the ceremony, - R1 and R7 are identical or different from each other, and are C1-C20 hydrocarbon chains which may have one or more hydrogen atoms or aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated heteroatoms; - X is selected from -C(=O)-, -CH2-, and -CN; - R2 is: (i) There is no case where X represents -CN (ii) or hydrogen atom (iii) or -OR3, R3 is a hydrogen atom, or a C1-C20 hydrocarbon chain which may have one or more aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated heteroatoms. (iv) or -NR4R5, R4 and R5 are identical or different from each other, and are a C1-C20 hydrocarbon chain which may have one or more hydrogen atoms or aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated heteroatoms; n is either 1 or 2; * This represents a chiral carbon.

[0083] These mercaptans are called functionalized mercaptans because, in addition to the chemical functional group -SH, they also contain at least one amine-type functional group -NR1R7.

[0084] Preferably, n is 2.

[0085] Preferably, X is -C(=O)-.

[0086] Preferably, R2 is -OR3, and R3 is as defined above. R3 may be a hydrogen atom in particular, or a linear or branched saturated hydrocarbon chain having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms. In particular, R3 is H.

[0087] R1 and R7 are either the same as or different from each other, preferably a hydrogen atom, or a linear or branched saturated hydrocarbon chain having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms. Preferably, R1 and R7 are H.

[0088] In particular, X is -C (=O)-, R2 is -OR3, and R3 is as defined above.

[0089] The functionalized mercaptan of formula (I) can be selected from the group consisting of homocysteine, cysteine, and their derivatives.

[0090] In particular, the functionalized mercaptans of formula (I) are L-homocysteine ​​and L-cysteine.

[0091] The preferred functionalized mercaptan of formula (I) is homocysteine, and in particular L-homocysteine ​​of the following formula: [ka]

[0092] In the case of L-homocysteine, n is 2, X is -C(=O)-, R2 is -OR3, R3 is H, and R1 and R7 are H.

[0093] The structure of the chiral carbon atom has been observed to be preserved throughout the reaction in stage c). Therefore, the functionalized mercaptan of formula (I) obtained according to the process of the present invention may be enantiomerically pure.

[0094] The functionalized mercaptan of formula (I) is a chiral compound. In this specification, unless the form of the enantiomer is specified, the compound is included regardless of the form of the enantiomer.

[0095] According to one embodiment, the reaction medium at the end of stage c) does not contain sulfides or polysulfides, and in particular does not contain sulfides or polysulfides corresponding to the functionalized mercaptan of formula (I) obtained. For example, the reaction medium at the end of stage c) contains less than 10 mol%, preferably less than 5 mol%, of sulfides and polysulfides relative to the total number of moles of the compound of formula (II) converted to the compound of formula (I).

[0096] Sulfides are understood to be the sulfides of the compounds of formula (I), particularly those of formula (III) below: R2-XC * H(NR1R7)-(CH2) n -S-(CH2) n -(NR1R7)C * HX-R2(III) * R1, R2, R7, X, and n are equivalent to those above.

[0097] Polysulfides are understood to be polysulfides of formula (IV) below, corresponding to the compounds of formula (I): R2-XC * H(NR1R7)-(CH2) n -(S) m -(CH2) n -(NR1R7)C * HX-R2(IV) * R1, R2, R7, X, and n are defined above, and m is an integer between 2 and 6, including upper and lower bounds, for example, m is 2 or 3. Preferably, m is 2 (corresponding to a disulfide).

[0098] In particular, if the compound of formula (I) is L-homocysteine, the reaction medium at the end of stage c) does not contain either L-homocysteine ​​sulfide or L-homocystine.

[0099] Preferably, following the reaction of the compound of formula (II) with H2S during stage c), the following are obtained: a functionalized mercaptan of formula (I) as defined above and a compound of formula (V)GH, where G is defined below: a compound of the type (i')R6-C(O)-OH, (II')(R7O)(R8O)-P(O)-OH, or (iii')R9O-SO2-OH; R6, R7, R8, and R9 are defined below. In particular, if compound (II) is O-acetyl-L-homoserine, L-homocysteine ​​and acetic acid are obtained. The compound of formula (V) may be involved in the acidification of the reaction medium during stage c). Thus, the pH of the reaction medium can be maintained at 4-9, for example 5-8, preferably 6-7.5, more specifically 6.2-7.2, especially during stage c) as described above and by the addition of the base as defined above.

[0100] Compounds of general formula (II): Regarding the compound of the following general formula (II): R2-XC * H(NR1R7)-(CH2) n -G (II) * R1, R2, R7, X, and n are as defined for the compound of formula (I), G represents either (i) R6-C(O)-O-, or (ii) (R7O)(R8O)-P(O)-O-, or (iii) R9O-SO2-O-; R6 may have a hydrogen atom, or one or more linear, branched, or cyclic, saturated or unsaturated aromatic groups, -OR 10 , (=O), -C(O)OR 11 , and -NR 12 R 13 A hydrocarbon chain having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, which may be substituted by one or more groups selected from: R10 , R 11 , R 12 and R 13 Each of these is independently selected from the following: H, or linear, branched, or cyclic, saturated or unsaturated hydrocarbon chains having 1 to 20, preferably 1 to 10 carbon atoms; R7 and R8 are either the same as or different from each other, and are a proton, alkali metal, alkaline earth metal, or ammonium, preferably a proton or alkali metal, more specifically H + or Na + and; R9 is selected from protons, alkali metals, alkaline earth metals, and ammonium, preferably a proton or alkali metal, more specifically a proton H + or Na + and; In particular, G represents either R6-C(O)-O- or R9O-SO2-O-; preferably, G is R6-C(O)-O-. In particular, R6 is a hydrogen atom, or a linear or branched, saturated or unsaturated, -OR 10 , (=O) and -C(O)OR 11 A hydrocarbon chain having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, which may be substituted with one or more groups selected from; R 10 and R 11 Each of these is independently selected from the following: H, or a linear or branched, saturated or unsaturated hydrocarbon chain having 1 to 10, preferably 1 to 5 carbon atoms. More specifically, R 10 and R 11 H is H. In particular, R 12 and R 13 H is H. It is understood that aromatic groups preferentially consist of phenyl groups.

[0101] Compounds of general formula (II) are particularly serine (when n is 1) or homoserine (when n is 2), and especially derivatives of L-serine or L-homoserine. For example, they can be selected from the group consisting of the following: O-phospho-L-homoserine, O-succinyl-L-homoserine, O-acetyl-L-homoserine, O-acetoacetyl-L-homoserine, O-propio-L-homoserine, O-coumaroyl-L-homoserine, O-malonyl-L-homoserine, O-hydroxymethylglutaryl-L-homoserine, O-pimeryl-L-homoserine, O-sulfato-L-homoserine, O-phospho-L-serine, O-succinyl-L-serine, O-acetyl-L-serine, O-acetoacetyl-L-serine, O-propio-L-serine, O-coumaroyl-L-serine, O-malonyl-L-serine, O-hydroxymethylglutaryl-L-serine, O-pimeryl-L-serine, and O-sulfato-L-serine.

[0102] More specifically, you can choose from the following group: O-phospho-L-homoserine, O-succinyl-L-homoserine, O-acetyl-L-homoserine, O-acetoacetyl-L-homoserine, O-propio-L-homoserine, O-coumaroyl-L-homoserine, O-malonyl-L-homoserine, O-hydroxymethylglutaryl-L-homoserine, O-pimeryl-L-homoserine, and O-sulfato-L-homoserine.

[0103] Compounds of general formula (II) can be selected from the following group: O-phospho-L-homoserine, O-succinyl-L-homoserine, O-acetyl-L-homoserine, O-sulfato-L-homoserine, and O-propio-L-homoserine.

[0104] Compounds of general formula (II) can be selected from the following group: O-phospho-L-homoserine, O-succinyl-L-homoserine, O-acetyl-L-homoserine.

[0105] A very preferred compound of formula (II) is O-acetyl-L-homoserine (OAHS) when n is 2, X is -C(=O)-, R2 is -OR3, R3 is H, R1 and R7 are H, G is -OC(O)-R6, and R6 is methyl.

[0106] Compounds of formula (II) are commercially available or can be obtained by any technique known to those skilled in the art.

[0107] These can be obtained, for example, through a fermentation process from hydrocarbon and nitrogen sources, as described in International Publication No. WO2008 / 013432.

[0108] These can be obtained, for example, by fermenting renewable starting materials. Renewable starting materials can be selected from glucose, sucrose, starch, molasses, glycerol, and bioethanol, with glucose being preferred.

[0109] L-serine derivatives can also be produced by acetylation of L-serine, and L-serine itself can sometimes be obtained by fermenting renewable starting materials. Renewable starting materials can be selected from glucose, sucrose, starch, molasses, glycerol, and bioethanol, with glucose being preferred.

[0110] L-homoserine derivatives can also be produced by acetylation of L-homoserine, and L-homoserine itself can sometimes be obtained by fermenting renewable starting materials. Renewable starting materials can be selected from glucose, sucrose, starch, molasses, glycerol, and bioethanol, with glucose being preferred.

[0111] Sulfhydrase: The reaction between at least one compound of formula (II) and H2S is carried out in the presence of at least one enzyme selected from sulfhydrases, preferably a sulfhydrase associated with the compound of formula (II). Sulfhydrases associated with the compound of formula (II) are easily identifiable by sharing the same name; for example, O-acetyl-L-homoserine sulfhydrase (OAHS sulfhydrase) is associated with O-acetyl-L-homoserine.

[0112] Sulfhydrases can, in particular, catalyze the reaction (enzymatic reaction) between the compound of formula (II) and H2S. A "catalyst" is generally understood to be a substance that accelerates a reaction and remains unchanged at the end of the reaction. Sulfhydrases, and optionally their cofactors, can be used in catalytic amounts. A "catalyst" is understood to be an amount sufficient to catalyze the reaction. More specifically, the reagent used in catalytic amounts is used in smaller amounts than the reagent used in stoichiometric proportions, for example, about 0.01% to 20% by weight.

[0113] The sulfhydrilase enzyme preferably belongs to a transferase class specifically designated in the EC2.XXXX (or representative (noted)EC2) classification. The EC classification of Enzyme Commission numbers is widely used and can be searched on the website https: / / enzyme.expasy.org / . In particular, the enzyme refers to a transferase selected from sulfhydrases of the EC2.5.X.XX class (or representative EC2.5) that transfers alkyl or aryl groups other than methyl groups.

[0114] Sulfhydrases are specifically classified as class EC2.5.1.XX (where XX varies depending on the enzyme's substrate).

[0115] for example: - O-acetylhomoserine sulfhydrase is of type EC2.5.1.49. - O-phosphoserine sulfhydrase is of type EC2.5.1.65. - O-succinyl homoserine sulfhydrase is of type EC2.5.1.49.

[0116] for example: - O-acetyl-L-homoserine sulfhydrase is of type EC2.5.1.49. - O-phospho-L-serine sulfhydrase is of type EC2.5.1.65. - O-succinyl-L-homoserine sulfhydrase is of type EC2.5.1.49.

[0117] Therefore, especially when the compound of formula (II) is L-homoserine or a derivative of L-serine, the sulfhydrase to be used is O-phospho-L-homoserine sulfhydrase, O-succinyl-L-homoserine sulfhydrase, O-acetyl-L-homoserine sulfhydrase, O-acetoacetyl-L-homoserine sulfhydrase, O-propio-L-homoserine sulfhydrase, O-coumaroyl-L-homoserine sulfhydrase, O-malonyl-L-homoserine sulfhydrase, O-hydroxymethylglutaryl-L-homoserine sulfhydrase, O-pimeryl-L-homoserine sulf You can choose from sulfurylase, O-sulfato-L-homoserine sulfurylase, O-phospho-L-serine sulfurylase, O-succinyl-L-serine sulfurylase, O-acetyl-L-serine sulfurylase, O-acetoacetyl-L-serine sulfurylase, O-propio-L-serine sulfurylase, O-coumaroyl-L-serine sulfurylase, O-malonyl-L-serine sulfurylase, O-hydroxymethylglutaryl-L-serine sulfurylase, O-pimeryl-L-serine sulfurylase, and O-sulfato-serine sulfurylase.

[0118] More specifically, the sulfhydrase used can be selected from O-phospho-L-homoserine sulfhydrase, O-succinyl-L-homoserine sulfhydrase, O-acetyl-L-homoserine sulfhydrase, O-acetoacetyl-L-homoserine sulfhydrase, O-propio-L-homoserine sulfhydrase, O-coumaroyl-L-homoserine sulfhydrase, O-malonyl-L-homoserine sulfhydrase, O-hydroxymethylglutaryl-L-homoserine sulfhydrase, O-pimeryl-L-homoserine sulfhydrase, and O-sulfato-L-homoserine sulfhydrase.

[0119] In particular, the sulfhydrase can be selected from O-phospho-L-homoserine sulfhydrase, O-succinyl-L-homoserine sulfhydrase, O-acetyl-L-homoserine sulfhydrase, O-sulfato-L-homoserine sulfhydrase, and O-propio-L-homoserine sulfhydrase.

[0120] The sulfhydrase can be selected from O-phospho-L-homoserine sulfhydrase, O-succinyl-L-homoserine sulfhydrase, and O-acetyl-L-homoserine sulfhydrase.

[0121] Preferably, the enzyme is O-acetyl-L-homoserine sulfhydrase (OAHS sulfhydrase).

[0122] Sulfhydrases, particularly O-acetyl-L-homoserine sulfhydrases, may arise from or originate from the following bacterial strains: Pseudomonas sp., Chromobacterium sp., Leptospira sp., and Hyphomonas sp.

[0123] Sulfhydrase can function in the presence of a cofactor, as is well known to those skilled in the art, such as pyridoxal 5'-phosphate (also known as PLP) or one of its analogues, preferably pyridoxal 5'-phosphate.

[0124] As an analogue of the cofactor pyridoxal phosphate, α 5 - Pyridoxal methylphosphate, 5'-methylpyridoxal-P, pyridoxal-5'-sulfate, α 5 -Examples include pyridoxal acetate or any other known derivative (Groman et al., Proc. Nat. Acad. Sci. USA Vol.69, No.11, pp.3297-3300, November 1972).

[0125] According to one embodiment, a cofactor of sulfhydrinase can be added to the reaction medium. Therefore, a cofactor of sulfhydrinase, such as pyridoxal 5'-phosphate, can be provided before stage c) or added during stage c). If stage c) is carried out in an aqueous solution, the enzyme and optionally its cofactor can be dissolved in water beforehand before being added to the solution.

[0126] According to another embodiment, cells, such as bacterial cells or other cells, can produce or overproduce the cofactor while simultaneously expressing or overexpressing a sulfhydrinase enzyme, thereby avoiding the step of supplementing the cofactor.

[0127] According to one embodiment, sulfhydrase and optionally its cofactors are: - For example, in aqueous solution, in a separated and / or purified form; The separation and / or purification of the enzyme produced can be carried out by any means known to those skilled in the art. Examples include electrophoresis, molecular sieving, ultracentrifugation, differential precipitation with ammonium sulfate (e.g.), ultrafiltration, membrane filtration or gel filtration, ion exchange, separation by hydrophobic interactions, or techniques selected from, for example, IMAC-type affinity chromatography. - Or present in the crude extract, i.e., in the extract of crushed cells (lysate); the target enzyme may or may not be overexpressed in the host cell (hereinafter referred to as the host cell). The host cell can be any host cell suitable for producing the target enzyme from the expression of the corresponding coding gene. This gene is located in the host genome or is delivered by an expression vector.

[0128] For the purposes of this invention, "host cell" is understood to be a prokaryotic cell or a eukaryotic cell. Host cells commonly used for the expression of recombinant or non-recombinant proteins include bacterial cells such as Escherichia coli, Bacillus sp., or Pseudomonas; yeast cells such as Saccharomyces cerevisiae or Pichia pastoris; fungal cells such as Aspergillus niger, Penicillium funiculosum, or Trichoderma reesei; insect cells such as Sf9 cells; or mammalian (especially human) cells such as HEK293, PER-C6, or CHO cell lines.

[0129] Preferably, the target enzyme and, optionally, cofactors are expressed in the bacterium Escherichia coli. Preferably, the target enzyme is expressed in Escherichia coli strains such as BL21(DE3).

[0130] Cell lysates can be obtained according to various known techniques, including sonication, pressure (French press), and the use of chemicals (e.g., xylene, Triton). The resulting lysates correspond to crude extracts of pulverized cells. - Or it is present throughout the cell. For this reason, the same method as described above can be used without performing a cell lysis step.

[0131] According to one embodiment, the amount of biomass expressing the sulfhydrilase enzyme is 0.1% to 10% by weight, preferably 1% to 5% by weight, relative to the mass of the compound of formula (II), and / or the amount of cofactor relative to the compound of formula (II) is 0.1% to 10% by weight, preferably 0.5% to 5% by weight.

[0132] The reaction medium may also contain the following: - One or more solvents optionally selected from water, phosphate buffer, Tris-HCl, Tris base, ammonium bicarbonate, ammonium acetate, buffers such as HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), CHES (N-cyclohexyl-2-aminoethanesulfonic acid), or salts of sodium chloride, potassium chloride, or media thereof; - Optional additives, such as surfactants, to particularly enhance the solubility of one or more reagents or substrates.

[0133] The various components that can be used in the reaction of stage c) above are readily available commercially or can be prepared by techniques known to those skilled in the art. These various elements can take the form of solids, liquids, or gases and can be used in the process of the present invention as solutions or soluble in water or any other solvent, which is very advantageous. The enzymes used can also be grafted onto a support (in the case of supported enzymes).

[0134] According to a preferred embodiment, the compound of formula (II) is O-acetyl-L-homoserine, the enzyme used is O-acetyl-L-homoserine sulfhydrase, and the resulting functionalized mercaptan of formula (I) is L-homocysteine.

[0135] The present invention also relates to compositions, preferably aqueous solutions, comprising the following: - Compound of formula (II) as defined above; - A sulfhydrase, preferably a sulfhydrase associated with a compound of formula (II), wherein the sulfhydrase is as defined above; and - Preferably an excess of dissolved H2S.

[0136] Preferably, the composition comprises the following: - O-acetyl-L-homoserine; - O-acetyl-L-homoserine sulfhydrase; and - Preferably an excess of dissolved H2S.

[0137] The aforementioned composition corresponds in particular to the reaction medium defined above.

[0138] The conditions, characteristics, and optional components are as defined above for the reaction medium.

[0139] In particular, the compositions according to the present invention do not contain dissolved oxygen. Preferably, H2S is in excess of the compound of formula (II), and preferably in a molar excess. Therefore, the amount of H2S may be hyperstoichiometric relative to the amount of the compound of formula (II).

[0140] In particular, the molar ratio of the H2S / formula (II) compound is 1.1 to 20, preferably 1.1 to 10, more preferably 2 to 8, for example 3.5 to 8, and even more preferably 3.5 to 5.

[0141] The composition may contain the sulfhydrase cofactors defined above.

[0142] In particular, the composition according to the present invention makes it possible to carry out the process according to the present invention. [Brief explanation of the drawing]

[0143] [Figure 1] Figure 1 shows the yield (%) of the enzymatic synthesis of L-homocysteine ​​after 1 hour of reaction, as a function of H2S partial pressure (bar).

[0144] The following examples illustrate the present invention, but do not limit it in any way. [Examples]

[0145] The general definitions of conversion rate, selectivity, and yield are as follows: Conversion rate = (Number of moles of reactants in the initial state - Number of moles of reactants remaining after the reaction) / (Number of moles of reactants in the initial state) Selectivity = Number of moles of reactants converted to the target product / (Number of moles of reactants in the initial state - Number of moles of reactants remaining after the reaction) Yield = Conversion Rate × Selectivity

[0146] Example 1: Enzymatic preparation of L-homocysteine ​​from O-acetyl-L-homoserine under H2S partial pressure

[0147] Stage 1: Preparation of O-acetyl-L-homoserine (OAHS) O-acetyl-L-homoserine was synthesized from L-homoserine and acetic anhydride according to the protocol described in Sadamu Nagai's work "Synthesis of O-acetyl-L-homoserine," Academic Press (1971), vol. 17, pp. 423-424.

[0148] Stage 2: Preparation of the reaction medium Dissolve 10 g / l of O-acetyl-L-homoserine obtained in Stage 1) in 250 ml of water and add it to a thermostat-controlled 500 ml stainless steel reactor. Bring the solution to 37°C while mechanically stirring. Add 5 g / l of OAHS sulfhydrase and 0.4 g / l of pyridoxal phosphate cofactor to the reaction medium to a total volume of 300 ml. Maintain the pH at the set value of 6.5 using aqueous ammonia solution (4 M). Next, the reaction medium is degassed by nitrogen bubbling for approximately 10 minutes.

[0149] Stage 3: H2S addition under pressure To precisely control the pressure of the added hydrogen sulfide, the reactor is placed under vacuum by removing all gases present in the reactor's headspace. Next, a constant pressure of H2S is applied (PH2S=Ptotal). The start of the reaction is confirmed by the gradual acidification of the reaction medium (by the gradual release of the acetic acid co-product), and the pH of the solution is maintained at approximately 6.5 by the gradual addition of ammonium hydroxide (4M).

[0150] analysis The reaction yield is measured by argentometric potentiometric titration one hour after the reaction, using an approach that quantifies the formed mercaptan (the results are also confirmed by NMR and HPLC analysis).

[0151] result The yield of L-homocysteine ​​after 1 hour of reaction was determined by performing several tests while varying the H2S partial pressure in the gas headspace of the reactor used. The results indicate the existence of three phases (see Figure 1). - Increased yield at H2S partial pressures from 0 bar to 0.25 bar; - Plateau phase with a yield of 90% to 100% at H2S partial pressures of 0.25 bar to 2 bar; - Decreased yield at H2S partial pressures between 2 bar and 4 bar.

[0152] Example 2: Enzymatic preparation of L-homocysteine ​​from O-acetyl-L-homoserine under H2S partial pressure and in a non-degassed reaction medium.

[0153] Stage 1: Preparation of O-acetyl-L-homoserine (OAHS) O-acetyl-L-homoserine was synthesized from L-homoserine and acetic anhydride according to the protocol described in Sadamu Nagai's work "Synthesis of O-acetyl-L-homoserine," Academic Press (1971), vol. 17, pp. 423-424.

[0154] Stage 2: Preparation of the reaction medium Dissolve 10 g / l of O-acetyl-L-homoserine obtained in Stage 1) in 250 ml of water and add it to a thermostat-controlled 500 ml stainless steel reactor. Bring the solution to 37°C while mechanically stirring. Add 5 g / l of OAHS sulfhydrase and 0.4 g / l of pyridoxal phosphate cofactor to the reaction medium to a total volume of 300 ml. Maintain the pH at the set value of 6.5 using aqueous ammonia solution (4 M).

[0155] Stage 3: H2S addition under pressure To precisely control the pressure of the added hydrogen sulfide, the reactor is placed under vacuum by removing all gases present in the reactor's headspace. Next, an H2S pressure of 0.25 bar is applied. The start of the reaction is confirmed by the gradual acidification of the reaction medium (by the gradual release of the acetic acid co-product), and the pH of the solution is maintained at approximately 6.5 by the gradual addition of ammonium hydroxide (4M).

[0156] analysis The reaction yield is measured by argentometric potentiometric titration one hour after the reaction, using an approach that quantifies the formed mercaptan (the results are also confirmed by NMR and HPLC analysis).

[0157] result Yield of L-homocysteine ​​in Tfinal: 88.4% [Note] This disclosure is in the following manner <1> ~ <12> This also includes. <1> A process for synthesizing at least one functionalized mercaptan of the following general formula (I): R 2 -XC * H(NR 1 R 7 )-(CH 2 ) n -SH (I) During the ceremony, - R 1 and R 7 These are hydrocarbon chains having 1 to 20 carbon atoms, which may have one or more identical or different hydrogen atoms, or aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated heteroatoms; - X is -C(=O)-, -CH 2 - and -CN are selected; - R 2 teeth: (i) There is no case where X represents -CN (ii) or hydrogen atom (iii) or -OR 3 、R 3 This is a hydrocarbon chain having 1 to 20 carbon atoms, which may have one or more heteroatoms, including hydrogen atoms, or aromatic or non-aromatic, linear, branched, or cyclic, saturated or unsaturated hydrocarbon chains. (iv) or -NR 4 R 5 、R 4 and R 5 These are hydrocarbon chains having 1 to 20 carbon atoms, which may have one or more identical or different hydrogen atoms, or aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated heteroatoms; n is either 1 or 2; * represents a chiral carbon; The process described above includes the following stages: a) To provide at least one compound of the following general formula (II): R 2 -XC * H(NR 1 R 7 )-(CH 2 )n -G (II) During the ceremony, * 、R 1 、R 2 、R 7 X and n are as defined for equation (I), G is (i)R 6 -C(O)-O-, or (ii)(R 7 O)(R 8 O)-P(O)-O-, or (iii)R 9 O-SO 2 Represents either -O-; R 6 It may have a hydrogen atom, or one or more linear, branched, or cyclic, saturated or unsaturated aromatic groups, -OR 10 , (=O), -C(O)OR 11 , -NR 12 R 13 A hydrocarbon chain having 1 to 20 carbon atoms, which may be substituted by one or more groups selected from; R 10 、R 11 、R 12 and R 13 Each of these is independently selected from the following: H, or linear, branched, or cyclic, saturated or unsaturated hydrocarbon chains having 1 to 20 carbon atoms; R 7 and R 8 These are either identical or different from one another, and are protons, alkali metals, alkaline earth metals, or ammonium; R 9 It is selected from protons, alkali metals, alkaline earth metals, and ammonium; b)H 2 S provided; c) At least one of the compounds of formula (II) and H in the presence of at least one enzyme selected from sulfhydrylases, preferably sulfhydrylases associated with the compound of formula (II). 2 Reaction with S; The above reaction takes place in a reactor, and H in the gas headspace of the reactor. 2 The partial pressure of S is 0.01 bar to 4 bar at the reaction temperature, for example, 0.01 bar to 3 bar, preferably 0.1 bar to 3 bar, for example, 0.1 bar to 2.5 bar; d) Obtain at least one functionalized mercaptan of formula (I); e) Selective separation of at least one functionalized mercaptan of formula (I) obtained in stage d); and f) Optional additional functionalization and / or optional deprotection of the functionalized mercaptan of formula (I) obtained in stage d) or e); Stages a) and b) are performed simultaneously by choice. <2> H in the gas head space of the reactor 2 The partial pressure S is between 0.25 bar and 2 bar. <1> The synthesis process described above. <3> The aforementioned H 2 S is in excess of the compound of formula (II) above. <1> or <2> The synthesis process described above. <4> Stage c) is carried out in an aqueous solution. <1> ~ <3> The synthesis process described in any one of the following. <5> The aforementioned H 2 S partial pressure corresponds to the total pressure in the gas head space. <1> ~ <4> The synthesis process described in any one of the following. <6> The aforementioned H 2 The partial pressure S is kept constant throughout the entire duration of stage c). <1> ~ <5> The synthesis process described in any one of the following. <7> The compound of formula (II) is selected from the group consisting of O-phospho-L-homoserine, O-succinyl-L-homoserine, O-acetyl-L-homoserine, O-acetoacetyl-L-homoserine, O-propio-L-homoserine, O-coumaroyl-L-homoserine, O-malonyl-L-homoserine, O-hydroxymethylglutaryl-L-homoserine, O-pimeryl-L-homoserine, and O-sulfato-L-homoserine, and is preferably O-acetyl-L-homoserine. <1> ~ <6> The synthesis process described in any one of the following. <8> The functionalized mercaptan in formula (I) above is L-homocysteine. <1> ~ <7> The synthesis process described in any one of the following. <9> The compound of formula (II) is O-acetyl-L-homoserine, the enzyme used is O-acetyl-L-homoserine sulfhydrase, and the functionalized mercaptan of formula (I) is L-homocysteine. <1> ~ <8> The synthesis process described in any one of the following. <10> Stage c) is essentially carried out in the absence of oxygen, preferably in the absence of oxygen. <1> ~ <9> The process described in any one of the following. <11> The temperature during stage c) is 10°C to 60°C, preferably 20°C to 40°C, more specifically 25°C to 40°C. <1> ~ <10> The process described in any one of the following. <12> - <1> Compounds of formula (II) defined by; - Sulfhydrase; and - Dissolved H 2 S A composition containing the following:

Claims

1. A process for synthesizing at least one functionalized mercaptan of the following general formula (I): R ２ -X-C ＊ H(NR １ R ７ )-(CH ２ ) ｎ -SH (I) During the ceremony, - R １ and R ７ These are hydrocarbon chains having 1 to 20 carbon atoms, which may be identical or different from each other, and may have one or more hydrogen atoms, or aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated heteroatoms; - X is selected from -C(=O)-, -CH ２ - and -CN; - R ２ teeth: (i) There is no case where X represents -CN. (ii) or hydrogen atom (iii) or - OR ３ , R ３ This is a hydrocarbon chain having 1 to 20 carbon atoms, which may have one or more heteroatoms, including hydrogen atoms, or aromatic or non-aromatic, linear, branched, or cyclic, saturated or unsaturated heteroatoms. (iv) or -NR ４ R ５ , R ４ and R ５ These are hydrocarbon chains having 1 to 20 carbon atoms, which may be identical or different from each other, and may have one or more hydrogen atoms, or aromatic or non-aromatic, linear, branched or cyclic, saturated or unsaturated heteroatoms; n is either 1 or 2; ＊ represents a chiral carbon; The process described above includes the following stages: a) To provide at least one compound of the following general formula (II): R ２ -X-C ＊ H(NR １ R ７ )-(CH ２ ) ｎ -G (II) During the ceremony, ＊ , R １ , R ２ , R ７ X and n are as defined for equation (I), G is (i)R ６ -C(O)-O-, or (ii)(R １４ O) (R ８ O)-P(O)-O-, or (iii)R ９ O-SO ２ Represents either -O-; R ６ It may have a hydrogen atom, or one or more linear, branched, or cyclic, saturated or unsaturated aromatic groups, -OR １０ , (=O), -C(O)OR １１ , -NR １２ R １３ A hydrocarbon chain having 1 to 20 carbon atoms, which may be substituted with one or more groups selected from; R １０ , R １１ , R １２ and R １３ Each of these is independently selected from the following: H, or linear, branched, or cyclic, saturated or unsaturated hydrocarbon chains having 1 to 20 carbon atoms; R １４ and R ８ These are either identical or different from one another, and are protons, alkali metals, alkaline earth metals, or ammonium; R ９ It is selected from protons, alkali metals, alkaline earth metals, and ammonium; b) H ２ Provided by S; c) At least one compound of formula (II) and H in the presence of at least one enzyme selected from sulfhydrylases. ２ Reaction with S; The above reaction takes place in a reactor, and H in the gas headspace of the reactor. ２ The partial pressure of S is 0.01 bar to 4 bar at the reaction temperature; and d) To obtain at least one functionalized mercaptan of formula (I), The compound of formula (II) is selected from the group consisting of O-phospho-L-homoserine, O-succinyl-L-homoserine, O-acetyl-L-homoserine, O-acetoacetyl-L-homoserine, O-propio-L-homoserine, O-coumaroyl-L-homoserine, O-malonyl-L-homoserine, O-hydroxymethylglutaryl-L-homoserine, O-pimeryl-L-homoserine, and O-sulfato-L-homoserine. The enzyme used is selected from the group consisting of O-phospho-L-homoserine sulfhydrase, O-succinyl-L-homoserine sulfhydrase, O-acetyl-L-homoserine sulfhydrase, O-acetoacetyl-L-homoserine sulfhydrase, O-propio-L-homoserine sulfhydrase, O-coumaroyl-L-homoserine sulfhydrase, O-malonyl-L-homoserine sulfhydrase, O-hydroxymethylglutaryl-L-homoserine sulfhydrase, O-pimeryl-L-homoserine sulfhydrase, and O-sulfato-L-homoserine sulfhydrase. The functionalized mercaptan in formula (I) is L-homocysteine.

2. H in the gas head space of the reactor ２ The synthesis process according to claim 1, wherein the partial pressure S is 0.25 bar to 2 bar.

3. The aforementioned H ２ The synthesis process according to claim 1 or claim 2, wherein S is in excess relative to the compound of formula (II).

4. The aforementioned H ２ The synthesis process according to claim 3, wherein the molar ratio of S to the compound of formula (II) is 2 to 20.

5. The synthesis process according to any one of claims 1 to 4, wherein stage c) is carried out in an aqueous solution.

6. The aforementioned H ２ The synthesis process according to any one of claims 1 to 5, wherein the partial pressure S corresponds to the total pressure in the gas headspace.

7. The aforementioned H ２ The synthesis process according to any one of claims 1 to 6, wherein the partial pressure S is kept constant throughout the entire duration of stage c).

8. The synthesis process according to any one of claims 1 to 7, wherein the compound of formula (II) is O-acetyl-L-homoserine, and the enzyme used is O-acetyl-L-homoserine sulfhydrase.

9. The process according to any one of claims 1 to 8, wherein stage c) is carried out in the absence of oxygen.

10. The process according to any one of claims 1 to 9, wherein the temperature during stage c) is 10°C to 60°C.

11. - Compound of formula (II) as defined in claim 1; - Sulfhydrase; and - Dissolved H ２ S Includes, The aforementioned H ２ The molar ratio of S to the compound of formula (II) is 2 to 20. The sulfhydrase is selected from the group consisting of O-phospho-L-homoserine sulfhydrase, O-succinyl-L-homoserine sulfhydrase, O-acetyl-L-homoserine sulfhydrase, O-acetoacetyl-L-homoserine sulfhydrase, O-propio-L-homoserine sulfhydrase, O-coumaroyl-L-homoserine sulfhydrase, O-malonyl-L-homoserine sulfhydrase, O-hydroxymethylglutaryl-L-homoserine sulfhydrase, O-pimeryl-L-homoserine sulfhydrase, and O-sulfato-L-homoserine sulfhydrase.

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