Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/20—Processes
  • C25B3/29—Coupling reactions

Definitions

• the present invention relates to a process for the synthesis of vinyl or allyl aryl compound from a heterogeneous coupling reaction by electrolytic route between aryl compounds and vinyl compounds or allyl compounds.
• cobalt salts in particular cobaltous, as catalysts for the electrochemical coupling between an aryl derivative and a vinyl derivative.
• one of the aims of the present invention is to provide a coupling process between vinyl derivatives and aryl derivatives which does not require the use of expensive catalysts.
• Another object of the present invention is to provide a process of the above type which gives good yields.
• Another object of the present invention is to provide a process of the above type which is doubly ipso, the connection between the vinyl molecule and the aryl molecule being carried out at the place where the two leaving groups were located.
• Another object of the present invention is to provide a process which gives few parasitic reactions; in particular a reaction which gives little symmetrical coupling and which gives few reductions to lead to hydrogenated compounds in place of the leaving groups.
• Another object of the present invention is to provide a coupling process between allylic derivatives and aryl derivatives which does not require the use of expensive catalysts.
• Another object of the present invention is to provide a process of the above type which gives good yields.
• Another object of the present invention is to provide a process of the preceding type which is doubly ipso (here, the ablative from the Latin "ipse” is used to indicate that the functionalization is carried out on the same carbon as that which carried the leaving group ), the link between the molecule carrying the unsaturation, in particular allylic, even homoallylic, and the aryl molecule being produced at the place where the two leaving groups were located.
• Another object of the present invention is to provide a process which gives few parasitic reactions; in particular a reaction which gives little symmetrical coupling and which gives little reduction to lead to hydrogenated compounds in place of the leaving groups.
• These aims, and others which will appear subsequently, are achieved by means of an electrolytic heterocoupling process between an aryl (pseudo) halide and a carrier of ethylenic unsaturation and of a leaving group, advantageously an ester, or even an ether, in particular of allyl and of vinyl, which consists in subjecting the two substrates to cathodic reduction in the presence of cobalt cobaltous.
• an ester is defined as the product of condensation between a carrier of a hydroxyl function and a Bronstedt acid, that is to say a carrier of an acidic hydrogen
• the unsaturation is advantageously close to the atom which was a carrier of acidic hydrogen, that is to say that said carrier atom is advantageously in vinyl, allylic, or even homoallylic position; preferably in vinyl or allylic position.
• L represent a divalent arm ensuring the link between the vinyl unsaturation and the rest of the acid (noted here Y) after having ignored the hydrogen.
• Y the rest of the acid
• L is a nothing, -L- then symbolizing the single bond linking Y and the vinyl unsaturation.
• L is an alkylene group; preferably ethylene or methylene, more preferably methylene. In the latter case, the ester is allylic.
• pseudohalogen is intended to denote a group the departure of which leads to an oxygenated anion, the anionic charge being carried by the chalcogen atom and the acidity of which is at least equal to that of acetic acid, advantageously at the second acidity of sulfuric acid, and preferably that of trifluoroacetic acid.
• pKa for medium to high acidities from carboxylic acids to acetic acid and to be placed on the scale of Hammett constants from l trifluoroacetic acid.
• lato sensu carboxylate any radical such that its anionic form contains the atomic sequence -CO-O " ; thus not only are the carboxylate functions linked to a carbon atom, but also carbamic acids and alkylcarbonates. 'We want to avoid any parasitic reaction, it is preferable to avoid that the substituents include reactive hydrogens such as hydrogens on the amides (which are therefore advantageously protected or peralkylated) or on an oxygen.
• Ri, R 2 and R 3j, different or not, are chosen from hydrogen, the functions which are more difficult to reduce than the function Y and from hydrocarbon radicals, in particular alkyls and aryls.
• the ether functions when y forms an ester, the ether functions, the carboxylic functions (linked or not to the rest of the molecule by carbon), the functions among which Y is chosen on the condition that these functions are less reducible than Y.
• the order of reducibility can be easily determined under the operating conditions by routine experiments.
• the halides the higher the atomic number, the more the halide is reducible and, more generally (and coarser), the more the acid corresponding to the group. therefore the stronger, the more the corresponding vinyl ester is reducible (however, it should be noted that the anions can themselves be reduced and cause parasitic reactions).
• the hydrocarbon radicals are preferably either of aromatic nature or of aliphatic nature, that is to say that the carbon ensuring the link with the rest of the molecule is sp 3 hybridization; these aliphatic radicals are in general of alkyls (alkyl is taken in its etymological sense of an alcohol from which the OH function has been removed), including aralkyls. It should be noted that the hydrocarbon radicals having a double bond conjugated with the double bond give only very poor results. To be effective, it is desirable that the cobalt be present at a minimum concentration of at least 10 "3 M.
• the cobalt is not too concentrated, so we prefer that the cobalt content is at most equal to 0.2 M.
• the reaction medium advantageously comprises a solvent, this solvent must be sufficiently polar to dissolve the metals or more exactly the metal salts used, and it must be sufficiently lipophilic to dissolve, at least in part, the substrates whose aryl is to be formed vinyl.
• solvents which are sufficiently weak in acid so that the reactions with hydrogen are as weak as possible.
• primary alcohols are too acidic.
• polar aprotic solvents such as, for example, alone or as a mixture:
• purely oxygenated solvents in particular ethers, preferably polyethers such as dimethoxy-1, 2-ethane, or cyclic ethers such as THF or dioxane;
• sulfones for example sulfolane
• sulfoxides such as DMSO
• the solvents used can themselves play the role of complexing agents or coordinating agents. They can in particular, and this is advantageous, present one or more of the coordination functions mentioned above.
• the solvent can be a mixture of an apolar solvent and a polar solvent as defined above by the donor index. To facilitate the separation of the products from the reaction media, it is preferable that said solvent has a boiling point which is substantially different from the compound to be synthesized and from the starting compound.
• saline electrolytes are sometimes used, sometimes called bottom salts, possibly modified by the presence of complexing agents. These electrolytes are chosen so as not to disturb the reactions at the anode and at the cathode. The latter is advantageously inert.
• the bottom salt in the case where a soluble anode is used, a salt whose cations correspond to the metals of the anode.
• soluble anodes mention may be made of anodes containing iron and / or cobalt, and in particular anodes made of cobalt alloy, of cobalt itself, or of ferro-cobalt.
• the electrolyte can be chosen so as to have as cations metals with strong transporting power such as divalent, advantageously trivalent, of the aluminum type, and this provided that this does not disturb the basic reaction.
• the metals used in the base salts it is desirable to use those which exhibit, in addition to degree 0, only one stable degree of oxidation.
• the electrolyte can be chosen so that these cations are directly soluble in the reaction medium.
• “onium” means positively charged organic compounds whose name assigned to them by the nomenclature has an affix, generally suffix, "onium” (such as sulfonium [trisubstituted sulfur], phosphonium [tetrasubstituted phosphorus], ammonium [tetrasubstituted nitrogen] ).
• the most used are tetraaicoyiammoniums, the alkyl groups taken in their etymological sense generally have from 1 to 12 carbon atoms, preferably from 1 to 4 carbon atoms. Phase transfer agents can also be used.
• the anions can be usual anions for the indifferent electrolytes, but it is preferable that they are chosen from those released by the reaction, essentially halides, or for example by complex anions of type BF 4 -, PF 6 -, CI0 4 - Among the preferred anions, mention may be made of those derived from fluorinated acids or their imides (TFSI, triflate, etc.). As an indication, it should be noted that DMF, used with tetrafluoroborate tetrabutylammonium as a background salt at a concentration of 0.01 M, has given good results.
• Said electrolysis can be carried out at numerous temperatures, but it is preferable to conduct this electrolysis at a temperature at most equal to 100 ° and at most equal to the boiling point of the solvent.
• An interval giving good results is the interval between 0 and 50 ° C; it is a closed interval, that is to say comprising the limits.
• Pressure is of little importance on electrolysis, unless one of the reactants or the solvent has particularly low boiling points.
• aryl substrates (Ar-X) capable of being coupled with the compounds carrying ethylenic unsaturation according to the present invention represent a wide range of compounds.
• Halides are generally halides corresponding to relatively heavy halogens, that is to say halogens heavier than fluorine.
• halogen when the halogen is linked to an aromatic nucleus depleted in electrons, it is preferable to use bromines or chlorines as halogen, the chlorines being reserved for nuclei particularly depleted in electrons.
• the condition is almost always fulfilled by six-membered heterocycles; but in the case of homocyclic aryl hexacyclic substrates, to use a chloride, it is preferable that the sum of the Hammett constants ⁇ p of the substituents (without taking into account the leaving halide) is at least equal to 0.40, preferably to 0.50.
• nuclei that are particularly enriched in electrons can use iodine as the halide.
• the electron depletion of the nucleus may be due either to the presence of electron-withdrawing groups as substituents or, in the case of six-membered nuclei, to the replacement of a carbon by a heteroatom .
• the electron-depleted nucleus can be a six-membered heterocyclic nucleus, in particular heterocyclic nuclei having a nitrogen column atom and more particularly nitrogen.
• acyl groups nitrile groups, sulfone groups, carboxylate groups, trifluoromethyl groups or more generally perfluoroalkyl groups and halogens of lower rank than the halide. , which will be replaced by the allylic radical.
• donor groups that is to say giving poor results with chlorine but good with bromine, mention may be made of alkyloxy groups, alkyl groups, amino and dialkoylamine groups.
• aromatic substrate derivative of the present process advantageously corresponds to the following formula: where:
• - Z represents a trivalent link -CfR ⁇ ⁇ , an atom of column V, advantageously a nitrogen;
• - X represents the leaving halogen;
• R, R 1 ( R 2 , R 3 can be linked to form rings.
• aryls can be in particular of formula:
• - Zi is chosen from the same meanings as those given for Z;
• the radicals Ri, R 2 , R 3 are chosen from the substituents mentioned above and in particular: • the electron-withdrawing groups, in particular the acyl groups, the nitrile groups, the sulfone groups, the carboxylate groups, the trifluoromethyl groups, or more generally the perfluoroalkyl groups and the halogens of lower rank than the halide which will be transformed into coupling product; " The donor groups, in particular the aryloxyl, alkyloxyl groups, the hydrocarbyl groups such as aryl and alkyl (the latter word being taken in its etymological meaning), the amino groups, including the mono and disubstituted by alcoylamine hydrocarbon groups. It is desirable that the substrates have at most 50 carbon atoms, advantageously at most 30 carbon atoms, preferably at most 20 carbon atoms.
• halides preferably aryl chlorides, carrying in particular in the meta position, an aliphatic carbon (ie sp 3 ) carrying at least two fluorines.
• halides preferably trifluoromethylaryl chlorides.
• the cobalt is coordinated, however the optimal conditions of coordination are a little different for the vinyl esters on the one hand and for the other esters, in particular of allyl, on the other hand.
• the present description now focuses more specifically on the implementation in which the ester is vinyl; in this case, L is a nothingness and therefore -L- is a simple bond: the above equation then becomes:
• the number of carbons in the vinyl derivative is less than fifty, advantageously thirty.
• the donor index D of these solvents, or of these solvating agents can be greater than or equal to 10, preferably less than or equal to 30, advantageously between 20 and 30, the terminals being included.
• Said donor index corresponds to the ⁇ H (enthalpy variation) expressed in kilocalories of the association of said polar aprotic solvent or of said coordinator with antimony pentachloride.
• the cobalt be present at a minimum concentration of at least 10 "3 M.
• the cobalt is not too concentrated, so we prefer that the cobalt content is at most equal to 0.2 M.
• the reaction medium advantageously comprises a solvent, this solvent must be sufficiently polar to dissolve the metals, or more exactly the metal salts used, and it must be sufficiently lipophilic to dissolve, at least in part, the substrates for which it is desired to form the vinyl aryl.
• solvents which are sufficiently weak in acid so that the reactions with hydrogen are as weak as possible.
• primary alcohols are too acidic.
• so-called polar aprotic solvents such as, for example, alone or as a mixture:
• purely oxygenated solvents in particular ethers, preferably polyethers such as dimethoxy-1, 2-ethane or cyclic ethers such as THF or dioxane; • amides or ureas (DMF, N-methylpyrrolidone-2, imidazolidone, tetramethylurea, dimethoxypropylene-urea, etc.);
• sulfones for example sulfolane
• sulfoxides such as DMSO
• the solvents used can themselves play the role of complexing agents or coordinating agents. They can in particular, and this is advantageous, present one or more of the coordination functions mentioned above.
• the solvent can be a mixture of an apolar solvent and a polar solvent as defined above by the donor index.
• cobalt-specific complexing agents advantageously polydent, most often bidental.
• nitriles preferably aromatic and / or bidentes
• pyridines and derivatives of the pyridine nucleus such as quinoline.
• the bipyridyls being bidentes also give very good results as coordinators distinct from the solvent.
• the preferred complexing agents are those which do not carry a charge, especially a negative charge, on the atom, or the atoms carrying the bond, coordinating the cobalt; it is also preferable that when said complexing agent carries a charge, the latter is located by the shortest route at least 4, and even advantageously at least 5 atoms, preferably 6, especially when said charge is negative.
• cyanides are not desirable as complexing cobalt.
• the ratio (coordinator (s) / cobalt) between coordinator (s), expressed in moles for monodentates and in equivalent for polydents and cobalt ions (expressed in moles) or at least equal to 0.5, advantageously to 1, preferably to 2, more preferably to 4.
• said solvent has a boiling point which is substantially different from the compound to be synthesized and from the starting compound.
• saline electrolytes sometimes called background salts
• these electrolytes are chosen so as not to disturb the reactions at the anode and at the cathode.
• the latter is advantageously inert.
• soluble anodes mention may be made of anodes containing iron and / or cobalt, and in particular anodes made of cobalt alloy, of cobalt itself, or of ferro-cobalt.
• the electrolyte can be chosen so as to have as cations metals with strong transporting power such as divalent, advantageously trivalent, of the aluminum type, and this provided that this does not disturb the basic reaction.
• metals used in the base salts it is desirable to use those which exhibit, in addition to degree 0, only one stable degree of oxidation.
• the electrolyte can be chosen so that these cations are directly soluble in the reaction medium.
• the medium is not very polar, rather than making the metal cations soluble by means of adjuvants, it may be advantageous to use stable "oniums" in the field of electrical inactivity.
• onium means positively charged organic compounds whose name assigned to them by the nomenclature has an affix, generally suffix, "onium” (such as sulfonium [trisubstituted sulfur], phosphonium [tetrasubstituted phosphorus], ammonium [tetrasubstituted nitrogen] ).
• onium such as sulfonium [trisubstituted sulfur], phosphonium [tetrasubstituted phosphorus], ammonium [tetrasubstituted nitrogen] ).
• the most used are tetraaicoyiammoniums, the alkyl groups taken in their etymological sense generally have from 1 to 12 carbon atoms, preferably from 1 to 4 carbon atoms. Phase transfer agents can also be used.
• the anions can be usual anions for the indifferent electrolytes, but it is preferable that they are chosen from those released by the reaction, essentially halides, or for example by complex anions of type BF 4 -, PF 6 -, CI0 4 -.
• preferred anions mention may be made of those derived from fluorinated acids or their imides (TFSI, triflate, etc.).
• FTSI fluorinated acids or their imides
• Said electrolysis can be carried out at numerous temperatures, but it is preferable to conduct this electrolysis at a temperature at most equal to 100 ° and at most equal to the boiling point of the solvent.
• An interval giving good results is the interval between 0 and 50 ° C; it is a closed interval, that is to say comprising the limits.
• Pressure is of little importance on electrolysis, unless one of the reactants or the solvent has particularly low boiling points.
• the vinyl ester has the following formula (II):
• Another object of the present invention is to provide a medium which can be used for carrying out electrolysis and which leads to heterocouplings. This object was achieved by means of a composition, comprising at least: • a cobalt salt,
• the solvent and the cobalt coordinating agent can constitute a single entity, and even a single compound when the solvent is a single compound.
• the cobalt content is advantageously between and 2.10 “3 and 10 " 1 M, preferably between 5.10 “3 and 5.10 “ 2 M (closed interval, that is to say including the limits).
• Said composition further comprises an aryl halide, the preferred chemical characteristics of which will be detailed later. This aryl halide is advantageously present at a concentration of 0.1 to 1 M. It is desirable that the molar ratio (dissolved species) of cobalt to vinyl ester ranges from 10 "2 to 1/2, preferably 0.05 at 0.2 (closed interval, that is to say including the limits).
• the important limit values are the minimum values. If using a cobalt soluble anode, these values can be exceeded.
• the molar ratio (of course species) of vinyl ester on aryl halide is at least equal to 1, and advantageously to 1.5, preferably to 2, and is at most equal to 5, advantageously to 4, preferably to 3.
• this ratio goes from 1 to 5 (closed interval, that is to say including the limits).
• the intensity and the surface of the reactive electrode, more precisely of the electrode where the reaction takes place are chosen, so that the current density / is between 5 and 5.10 2 A / m 2 , preferably between 20 and 200 A / m 2 (closed interval, that is to say including the terminals).
• the aryl substrates capable of being coupled with the vinyls according to the present invention represent a wide range of compounds.
• the halides are generally halides corresponding to relatively heavy halogens, that is to say to halogens heavier than fluorine; these substrates are denoted by formula (I):
• halogen when the halogen is linked to an aromatic nucleus depleted in electrons, it is preferable to use as halogen from bromine or chlorine, chlorine being reserved for nuclei particularly depleted in electrons.
• the condition is almost always fulfilled by six-membered heterocycles; but in the case of homocyclic aryl hexacyclic substrates, to use a chloride, it is preferable that the sum of the Hammett constants ⁇ p of the substituents (without taking into account the leaving halide) is at least equal to 0.40, preferably to 0.50.
• nuclei that are particularly enriched in electrons can use iodine as the halide.
• the electron depletion of the nucleus may be due either to the presence of electron-withdrawing groups as substituents or, in the case of six-membered nuclei, to the replacement of a carbon by a heteroatom .
• the electron-depleted nucleus can be a six-membered heterocyclic nucleus, in particular heterocyclic nuclei having a nitrogen column atom and more particularly nitrogen.
• acyl groups nitrile groups, sulfone groups, carboxylate groups, trifluoromethyl groups, or more generally perfluoroalkyl groups and halogens of lower rank than halide, which will be replaced by the vinyl radical.
• aromatic substrate derivative of the present process advantageously corresponds to the following formula:
• aryl compounds can be chosen in particular from those of the following formulas:
• - Zi is chosen from the same meanings as those given for Z;
• radicals Ri, R 2 , R 3 are chosen from the substituents mentioned above and in particular: • electron-withdrawing groups, in particular acyl groups, nitrile groups, sulfone groups, carboxylate groups, trifluoromethyl groups, or more generally perfluoroalkyl groups and halogens of lower rank than the halide which will be transformed into a product of coupling;
• the donor groups in particular the aryloxyl, alkyloxyl groups, the hydrocarbyl groups such as aryl and alkyl (the latter word being taken in its etymological meaning), the amino groups, including the mono and disubstituted by alcoylamine hydrocarbon groups.
• the substrates have at most 50 carbon atoms, advantageously at most 30 carbon atoms, preferably at most 20 carbon atoms.
• halides preferably aryl chlorides, carrying in particular in the meta position, an aliphatic carbon (ie sp 3 ) carrying at least two fluorides, for example halides, preferably trifluoromethylaryl chlorides .
• One of the advantages of the present invention is that it requires only complexing agents, or coordinators, which are easy to access, such as nitriles (preferably aromatic or bidental) or else pyridines and derivatives of the pyridine nucleus, such as quinoline. Furthermore, the bipyridyls being bidentes, also give good results as a separate coordinator of the solvent.
• the present description now deals with the implementation of the electrolytic heterocoupling between an aryl (pseudo) halide and an allyl ester, or even an ether, which consists in subjecting the two substrates to cathodic reduction in the presence of cobalt. cobaltous.
• - Y corresponds to a leaving group capable of existing in the Y " form, such as phenate, or even alcoholate, but advantageously chosen from halogens and lato sensu carboxylates and pseudohalogens.
• Ra and Rb which may be identical or different, are chosen from hydrocarbyles (that is to say the groups whose open bond is carried by a carbon and which comprises both hydrogen and oxygen) and hydrogens. It is desirable to avoid steric hindrance problems that at least one, preferably two, of the Ra and Rb is hydrogen.
• pseudohalogen is intended to denote a group the departure of which leads to an oxygenated anion, the anionic charge being carried by the chalcogen atom and the acidity of which is most often at least equal to that of acetic acid, advantageously at the second acidity of sulfuric acid and preferably that of trifluoroacetic acid.
• carboxylate any radical such that its anionic form contains the atomic sequence -CO-O " ; thus, not only are the carboxylate functions linked to a carbon atom, but also carbamic acids and alkylcarbonates.
• substituents comprise reactive hydrogens such as hydrogens on the amides (which are therefore advantageously protected or peralkylated) or on an oxygen.
• R 2 and R 3 are chosen from hydrogen, the functions which are more difficult to reduce than the function Y and from the hydrocarbon radicals, sometimes designated in the present application by the term
• “Hydrocarbyls” in particular alkyls and aryls; alkyls being taken in its etymological sense from an alcdol from which the OH function has been removed, and of course comprises the aralkyls
• the ether and carboxylic functions the functions from which Y is chosen provided that these functions are less reducible than Y.
• the order of reducibility can be easily determined under the operating conditions by routine experiments. As an indication, it can be indicated that with regard to halides, the higher the atomic number, the more the halide is reducible and more generally (and coarser), the more the acid corresponding to the group. leaving is strong, more the corresponding allyl ester is reducible, (it is however necessary to pay attention to the fact that the anions can themselves be reduced and to cause parasitic reactions).
• hydrocarbon radicals are preferably either of aromatic nature or of aliphatic nature, that is to say that the carbon ensuring the link with the rest of the molecule is sp 3 hybridization; these aliphatic radicals are generally alkyls (alkyl is taken in its etymological sense from an alcohol from which the OH function has been removed), including aralkyls. It should be noted that the hydrocarbon radicals having a double bond conjugated with the allyl seat of the reaction give only very poor results.
• the number of carbons of the allylic derivative is less than fifty, advantageously thirty.
• the reaction is indeed an ipso reaction (here, the ablative from the Latin “ipse” is used to indicate that the functionalization is done on the same carbon as that which carried the halide or pseudohalide leaving), but in certain cases, of course when the allyl group is not palindromic, small amounts of product corresponding to SN'2 have been observed.
• the donor index D of these solvents, or of these solvating agents can be greater than or equal to 10, preferably less than or equal to 30, advantageously between 20 and 30, the terminals being included.
• Said donor index corresponds to the ⁇ H (enthalpy variation) expressed in kilocalories of the association of said polar aprotic solvent or of said coordinator with antimony pentachloride.
• the atom coordinating the cobalt in said solvent or solvating agent is an atom from the column of nitrogen, and advantageously nitrogen itself.
• a specific coordinating agent which does not act as a solvent, mention may be made of the functions, or group, of pyridine, nitrile, phosphine, stibine and imine.
• the cobalt be present at a minimum concentration of at least 10 ⁇ 3 M.
• the cobalt is not too concentrated, so we prefer that the cobalt content is at most equal to 0.2 M.
• the reaction medium advantageously comprises a solvent, this solvent must be sufficiently polar to dissolve the metals or more exactly the metal salts used, and it must be sufficiently lipophilic to dissolve, at least in part, the substrates whose aryl is to be formed allyl.
• solvents which are sufficiently weak in acid so that the reactions with hydrogen are as weak as possible.
• primary alcohols are too acidic.
• so-called polar aprotic solvents such as, for example, alone or as a mixture:
• purely oxygenated solvents in particular ethers, preferably polyethers such as dimethoxy-1, 2-ethane or cyclic ethers such as THF or dioxane; • amides or ureas (DMF, N-methylpyrrolidone-2, imidazolidone, tetramethylurea, dimethoxypropylene-urea, etc.);
• sulfones for example sulfolane
• sulfoxides such as DMSO
• the solvents used can themselves play the role of complexing agents or coordinating agents. In particular, they may present one or more of the coordination functions mentioned above.
• the solvent can be a mixture of an apolar solvent and a polar solvent as defined above by the donor index.
• the solvent is not in itself a cobalt complexing agent strong enough to obtain optimal results, it is then desirable to use one of the specific cobalt complexing agents, advantageously non-polydent, and even non-bidental, especially when the one of the teeth is a pyridine function.
• the specific cobalt complexing agents advantageously non-polydent, and even non-bidental, especially when the one of the teeth is a pyridine function.
• nitriles preferably aromatic and / or bidentes
• pyridines and derivatives of the pyridine nucleus such as quinoline. Alone, dinitriles give very good results.
• bipyridyls being bidentes, give poor results as complexing agents distinct from the solvent.
• the complexing agents of bidentate cobalt comprising at least a pyridine tooth to be in an amount less than that of cobalt (expressed in moles per liter).
• the complexing agents of pyridine nature expressed in equivalent of pyridine or strong function are less than twice the amount expressed in mole of cobalt salts , preferably less than once.
• the preferred complexing agents are those which do not carry a charge, especially a negative charge, on the atom, or on the atoms carrying the bond coordinating cobalt; it is also preferable that when said complexing agent carries a charge, the latter is located by the shortest route at least 4, and even advantageously at least 5 atoms, preferably 6, especially when said charge is negative.
• cyanides are not desirable as complexing agents for cobalt.
• said solvent it is preferable for said solvent to have a boiling point which is substantially different from the compound to be synthesized and from the starting compound.
• saline electrolytes are sometimes used, sometimes called bottom salts, possibly modified by the presence of complexing agents. These electrolytes are chosen so as not to disturb the reactions at the anode and at the cathode. The latter is advantageously inert.
• a salt whose cations correspond to the metals of the anode in the case where a soluble anode is used, a salt whose cations correspond to the metals of the anode.
• soluble anodes mention may be made of anodes containing iron and / or cobalt, and in particular anodes made of cobalt alloy, of cobalt itself, or of ferro-cobalt.
• the electrolyte can be chosen so as to have as cations metals with strong transporting power such as divalent, advantageously trivalent, of the aluminum type, and this provided that this does not disturb the basic reaction.
• the metals used in the base salts it is desirable to use those which exhibit, in addition to degree 0, only one stable degree of oxidation.
• the electrolyte can be chosen so that these cations are directly soluble in the reaction medium.
• the medium is not very polar, rather than making the metal cations soluble by means of adjuvants, it may be advantageous to use stable "oniums" in the field of electrical inactivity.
• onium means positively charged organic compounds whose name assigned to them by the nomenclature has an affix, generally suffix, "onium” (such as sulfonium [trisubstituted sulfur], phosphonium [tetrasubstituted phosphorus], ammonium [tetrasubstituted nitrogen] ).
• onium such as sulfonium [trisubstituted sulfur], phosphonium [tetrasubstituted phosphorus], ammonium [tetrasubstituted nitrogen] ).
• the most used are tetraaicoyiammoniums, the alkyl groups taken in their etymological sense generally have from 1 to 12 carbon atoms, preferably from 1 to 4 carbon atoms. Phase transfer agents can also be used.
• the anions can be usual anions for indifferent electrolytes, but it is preferable that they are chosen from those released by the reaction, essentially halides, or for example by complex anions of type BF 4 -, PF ⁇ -, CI0 4 -.
• preferred anions mention may be made of those derived from fluorinated acids or their imides (bis-trifluoromethylsulfonimide, triflate, etc.).
• DMF used with tetrabutylammonium tetrafluoroborate as a background salt at a concentration of 0.01 M, has given good results.
• Said electrolysis can be carried out at numerous temperatures, but it is preferable to conduct this electrolysis at a temperature at most equal to 100 and at most equal to the boiling point of the solvent.
• An interval giving good results is the interval between 0 and 50 ° C; it is a closed interval, that is to say comprising the limits.
• Pressure is of little importance on electrolysis, unless one of the reactants or the solvent has particularly low boiling points. However, for practical reasons, it is preferable to place yourself at atmospheric pressure in the place where you are.
• Another object of the present invention is to provide a medium which can be used for carrying out electrolysis and which leads to heterocouplings. This object was achieved by means of a composition, comprising at least:
• the solvent and the cobalt coordinating agent can constitute a single entity, and even a single compound when the solvent is a single compound.
• the cobalt content is advantageously between 2.10 “3 and 10 " 1 M, preferably between 5.10 "3 and 5.10 " 2 M (closed interval, that is to say including the limits).
• the upper limit values may be exceeded.
• Said composition further comprises an aryl halide (Ar-X) whose preferred chemical characteristics will be detailed later. This aryl halide is advantageously present at a concentration of at least 0.01 M, preferably 0.1 to 1 M.
• ester or allyl ether is at least at a (dissolved) concentration of 0.01 M.
• the molar ratio (dissolved species) of cobalt to allyl ester should be from 10 "2 to 1/2, preferably from 0.05 to 0.2 (closed interval, that is to say including the limits)
• the important limit values are the minimum values, when using a cobalt soluble anode these values may be exceeded.
• the molar ratio (of course species) of ester, or ether, of allyl on aryl halide is at least equal to 1 and advantageously to 1.5, preferably to 2 and to be at most equal to 5, advantageously to 4, preferably to 3.
• this ratio goes from 1 to 5 (closed interval, that is to say comprising the terminals).
• the intensity and the surface of the reactive electrode, more precisely of the electrode where the reaction takes place are chosen, so that the current density / is between 5 and
• the aryl substrates (Ar-X) capable of being coupled with the allyls according to the present invention represent a wide range of compounds.
• the halides are generally halides corresponding to relatively heavy halogens, that is to say halogens heavier than fluorine.
• halogen when the halogen is linked to an aromatic nucleus depleted in electrons, it is preferable to use bromines or chlorines as halogen, the chlorines being reserved for nuclei particularly depleted in electrons.
• the condition is almost always fulfilled by six-membered heterocycles; but in the case of homocyclic aryl hexacyclic substrates, to use a chloride, it is preferable that the sum of the Hammett constants ⁇ p of the substituents (without taking into account the leaving halide) is at least equal to 0.40, preferably to 0.50.
• nuclei that are particularly enriched in electrons can use iodine as the halide.
• the electron depletion of the nucleus may be due either to the presence of electron-withdrawing groups as substituents or, in the case of six-membered nuclei, to the replacement of a carbon by a heteroatom .
• the electron-depleted nucleus can be a six-membered heterocyclic nucleus, in particular heterocyclic nuclei having a nitrogen column atom and more particularly nitrogen.
• acyl groups nitrile groups, sulfone groups, carboxylate groups, trifluoromethyl groups or more generally perfluoroalkyl groups and halogens of lower rank than the halide. , which will be replaced by the allylic radical.
• aryls can be in particular of formula:
• the electron-withdrawing groups in particular the acyl groups, the nitrile groups, the sulfone groups, the carboxylate groups, the trifluoromethyl groups, or more generally the perfluoroalkyl groups and the halogens of lower rank than the halide which will be transformed into a product of coupling.
• Donor groups in particular aryloxy, alkyloxy groups, hydrocarbyl groups such as aryl and alkyl (the latter word being taken in its etymological meaning), amino groups, including mono and disubstituted by alkylamino hydrocarbon groups.
• the substrates have at most 50 carbon atoms, advantageously at most 30 carbon atoms, preferably at most 20 carbon atoms.
• halides preferably aryl chlorides, carrying in particular in the meta position, an aliphatic carbon (ie sp 3 ) carrying at least two fluorines.
• halides preferably trifluoromethylaryl chlorides.
• coordinators which are easy to access, such as nitriles (preferably aromatic or bidental) or else pyridines and derivatives of the pyridine nucleus, such as quinoline.
• bipyridyls being bidentes, also give good results as a separate coordinator from the solvent.
• GF represents a functional group corresponding to R in the general formula and Y is here a carboxylate of formula Y-COO-
• Aryl bromide 7.5 millimoles
• Electrolyte indifferent tetrabutyl ammonium tetrafluoroborate (10 "2 M)
• Electrode surface 20 cm 2
• Aryl bromide 5 millimoles
• Electrolyte indifferent tetrabutyl ammonium tetrafluoroborate (10 v " 2 * M")
• Electrode surface 20 cm 2
• Y is here a carboxylate of formula Y'-COO-
• Heroaryl halide 5 millimoles
• Electrolyte indifferent tetrabutyl ammonium tetrafluoroborate (10 "2 M)
• Electrode surface 20 cm 2
• Y is here a carboxylate of formula Y'-COO-
• Aromatic bromide 7.5 millimoles (aromatic chloride: 5 millimoles)
• Electrolyte indifferent tetrabutyl ammonium tetrafluoroborate (10 "2 M)
• Electrode surface 20 cm 2
• Electrolyte indifferent tetrabutylammonium tetrafluoroborate (10 "2 M)
• Electrode surface 20 cm 2 Duration of electrolysis: 4 hours
• Aryl bromide 10 millimoles
• Cobalt bromide 1 millimole
• 2,2'-bipyridine 10 millimoles
• Vinyl acetate 25 millimoles
• Single compartment electrolysis cell provided with an iron anode and a cathode constituted by a stainless steel grid (cathodes constituted by nickel foam or a gold grid can also be used).
• Electrolyte indifferent tetrabutylammonium tetrafluoroborate (10 "2 M)
• Electrode surface 20 cm 2
• Electrolytic heterocoupling process between an aryl (pseudo) halide and a vinyl ester which consists in subjecting the two substrates to cathodic reduction in the presence of cobalt cobalt.

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