Method for preparing hydroboranes by hydrogenolysis of (pseudo-)haloboranes

Abstract

The invention relates to a method for preparing hydroboranes by hydrogenolysis of corresponding (pseudo-)haloboranes, in the presence of dihydrogen H2, a base and a catalyst. The method of the invention falls within a circularity approach to boron, enabling recycling of (pseudo-)haloborane compounds, which are a waste commonly encountered in boron chemistry, to hydroboranes with higher added values.

Description

PROCESS FOR THE PREPARATION OF HYDROBORANES BY HYDROGENOLYSIS OF (PSEUDO-)HALO-BORANES Technical field of the invention

[0001] The present invention lies in the field of boron chemistry and more particularly in the synthesis of hydroboranes having one, two or three BH bonds per boron atom.

[0002] In particular, the present invention relates to a process for the preparation of hydroboranes by the hydrogenolysis of corresponding (pseudo-)haloboranes in the presence of dihydrogen H2, a base and a catalyst.

[0003] The process of the invention is part of an approach to circularity of the element boron by allowing the recycling of (pseudo-) haloborane compounds, common waste from boron chemistry, towards hydroboranes with higher added values. Technical background

[0004] The interest of hydroboranes in chemistry is multiple. They are used in organic synthesis for the reduction of carbonyl functions and unsaturated carbon-carbon bonds or during the synthesis of boronic esters used for Suzuki coupling for example. They also serve as sources of hydrides in the production of industrial molecules such as methanol, formic acid, ammonia, etc. from inorganic molecules (CO2, NO x ).

[0005] The synthesis of hydroboranes is currently based mainly on the synthesis of borane BH3, the industrial synthesis of which is carried out in two stages as shown in and described by HI Schlesingeret al., J. Am. Chem. Soc., 1953, 75 (1), 205–209 and doi.org / 10.1002 / 14356007.a04_309; US3259474:

[0006] - reduction of trimethylborate (B(OMe)3) to sodium borohydride (NaBH4) by metallic sodium under hydrogen pressure at high temperature (Brown-Schlesinger or Bayer processes),

[0007] - reaction of sodium borohydride with trifluoroborane (BF3).

[0008] This process has a low energy balance since it is necessary to provide thermal and chemical energy to produce an over-reduced intermediate product and relies, particularly in the first step, on hazardous reagents, in particular metallic sodium. The material balance is also low since only 57% of the boron used is recovered in the form of BH3. On a laboratory scale, it was recently shown by Camaioni that trichloroborane (BCl3) in the presence of a nitrogenous base is able to activate hydrogen. Recombination of chlorines leads to partial hydrogenolysis of trichloroborane to dichloroborane (HBCl2). This method is however limited by a maximum theoretical yield of 50% () and does not allow the formation of ClBH2 and BH3 (Ginovska, B. et al., Chemistry – A European Journal, 2015, 21(44), 15713–15719).

[0009] Hydrogen activation can be achieved heterolytically by the combination of a Lewis acid and a Lewis base. Frustrated Lewis Pairs (FLPs) are well-documented special cases, particularly with the use of aminoborane derivatives. However, few examples deal with halogenated analogues such as aminochloroboranes. Fontaine's group has shown that a system based on a bisaryl chloroborane functionalized with 2,2,6,6-tetramethylpiperidine (TMP) groups allows hydrogen activation in the zwitterionic form bisaryl chloroborohydride and an ammonium salt of TMP (M.-A. Courtemanche et al., Dalton Trans., 2016, 45(14), 6129–6135). This product can also be considered as the addition product of HCl on the corresponding borane, and the authors demonstrate this by treating the latter with a strong base, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) which allows the formation of the supposed borane.This reactivity is however limited to a particular reagent, activated by its FLP character, the activation of hydrogen is done intramolecularly, as shown in. This same group also recalls that these hydrogenolysis reactions of haloboranes into boranes are thermodynamically unfavorable and would tend towards the formation of lower energy haloborohydride and polyhaloborane derivatives (K. Chernichenko et al., Dalton Trans., 2017, 46(7), 2263–2269).

[0010] An alternative route, reported by Mertens and his group (C. Relleret al., Eur. J. Inorg. Chem. 2014, 450-459) consists of carrying out the hydrodechlorination of BCl3 using a nickel boride catalyst, under hydrogen and in the presence of triethylamine (NEt3). This reaction nevertheless requires high hydrogen pressures (P ≥ 60 bar) and temperature (T ≥ 130°C) and leads to a mixture of different compounds: Et3NBHCl2, Et3NBH2Cl, Et3BH3. The activation mode of this reaction is based, according to the authors, on the radical abstraction of a hydrogen atom from triethylamine by the catalyst during an activation step. The resulting α-amino alkyl radical reacts with the adduct Et3NBCl3 to abstract a chlorine atom and lead to the formation of an iminium salt. The iminium salt is hydrogenated by the Ni3B catalyst in a second part of the catalytic cycle to reform triethylamine.Thus, the hydrogenolysis of B–Cl bonds is not by heterolytic cleavage of the H–H bond according to an FLP mechanism but by a hydrogenation process by heterogeneous catalysis with Ni3B (10.1080 / 00304949709355171) with the base serving to activate chloroborane and not hydrogen. Alternatively, the preparation of higher added value hydroboranes such as alkylboranes and alkoxyboranes is possible by the metathesis reaction of sigma bonds between their halogenated or (pseudo-)halogenated analogues with a hydride donor, usually borane as shown in (H. Brownet al.,Journal of Organometallic Chemistry,1979,168(3), 281–293). This very non-selective process generally leads to statistical distributions of the different possible products and subsequent purification steps are required in order to isolate the product(s) of interest.Silanes can also be used as hydride transfer agents for the synthesis of various hydroboranes from the corresponding haloboranes. Stephan's group (A. Yeganeh-Salman,et al.,Dalton Trans.,2022,51(47), 17962–17966) uses a stoichiometric amount of triethylsilane (Et3SiH) activated by a triphenylcarbenium salt [CPh3][B(C6F5)4], this method generates in return a stoichiometric amount of triethylchlorosilane as a by-product of the reaction. To the inventors' knowledge, industrially applicable synthetic methods for obtaining these high added value boranes have never been reported from hydrogen. It is also important to remember that these processes require, in theory, stoichiometric amounts of water reagents, and in practice, excesses of these reagents are often required. This leads to the generation of (over-)stoichiometric quantities of waste, the reprocessing of which is complex.In the case of the synthesis of alkylboranes and alkoxyboranes, a more selective method is preferred by reaction between borane (BH3) and respectively alkenes or alcohols, always with selectivity problems. This method again requires the production of borane (BH3) and therefore relies on energy-intensive processes, and does not allow circularity of boron.

[0011] There is therefore a real need for a new hydroborane synthesis route that can produce hydroboranes with an improved and more economical energy balance compared to known synthesis routes.

[0012] In particular, there is a real need for a new efficient hydroborane synthesis route that can achieve high yields of hydroboranes formed under optimized operating conditions (yield > 50% for the desired product obtained) minimizing boron losses in the form of waste.

[0013] More specifically, there is a real need for a route to synthesize hydroboranes as described above, from a wide range of boron-containing reagents of interest.

[0014] More particularly, there is a real need for a route to synthesize hydroboranes as described above, starting from dihydrogen (H2) as the hydride source.

[0015] Furthermore, there is a real need for a safer route to synthesize hydroboranes, particularly by reducing the quantity of risky reagents and their danger.

[0016] The present invention aims precisely to meet these needs by providing a process for preparing a hydroborane of formula (I)

[0017] (R1) o (R2) m BH n

[0018] from dihydrogen H2 and a (pseudo-)haloborane of formula (II)

[0019] (R1) o (R2) m BX n

[0020] in which

[0021] - R1 and R2, which may be identical or different, are an alkyl group containing 1 to 12 carbon atoms, a cycloalkyl group containing 3 to 12 carbon atoms, an aryl group containing 6 to 20 carbon atoms, an alkoxy group in which the alkyl group contains 1 to 12 carbon atoms, a cycloalkoxy (-O-cycloalkyl) group in which the cycloalkyl group contains 3 to 12 carbon atoms, an aryloxy group in which the aryl group contains 6 to 20 carbon atoms, a -NR3R4 group, with R3 and R4, which may be identical or different, representing a hydrogen atom, an alkyl group containing 1 to 12 carbon atoms, a cycloalkyl group containing 3 to 12 carbon atoms, an aryl group containing 6 to 20 carbon atoms, said alkyl and cycloalkyl groups being optionally substituted; or

[0022] - R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 12 members, said heterocycle group being optionally substituted;

[0023] - n is 1, 2, 3;

[0024] - m is 0, 1;

[0025] - o is 0, 1;

[0026] - X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group;

[0027] characterized in that the (pseudo-)haloborane of formula (II) is brought into contact with

[0028] (A) a catalyst selected from a metal complex in which the metal is a transition metal selected from chromium, tungsten, manganese, rhenium, silver, rhodium, cobalt, iron, nickel, copper, iridium, ruthenium, osmium, molybdenum, gold, platinum and palladium, and the ligands bound to the transition metals are selected from:

[0029] - nitrogenous bases such as tertiary amines selected from 4-dimethylaminopyridine (DMAP), 1,4-diazabicyclo[2.2.2]octane (DABCO), N-diisopropylethylamine (DIPEA or DIEA), bipyridyl (bipy), terpyridine (terpy); phenanthroline (phen), ethylenediamine, N,N,N',N'-tetramethylethylenediamine (TMEDA), quinoline and pyridine;

[0030] - phosphorus bases such as alkyl and aryl phosphines selected from triphenylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), triisopropylphosphine, tris[2-diphenylphosphino)ethyl]phosphine (PP3), 4,5-bis-(di-i-propylphosphinomethyl) acridine, 4,5-bis-(di-phenylphosphinomethyl) acridine, tricyclohexylphosphine, 1,2-bis-diphenylphosphinoethane (dppe), 1,2-bis(diphenylphosphino)ethane (dppb); RPOCOP = (C6H4){1,3-OPR2}2) where R is an aryl group having 6 to 20 carbon atoms such as phenyl or an alkyl group having 1 to 12 carbon atoms such as tert-butyl and isopropyl, in particular, 1,3-bis[(di-tert-butylphosphino)oxy]benzene ((tBu)2P-O-C6H4-OP(tBu)2); R’ PNP = R'2PCH2CH2N(H)CH2CH2PR'2where R' is an aryl group having 6 to 20 carbon atoms such as phenyl or an alkyl group having 1 to 12 carbon atoms such as tert-butyl and isopropyl, in particular, bis[2-diphenylphosphino)ethyl]amine {((C6H5)2P-CH2-CH2)2NH} and bis[2-di-isopropylphosphino)ethyl]amine {((CH3)2CH)2P-CH2-CH2)2NH};

[0031] - oxygenated bases such as acetate (CH3COO - ), acetylacetonate ([CH3COCHCOCH3] − ), methanolate (CH3-O − ), ethanolate (CH3-CH2-O − ) ;

[0032] - carbon ligands chosen from CO, CN - ;

[0033] - halogens chosen from Cl - , Br - , I - ;

[0034] - a hydrogen atom;

[0035] - N-heterocyclic carbenes derived from an imidazolium salt chosen from the salts of 1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-3-ium, 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydro-1H-imidazol-3-ium, 1,3-bis(2,4,6-trimethylphenyl)-1H-imidazol-3-ium, 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydro-1H-imidazol-3-ium, 4,5-dichloro-1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-3-ium, 1,3-di-tert-butyl-1H-imidazol-3-ium, 1,3-di-tert-butyl-4,5-dihydro-1H-imidazol-3-ium,

[0036] or a mixture of these ligands,

[0037] the metal complex optionally comprising a counter anion chosen from PF6 - , BF4 - , CF3SO3 - ouOTf -,a boron compound having at least 3 substituents selected from a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogen selected from Cl - , Br - , I - , or a mixture of these substituents, said alkyl, cycloalkyl and aryl groups being optionally substituted,

[0038] the complex composed of boron optionally comprising a counter cation chosen from Li + , N / A + , K + orMg 2+ ,a heterocyclic boron compound such as 9-borabicyclo[3.3.1]nonane or 9-BBN or a substituted derivative thereof such as 9-chloro-borabicyclo[3.3.1]nonane or Cl-9-BBN, 9-iodo-borabicyclo[3.3.1]nonane or I-9-BBN, 9-triflate-borabicyclo[3.3.1]nonane or TfO-9-BBNun (pseudo-)haloborane of formula (II) as defined above; and

[0039] (B) a nitrogenous or phosphorous base having a pKa of between 5 and 50 in DMSO or in acetonitrile chosen from

[0040] . a tertiary amine comprising an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, in particular triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe),

[0041] . a phosphazene, in particular latert-butylimino-tri(pyrrolidino) phosphorane or BTPP,

[0042] . a proazaphosphatrane base, including 2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, 2,8,9-triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, 2,8,9-trimethyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane; and

[0043] (C) in a solvent or a mixture of at least two solvents chosen from: ethers chosen from diethyl ether, THF, dioxane, anisole, and diglyme, tertiary amines chosen from triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe), hydrocarbons and aromatics chosen from benzene, toluene, xylene, pentane, hexane, cyclohexane, pyridine-based solvents chosen from lutidine, or 2,6-di-tertbutylpyridine, alkyl halides chosen from chloroform and methylene chloride, aryl halides chosen from chlorobenzene and dichlorobenzene;

[0044] (D) under hydrogen pressure between 0.1 bar and 300 bar.

[0045] The present invention proposes a new route for the synthesis of hydroboranes, which allows a significant improvement in the energy balance of the reaction. The known processes for transforming boron-chlorine bonds into boron-hydrogen bonds require significant energy expenditure in their operations (temperature) and in the choice of reagents used (energy-intensive preparation methods, low energy efficiency). The process of the invention meets a need to produce hydroboranes in an energy-efficient manner.

[0046] The present invention provides a novel route for synthesizing hydroboranes leading to high yields and across a wide range of targets of interest. Previously described synthetic routes describe low yields and lead to significant boron losses in the form of waste. The present invention addresses a need to efficiently produce hydroboranes without losses, particularly significant losses, of boron.

[0047] The present invention provides a novel route for the synthesis of hydroborane based on the activation of hydrogen by a catalyst and a base. Conventional methods for the preparation of hydroboranes rely essentially on borane (BH3) itself prepared from pyrophoric reagents in stoichiometric quantities. The present invention addresses a need to produce hydroboranes more safely by reducing the quantity of risky reagents and their hazard.

[0048] A route for the preparation of hydroboranes based on FLP-type reactivity for dihydrogen activation will allow combining the advantages of using hydrogen: abundance, atom economy, and limited by-product formation with those of conventional hydrous reagents: high reactivity. The hydrogenolysis of (pseudo-)haloboranes by an FLP mechanism requires the specific and non-obvious selection of a Lewis acid / base pair allowing firstly the activation of hydrogen leading to an intermediate hydrous species, and secondly the transfer of the hydride to the (pseudo-)haloborane.

[0049] Another object of the invention is the use of the method of the invention

[0050] - in organic synthesis, for example, for the reduction of carbonyl function or for the preparation of boronic ester by borylation reaction

[0051] - in inorganic synthesis, for example, in the production of industrial molecules such as methanol, formic acid, ammonia, etc.,

[0052] - for the depolymerization of lignin, and

[0053] - for the depolymerization of oxygenated polymers such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), polycarbonate (PC-BPA), etc.

[0054] The invention also relates to the use of a process according to the invention for the recycling of (pseudo-)haloboranes derived from the corresponding hydroboranes. Brief description of the figures

[0055] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0056] represents the industrial synthesis route of borane BH3.

[0057] represents the substoichiometric hydrogenolysis of BCl3assisted by lutidine described by Camaioni.

[0058] represents a hydrogenolysis reaction of a bis aryl chloroborane functionalized by 2,2,6,6-tetramethylpiperidine (TMP) groups to form the corresponding borane.

[0059] represents a sigma bond metathesis reaction between a boron substituted by one or more halogens and / or oxygen groups (BX) and a water source, generally borane (BH3) or silanes.

[0060] represents the chemical structure of certain compounds cited in this presentation. Detailed description of the invention

[0061] The present invention relates to a process for the preparation of a hydroborane of formula (I)

[0062] (R1) o (R2) m BH n

[0063] from dihydrogen H2 and a (pseudo-)haloborane of formula (II)

[0064] (R1) o (R2) m BX n

[0065] in which

[0066] - R1 and R2, which may be identical or different, are an alkyl group containing 1 to 12 carbon atoms, a cycloalkyl group containing 3 to 12 carbon atoms, an aryl group containing 6 to 20 carbon atoms, an alkoxy group in which the alkyl group contains 1 to 12 carbon atoms, a cycloalkoxy (-O-cycloalkyl) group in which the cycloalkyl group contains 3 to 12 carbon atoms, an aryloxy group in which the aryl group contains 6 to 20 carbon atoms, a -NR3R4 group, with R3 and R4, which may be identical or different, representing a hydrogen atom, an alkyl group containing 1 to 12 carbon atoms, a cycloalkyl group containing 3 to 12 carbon atoms, an aryl group containing 6 to 20 carbon atoms, said alkyl and cycloalkyl groups being optionally substituted; or

[0067] - R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 12 members, said heterocycle group being optionally substituted;

[0068] - n is 1, 2, 3;

[0069] - m is 0, 1;

[0070] - o is 0, 1;

[0071] - X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group;

[0072] characterized in that the (pseudo-)haloborane of formula (II) is brought into contact with

[0073] (A) a catalyst selected from a metal complex in which the metal is a transition metal selected from chromium, tungsten, manganese, rhenium, silver, rhodium, cobalt, iron, nickel, copper, iridium, ruthenium, osmium, molybdenum, gold, platinum and palladium, and the ligands bound to the transition metals are selected from:

[0074] - nitrogenous bases such as tertiary amines chosen from 4-dimethylaminopyridine (DMAP), 1,4-diazabicyclo[2.2.2]octane (DABCO), N-diisopropylethylamine (DIPEA or DIEA), bipyridyl (bipy), terpyridine (terpy); phenanthroline (phen), ethylenediamine, N,N,N',N'-tetramethylethylenediamine (TMEDA), quinoline and pyridine;

[0075] - phosphorus bases such as alkyl and aryl phosphines selected from triphenylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), triisopropylphosphine, tris[2-diphenylphosphino)ethyl]phosphine (PP3), 4,5-bis-(di-i-propylphosphinomethyl) acridine, 4,5-bis-(di-phenylphosphinomethyl) acridine, tricyclohexylphosphine, 1,2-bis-diphenylphosphinoethane (dppe), 1,2-bis(diphenylphosphino)ethane (dppb); RPOCOP = (C6H4){1,3-OPR2}2) where R is an aryl group having 6 to 20 carbon atoms such as phenyl or an alkyl group having 1 to 12 carbon atoms such as tert-butyl and isopropyl, in particular, 1,3-bis[(di-tert-butylphosphino)oxy]benzene ((tBu)2P-O-C6H4-OP(tBu)2); R’ PNP = R'2PCH2CH2N(H)CH2CH2PR'2where R' is an aryl group having 6 to 20 carbon atoms such as phenyl or an alkyl group having 1 to 12 carbon atoms such as tert-butyl and isopropyl, in particular, bis[2-diphenylphosphino)ethyl]amine {((C6H5)2P-CH2-CH2)2NH} and bis[2-di-isopropylphosphino)ethyl]amine {((CH3)2CH)2P-CH2-CH2)2NH};

[0076] - oxygenated bases such as acetate (CH3COO - ), acetylacetonate ([CH3COCHCOCH3] − ), methanolate (CH3-O − ), ethanolate (CH3-CH2-O − ) ;

[0077] - carbon ligands chosen from CO, CN - ;

[0078] - halogens chosen from Cl - , Br - , I - ;

[0079] - a hydrogen atom;

[0080] - N-heterocyclic carbenes derived from an imidazolium salt chosen from the salts of 1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-3-ium, 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydro-1H-imidazol-3-ium, 1,3-bis(2,4,6-trimethylphenyl)-1H-imidazol-3-ium, 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydro-1H-imidazol-3-ium, 4,5-dichloro-1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-3-ium, 1,3-di-tert-butyl-1H-imidazol-3-ium, 1,3-di-tert-butyl-4,5-dihydro-1H-imidazol-3-ium,

[0081] or a mixture of these ligands,

[0082] the metal complex optionally comprising a counter anion chosen from PF6 - , BF4 - , CF3SO3 - ouOTf -,a boron compound having at least 3 substituents selected from a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogen selected from Cl - , Br - , I - , or a mixture of these substituents, said alkyl, cycloalkyl and aryl groups being optionally substituted,

[0083] the complex composed of boron optionally comprising a counter cation chosen from Li + , N / A + , K + orMg 2+ ,,a heterocyclic boron compound such as 9-borabicyclo[3.3.1]nonane or 9-BBN or a substituted derivative thereof such as 9-chloro-borabicyclo[3.3.1]nonane or Cl-9-BBN, 9-iodo-borabicyclo[3.3.1]nonane or I-9-BBN, 9-triflate-borabicyclo[3.3.1]nonane or TfO-9-BBN, ,a (pseudo-)haloborane of formula (II) as defined above; and

[0084] (B) a nitrogenous or phosphorous base having a pKa of between 5 and 50 in DMSO or in acetonitrile chosen from

[0085] . a tertiary amine comprising an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, in particular triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe),

[0086] . a phosphazene, in particular latert-butylimino-tri(pyrrolidino) phosphorane or BTPP,

[0087] . a proazaphosphatrane base, including 2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, 2,8,9-triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, 2,8,9-Trimethyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane; and

[0088] (C) in a solvent or a mixture of at least two solvents chosen from: ethers chosen from diethyl ether, THF, dioxane, anisole, and diglyme, tertiary amines chosen from triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe), hydrocarbons and aromatics chosen from benzene, toluene, xylene, pentane, hexane, cyclohexane, pyridine-based solvents chosen from lutidine, or 2,6-di-tertbutylpyridine, alkyl halides chosen from chloroform and methylene chloride, aryl halides chosen from chlorobenzene and dichlorobenzene;

[0089] (D) under hydrogen pressure between 0.1 bar and 300 bar.

[0090] The hydrogenolysis of the BX function is based on two distinct steps. 1) The catalyst / base pair must allow the cleavage of the HH bond of the hydrogen according to an FLP mechanism (frustrated Lewis pairs). 2) The intermediately formed catalytic species [catalystH] - , must have sufficient hydric character to transfer a hydride onto the (pseudo-)haloborane substrate. The process of the invention is based on the judicious and non-obvious selection of the elements of the catalyst / base pair in order to allow each of these steps without inhibiting the reactivity of the other. Too strong or too weak Lewis acid and base characters have the effect of inhibiting the reaction by non-activation of the hydrogen. Similarly, too strong a Lewis acid character will not allow the transfer of the hydride during the second step.

[0091] Thermodynamics shows that this hydrogenolysis reaction of (pseudo-)haloborane to hydroborane is unfavorable. The Gaussian DFT (density functional theory) calculation of the transformation of Cy2BCl to Cy2BH in the presence of triethylamine and hydrogen shows a positive free enthalpy of + 10.3 kcal / mol.

[0092] The synthesis of (pseudo-)haloborane (BX) derivative is reported by addition of the corresponding acid (XH) to hydroborane (BH) with evolution of hydrogen (HC Brownet al.,Journal of Organometallic Chemistry,1979,168(3), 281–293; HC Brownet al.,J. Org. Chem.,1993,58(1), 147–153) The process of the invention, which is the reverse reaction to that reported in the literature, then appears counterintuitive for a person skilled in the art.

[0093] The present invention makes it possible to produce hydroboranes from (pseudo-)haloboranes under milder conditions than those reported in the literature, i.e. with a lower energy input (thermal and chemical), greater selectivity towards the products formed, while reducing the danger of the reagents used.

[0094] For the purposes of the invention, “borane” means a boron-based molecule having BH and / or BC bonds.

[0095] For the purposes of the invention, the term “hydroborane” designates boranes specifically having one or more BH bonds.

[0096] For the purposes of the invention, the term “haloborane” designates boranes specifically having one or more B-halogen bonds, the halogen being F - , Cl - , Br - Yes - .

[0097] For the purposes of the invention, the term "pseudo-haloborane" designates boranes linked to one or more groups which are not halogens but which behave like halogens, such as, for example, the group -OSO2CF3 - or -OTf - .

[0098] In the context of the present invention, the term "alkyl" is understood to mean, within the meaning of the present invention, a linear, branched and saturated carbon radical, optionally substituted, comprising 1 to 12 carbon atoms. In certain cases, the alkyl may comprise, for example, 1 to 10 carbon atoms, for example 1 to 8 carbon atoms, for example 1 to 6 carbon atoms. As saturated, linear or branched alkyl, mention may be made, for example, of the methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl, undecyl, dodecanyl radicals and their branched isomers.

[0099] For the purposes of the present invention, the term "cycloalkyl" means a mono- or polycyclic, saturated, optionally substituted carbon radical comprising 3 to 12 carbon atoms. In certain cases, the alkyl may comprise, for example, 3 to 10 carbon atoms, for example 5 to 10 carbon atoms. Cyclic alkyl radicals that may be mentioned include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3,3,1]nonane, adamantyl and isopinocampheyl radicals.

[0100] The alkyl and cycloalkyl groups may be optionally substituted by one or more alkoxy groups; one or more aryloxy groups; one or more halogens chosen from fluorine, chlorine, bromine or iodine atoms; one or more nitro groups (-NO2); one or more nitrile groups (-CN); one or more aryl groups; one or more trifluoromethyl groups (-CF3); with the alkoxy and aryl groups as defined within the scope of the present invention.

[0101] The term "aryl" denotes a mono- or polycyclic aromatic substituent comprising from 6 to 20 carbon atoms. The aryl group may comprise, for example, 6 to 10 carbon atoms, for example 6 to 8 carbon atoms. The aryl group may comprise, for example, 6 carbon atoms. In the context of the invention, the aryl group may be mono- or polycyclic. By way of example, mention may be made of phenyl, benzyl, naphthyl, o-tolyl, m-tolyl, p-tolyl, mesityl, p-nitrophenyl, o-methoxyphenyl, m-methoxyphenyl and p-methoxyphenyl, o-methoxybenzyl, p-methoxybenzyl, m-methoxybenzyl, o-methylbenzyl, p-methylbenzyl and m-methylbenzyl.The aryl group may be optionally substituted by one or more alkoxy groups; one or more aryloxy groups; one or more halogens selected from fluorine, chlorine, bromine and iodine atoms; one or more nitro groups (-NO2); one or more nitrile groups (-CN); one or more trifluoromethyl groups (-CF3); one or more alkyl groups, with the alkoxy and alkyl groups as defined within the scope of the present invention.

[0102] The term "alkoxy" means an alkyl group, as defined above, linked through an oxygen atom (-O-alkyl).

[0103] The term "cycloalkoxy" means a cycloalkyl group, as defined above, linked through an oxygen atom (-O-cycloalkyl).

[0104] The term "aryloxy" means an aryl group, as defined above, linked through an oxygen atom (-O-aryl).

[0105] By "halogen" is meant a substituent chosen from fluorine, chlorine, bromine and iodine atoms or in the form of an anion (also called halide) chosen from F - , Cl - , Br - and I - .

[0106] The term "heterocycle" or "heterocyclic" means a mono- or polycyclic group or substituent, comprising from 5 to 12 members, for example 5 to 10 members, saturated or unsaturated, and containing from 1 to 3 identical or different heteroatoms, chosen from nitrogen, oxygen and / or boron. For example, catecholboranyl or CatB-, 9-borabicyclo[3.3.1]nonanyl or 9-BBN, pinacolboranyl or -Bpin may be mentioned.

[0107] The heterocycles may be optionally substituted by one or more alkoxy groups (-O-alkyl); one or more aryloxy groups (-O-aryl); one or more halogens selected from fluorine, chlorine, bromine and iodine; one or more nitro groups (-NO2); one or more nitrile groups (-CN); one or more trifluoromethyl groups (-CF3); one or more alkyl groups or radicals; one or more aryl groups or radicals; with alkyl, and aryl as defined within the scope of the present invention.

[0108] For the purposes of the invention, the term "catalyst" means any compound capable of causing a reaction by its mere presence or intervention. It can also modify, in particular by increasing, the speed of the chemical reaction in which it participates. The catalyst is regenerated at the end of the reaction and does not appear in the overall balance of the reaction. This definition includes catalysts, i.e. compounds which exert their catalytic activity without needing to undergo any modification or conversion, and compounds (also called pre-catalysts) which are introduced into the reaction medium and which are converted there into a catalyst.

[0109] By "yield" we mean the ratio between the quantity of product obtained and the maximum quantity that would be obtained if the reaction were complete.

[0110] It should be noted that in all the compounds, substituents, radicals, groups and groups, solvents, reagents, etc. cited and / or defined in the context of the present invention, one or more hydrogen atoms may be, optionally, replaced by one or more deuterium ( 2 H).

[0111] Examples of deuterated solvents include THF-d8, benzene-d6, toluene-d8, cyclohexane-d12, methylene chloride-d2, chlorobenzene-d5, CDCl3. This list is not exhaustive.

[0112] According to a first embodiment, in the process of the invention, R1 and R2, identical or different, may represent a hydrogen atom, an alkyl group comprising 1 to 12 carbon atoms, a cycloalkyl group comprising 3 to 12 carbon atoms, an aryl group comprising from 6 to 20 carbon atoms, said alkyl, cycloalkyl and aryl groups being optionally substituted.

[0113] Preferably, in this embodiment, R1 and R2, identical or different, represent a hydrogen atom, an alkyl group comprising 1 to 10 carbon atoms, a cycloalkyl comprising 5 to 10 carbon atoms, an aryl group comprising from 6 to 10 carbon atoms, said alkyl, cycloalkyl and aryl groups being optionally substituted.

[0114] More preferably, R1 and R2, identical or different, are a hydrogen atom, cyclohexyl, bicyclo[2,1,1] hexyl, bicyclo[2,2,1] heptyl, bicyclo[3.3.1]nonane, isopinocampheyl, phenyl, benzyl, naphthyl, o-tolyl, m-tolyl, p-tolyl.

[0115] According to a second embodiment, in the process of the invention, R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 12 members, said heterocycle group being optionally substituted.

[0116] Preferably, in this embodiment, R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle having 5 to 10 members, the heterocycle being optionally substituted.

[0117] More preferably, R1 and R2 taken together with the boron atom to which they are bonded, form a catecholboranyl or CatB-, 9-borabicyclo[3.3.1] nonanyl or 9-BBN, pinacolboranyl or -Bpin.

[0118] In all embodiments and variations of the invention, X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group.

[0119] In all embodiments and variations of the invention,

[0120] - n is 1, 2, 3;

[0121] - m is 0, 1;

[0122] - o is 0, 1.

[0123] According to a third embodiment, the catalyst (A) is chosen from a metal complex whose metal is a transition metal chosen from manganese, iron, cobalt, iridium, rhodium, rhenium, and ruthenium, and the ligands linked to the transition metals are chosen from:

[0124] - nitrogenous bases such as 4-dimethylaminopyridine (DMAP), 1,4-diazabicyclo[2.2.2]octane (DABCO), bipyridyl (bipy), terpyridine (terpy); phenanthroline (phen), ethylenediamine, N,N,N',N'-tetramethylethylenediamine (TMEDA), quinoline and pyridine,

[0125] - phosphorus bases such as alkyl and aryl phosphines selected from triphenylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), triisopropylphosphine, tris[2-diphenylphosphino)ethyl]phosphine (PP3), tricyclohexylphosphine, 4,5-bis-(di-i-propylphosphinomethyl)acridine, 4,5-bis(diphenylphosphino)acridine, 1,2-bis-diphenylphosphinoethane (dppe), 1,2-bis(diphenylphosphino)ethane (dppb); t Bu POCOP = (C6H3){1,3-OPtBu2}2), Ph PNP = Ph2PCH2CH2N(H)CH2CH2PPh 2, iPr PNP = iPr2PCH2CH2N(H)CH2CH2PiPr2,

[0126] - carbon ligands chosen from CO, CN - ,

[0127] - halogens chosen from Cl - , Br - , I - ,

[0128] - a hydrogen atom,

[0129] or a mixture of these ligands.

[0130] According to a preferred variant of this embodiment, the catalyst (A) is chosen from a metal complex whose metal is iridium or ruthenium, and the ligands linked to the transition metals are chosen from:

[0131] - phosphorus bases such as, t Bu POCOP = (C6H3){1,3-OPtBu2}2); 4,5-bis-(di-i-propylphosphinomethyl)acridine, 4,5-bis(diphenylphosphino)acridine,

[0132] - carbon ligands such as CO,

[0133] - halogens chosen from Cl - , Br - , I - ,

[0134] - a hydrogen atom,

[0135] or a mixture of these ligands.

[0136] According to an even more preferred variant of this embodiment, the catalyst (A) ruthenium chlorocarbonylhydrido[4,5-bis-(di-iso-propyl phosphinomethyl)acridine], [Ir( t Bu POCOP)HCl].

[0137] According to a fourth embodiment, the catalyst (A) is a boron compound comprising at least 3 substituents, chosen from a hydrogen atom, an alkyl group comprising 1 to 12 carbon atoms, a cycloalkyl group comprising 3 to 12 carbon atoms, an aryl group comprising from 6 to 20 carbon atoms, a halogen chosen from Cl - , Br - , I - , or a mixture of these substituents, said alkyl, cycloalkyl and aryl groups being optionally substituted.

[0138] According to a variant of this embodiment, the catalyst (A) is a boron compound comprising 4 substituents, one being a hydrogen atom while the other 3 substituents are chosen from

[0139] - a hydrogen atom,

[0140] - an alkyl group containing 1 to 12 carbon atoms, in particular ethyl, propyl, isopropyl, butyl and isobutyl,

[0141] - a cycloalkyl group containing 5 to 10 carbon atoms, in particular cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3.3.1]nonane, isopinocampheyl,

[0142] - an aryl group containing 6 to 20 carbon atoms, in particular phenyl (-Ph) and pentafluorophenyl (-C6F5),

[0143] ; - a halogen chosen from Cl - , Br - , I - , or a mixture of these substituents. In this variant the catalyst comprises a counter cation chosen from Li + , N / A + , K + .

[0144] According to an even more preferred variant of this embodiment, the catalyst (A) is potassium triethylborohydride or KEt3BH.

[0145] According to another variant of this embodiment, the catalyst (A) is a boron compound comprising 3 substituents chosen from

[0146] - a hydrogen atom,

[0147] - an alkyl group containing 1 to 12 carbon atoms, in particular ethyl, propyl, isopropyl, butyl and isobutyl,

[0148] - a cycloalkyl group containing 5 to 10 carbon atoms, in particular cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3.3.1]nonane, isopinocampheyl,

[0149] - an aryl group containing 6 to 20 carbon atoms, in particular phenyl (Ph) and pentafluorophenyl (-C6F5) ,

[0150] - a halogen chosen from Cl - , Br - , I - ,

[0151] or a mixture of these substituents.

[0152] According to a preferred variant of this other variant of this embodiment, the catalyst (A) is dicyclohexylborane or Cy2BH, chlorodicyclohexylborane or Cy2BCl, bis(bicyclo[2,2,1]-2-heptyl)chloroborane, chloro-diisopinocampheylborane or Cl-DIP, triphenylborane or BPh3.

[0153] According to a more preferred variant of this other variant of this embodiment, the catalyst (A) is dicyclohexylborane or Cy2BH.

[0154] According to another more preferred variant of this other variant of this embodiment, the catalyst (A) is triphenylborane or BPh3.

[0155] According to a fifth embodiment, the catalyst (A) is a borane of formula (I) in which

[0156] - R1 and R2, identical or different, represent an alkyl group comprising 1 to 12 carbon atoms, a cycloalkyl group comprising 3 to 12 carbon atoms, said alkyl, cycloalkyl groups being optionally substituted;

[0157] - n is 1, 2, 3;

[0158] - m is 0, 1;

[0159] - o is 0, 1.

[0160] According to a preferred variant of this embodiment, the catalyst (A) is a borane of formula (I) in which

[0161] - R1 and R2, identical or different, are a cycloalkyl group comprising 5 to 10 carbon atoms, in particular cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3.3.1]nonane, isopinocampheyl, said cycloalkyl group being optionally substituted;

[0162] - n is 1, 2, 3;

[0163] - m is 0, 1;

[0164] - o is 0, 1.

[0165] According to an even more preferred variant of this embodiment, the catalyst (A) is dicyclohexylborane or Cy2BH.

[0166] According to a sixth embodiment, the catalyst (A) is a (pseudo-) haloborane of formula (II) in which

[0167] - R1 and R2, identical or different, represent an alkyl group comprising 1 to 12 carbon atoms, a cycloalkyl group comprising 3 to 12 carbon atoms, said alkyl, cycloalkyl groups being optionally substituted;

[0168] - n is 1, 2, 3;

[0169] - m is 0, 1;

[0170] - o is 0, 1;

[0171] - X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group.

[0172] According to a preferred variant of this embodiment, the catalyst (A) is a (pseudo-)haloborane of formula (II) in which

[0173] - R1 and R2, identical or different, are a cycloalkyl group comprising 5 to 10 carbon atoms, in particular cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3.3.1]nonane, isopinocampheyl, said cycloalkyl group being optionally substituted;

[0174] - n is 1, 2, 3;

[0175] - m is 0, 1;

[0176] - o is 0, 1;

[0177] - X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group.

[0178] According to an even more preferred variant of this embodiment, the catalyst (A) is chlorodicyclohexylborane or Cy2BCl, dicyclohexylborane triflate, chloro-diisopinocampheylborane or Cl-DIP, bis(bicyclo[2,2,1]-2-heptyl)chloroborane.

[0179] According to a seventh embodiment, the catalyst (A) is a borane of formula (I) in which

[0180] - R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 12 members, said heterocycle group being optionally substituted;

[0181] - n is 1, 2, 3;

[0182] - m is 0, 1;

[0183] - o is 0, 1.

[0184] According to a preferred variant of this embodiment, the catalyst (A) is a borane of formula (I) in which

[0185] - R1 and R2 taken together with the boron atom to which they are linked, form a heterocycle comprising 5 to 10 members, in particular 9-borabicyclo[3.3.1]nonanyl or 9-BBN, said heterocycle group being optionally substituted;

[0186] - n is 1, 2, 3;

[0187] - m is 0, 1;

[0188] - o is 0, 1.

[0189] According to an even more preferred variant of this embodiment, the catalyst (A) is 9-borabicyclo[3.3.1]nonane or 9-BBN.

[0190] According to an eighth embodiment, the catalyst (A) is a (pseudo-) haloborane of formula (II) in which

[0191] - R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 12 members, said heterocycle group being optionally substituted;

[0192] - n is 1, 2, 3;

[0193] - m is 0, 1;

[0194] - o is 0, 1;

[0195] - X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group.

[0196] According to a preferred variant of this embodiment, the catalyst (A) is a (pseudo-)haloborane of formula (II) in which

[0197] - R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 10 members, in particular catecholboranyl or CatB-, 9-borabicyclo[3.3.1]nonanyl or 9-BBN, pinacolboranyl or -Bpin, said heterocycle group being optionally substituted;

[0198] - n is 1, 2, 3;

[0199] - m is 0, 1;

[0200] - o is 0, 1;

[0201] - X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group.

[0202] According to an even more preferred variant of this embodiment, the catalyst (A) is 9-borabicyclo[3.3.1]nonane or 9-BBN, 9-chloro-borabicyclo[3.3.1]nonane or Cl-9-BBN, 9-triflate-borabicyclo[3.3.1]nonane or TfO-9-BBN.

[0203] In all embodiments and variants of the invention, the amount of catalyst used in the process of the invention is from 0.1 to 100 mol%, preferably from 0.1 to 10 mol%, more preferably from 2 to 10 mol%, relative to the (pseudo-)haloborane of formula (II).

[0204] According to a ninth embodiment, the base (B) is a nitrogenous or phosphorous base having a pKa of between 5 and 50 in DMSO or in acetonitrile chosen from

[0205] . a tertiary amine comprising an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, in particular triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe),

[0206] . a phosphazene, in particular latert-butylimino-tri(pyrrolidino)phosphorane or BTPP,

[0207] . a proazaphosphatrane base, in particular 2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, 2,8,9-triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane.

[0208] According to a preferred variant of this embodiment, the base (B) is a tertiary amine comprising an alkyl group comprising 1 to 8 carbon atoms, a cycloalkyl group comprising 5 to 10 carbon atoms, an aryl group comprising 6 to 10 carbon atoms, in particular triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe).

[0209] In all embodiments and variants of the invention, the amount of base used in the process of the invention is from 1 to 30 equivalents, preferably from 1 to 20 equivalents, more preferably from 1 to 2 equivalents, relative to the number of BX bonds to be hydrogenolyzed. The base can also be used in excess, in particular when it is used as a solvent for the reaction.

[0210] The preparation of a hydroborane of formula (I) from a (pseudo-) haloborane of formula (II) takes place in a solvent or a mixture of at least two solvent(s)(C), preferably chosen from: ethers chosen from diethyl ether, THF, dioxane, anisole, and diglyme, amines chosen from triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe), pyridine-based solvents such as lutidine, hydrocarbons and aromatics chosen from benzene, toluene, xylene, pentane, hexane, cyclohexane, alkyl halides chosen from chloroform and methylene chloride, aryl halides chosen from chlorobenzene and dichlorobenzene.

[0211] In solution, the concentration of (pseudo-)haloborane of formula (II) is between 0.01 and 10M, preferably 0.05 and 5M, more preferably 0.1M and 1M.

[0212] Preferably, the preparation of a hydroborane of formula (I) from a (pseudo-)haloborane of formula (II) takes place (D) at a hydrogen pressure of between 1 and 50, 1 bar and 15 bar. According to a preferred variant of the invention, the hydrogen pressure is 10 bar.

[0213] The temperature for preparing a hydroborane of formula (I) from a (pseudo-) haloborane of formula (II) and dihydrogen H2 according to the process of the invention is between -78°C and 150°C, preferably between 0 and 30°C. According to a preferred variant of the invention, the temperature is 25°C.

[0214] The reaction time depends on the conversion rate of the (pseudo-) haloborane of formula (II) to the hydroborane of formula (I). The reaction is advantageously continued until the (pseudo-) haloborane is completely converted. The reaction time can thus be from 1 to 300 hours, preferably from 5 to 270 hours.

[0215] Another object of the invention is the use of the method of the invention

[0216] - in organic synthesis, for example, for the reduction of carbonyl function or for the preparation of boronic ester by borylation reaction

[0217] - in inorganic synthesis, for example, in the production of industrial molecules such as methanol, formic acid, ammonia, etc.,

[0218] - for the depolymerization of lignin, and

[0219] - for the depolymerization of oxygenated polymers such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), polycarbonate (PC-BPA), etc.

[0220] The application of the method of the invention is integrated into processes for recycling (pseudo-)haloboranes resulting from the use of the corresponding hydroboranes. Thus, the present invention also relates to the use of the method of the invention for recycling (pseudo-)haloboranes resulting from the corresponding hydroboranes. EXAMPLES General operating procedure

[0221] All reactions are carried out under a strict atmosphere of ultrapure argon (< 5 ppm of oxygen or water), using Schlenk-type glassware and associated vacuum manifold techniques, or a MBraun LabMaster DP glove box. The glassware is dried for at least 2 hours at 60°C for NMR tubes and 120°C for the rest, or flame-dried just before use. The various products used were purchased from Sigma Aldrich with the exception of deuterated solvents purchased from Eurisotop, dicyclohexylmethylamine purchased from Fischer, ruthenium chlorocarbonylhydrido[4,5-bis-(di-i-propylphosphino methyl)acridine] purchased from STREM, B-Cl-9-BBN synthesized in the laboratory from 9-BBN and HCl in diethyl ether according to the literature (Brown, HC et al., J. Organomet. Chem., 1979, 168 (3), 281–293), [Ir( t BuPOCOP)HCl] synthesized in the laboratory according to the literature (M. Brookhart et al., Journal of American Chemical Society, 2004, 126 (6), 1804–1811). The solvents are dried by standard methods, and are distilled immediately before use or stored on a 4 Å molecular sieve. Said molecular sieve is dried under vacuum at 150 °C for 24 hours before use. All reagents are, if necessary, dried or degassed before use. The dihydrogen is used from a Hydrogen Premium Plus bottle (< 1 ppm of dioxygen or water) from the company Air Products.

[0222] Most of the reactions in this project were carried out in New Era NMR tubes (maximum 20 bar). After the reagents and solvents were introduced into these tubes in the glove box, the reactions required a hydrogen atmosphere. The tubes were then degassed (to remove all the argon) by three freeze / vacuum cycles. At room temperature, the gas was introduced and the reaction was rotated on a tube turner made in the laboratory, or placed in an oil bath, or dedicated heating block, if the reaction was carried out at a higher temperature.

[0223] Small volume autoclaves (4mL max of reaction medium) allow working on a larger scale than in NMR tubes. The reactors are made of stainless steel (SS316). The structure is composed of 2 parts: a connection part (the head), made of commercial components purchased from Swagelok France; and another part, the reactor itself, manufactured by our laboratory.

[0224] A large part of the experiments that must be carried out under an inert atmosphere are carried out using a "simple" vacuum ramp. This ramp is only used in the presence of a good or even excellent vacuum (8x10 -1 mbar max, 2x10 -1 mbar min), in the absence of leaks (good vacuum resistance in static mode for 1 hour).

[0225] NMR spectra of the elements 1 H, 11 B, 13 C, 19 F, 29 If and 31 P are acquired via a Bruker AVANCE Neo 400 MHz spectrometer at 25°C.

[0226] In a pressure-resistant reactor conditioned under an inert atmosphere (argon, nitrogen) are added the catalyst (X1mol%), the base (X2equivalents), the solvent and the (pseudo-)haloborane (x mol / L). The reactor atmosphere is removed and replaced with hydrogen at the chosen pressure. The mixture is stirred for a given time at a given temperature.

[0227] The conversion of (pseudo-)haloboranes is monitored by NMR 11 B and the 1 H and can be quantified by titration of the product after reaction with an alkene or alkyne.

[0228] The hydrogenolysis products of (pseudo-)haloboranes can be obtained pure or can be purified, for example by recrystallization from a suitable solvent. The person skilled in the art is able to find the recrystallization conditions. Example 1:

[0229] B-Chlorocatecholborane (0.1 mmol, 1 eq.), chlorodicyclohexylborane (0.01 mmol, 10 mol%), triethylamine (0.21 mmol, 2.1 eq.) and benzene (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is stirred for 11 days at room temperature (20 ± 5°C). A yield of 68% catecholborane, determined by NMR, is obtained. Example 2:

[0230] Dichlorophenylborane (0.1 mmol, 1 eq.), chlorodicyclohexylborane (0.01 mmol, 10 mol%), triethylamine (0.21 mmol, 2.1 eq.) and benzene d6 (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is stirred for 5 days at room temperature (20 ± 5°C). A yield greater than 99% of PhBHCl, determined by NMR, is obtained. Example 3:

[0231] Boron trichloride in toluene solution (1M, 100µL, 0.1 mmol), chlorodicyclohexylborane (0.01 mmol, 10%), triethylamine (0.2 mmol, 2 eq.) and benzene (0.3mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is heated at 120°C for 4 days. A yield greater than 62% of BHCl2, determined by NMR, is obtained. Example 4:

[0232] Dichlorophenyl borane (0.1 mmol, 1 eq.), 9-borabicyclo[3.3.1]nonane (0.01 mmol, 10 mol%), triethylamine (0.3 mmol, 3 eq.) and benzene (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is heated at 80°C for 9 days. Yields of 45% of PhBH2 and 54% of PhBClH, determined by NMR, are obtained as a mixture. Example 5:

[0233] B-chlorocatecholborane (0.1 mmol, 1 eq.), [Ir( tBu POCOP)HCl] (0.002 mmol, 2 mol%), triethylamine (0.2 mmol, 2 eq.) and benzene (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is stirred for 4 days at room temperature (20 ± 5°C). A yield of 24% of catecholborane, determined by NMR, is obtained. Example 6:

[0234] B-Chlorocatecholborane (0.1 mmol, 1 eq.), chlorocarbonylhydrido[4,5-bis-(di-i-propylphosphinomethyl)acridine]ruthenium(II) (0.005 mmol, 5 mol%), triethylamine (0.2 mmol, 2 eq.) and benzene (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is heated at 80°C for 6 days. A 21% yield of catecholborane, determined by NMR, is obtained. Example 7:

[0235] 9-Iodo-9-borabicyclo[3.3.1]nonane in hexane solution (1M, 100µL, 0.1 mmol, 1 eq), [Ir( tBu POCOP)HCl] (0.01 mmol, 10 mol%), dicyclohexylmethylamine (0.2 mmol, 2 eq.) and benzene (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is heated at 80°C for 4 days. The excess hydrogen is removed and the 9-borabicyclo[3.3.1]nonane formed is titrated by reaction with 4-octyne (0.2 mmol). A yield of 48% is obtained. Example 8:

[0236] Chlorodicyclohexylborane (0.1 mmol, 1 eq.), triethylamine (0.11 mmol, 1.1 eq.) and benzene (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is stirred for 18 h at room temperature (20 ± 5°C). The excess hydrogen is removed and the dicyclohexylborane formed is titrated by reaction with 4-octyne (0.2 mmol). A yield of 83% is obtained. Example 9:

[0237] Chlorodicyclohexylborane (0.1 mmol, 1 eq.), dicyclohexylmethylamine (0.11 mmol, 1.1 eq.) and dichloromethane (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is stirred for 18 h. The excess hydrogen is removed and the dicyclohexylborane formed is titrated by reaction with 4-octyne (0.2 mmol). A yield of 57% is obtained. Example 10:

[0238] Chlorodicyclohexylborane (0.1 mmol, 1 eq.), tert-butylimino-tri(pyrrolidino)phosphorane (0.11 mmol, 1.1 eq.) and dichloromethane (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is stirred for 18 h at room temperature (20 ± 5°C). The excess hydrogen is removed and the dicyclohexylborane formed is titrated by reaction with 4-octyne (0.2 mmol). A yield of 41% is obtained. Example 11:

[0239] 9-Borabicyclo[3.3.1]nonyl trifluoromethanesulfonate in hexane solution (0.5M, 200µL, 0.1 mmol, 1 eq.), triethylamine (0.11 mmol, 1.1 eq.) and benzene (0.3 mL) are introduced into a New Era NMR tube under an inert atmosphere. The inert atmosphere is removed and the tube is charged with hydrogen (10 bar). The mixture is stirred for 46h at room temperature (20 ± 5°C). The excess hydrogen is removed and the dicyclohexylborane formed is titrated by reaction with 4-octyne (0.2 mmol). A yield of 67% is obtained. Example 12:

[0240] A solution of the adduct 9-chloro-9-borabicyclo[3.3.1]nonane - diethyl ether (1 mmol, 1 eq.), triethylamine (1.1 mmol, 1.1 eq.) in anisole (2 mL) are introduced under a hydrogen atmosphere into a conditioned autoclave. The autoclave is pressurized under hydrogen (15 bar). The mixture is stirred for 24 h at room temperature (20 ± 5 °C). The reactor is degassed and the reaction mixture is recovered under an inert atmosphere. The by-products are precipitated by the addition of THF and the suspension is filtered through Celite. The solvents are removed under reduced pressure. An isolated yield of 84% of 9-borabicyclo[3.3.1]nonane dimer is obtained.

[0241] The results are shown in the following table:

[0242]

[0243]

[0244] Some abbreviations used in the context of the present invention are indicated below:

[0245] BTPP: tert-butylimino-tri(pyrrolidino)phosphorane

[0246] CatBCl: chloro catecolborane

[0247] BBN: borabicyclo[3.3.1]nonane

[0248] DIP: diisopinocampheylborane

[0249] DIPEA:N,N-diisopropylethylamine

[0250] TBD: 1,5,7-triazabicyclo[4.4.0]dec-5-ene

Claims

Process for the preparation of a hydroborane of formula (I)(R1) o (R2) m BH n from dihydrogen H2 and a (pseudo-)haloborane of formula (II)(R1) o (R2) m BX nin which- R1 and R2, which may be identical or different, are an alkyl group containing 1 to 12 carbon atoms, a cycloalkyl group containing 3 to 12 carbon atoms, an aryl group containing 6 to 20 carbon atoms, an alkoxy group whose alkyl group contains 1 to 12 carbon atoms, a cycloalkoxy (-O-cycloalkyl) group whose cycloalkyl group contains 3 to 12 carbon atoms, an aryloxy group whose aryl group contains 6 to 20 carbon atoms, a -NR3R4 group, with R3 and R4, which may be identical or different, representing a hydrogen atom, an alkyl group containing 1 to 12 carbon atoms, a cycloalkyl group containing 3 to 12 carbon atoms, an aryl group containing 6 to 20 carbon atoms, said alkyl and cycloalkyl groups being optionally substituted; or- R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 12 members, said heterocycle group being optionally substituted;- n is 1, 2, 3;- m is 0, 1;- o is 0, 1;- X represents Cl; - , Br - , I -, -OSO2R with R being a group -CF3, -CH3or o-tolyl, m-tolyl, p-tolyl;characterized in that the (pseudo-)haloborane of formula (II) is brought into contact with(A)a catalyst chosen froma metal complex whose metal is a transition metal chosen from chromium, tungsten, manganese, rhenium, silver, rhodium, cobalt, iron, nickel, copper, iridium, ruthenium, osmium, molybdenum, gold, platinum and palladium, and the ligands bound to the transition metals are chosen from:- nitrogenous bases such as tertiary amines chosen from 4-dimethylaminopyridine (DMAP), 1,4-diazabicyclo[2.2.2]octane (DABCO), N-diisopropylethylamine (DIPEA or DIEA), bipyridyl (bipy), terpyridine (terpy); phenanthroline (phen), ethylenediamine, N,N,N',N'-tetramethylethylenediamine (TMEDA), quinoline and pyridine;- phosphorus bases such as alkyl and aryl phosphines selected from triphenylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), triisopropylphosphine, tris[2-diphenylphosphino)ethyl]phosphine (PP3), 4,5-bis-(di-i-propylphosphinomethyl) acridine, 4,5-bis-(di-phenylphosphinomethyl) acridine, tricyclohexylphosphine, 1,2-bis-diphenylphosphinoethane (dppe), 1,2-bis(diphenylphosphino)ethane (dppb);. R POCOP = (C6H4){1,3-OPR2}2) where R is an aryl group having 6 to 20 carbon atoms such as phenyl or an alkyl group having 1 to 12 carbon atoms such as tert-butyl and isopropyl, in particular, 1,3-bis[(di-tert-butylphosphino)oxy]benzene ((tBu)2P-O-C6H4-OP(tBu)2); R’PNP = R'2PCH2CH2N(H)CH2CH2PR'2where R' is an aryl group with 6 to 20 carbon atoms such as phenyl or an alkyl group with 1 to 12 carbon atoms such as tert-butyl and isopropyl, in particular, bis[2-diphenylphosphino)ethyl]amine {((C6H5)2P-CH2-CH2)2NH} and bis[2-di-isopropylphosphino)ethyl]amine {((CH3)2CH)2P-CH2-CH2)2NH};- oxygenated bases such as acetate (CH3COO - ), acetylacetonate ([CH3COCHCOCH3] − ), methanolate (CH3-O − ), ethanolate (CH3-CH2-O − ) ;- the carbon ligands chosen from CO, CN - ;- halogens chosen from Cl - , Br - , I - ;- a hydrogen atom ;- N-heterocyclic carbenes derived from an imidazolium salt chosen from the salts of 1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-3-ium, 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydro-1H-imidazol-3-ium, 1,3-bis(2,4,6-trimethylphenyl)-1H-imidazol-3-ium, 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydro-1H-imidazol-3-ium, 4,5-dichloro-1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-3-ium, 1,3-di-tert-butyl-1H-imidazol-3-ium, 1,3-di-tert-butyl-4,5-dihydro-1H-imidazol-3-ium, or a mixture of these ligands, the metal complex optionally comprising a counter anion chosen from PF6 - , BF4 - , CF3SO3 - Or OTf-,un composé de bore comportant au moins 3 substituants choisis parmi un atome d’hydrogène, un groupe alkyle comportant 1 à 12 atomes de carbone, un groupe cycloalkyle comportant 3 à 12 atomes de carbone, un groupe aryle comportant de 6 à 20 atomes de carbone, un halogène choisi parmi Cl-, Br-, I-, ou un mélange de ces substituants, lesdits groupes alkyle, cycloalkyle et aryle étant éventuellement substitués,le complexe composé de bore comportant éventuellement un contre cation choisi parmi Li+, Na+, K+ouMg2+,,un composé hétérocyclique de bore comme le 9-borabicyclo[3.3.1] nonane ou 9-BBN ou un de ses dérivés substitués comme le 9-chloro-borabicyclo[3.3.1]nonane ou Cl-9-BBN, le 9-iodo-borabicyclo[3.3.1]nonane ou I-9-BBN, le 9-triflate-borabicyclo[3.3.1]nonane ou TfO-9-BBN, ,un (pseudo-)haloborane de formule (II) tel que défini ci-dessus ; et(B)une base azotée ou phosphorée présentant un pKa compris entre 5 et 50 dans le DMSO ou dans l’acétonitrile choisie parmi. une amine tertiaire comprenant un groupe alkyle comportant 1 à 12 atomes de carbone, un groupe cycloalkyle comportant 3 à 12 atomes de carbone, un groupe aryle comportant de 6 à 20 atomes de carbone, notamment la triéthylamine (NEt3), la N,N-diisopropyléthylamine (DIPEA) et la N,N-dicyclohexylméthylamine (Cy2NMe),. un phosphazène notamment latert-butylimino-tri(pyrrolidino) phosphorane ou BTPP,. une base de type proazaphosphatrane, notamment la 2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, la 2,8,9-triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, 2,8,9-trimethyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane ; et(C)dans un solvant ou un mélange d’au moins deux solvant(s) choisi(s) parmi :les éthers choisis parmi l’éther diéthylique, le THF, le dioxane, l’anisole, et le diglyme,les amines tertiaires choisies parmi triéthylamine (NEt3), la N,N-diisopropyléthylamine (DIPEA) et la N,N-dicyclohexylméthylamine (Cy2NMe),les hydrocarbures et aromatiques choisis parmi le benzène, le toluène, le xylène, le pentane, l’hexane, le cyclohexane,les solvants à base pyridine choisis parmi la lutidine, ou encore la 2,6-di-tert-butylpyridine,les halogénures d’alkyle choisis parmi le chloroforme et le chlorure de méthylène,les halogénures d’aryles choisis parmi le chlorobenzène et le dichlorobenzène ;(D)sous pression d’hydrogène comprise entre 0,1 bar et 300 bar. Process according to claim 1, characterized in that R1 and R2, identical or different, represent an alkyl group comprising 1 to 12 carbon atoms, a cycloalkyl group comprising 3 to 12 carbon atoms, an aryl group comprising from 6 to 20 carbon atoms, said alkyl, cycloalkyl and aryl groups being optionally substituted. Process according to one of claims 1 or 2, characterized in that R1 and R2, identical or different, are cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3.3.1]nonane, isopinocampheyl, phenyl, benzyl, naphthyl, o-tolyl, m-tolyl, p-tolyl. Process according to claim 1, characterized in that R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 10 members, said heterocycle group being optionally substituted. Process according to one of claims 1 or 4, characterized in that R1 and R2 taken together with the boron atom to which they are bonded, form a catecholboranyl or CatB-, 9-borabicyclo[3.3.1] nonanyl or 9-BBN, pinacolboranyl or -Bpin. Process according to any one of claims 1 to 5, characterized in that the catalyst (A) is chosen from a metal complex whose metal is iridium or ruthenium, and the ligands linked to the transition metals are chosen from:- phosphorus bases such as, t Bu POCOP = (C6H3){1,3-OPtBu2}2); 4,5-bis-(di-i-propylphosphinomethyl)acridine,- carbon ligands such as CO,- halogens selected from Cl - , Br - , I - ,- a hydrogen atom, or a mixture of these ligands. Process according to any one of claims 1 to 6, characterized in that the catalyst (A) is ruthenium chlorocarbonylhydrido[4,5-bis-(di-iso-propyl phosphinomethyl)acridine], [Ir( t Bu POCOP)HCl]. Process according to any one of claims 1 to 7, characterized in that the catalyst (A) is 9-borabicyclo[3.3.1]nonane or 9-BBN or one of its substituted derivatives such as 9-chloro-borabicyclo[3.3.1]nonane or Cl-9-BBN, 9-triflate-borabicyclo[3.3.1]nonane or TfO-9-BBN. Process according to any one of Claims 1 to 7, characterized in that the catalyst (A) is a boron compound comprising 3 substituents chosen from - a hydrogen atom, - an alkyl group comprising 1 to 12 carbon atoms, in particular ethyl, propyl, isopropyl, butyl and isobutyl, - a cycloalkyl group comprising 5 to 10 carbon atoms, in particular cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3,3,1]nonane, isopinocampheyl, - an aryl group comprising from 6 to 20 carbon atoms, in particular phenyl (Ph) and pentafluorophenyl (-C6F5), - a halogen chosen from Cl - , Br - , I - , or a mixture of these substituents. Process according to claim 9, characterized in that the catalyst (A) is chlorodicyclohexylborane or Cy2BCl, bis(bicyclo[2,2,1]-2-heptyl)chloroborane, chloro-diisopinocampheylborane or Cl-DIP, triphenylborane or BPh3. Process according to claim 9, characterized in that the catalyst (A) is dicyclohexylborane or Cy2BH. Process according to claim 9, characterized in that the catalyst (A) is triphenylborane or BPh3. Process according to any one of Claims 1 to 5, characterized in that the catalyst (A) is a boron compound comprising 4 substituents, one being a hydrogen atom while the other 3 substituents are chosen from: - a hydrogen atom, - an alkyl group comprising 1 to 12 carbon atoms, in particular ethyl, propyl, isopropyl, butyl and isobutyl, - a cycloalkyl group comprising 5 to 10 carbon atoms, in particular cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3,3,1]nonane, isopinocampheyl, - an aryl group comprising 6 to 20 carbon atoms, in particular phenyl (-Ph) and pentafluorophenyl (-C6F5), - a halogen chosen from Cl - , Br - , I -, or a mixture of these substituents, the boron compound comprising a counter cation chosen from Li + , N / A + , K + . Process according to claim 13, characterized in that the catalyst (A) is potassium triethylborohydride or KEt3BH. Process according to any one of Claims 1 to 5, characterized in that the catalyst (A) is a (pseudo-)haloborane of formula (II) in which- R1 and R2, identical or different, represent a cycloalkyl group comprising 5 to 10 carbon atoms, in particular cyclohexyl, bicyclo[2,1,1]hexyl, bicyclo[2,2,1]heptyl, bicyclo[3,3,1]nonane, isopinocampheyl, said cycloalkyl group being optionally substituted;- n is 1, 2, 3;- m is 0, 1;- o is 0, 1;- X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group. Process according to claim 15, characterized in that the catalyst (A) is chlorodicyclohexylborane or Cy2BCl, dicyclohexylborane triflate, chloro-diisopinocampheylborane or Cl-DIP, bis(bicyclo[2,2,1]-2-heptyl)chloroborane. Process according to any one of claims 1 to 5, characterized in that the catalyst (A) is a (pseudo-)haloborane of formula (II) in which- R1 and R2 taken together with the boron atom to which they are bonded, form a heterocycle comprising from 5 to 10 members, in particular, 9-borabicyclo[3.3.1]nonanyl or 9-BBN, said heterocycle group being optionally substituted;- n is 1, 2, 3;- m is 0, 1;- o is 0, 1;- X represents Cl - , Br - , I - , -OSO2R with R being a -CF3, -CH3 or o-tolyl, m-tolyl, p-tolyl group. Process according to claim 17, characterized in that the catalyst (A) is 9-chloro-borabicyclo[3.3.1]nonane or Cl-9-BBN, 9-triflate-borabicyclo[3.3.1]nonane or TfO-9-BBN. Process according to any one of claims 1 to 18, characterized in that the quantity of catalyst used in the process of the invention is from 0.1 to 100 mol%, relative to the (pseudo-)haloborane of formula (II). Process according to any one of Claims 1 to 19, characterized in that the base (B) is a tertiary amine comprising an alkyl group comprising 1 to 8 carbon atoms, a cycloalkyl group comprising 5 to 10 carbon atoms, an aryl group comprising 6 to 10 carbon atoms, in particular triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe). Process according to any one of claims 1 to 20, characterized in that the quantity of base used is from 1 to 30 equivalents, relative to the number of BX bonds to be hydrogenolyzed. Process according to any one of Claims 1 to 21, characterized in that the preparation of a hydroborane of formula (I) from a (pseudo-) haloborane of formula (II) takes place in a solvent or a mixture of at least two solvent(s)(C), chosen from: ethers chosen from diethyl ether, THF, dioxane, anisole, and diglyme, amines chosen from triethylamine (NEt3), N,N-diisopropylethylamine (DIPEA) and N,N-dicyclohexylmethylamine (Cy2NMe), lutidine, hydrocarbons and aromatics chosen from benzene, toluene, xylene, pentane, hexane, cyclohexane, alkyl halides chosen from chloroform and methylene chloride, aryl halides chosen from chlorobenzene and dichlorobenzene. Process according to any one of claims 1 to 22, characterized such that in solution, the concentration of (pseudo-)haloborane of formula (II) is between 0.01M and 10M. Process according to any one of claims 1 to 23, characterized in that the preparation of a hydroborane of formula (I) from dihydrogen H2 and a (pseudo-)haloborane of formula (II) takes place (D) at a hydrogen pressure of between 1 bar and 50 bar. Use of the process of the invention according to any one of claims 1 to 24,- in organic synthesis for the reduction of carbonyl function or for the preparation of boronic ester by borylation reaction,- in inorganic synthesis in the production of industrial molecules such as methanol, formic acid, ammonia,- for the depolymerization of lignin, and- for the depolymerization of oxygenated polymers such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), polycarbonate (PC-BPA). Use of a process according to any one of claims 1 to 24, for the recycling of (pseudo-)haloboranes from the corresponding hydroboranes.

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