Selective hydrogenation

Abstract

The present invention relates to the partial (selective) hydrogenation of carbon-carbon triple bonds, i.e. The hydrogenation of alkynes to olefins, using specific homogeneous catalysts.

Description

[0001] The present invention relates to the use of a specific homogeneous catalyst for the partial (selective) hydrogenation of carbon-carbon triple bonds.

[0002] This catalyst is used for selective hydrogenation, i.e., the hydrogenation of alkynes to alkenes. Thus, if a compound contains both double bonds and triple bonds, only the triple bonds are reduced to double bonds.

[0003] Homogeneous catalysis refers to a reaction in which the catalyst and the reactants are in the same phase, mainly in solution.

[0004] The aim of this study is to improve the selectivity of the selective hydrogenation reaction catalyzed by such catalysts.

[0005] It has been found that transition metal catalysts with a specific bidentate phosphine ligand system have good hydrogenation efficiency under mild reaction conditions.

[0006] According to the present invention, the catalyst for the selective hydrogenation reaction has the following formula (I)

[0007] [M + (L1)(L2) n X(I),

[0008] where

[0009] M is Rh or Ir, and

[0010] L1 is a bidentate phosphine ligand of formula (II)

[0011] (R)2-P-A-P-(R 1 )2(II),

[0012] where

[0013] R is a substituted or unsubstituted cyclohexyl, a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl, and

[0014] R1 is a substituted or unsubstituted cyclohexyl, a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl, and

[0015] A is a bridging group selected from the group consisting of the following groups

[0016] where m is an integer with a value of 1-6; and

[0017]

[0018]

[0019] where z is 0 or 1,

[0020] and

[0021] L2 is a bidentate ligand or a monodentate ligand,

[0022] provided that

[0023] when L2 is a bidentate ligand, n is 1 and L2 is not the bidentate ligand represented by formula (II); when L2 is a monodentate ligand, n is 2 and

[0024] X is an anion;

[0025] and any dashed line in the structural formula represents a bond by which a substituent is attached to the rest of the molecule.

[0026] The catalyst of the present invention is used for the selective catalytic hydrogenation of starting materials, particularly starting materials containing carbon-carbon triple bonds, more particularly alkynol compounds, and more preferably α-alkynol compounds.

[0027] Therefore, a first aspect of the present invention relates to a method (H) for selective hydrogenation, comprising the step of selectively hydrogenating an alkyne to an alkene in the presence of at least one catalyst represented by formula (I),

[0028] [M + (L1)(L2) n X (I)

[0029] where

[0030] M is Rh or Ir, and

[0031] L1 is a bidentate phosphine ligand having the formula (II)

[0032] (R)2-P-A-P-(R 1 )2 (II),

[0033] where

[0034] R is a substituted or unsubstituted cyclohexyl, a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted anthryl, an anisyl, a tert-butyl or an isopropyl, and

[0035] R1 is a substituted or unsubstituted cyclohexyl, a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted anthryl, an anisyl, a tert-butyl or an isopropyl, and

[0036] A is a bridging group selected from the group consisting of

[0037] ---(CH2) m --- where m is an integer with a value of 1-6;

[0038]

[0039] where z is 0 or 1,

[0040] and

[0041] L2 is a bidentate ligand or a monodentate ligand,

[0042] provided that

[0043] when L2 is a bidentate ligand, n is 1, and L2 is not the bidentate ligand represented by formula (II); when L2 is a monodentate ligand, n is 2, and

[0044] X is an anion.

[0045] The catalyst represented by formula (I) is a homogeneous catalyst.

[0046] Therefore, the present invention also relates to a method (H1) for selective hydrogenation, which is the method (H) for selective hydrogenation, in which a starting material containing a carbon-carbon triple bond is selectively hydrogenated.

[0047] Therefore, the present invention also relates to a method (H2) for selective hydrogenation, which is the method (H) or (H1) for selective hydrogenation, in which an alkynol compound is selectively hydrogenated.

[0048] Therefore, the present invention also relates to a method (H2') for selective hydrogenation, which is the method (H) or (H1) for selective hydrogenation, in which an α-alkynol compound is selectively hydrogenated.

[0049] More preferably, the present invention also relates to a method for selective hydrogenation of a compound represented by formula (III)

[0050]

[0051] wherein

[0052] R 2 is a straight-chain or branched C1-C 35 -alkyl; or a straight-chain or branched C2-C 35 -alkenyl, wherein the C chain may be substituted,

[0053] R 3 is H or a straight-chain or branched C1-C4-alkyl, wherein the C chain may be substituted,

[0054] R 4 is H or a cyclic, straight-chain or branched C1-C6-alkyl, wherein the C chain may be substituted; or a C3-C 12 -cyclic aromatic group, which may be substituted,

[0055] R 5is H or OH or OC1-C4-alkyl; or is O(CO)C1-C4-alkyl.

[0056] The product of the selective hydrogenation is a compound of formula (IV)

[0057]

[0058] wherein

[0059] R 2 、R 3 、R 4 and R 5 have the same meanings as defined in formula (III).

[0060] More preferably, the present invention also relates to a method for selective hydrogenation, wherein the compound of formula (III)

[0061]

[0062] wherein

[0063] R 2 is a straight-chain or branched C1-C 30 -alkyl; or is a straight-chain or branched C2-C 30 -alkenyl, wherein the C chain may be substituted,

[0064] R 3 is C1-C2-alkyl,

[0065] R 4 is H or a straight-chain or branched C1-C6-alkyl, wherein the C chain may be substituted,

[0066] R 5 is OH or OC1-C2-alkyl,

[0067] is selectively hydrogenated to a compound of formula (IV)

[0068]

[0069] Even more preferably, the present invention also relates to a method for selective hydrogenation, wherein the compound of formula (III)

[0070]

[0071] wherein

[0072] R 2 is a straight-chain or branched C1-C 20 -alkyl; or is a straight-chain or branched C2-C 20 -alkenyl, wherein the C chain may be substituted,

[0073] R3 is a C1-C2-alkyl group,

[0074] R 4 is H,

[0075] R 5 is OH or O(CO)C1-C2-alkyl,

[0076] is selectively hydrogenated to a compound represented by formula (IV)

[0077]

[0078] The most preferred compounds among the compounds of formula (III) are the compounds represented by the following formulae (IIIa) to (IIId)

[0079]

[0080] Therefore, the present invention also relates to a method of selective hydrogenation (H3), which is the method of selective hydrogenation (H), (H1) or (H2), wherein the compound represented by formula (III)

[0081]

[0082] wherein

[0083] R 2 is a straight-chain or branched C1-C 35 -alkyl group; or a straight-chain or branched C2-C 35 -alkenyl group, wherein the C chain may be substituted,

[0084] R 3 is H; a straight-chain or branched C1-C4-alkyl group, wherein the C chain may be substituted,

[0085] R 4 is H; a cyclic, straight-chain or branched C1-C6-alkyl group, wherein the C chain may be substituted; or a C5–C 12 -cyclic aromatic group, which may be substituted,

[0086] R 5 is H or OH or OC1-C4-alkyl or O(CO)C1-C4-alkyl,

[0087] is selectively hydrogenated to a compound represented by formula (IV)

[0088]

[0089] Therefore, the present invention also relates to a method of selective hydrogenation (H3'), which is the method of selective hydrogenation (H), (H1), (H2) or (H2'), wherein the compound represented by formula (III)

[0090]

[0091] wherein

[0092] R 2 is a straight-chain or branched C1-C 30 -alkyl; or a straight-chain or branched C2-C 30 -alkenyl, wherein the C chain may be substituted,

[0093] R 3 is a C1-C2-alkyl,

[0094] R 4 is H; a cyclic, straight-chain or branched C1-C6-alkyl, wherein the C chain may be substituted,

[0095] R 5 is OH or O(CO)C1-C2-alkyl,

[0096] is selectively hydrogenated to the compound shown in formula (IV)

[0097]

[0098] Therefore, the present invention also relates to a method of selective hydrogenation (H3”), which is the method of selective hydrogenation (H), (H1), (H2) or (H2’), wherein the compound shown in formula (III)

[0099]

[0100] wherein

[0101] R 2 is a straight-chain or branched C1-C20-alkyl; or a straight-chain or branched C2-C20-alkenyl, wherein the C chain may be substituted,

[0102] R 3 is a C1-C2-alkyl,

[0103] R 4 is H,

[0104] R 5 is OH or O(CO)C1-C2-alkyl,

[0105] is selectively hydrogenated to the compound shown in formula (IV)

[0106]

[0107] Accordingly, the present invention also relates to a method of selective hydrogenation (H3”’), which is the method of selective hydrogenation (H), (H1), (H2) or (H2’), wherein the compound represented by formula (IIIa), (IIIb), (IIIc) or (IIId)

[0108]

[0109] is selectively hydrogenated to the corresponding compound represented by formula (IVa), (IVb), (IVc) or (IVd)

[0110]

[0111] As described above, the selective hydrogenation according to the present invention is carried out using a specific catalyst represented by formula (I).

[0112] The preferred catalyst represented by formula (I) is a catalyst wherein M is Rh.

[0113] Accordingly, the present invention also relates to a method of selective hydrogenation (H4), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”) or (H3”’), wherein a catalyst represented by formula (I) is used, wherein M is Rh.

[0114] The preferred catalysts represented by formula (I) are those wherein L1 is a bidentate phosphine ligand selected from the group consisting of ligands represented by the following formulas (IIa) to (IIp)

[0115]

[0116]

[0117] More preferred catalysts represented by formula (I) are those wherein L1 is a bidentate phosphine ligand selected from the group consisting of ligands represented by the following formulas

[0118]

[0119] Accordingly, the present invention also relates to a method of selective hydrogenation (H5), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’) or (H4), wherein a catalyst represented by formula (I) is used, wherein L1 is a bidentate phosphine ligand selected from the group consisting of ligands represented by formulas (IIa) to (IIp)

[0120]

[0121]

[0122] Accordingly, the present invention also relates to a method of selective hydrogenation (H5’), which is the method of hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), or (H4), wherein a catalyst represented by formula (I) is used, wherein

[0123] L1 is a bidentate phosphine ligand selected from the group consisting of the ligands described below

[0124]

[0125]

[0126] Preferred catalysts are those in which L2 is a bidentate ligand selected from the group consisting of cyclohexadiene, cycloheptadiene, 1,5-cyclooctadiene (COD), and norbornadiene (NBD), and n is 1.

[0127] Accordingly, the present invention also relates to a method of selective hydrogenation (H6), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), or (H5’), wherein a catalyst represented by formula (I) is used, wherein L2 is a bidentate ligand selected from the group consisting of cyclohexadiene, cycloheptadiene, 1,5-cyclooctadiene (COD), and norbornadiene (NBD), and n is 1.

[0128] If L2 is a monodentate ligand, then n = 2, i.e., the catalyst represented by formula (I) has two identical monodentate ligands.

[0129] Therefore, more preferred catalysts are those in which L2 is a monodentate ligand selected from the group consisting of R6OH (wherein R6 is a straight-chain or branched C1-C8-alkyl group), cyclooctene, cycloheptene, cyclohexene, norbornene, and ethylene, and n is 2. Particularly preferred is that the carbonyl group is not the monodentate ligand L2.

[0130] Accordingly, the present invention also relates to a method of selective hydrogenation (H7), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), or (H5’), wherein a catalyst represented by formula (I) is used, wherein L2 is a monodentate ligand selected from the group consisting of R6OH (wherein R6 is a straight-chain or branched C1-C8-alkyl group), cyclooctene, cycloheptene, cyclohexene, norbornene, and ethylene, and n is 2.

[0131] Preferred catalysts are those in which X is a halide (such as Cl - , I -, Br - , F - ), BF4 - , PF6 - , tetra[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - , ClO4 - , TfO - or SbF6 - catalyst. TfO - represents trifluoromethanesulfonate.

[0132] A more preferred catalyst is one in which X is BF4 - , PF6 - , tetra[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - , ClO4 - , TfO - or SbF6 - catalyst.

[0133] Accordingly, the present invention also relates to a method of selective hydrogenation (H8), which is the method of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3''), (H3'''), (H4), (H5), (H5'), (H6) or (H7), wherein a catalyst of formula (I) is used, wherein X is selected from the group consisting of halides (such as Cl - , I - , Br - , F - ), BF4 - , PF6 - , tetra[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - , ClO4 - , TfO - and SbF6 - group.

[0134] Accordingly, the present invention also relates to a method of selective hydrogenation (H8'), which is the method of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3''), (H3'''), (H4), (H5), (H5'), (H6) or (H7), wherein a catalyst of formula (I) is used, wherein X is selected from BF4- , PF6 - , tetra[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - , ClO4 - , TfO - and SbF6 - and the group consisting of.

[0135] The catalyst used for hydrogenation in the present invention is manufactured according to the prior art.

[0136] The hydrogenation in the present invention can be carried out without any solvent.

[0137] Accordingly, the present invention also relates to a method of selective hydrogenation (H9), which is a method of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3''), (H3'''), (H4), (H5), (H5'), (H6), (H7), (H8) or (H8'), wherein the hydrogenation is carried out without any solvent.

[0138] The hydrogenation in the present invention can be carried out in the presence of at least one inert solvent.

[0139] The hydrogenation can be carried out in a solvent (or a mixture of solvents). Suitable solvents include alkanes, esters, carbonates, lactones, ethers, amides, hydrocarbons, halogenated hydrocarbons, water, and alcohols. Preferred solvents are water, hexane, CH2Cl2, toluene, ethyl acetate, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-Me-THF), cyclopentyl methyl ether (CPME), methanol, ethanol, and isopropanol. Particularly preferred solvents are methanol, water, and hexane.

[0140] Accordingly, the present invention also relates to a method of selective hydrogenation (H10), which is a method of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3''), (H3'''), (H4), (H5), (H5'), (H6), (H7), (H8) or (H8'), wherein the hydrogenation is carried out in at least one solvent.

[0141] Accordingly, the present invention also relates to a method of selective hydrogenation (H10'), which is a method of selective hydrogenation (H10), wherein the solvent is selected from the group consisting of alkanes, esters, carbonates, lactones, ethers, amides, hydrocarbons, halogenated hydrocarbons, water, and alcohols.

[0142] Accordingly, the present invention also relates to a method of selective hydrogenation (H10”), which is the method of selective hydrogenation (H10), wherein the solvent is selected from the group consisting of water, hexane, CH2Cl2, toluene, ethyl acetate, tetrahydrofuran, 2-methyltetrahydrofuran, cyclopentyl methyl ether, methanol, ethanol, and isopropanol.

[0143] Accordingly, the present invention also relates to a method of selective hydrogenation (H10”’), which is the method of selective hydrogenation (H10), wherein the solvent is selected from the group consisting of methanol, water, and hexane.

[0144] The catalyst represented by formula (I) according to the present invention is generally used in an amount of 0.001 to 1 mol% (preferably 0.001 to 0.5 mol%) (based on the number of moles of the compound represented by formula (III)).

[0145] Accordingly, the present invention also relates to a method of selective hydrogenation (H11), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), (H5’), (H6), (H7), (H8), (H8’), (H9), (H10), (H10’), (H10”) or (H10”’), wherein at least one catalyst represented by formula (I) is used in an amount of 0.001 to 1 mol% (based on the number of moles of the compound represented by formula (III)).

[0146] Accordingly, the present invention also relates to a method of selective hydrogenation (H11’), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), (H5’), (H6), (H7), (H8), (H8’), (H9), (H10), (H10’), (H10”) or (H10”’), wherein at least one catalyst represented by formula (I) is used in an amount of 0.001 to 0.5 mol% (based on the number of moles of the compound represented by formula (III)).

[0147] The hydrogenation method can be carried out using (pure) H2 gas or a gas containing H2. Preferably, the hydrogenation method according to the present invention is carried out using (pure) H2 gas.

[0148] Accordingly, the present invention also relates to a method of selective hydrogenation (H12), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), (H5’), (H6), (H7), (H8), (H8’), (H9), (H10), (H10’), (H10”), (H10”’), (H11) or (H11’), wherein the hydrogenation method is carried out using (pure) H2 gas or a gas containing H2.

[0149] Accordingly, the present invention also relates to a method of selective hydrogenation (H12’), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), (H5’), (H6), (H7), (H8), (H8’), (H9), (H10), (H10’), (H10”), (H10”’), (H11) or (H11’), wherein the hydrogenation method is carried out using H2 gas.

[0150] The hydrogenation method can be carried out under ambient pressure or under pressure. Preferably, the hydrogenation method according to the present invention is carried out at a pressure of 1 to 50 bar, more preferably at a pressure of 1 to 30 bar. Generally, the reaction is carried out in an autoclave (or any other pressure-resistant container).

[0151] Accordingly, the present invention also relates to a method of selective hydrogenation (H13), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), (H5’), (H6), (H7), (H8), (H8’), (H9), (H10), (H10’), (H10”), (H10”’), (H11), (H11’), (H12) or (H12’), wherein the hydrogenation method is carried out under ambient pressure.

[0152] Accordingly, the present invention also relates to a method of selective hydrogenation (H13’), which is the method of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3”’), (H4), (H5), (H5’), (H6), (H7), (H8), (H8’), (H9), (H10), (H10’), (H10”), (H10”’), (H11), (H11’), (H12) or (H12’), wherein the hydrogenation method is carried out at a pressure of 1 - 50 bar, preferably at a pressure of 1 - 30 bar.

[0153] Hydrogenation is usually carried out at a temperature of -10 to 150 °C (preferably 10 to 100 °C).

[0154] Accordingly, the present invention also relates to a method for selective hydrogenation (H14), which is the method for selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3''), (H3'''), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10''),

[0155] (H10'''), (H11), (H11'), (H12), (H12'), (H13) or (H13'), wherein the hydrogenation method is carried out at a temperature of -10 to 150 °C.

[0156] The following examples are used to illustrate the present invention. The temperature is given in °C, and all percentages are weight-related. Examples

[0157] General catalyst synthesis (Example 1)

[0158] Rh(COD)acac (1 mmol) was dissolved in THF (3 mL), and the reaction mixture was cooled to -78 °C. The ligand (1.0 equivalent) dissolved in THF (7 mL) was added dropwise within 30 minutes, and then HBF4 (125 μL, 50% aqueous solution) was added. Then, the catalyst was mixed with diethyl ether (40 mL) for precipitation, filtered, washed with diethyl ether, and then dried. All other catalysts used in the following examples were prepared according to a method similar to that of Example 1.

[0159] Hydrogenation examples

[0160] Example 2: Hydrogenation reaction

[0161] 440 mmol of dehydroisophytol (the compound shown in formula (IIIb); i.e., DIP), 650 mL of methanol, and 4.4 mmol of [Rh(Cyc-Japhos)(NBD)]BF4 prepared according to Example 1 were placed in an autoclave. The mixture was stirred and H2 gas was introduced.

[0162] The temperature of the autoclave was controlled at 25 °C, and the hydrogen pressure was released after reaching the required reaction time. The reaction mixture was analyzed, and the results are shown in Table 1 (No. 1).

[0163] The following examples were all carried out according to a method similar to that of Example 2 (the differences in reaction conditions are listed in Tables 1-3)

[0164]

[0165] Table 1. *DIP = dehydroisophytol; IP = isophytol; DiIP = perhydrodehydroisophytol = 3,7,11,15 - tetramethylhexadecan - 3 - ol.

[0166]

[0167] Table 2. *DIP = dehydroisophytol; IP = isophytol; DiIP = perhydrodehydroisophytol = 3,7,11,15 - tetramethylhexadecan - 3 - ol.

[0168]

[0169] Table 3. *DIP = dehydroisophytol; IP = isophytol; DiIP = perhydrodehydroisophytol = 3,7,11,15 - tetramethylhexadecan - 3 - ol.

Claims

1. A selective hydrogenation method, comprising the step of selectively hydrogenating an alkyne to an alkene in the presence of at least one catalyst of formula (I): [[M + (L1)(L2) n X](I), Wherein: M is Rh or Ir, and L1 is a bidentate phosphine ligand of formula (II): [(R)2-P-A-P-(R 1 )2](II), Wherein: R is a substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthryl, methoxyphenyl, tert-butyl or isopropyl, and R 1 is a substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthryl, methoxyphenyl, tert-butyl or isopropyl, A is a bridging group selected from the group consisting of: ---(CH2) m ---, where m is an integer from 1 to 6; and Where z is 0 or 1, And L2 is a bidentate ligand or a monodentate ligand, Provided that When L2 is a bidentate ligand, then n is 1 and L2 is not the bidentate ligand of formula (II); When L2 is a monodentate ligand, then n is 2, and X is an anion; And any dashed line in the structural formula represents a bond by which the substituent is attached to the rest of the molecule.

2. The method according to claim 1, wherein the starting material containing a carbon-carbon triple bond is selectively hydrogenated.

3. The method according to claim 1 or 2, wherein the compound of formula (III) Wherein R 2 is a straight-chain or branched C1-C 35 -alkyl; or a straight-chain or branched C2-C 35 -alkenyl, where the C chain may be substituted, and R 3 is H; a straight-chain or branched C1-C4-alkyl group, where the C-chain may be substituted, and R 4 is H; a cyclic, straight-chain or branched C1-C6-alkyl group, where the C chain may be substituted; or a C5–C 12 -cyclic aromatic group, which may be substituted, and R 5 is H or OH or OC1-C4-alkyl or O(CO)C1-C4-alkyl, Is selectively hydrogenated to the compound of formula (IV) 4. The method according to any one of the preceding claims, wherein the compound of formula (III) Wherein R 2 is a straight-chain or branched C1-C 20 -alkyl; or a straight-chain or branched C2-C 20 -alkenyl, where the C chain may be substituted, and R 3 is a C1-C2-alkyl, and R 4 is H, and R 5 is OH or O(CO)C1-C2-alkyl, Is selectively hydrogenated to the compound of formula (IV) 5. The method according to any one of the preceding claims, wherein the catalyst of formula (I) is used, wherein M is Rh.

6. The method according to any one of the preceding claims, wherein the catalyst of formula (I) is used, wherein L1 is a bidentate phosphine ligand selected from the group consisting of ligands of formula (IIa) to formula (IIp) 7. The method according to any one of the preceding claims, wherein the catalyst of formula (I) is used, wherein L2 is a bidentate ligand selected from the group consisting of cyclohexadiene, cycloheptadiene, 1,5-cyclooctadiene (COD) and norbornadiene (NBD), and n is 1.

8. The method according to any one of claims 1 to 6, wherein the catalyst of formula (I) is used, wherein L2 is a monodentate ligand selected from the group consisting of R6OH, wherein R6 is a straight-chain or branched C1-C8-alkyl; cyclooctene, cycloheptene, cyclohexene, norbornene and ethylene, and n is 2.

9. A method according to any one of the preceding claims, wherein a catalyst of formula (I) is used, wherein X is selected from halides (such as Cl - , I - , Br - , F - ), BF4 - , PF6 - , tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - , ClO4 - , TfO - and SbF6 - .

10. The method according to any one of the preceding claims, wherein the hydrogenation method is carried out without a solvent.

11. The method according to any one of claims 1 to 9, wherein the hydrogenation method is carried out in at least one solvent.

12. The method according to any one of the preceding claims, wherein the amount of the at least one catalyst of formula (I) used is 0.001-1 mol% (based on the number of moles of the compound of formula (III)).

13. The method according to any one of the preceding claims, wherein the hydrogenation method is carried out using (pure) H2 gas or a gas containing H2.

14. The method according to any one of the preceding claims, wherein the hydrogenation method is carried out at a pressure of 1-50 bar.

15. The method according to any one of the preceding claims, wherein the hydrogenation method is carried out at a temperature of -10 to 150 °C.

16. The method according to any one of the preceding claims, characterized in that In the catalyst of formula (I), M = Rh.

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