Iron carbonyl complexes with chiral bidentate diphosphine ligands

Abstract

The present invention relates to: an iron carbonyl complex having the general formula LFe (CO) 3 (I), wherein L is a chiral bidentate diphosphine ligand; the invention also relates to a process for the preparation thereof and to the use thereof as a catalyst for the hydrogenation of olefins, such as alkyl-substituted olefins or prochiral alpha, beta-unsaturated aldehydes or ketones, with hydrogen.

Description

[0001] The present invention relates to: an iron carbonyl complex having the general formula LFe(CO)3(I) with a chiral bidentate diphosphine ligand, a method for preparing the same, and its use as a catalyst for hydrogenating olefins such as alkyl-substituted olefins or prochiral α,β-unsaturated aldehydes or ketones with hydrogen. Background Art

[0002] Olefins can be hydrogenated with hydrogen using a wide range of homogeneous catalysts. The noble metal catalysts used are usually rhodium, iridium or ruthenium-based transition metal complexes (see, for example, Applied Homogeneous Catalysis with Organometallic Compounds by Blaser et al., edited by B. Cornils, W. A. Herrmann, M. Beller, R. Paciello, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Vol. 3, 2018, 621 - 690).

[0003] In order to find alternatives to the noble metal catalysts mentioned, attempts are being made to use iron-based catalysts for hydrogenation (see, for example, Homogeneous Hydrogenation with Non-Precious Catalysts by Langer et al., edited by J. F. Teichert, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2020, 15 - 38).

[0004] J. Angelici et al. described the preparation of tricarbonyl iron complexes with dppe, dppp and other bidentate phosphine ligands in J. Am. Chem. Soc., 1992, 114, 160 - 165. The use of these compounds as catalysts was not described. Compounds of the type (L)Fe(CO)3 (L = bidentate diphosphine ligand) have a stable 18-electron complex coordination (C. Elschenbroich, A. Salzer Organometallchemie, Teubner Taschenbücher Chemie, Wiesbaden, 1990). For catalytic activity, at least one CO must usually be able to be eliminated under the reaction conditions.

[0005] P.-J. Chirik et al., Organometallics, 2014, 33, 5781 - 5790 described a method for the homogeneous catalysis of olefins with an iron-based catalyst. The catalyst used is a carbonyl-free iron compound that is very complex to synthesize.

[0006] P. Casey et al., Israel Journal of Chemistry 30, 1990, 299 - 304 relates to theoretical calculations of the "natural bite angle" of chelating diphosphine ligands. Among them, the iron carbonyl complex [1] with ligand [2] is described:

[0007]

[0008] So far, the use of iron tricarbonyl complexes or iron dicarbonyl complexes with bidentate phosphine ligands as catalysts has not been described.

[0009] It has unexpectedly been found that iron carbonyl complexes of general formula (I) with chiral bidentate diphosphine ligands can be used as hydrogenation catalysts and can constitute a cost - effective alternative to noble metal catalysts. The iron carbonyl complexes of general formula (I) can be characterized by high activity, high product selectivity, and / or high conversion rate. When using prochiral substrates, the iron carbonyl complexes of general formula (I) can provide high enantioselectivity. Another advantage of the iron carbonyl complexes of general formula (I) is the disposal of catalyst residues in a cost - effective manner.

[0010] The present invention relates to iron carbonyl complexes of general formula LFe(CO)3 (I), wherein,

[0011] L is a chiral bidentate diphosphine ligand preferably selected from compounds of the formula and its enantiomers, wherein

[0012] R 1 and R 2 are each independently an unbranched, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, which hydrocarbon group is saturated or may contain one or more, usually 1 to about 4 non - conjugated olefinic double bonds, and which hydrocarbon group is unsubstituted or bears one or more, usually 1 to 4 identical or different substituents selected from OR 9 、NR 10 R 11 、halogen, C6 - C 10 -aryl and C3 - C9 - heteroaryl, or

[0013] R 1 and R 2 together may also be a C2 - to C10 - alkylene or a C3 - to C10 - cycloalkylene group, wherein 1, 2, 3 or 4 non - adjacent CH2 groups may be replaced by O or N - R 9calternatively, where the alkylene and cycloalkylene groups are saturated or contain one or two non-conjugated olefinic double bonds, and where the alkylene and cycloalkylene groups are unsubstituted or carry one or more identical or different substituents selected from C1-C4-alkyl;

[0014] R 3 and R 4 are each independently hydrogen or a straight-chain or branched C1-C4-alkyl, and

[0015] R 5 、R 6 、R 7 and R 8 are the same or different and are unsubstituted or carry one or more substituents selected from the following: C6-C 10 -aryl: C1-C6-alkyl, C3-C6-cycloalkyl, C6-C 10 -aryl, C1-C6-alkoxy and amino;

[0016] R 9c is hydrogen, C1-C6-alkyl, C6-C 10 -aryl, C7-C 12 -arylalkyl or C7-C 12 -alkylaryl,

[0017] R 9 、R 10 and R 11 are each independently hydrogen, C1-C4-alkyl, C6-C 10 -aryl, C7-C 12 -arylalkyl or C7-C 12 -alkylaryl, where

[0018] R 10 and R 11 together may also be an alkylene chain having 2 to 5 carbon atoms, which may be interrupted by N or O.

[0019] Furthermore, the present invention relates to

[0020] -a process for preparing an iron carbonyl complex of general formula (I), which process comprises the reaction of a chiral bidentate diphosphine ligand L, preferably selected from compounds of formula and their enantiomers, with an iron precursor compound, where R 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 and R 8 have the definitions given above;

[0021] - The use of an iron carbonyl complex having the general formula (I) or an iron carbonyl complex formed therefrom and containing a fragment having the formula LFeCO (I') or LFeCO2 (I") as a precatalyst or catalyst, in particular for the preparation of organic compounds by hydrogenating unsaturated organic compounds with hydrogen; and

[0022] - A process for the preparation of organic compounds by hydrogenating unsaturated organic compounds with hydrogen in the presence of at least one iron carbonyl complex having the general formula (I) or an iron carbonyl complex formed therefrom and containing a fragment having the formula LFeCO (I') or LFeCO2 (I").

[0023] In a further preferred embodiment of the present invention, an iron carbonyl complex having the general formula (I) or an iron carbonyl complex formed therefrom and containing a fragment having the formula LFeCO (I') or LFeCO2 (I") is used for the preparation of optically active compounds by asymmetric hydrogenation of prochiral unsaturated compounds with hydrogen.

[0024] In the context of the present invention, suitable chiral bidentate diphosphine ligands include, for example, those compounds described in: I. Ojima (ed.), Catalytic Asymmetric Synthesis [Catalytic Asymmetric Synthesis], Wiley-VCH Verlag, 2nd edition, 2000 or E. N. Jacobsen, A. Pfaltz, H. Yamamoto (eds.), Comprehensive Asymmetric Catalysis [Comprehensive Asymmetric Catalysis], 2000, Springer [Springer-Verlag] or W. Tang, X. Zhang, Chem. Rev. [Chemical Reviews] 2003, 103, 3029-3069.

[0025] By way of example, the following compounds are listed as chiral ligands (1) to (91) and their enantiomers, which can preferably be used according to the present invention:

[0026]

[0027]

[0028]

[0029]

[0030]

[0031] In formulas (1) to (91), "Ph" should be understood to mean "phenyl", "Cy" means cyclohexyl, "Xyl" means dimethylphenyl, "Tol" means p-tolyl and "Bn" means benzyl.

[0032] Among the chiral ligands mentioned above, preferred are those chiral ligands belonging to general formula (II), (III) or (IV). Particularly preferred are those chiral ligands belonging to general formula (II).

[0033] Particularly preferred chiral bidentate diphosphine ligands are those having the general formula and their enantiomers, wherein,

[0034] R 1 and R 2 are each independently a straight-chain, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, which hydrocarbon group is saturated or may contain one or more, usually 1 to about 4 non-conjugated olefinic double bonds, and which hydrocarbon group is unsubstituted or bears one or more, usually 1 to 4, identical or different substituents selected from OR 9 、NR 10 R 11 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl, or

[0035] R 1 and R 2 together may also be a C2-C10 alkylene group or a C3-C10 cycloalkylene group, wherein 1, 2, 3 or 4 non-adjacent CH2 groups may be replaced by O or N-R 9c wherein the alkylene group and the cycloalkylene group are saturated or contain one or two non-conjugated olefinic double bonds, and wherein the alkylene group and the cycloalkylene group are unsubstituted or bear one or more identical or different substituents selected from C1-C4 alkyl groups;

[0036] R 3 and R 4 are each independently hydrogen or a straight-chain or branched C1-C4 alkyl group, and

[0037] R 5 、R 6 、R 7 and R 8 are the same or different and are unsubstituted or bear one or more substituents selected from the following C6-C 10 -aryl: C1-C6 alkyl, C3-C6 cycloalkyl, C6-C 10 -aryl, C1-C6 alkoxy and amino;

[0038] R 9cis hydrogen, C1-C6-alkyl, C6-C 10 -aryl, C7-C 12 -arylalkyl or C7-C 12 -alkylaryl,

[0039] R 9 、R 10 and R 11 are each independently hydrogen, C1-C4-alkyl, C6-C 10 -aryl, C7-C 12 -arylalkyl or C7-C 12 -alkylaryl, where

[0040] R 10 and R 11 together may also be an alkylene chain having 2 to 5 carbon atoms, which may be inserted with N or O.

[0041] Regarding formulas (II), (III) and (IV), the variables are specifically defined as follows:

[0042] R 1 and R 2 are each independently an unbranched, branched or C1-C4 hydrocarbon group, or

[0043] R 1 and R 2 together are C3-C7-alkanediyl, C3-C7-alkenediyl, C5-C7-cycloalkanediyl or C5-C7-cycloalkenediyl, where the four groups mentioned above are unsubstituted or carry one or more identical or different substituents selected from C1-C4-alkyl;

[0044] R 3 and R 4 are each independently hydrogen or a straight-chain or branched C1-C4-alkyl, and

[0045] R 5 、R 6 、R 7 and R 8 is phenyl.

[0046] According to the present invention, particularly preferred chiral bidentate diphosphine ligands are those having the general formula (II), especially compounds having the formula (1) or having the formula (IIa) or (IIb) (which are hereinafter referred to as "Chiraphos")

[0047]

[0048] and compounds having the formula (5) or having the formula (IId) or (IIc) (which are referred to as "Norphos")

[0049]

[0050] and a compound having formula (4) or having formula (IIe) or (IIf), which is referred to as "DIOP"

[0051]

[0052] and a compound having formula (91) or having formula (IIg) or (IIh),

[0053]

[0054] wherein Ph is phenyl and Bn is benzyl.

[0055] Most preferably, the chiral bidentate diphosphine ligand is a compound having the formula wherein Ph is phenyl.

[0056] According to the present invention, the selected chiral ligands are each used in the form of one of their two enantiomers. The chiral ligands typically have an enantiomeric excess (ee) of at least 80% ee, especially at least 90% ee, and in particular at least 95% ee.

[0057] The definitions of the variables given in the above and following formulas use collective terms that typically represent the corresponding substituents. Definition C n -C m indicates the possible number of carbon atoms in the corresponding substituent or substituent moiety in each case.

[0058] In the context of the present invention, the term "alkyl" encompasses unbranched or branched alkyl having 1 to 4, 6, 12 or 25 carbon atoms. These include, for example, C1-C6-alkyl such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 2-hexyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl, 1-ethyl-2-methylpropyl, etc. Preferably, "alkyl" is unbranched and branched C1-C6-alkyl.

[0059] In the context of the present invention, the term "cycloalkyl" encompasses cyclic saturated hydrocarbon groups having 3 to 6, 12 or 25 carbon ring members, such as C3-C8-cycloalkyl (e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl), or C7-C 12 -bicycloalkyl.

[0060] In the context of the present invention, the term "alkoxy" is an alkyl group having 1 to 6 carbon atoms and bonded via oxygen, such as C1-C6-alkoxy, e.g., methoxy, ethoxy, n-propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 2-methylpropoxy, 1,1-dimethylethoxy, pentyloxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 2,2-dimethylpropoxy, 1-ethylpropoxy, hexyloxy, 1-methylpentyloxy, 2-methylpentyloxy, 3-methylpentyloxy, 4-methylpentyloxy, 1,1-dimethylbutoxy, 1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, 3,3-dimethylbutoxy, 1-ethylbutoxy, 2-ethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2-trimethylpropoxy, 1-ethyl-1-methylpropoxy or 1-ethyl-2-methylpropoxy. Preferably, "alkoxy" is C1-C4-alkoxy.

[0061] In the context of the present invention, the term "alkenyl" encompasses straight-chain or branched hydrocarbon groups having 2 to 4, 6, 12 or 25 carbon atoms and containing at least one double bond, for example 1, 2, 3 or 4 double bonds. These include, for example, C2-C6-alkenyl such as vinyl, 1-propenyl, 2-propenyl, 1-methylethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-methyl-1-butenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1-methyl-3-butenyl, 2-methyl-3-butenyl, 3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl, 1,2-dimethyl-1-propenyl, 1,2-dimethyl-2-propenyl, 1-ethyl-1-propenyl, 1-ethyl-2-propenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 1-methyl-1-pentenyl, 2-methyl-1-pentenyl, 3-methyl-1-pentenyl, 4-methyl-1-pentenyl, 1-methyl-2-pentenyl, 2-methyl-2-pentenyl, 3-methyl-2-pentenyl, 4-methyl-2-pentenyl, 1-methyl-3-pentenyl, 2-methyl-3-pentenyl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl, 1-methyl-4-pentenyl, 2-methyl-4-pentenyl, 3-methyl-4-pentenyl, 4-methyl-4-pentenyl, 1,1-dimethyl-2-butenyl, 1,1-dimethyl-3-butenyl, 1,2-dimethyl-1-butenyl, 1,2-dimethyl-2-butenyl, 1,2-dimethyl-3-butenyl, 1,3-dimethyl-1-butenyl, 1,3-dimethyl-2-butenyl, 1,3-dimethyl-3-butenyl, 2,2-dimethyl-3-butenyl, 2,3-dimethyl-1-butenyl, 2,3-dimethyl-2-butenyl, 2,3-dimethyl-3-butenyl, 3,3-dimethyl-1-butenyl, 3,3-dimethyl-2-butenyl, 1-ethyl-1-butenyl, 1-ethyl-2-butenyl, 1-ethyl-3-butenyl, 2-ethyl-1-butenyl, 2-ethyl-2-butenyl, 2-ethyl-3-butenyl, 1,1,2-trimethyl-2-propenyl, 1-ethyl-1-methyl-2-propenyl, 1-ethyl-2-methyl-1-propenyl and 1-ethyl-2-methyl-2-propenyl. Preferably, "alkenyl" is a straight-chain C2-C 12 -alkenyl or a branched C3-C 12 -alkenyl, particularly preferably a straight-chain C2-C6-alkenyl or a branched C3-C6-alkenyl each having one double bond.

[0062] In the context of the present invention, the term "alkylene" refers to a divalent hydrocarbon group having from 2 to 25 carbon atoms. The divalent hydrocarbon group may be unbranched or branched. These include, for example, C2-C 16 -alkylene, such as 1,4-butylene, 1,5-pentylene, 2-methyl-1,4-butylene, 1,6-hexylene, 2-methyl-1,5-pentylene, 3-methyl-1,5-pentylene, 1,7-heptylene, 2-methyl-1,6-hexylene, 3-methyl-1,6-hexylene, 2-ethyl-1,5-pentylene, 3-ethyl-1,5-pentylene, 2,3-dimethyl-1,5-pentylene, 2,4-dimethyl-1,5-pentylene, 1,8-octylene, 2-methyl-1,7-heptylene, 3-methyl-1,7-heptylene, 4-methyl-1,7-heptylene, 2-ethyl-1,6-hexylene, 3-ethyl-1,6-hexylene, 2,3-dimethyl-1,6-hexylene, 2,4-dimethyl-1,6-hexylene, 1,9-nonylene, 2-methyl-1,8-octylene, 3-methyl-1,8-octylene, 4-methyl-1,8-octylene, 2-ethyl-1,7-heptylene, 3-ethyl-1,7-heptylene, 1,10-decylene, 2-methyl-1,9-nonylene, 3-methyl-1,9-nonylene, 4-methyl-1,9-nonylene, 5-methyl-1,9-nonylene, 1,11-undecylene, 2-methyl-1,10-decylene, 3-methyl-1,10-decylene, 5-methyl-1,10-decylene, 1,12-dodecylene, 1,13-tridecylene, 1,14-tetradecylene, 1,15-pentadecylene, 1,16-hexadecylene and the like. Preferably, the "alkylene" is an unbranched C2-C 12 -alkylene or a branched C3-C 12 -alkenyl, particularly an unbranched C2-C6-alkylene or a branched C3-C6-alkylene.

[0063] In a mono- or multi-branched alkylene, the carbon atom at the branch point or the carbon atoms at the corresponding branch points may independently have the R or S configuration or a mixture of the two configurations in the same or different ratios.

[0064] In the context of the present invention, the term "alkenylene" refers to a divalent hydrocarbon group having from 2 to 25 carbon atoms, which may be unbranched or branched, and in which the main chain has one or more double bonds, for example 1, 2 or 3 double bonds. These include, for example, C2-C 18-Alkenylene, such as ethylene, propylene, 1-, 2-butylene, 1-, 2-pentylene, 1-, 2-, 3-hexylene, 1,3-hexadienylene, 1,4-hexadienylene, 1-, 2-, 3-heptylene, 1,3-heptadienylene, 1,4-heptadienylene, 2,4-heptadienylene, 1-, 2-, 3-octenylene, 1,3-octadienylene, 1,4-octadienylene, 2,4-octadienylene, 1-, 2-, 3-nonenylene, 1-, 2-, 3-, 4-, 5-decenylene, 1-, 2-, 3-, 4-, 5-undecenylene, 2-, 3-, 4-, 5-, 6-dodecenylene, 2,4-dodecadienylene, 2,5-dodecadienylene, 2,6-dodecadienylene, 3-, 4-, 5-, 6-tridecenylene, 2,5-tridecadienylene, 4,7-tridecadienylene, 5,8-tridecadienylene, 4-, 5-, 6-, 7-tetradecenylene, 2,5-tetradecadienylene, 4,7-tetradecadienylene, 5,8-tetradecadienylene, 4-, 5-, 6-, 7-pentadecenylene, 2,5-pentadecadienylene, 4,7-pentadecadienylene, 5,8-pentadecadienylene, 1,4,7-pentadecatrienylene, 4,7,11-pentadecatrienylene, 4,6,8-pentadecatrienylene, 4-, 5-, 6-, 7-, 8-hexadecenylene, 2,5-hexadecadienylene, 4,7-hexadecadienylene, 5,8-hexadecadienylene, 2,5,8-hexadecatrienylene, 4,8,11-hexadecatrienylene, 5,7,9-hexadecatrienylene, 5-, 6-, 7-, 8-heptadecenylene, 2,5-heptadecadienylene, 4,7-heptadecadienylene, 5,8-heptadecadienylene, 5-, 6-, 7-, 8-, 9-octadecenylene, 2,5-octadecadienylene, 4,7-octadecadienylene, 5,8-octadecadienylene, etc. Preferably, the "alkenylene" is an unbranched C3-C 12 -alkenylene or a branched C4-C 12 -alkenylene, especially an unbranched C3-C8-alkenylene having one double bond.

[0065] The double bonds in the alkenylene can independently exist in the E or Z configuration or as a mixture of the two configurations.

[0066] In the context of the present invention, the term "halogen" encompasses fluorine, chlorine, bromine and iodine, preferably fluorine, chlorine or bromine.

[0067] In the context of the present invention, the term "aryl" encompasses mono- to trinuclear aromatic ring systems containing 6 to 14 carbon ring members. These include, for example, C6-C 10 -aryl, such as phenyl or naphthyl.

[0068] In the context of the present invention, the term "heteroaryl" encompasses mono- to trinuclear aromatic ring systems containing 6 to 14 carbon ring members, where one or more (e.g., 1, 2, 3, 4, 5, or 6) carbon atoms are replaced by nitrogen, oxygen, and / or sulfur atoms. These include, for example, C3-C9-heteroaryl such as 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 2-pyrrolyl, 3-pyrrolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 3-pyrazolyl, 4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-imidazolyl, 4-imidazolyl, 1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl, 1,2,4-thiadiazol-3-yl, 1,2,4-thiadiazol-5-yl, 1,2,4-triazol-3-yl, 1,3,4-oxadiazol-2-yl, 1,3,4-thiadiazol-2-yl, 1,3,4-triazol-2-yl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 3-pyridazinyl, 4-pyridazinyl, 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, 2-pyrazinyl, 1,3,5-triazin-2-yl, 1,2,4-triazin-3-yl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl, and the like. Preferably, "heteroaryl" is C5-C6-heteroaryl.

[0069] In the context of the present invention, the term "aralkyl" encompasses mono- to dinuclear aromatic ring systems containing 6 to 10 carbon ring members and bonded via a straight-chain or branched C1-C6-alkyl group. These include, for example, C7-C 12 -aralkyl such as phenylmethyl, 1-phenylethyl, 2-phenylethyl,

[0070] 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, and the like.

[0071] In the context of the present invention, the term "aralkyl" encompasses mono- to dinuclear aromatic ring systems containing 6 to 10 carbon ring members substituted by one or more (e.g., 1, 2, or 3) straight-chain or branched C1-C6-alkyl groups. These include, for example, C7-C 12-alkylaryl, such as 1-methylphenyl, 2-methylphenyl, 3-methylphenyl, 1-ethylphenyl, 2-ethylphenyl, 3-ethylphenyl, 1-propylphenyl, 2-propylphenyl, 3-propylphenyl, 1-isopropylphenyl, 2-isopropylphenyl, 3-isopropylphenyl, 1-butylphenyl, 2-butylphenyl, 3-butylphenyl, 1-isobutylphenyl, 2-isobutylphenyl, 3-isobutylphenyl, 1-sec-butylphenyl, 2-sec-butylphenyl, 3-sec-butylphenyl, 1-tert-butylphenyl, 2-tert-butylphenyl, 3-tert-butylphenyl, 1-(1-pentenyl)phenyl, 2-(1-pentenyl)phenyl, 3-(1-pentenyl)phenyl, 1-(2-pentenyl)phenyl, 2-(2-pentenyl)phenyl, 3-(2-pentenyl)phenyl, 1-(3-pentenyl)phenyl, 2-(3-pentenyl)phenyl, 3-(3-pentenyl)phenyl, 1-(1-(2-methylbutyl))phenyl, 2-(1-(2-methylbutyl))phenyl, 3-(1-(2-methylbutyl))phenyl, 1-(2-(2-methylbutyl))phenyl, 2-(2-(2-methylbutyl))phenyl, 3-(2-(2-methylbutyl))phenyl, 1-(3-(2-methylbutyl))phenyl, 2-(3-(2-methylbutyl))phenyl, 3-(3-(2-methylbutyl))phenyl, 1-(4-(2-methylbutyl))phenyl, 2-(4-(2-methylbutyl))phenyl, 3-(4-(2-methylbutyl))phenyl, 1-(1-(2,2-dimethylpropyl))phenyl, 2-(1-(2,2-dimethylpropyl))phenyl, 3-(1-(2,2-dimethylpropyl))phenyl, 1-(1-hexenyl)phenyl, 2-(1-hexenyl)phenyl, 3-(1-hexenyl)phenyl, 1-(2-hexenyl)phenyl, 2-(2-hexenyl)phenyl, 3-(2-hexenyl)phenyl, 1-(3-hexenyl)phenyl, 2-(3-hexenyl)phenyl, 3-(3-hexenyl)phenyl, 1-(1-(2-methylpentenyl))phenyl, 2-(1-(2-methylpentenyl))phenyl, 3-(1-(2-methylpentenyl))phenyl, 1-(2-(2-methylpentenyl))phenyl, 2-(2-(2-methylpentenyl))phenyl, 3-(2-(2-methylpentenyl))phenyl, 1-(3-(2-methylpentenyl))phenyl, 2-(3-(2-methylpentenyl))phenyl, 3-(3-(2-methylpentenyl))phenyl, 1-(4-(2-methylpentenyl))phenyl, 2-(4-(2-methylpentenyl))phenyl, 3-(4-(2-methylpentenyl))phenyl, 1-(5-(2-methylpentenyl))phenyl, 2-(5-(2-methylpentenyl))phenyl, 3-(5-(2-methylpentenyl))phenyl, 1-(1-(2,2-dimethylbutenyl))phenyl, 2-(1-(2,2-dimethylbutenyl))phenyl, 3-(1-(2,2-(3-(2,2-dimethylbutenyl))phenyl, 1-(3-(2,2-dimethylbutenyl))phenyl, 2-(3-(2,2-dimethylbutenyl))phenyl, 3-(3-(2,2-dimethylbutenyl))phenyl, 1-(4-(2,2-dimethylbutenyl))phenyl, 2-(4-(2,2-dimethylbutenyl))phenyl, 3-(4-(2,2-dimethylbutenyl))phenyl, etc.,

[0072] In a preferred embodiment, the present invention relates to an iron carbonyl complex having the general formula LFe(CO)3 (I), wherein,

[0073] L is a chiral bidentate diphosphine ligand selected from compounds having the formula and its enantiomers, wherein

[0074] R 1 and R 2 are each independently an unbranched, branched or C1-C4 hydrocarbon group, or

[0075] R 1 and R 2 together are a C3-C7 alkanediyl, C3-C7 alkenediyl, C5-C7 cycloalkanediyl or C5-C7 cycloalkenediyl group, wherein the four groups mentioned above are unsubstituted or carry one or more identical or different substituents selected from C1-C4 alkyl groups;

[0076] R 3 and R 4 are each independently hydrogen or a straight-chain or branched C1-C4 alkyl group, and

[0077] R 5 , R 6 , R 7 and R 8 are phenyl groups.

[0078] In this embodiment, the chiral bidentate diphosphine ligand L is particularly preferably a compound having the general formula (II).

[0079] Particularly preferred iron complexes having the general formula LFe(CO)3 (I) are listed in the following table:

[0080]

[0081]

[0082] Most preferably, the iron complexes are A-1 and A-2.

[0083] The iron carbonyl complex A-1 (Fe(CO)3 (R,R-Chiraphos)) crystallizes in an orthorhombic unit cell, space group P212121.

[0084] Figure 1 The asymmetric unit of the crystal structure of Fe(CO)3(R,R-Chiraphos) is shown.

[0085] Figure 2 The crystal structure of Fe(CO)3(R,R-Chiraphos) is shown. The iron complex has an axial-equatorial coordination of R,R-Chiraphos with the central atom.

[0086] The present invention also relates to the use of the above iron carbonyl complex of general formula (I) as a catalyst, in particular the use of the iron carbonyl complex of general formula (I) for the preparation of organic compounds by hydrogenating unsaturated organic compounds (such as unsaturated carbonyl compounds, olefins or imines) with hydrogen.

[0087] The iron carbonyl complex can advantageously be used for the preparation of optically active compounds by asymmetric hydrogenation of prochiral unsaturated compounds with hydrogen.

[0088] The present invention also relates to a process for the preparation of a compound by hydrogenating an unsaturated compound in the presence of at least one iron carbonyl complex of general formula (I).

[0089] In an advantageous configuration of the present invention, the process according to the invention has at least one or all of the following features a-h:

[0090] a) The hydrogenation is carried out at a hydrogen pressure of 5 to 200 bar, in particular at a hydrogen pressure of 10 to 100 bar;

[0091] b) The process is carried out batchwise or continuously;

[0092] c) The iron carbonyl complex is generated in situ by reaction of an achiral iron precursor compound with a chiral bidentate diphosphine ligand L and optionally CO before or during the hydrogenation;

[0093] d) The catalyst is pretreated with a gas mixture containing carbon monoxide or carbon monoxide / hydrogen before the hydrogenation;

[0094] e) The hydrogenation is carried out in the presence of carbon monoxide additionally supplied to the reaction mixture;

[0095] f) The hydrogenation is carried out with hydrogen having a carbon monoxide content in the range of 50 to 3000 ppm, in particular in the range of 100 to 2000 ppm;

[0096] g) The hydrogenation is carried out in a gas circulation reactor;

[0097] h) Hydrogenation is carried out in a gas circulation reactor, in which an unsaturated compound and hydrogen are introduced into the gas circulation reactor through a two-phase nozzle.

[0098] The unsaturated organic compound is preferably a disubstituted or trisubstituted, prochiral or achiral unsaturated organic compound, especially a prochiral or achiral unsaturated carbonyl compound, especially a prochiral or achiral α,β-unsaturated ketone or a prochiral or achiral α,β-unsaturated aldehyde.

[0099] Examples of preferred unsaturated organic compounds are compounds having the following general formula

[0100] wherein,

[0101] R 12 and R 13 are the same as or different from each other and each is hydrogen, C6-C 10 -aryl, C3-C9-heteroaryl, a straight-chain, branched-chain or cyclic hydrocarbon group having 1 to 25 carbon atoms, the hydrocarbon group being saturated or containing one or more (e.g., 1, 2, 3, 4 or 5) preferably non-conjugated olefinic double bonds, and the hydrocarbon group being unsubstituted or carrying one or more (e.g., 1, 2, 3 or 4) identical or different substituents selected from OR 17 、NR 16a R 16b 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl;

[0102] R 12 and R 13 or R 15 together form an optionally substituted 5- or 6-membered ring;

[0103] R 13 and R 12 or R 15 together form an optionally substituted 5- or 6-membered ring;

[0104] R 14 is hydrogen, C1-C6-alkoxy or a straight-chain, branched-chain or cyclic hydrocarbon group having 1 to 25 carbon atoms, the hydrocarbon group being saturated or containing one or more (e.g., 1, 2, 3, 4 or 5) preferably non-conjugated olefinic double bonds, and the hydrocarbon group being unsubstituted or carrying one or more (e.g., 1, 2, 3 or 4) identical or different substituents selected from OR 17 、NR 16a R 16b 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl; or

[0105] R14 Together with a group R 12 or R 13 it may also be a C3-C25 alkylene group, in which one, two, three or four non-adjacent CH2 groups may be replaced by O or N-R 16c wherein the alkylene group is saturated or contains one or more (e.g., 1, 2, 3, 4 or 5) preferably non-conjugated olefinic double bonds, and wherein the alkylene group is unsubstituted or bears one or more (e.g., 1, 2, 3 or 4) identical or different substituents selected from OR 17 NR 16a R 16b halogen, C1-C4-alkyl, C6-C 10 -aryl and C3-C9-heteroaryl, where two substituents may also together be a C2-C10 alkylene group, wherein the C2-C10 alkylene group is saturated or contains one or more (e.g., 1, 2, 3 or 4) non-conjugated olefinic double bonds, and wherein the C2-C10 alkylene group is unsubstituted or bears one or more (e.g., 1, 2, 3 or 4) identical or different substituents selected from OR 17 NR 16a R 16b halogen, C6-C 10 -aryl and C3-C9-heteroaryl; where

[0106] R 15 and R 17 are hydrogen, C1-C6-alkyl, C1-C6-alkenyl, C6-C 10 -aryl, C3-C9-heteroaryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl;

[0107] R 16a and R 16b are each independently hydrogen, C1- to C6-alkyl, C6- to C 10 -aryl, C7- to C 12 -aralkyl or C7- to C 12 -alkylaryl; or

[0108] R 16a and R 16b together may also be an alkylene chain having 2 to 5 carbon atoms, which may be inserted with N or O; and

[0109] R 16c is hydrogen, C1-C6-alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl.

[0110] Examples of compounds of general formula (VI) or (VII) are cyclohexene, 1-butene, 1-octene, 3,3-dimethylbutene, 2,3,3-dimethylbutene, CH2=CH(Ph)CH(CH3)2, (Ph)CH=CH(Ph), (Ph)CH=C(Ph), dimethyl itaconate, isophorone, pseudoionone, α-ionone, β-ionone, (+)-limonene and β-pinene.

[0111] Preferably, the prochiral α,β-unsaturated carbonyl compound is a prochiral α,β-unsaturated ketone or especially a prochiral α,β-unsaturated aldehyde.

[0112] Accordingly, the process according to the invention is preferably applicable to the preparation of optically active aldehydes or ketones by the asymmetric hydrogenation of prochiral α,β-unsaturated aldehydes or ketones. The process according to the invention is particularly preferably applicable to the preparation of optically active aldehydes by the asymmetric hydrogenation of prochiral α,β-unsaturated aldehydes.

[0113] In a preferred embodiment of the process according to the invention, the prochiral α,β-unsaturated carbonyl compound is selected from compounds of general formula wherein,

[0114] R 12 and R 13 are different from each other and each is an unbranched, branched or cyclic hydrocarbon group having 1 to 25 carbon atoms, which hydrocarbon group is saturated or contains one or more (e.g. 1, 2, 3, 4 or 5) preferably non-conjugated ethylenic double bonds, and which hydrocarbon group is unsubstituted or carries one or more (e.g. 1, 2, 3 or 4) identical or different substituents selected from OR 17 、NR 16a R 16b 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl;

[0115] R 14 is hydrogen or an unbranched, branched or cyclic hydrocarbon group having 1 to 25 carbon atoms, which hydrocarbon group is saturated or contains one or more (e.g. 1, 2, 3, 4 or 5) preferably non-conjugated ethylenic double bonds, and which hydrocarbon group is unsubstituted or carries one or more (e.g. 1, 2, 3 or 4) identical or different substituents selected from OR 17 、NR 16a R 16b 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl; or

[0116] R 14 is combined with the group R 12 or R 13together with one of them can also be a C3-C25 alkylene group, where 1, 2, 3 or 4 non-adjacent CH2 groups can be replaced by O or N-R 16c substituted, where the alkylene group is saturated or contains one or more (e.g., 1, 2, 3, 4 or 5) preferably non-conjugated olefinic double bonds, and where the alkylene group is unsubstituted or bears one or more (e.g., 1, 2, 3 or 4) identical or different substituents selected from OR 17 、NR 16a R 16b 、halogen, C1-C4-alkyl, C6-C 10 -aryl and C3-C9-heteroaryl substituents, where two substituents can also together be a C2-C10 alkylene group, where the C2-C10 alkylene group is saturated or contains one or more (e.g., 1, 2, 3 or 4) non-conjugated olefinic double bonds, and where the C2-C10 alkylene group is unsubstituted or bears one or more (e.g., 1, 2, 3 or 4) identical or different substituents selected from OR 17 、NR 16a R 16b 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl substituents; where

[0117] R 17 is hydrogen, C1-C6-alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl;

[0118] R 16a 、R 16b are each independently hydrogen, C1-C6-alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl; or

[0119] R 16a and R 16b together can also be an alkylene chain having 2 to 5 carbon atoms, which can be inserted with N or O; and

[0120] R 16c is hydrogen, C1-C6-alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl.

[0121] In the groups R 12 、R 13 and R 14The straight-chain, branched-chain or cyclic hydrocarbon group having 1 to 25 carbon atoms as mentioned in the definition is usually a straight-chain C1-C 25 -alkyl, straight-chain C2-C 25 -alkenyl, straight-chain C4-C 25 -alkanedienyl, branched-chain C3-C 25 -alkyl, branched-chain C3-C 25 -alkenyl, branched-chain C5-C 25 -alkanedienyl and C3-C 25 -cycloalkyl or C3-C 24 -cycloalkyl, and these groups are substituted by one or more (such as 1, 2, 3 or 4) C1- to C4-alkyl groups as defined above. The cyclic hydrocarbon group also includes those cyclic hydrocarbon groups having a benzene ring, which benzene ring is optionally substituted by one or more (such as 1, 2, 3, 4, 5 or 6) C1-C4-alkyl groups, wherein the benzene ring is directly bonded to the ethylenic unsaturated double bond or carbonyl group in formula (II) or bonded via a C1-C6-alkylene group.

[0122] Alkenyl should be understood to mean a straight-chain or branched-chain aliphatic hydrocarbon group that is mono-unsaturated. Alkanedienyl should be understood to mean a straight-chain or branched-chain aliphatic hydrocarbon group that is di-unsaturated. In the group R 14 the saturated C3- to C25-alkylene group as mentioned in the definition is usually a straight-chain or branched-chain C3-C 25 -alkylene as defined above.

[0123] In the group R 14 the C3- to C25-alkylene group having one or more (such as 1, 2, 3 or 4) non-conjugated ethylenic double bonds as mentioned in the definition is usually a straight-chain or branched-chain C3-C 25 -alkenylene as defined above.

[0124] Preferably, one of the groups R 12 and R 13 is methyl or ethyl, especially methyl, and the other group is a straight-chain, branched-chain or cyclic hydrocarbon group having 3 to 25 carbon atoms, which hydrocarbon group is saturated or contains one or more (such as 1, 2, 3, 4 or 5) preferably non-conjugated ethylenic double bonds, and which hydrocarbon group is unsubstituted or substituted by one or more (such as 1, 2, 3 or 4) identical or different substituents selected from OR 17 、NR 16a R 16b 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl.

[0125] In particular, the groups R 12 and R 13One of them is methyl or ethyl, especially methyl, and the other group is a straight-chain, branched-chain or cyclic hydrocarbon group having 3 to 25 carbon atoms, which hydrocarbon group is saturated or contains one or more (e.g., 1, 2 or 3) preferably non-conjugated olefinic double bonds.

[0126] R 14 Especially hydrogen.

[0127] In a very preferred embodiment of the process according to the invention, the prochiral α,β-unsaturated carbonyl compound is selected from compounds having the following general formula

[0128] wherein,

[0129] R 12 and R 13 are each a straight-chain or branched-chain hydrocarbon group having 2 to 25, especially 3 to 20 carbon atoms, which hydrocarbon group is saturated or contains 1, 2, 3, 4 or 5 non-conjugated olefinic double bonds, such as neral / geranial.

[0130] Accordingly, by the asymmetric hydrogenation of prochiral α,β-unsaturated aldehydes or ketones having the general formulas (VIII), (VIIIa) and (VIIIb), the process according to the invention enables the preparation of the corresponding α,β-saturated aldehydes or ketones of formula (VIII) (such as citronellal) in optically active form, wherein the carbon atoms bearing the groups R 12 and R 13 constitute the asymmetric center generated by the hydrogenation.

[0131] In the formula R 12 、R 13 and R 14 have the definitions given for formula (VIII), especially the definitions given for formulas (VIIIa) and (VIIIb).

[0132] The asymmetric (i.e., enantioselective) hydrogenation of α,β-unsaturated aldehydes of formula (VIIIa) or (VIIIb) according to the invention makes it possible to obtain the corresponding α,β-saturated aldehydes. Compounds of formula (VIIIa) and (VIIIb) form E / Z double bond isomers of each other. In principle, the corresponding optically active aldehydes can be obtained starting from the two double bond isomers of formula (VIIIa) and (VIIIb). Depending on the choice of the enantiomeric form of the catalyst, i.e., depending on the choice of the (+) or (-) enantiomer of the catalyst or the (+) or (-) enantiomer of the chiral ligand used, preferably one of the enantiomers of the optically active aldehyde is obtained in a manner according to the invention from the E or Z double bond isomer used. This also applies to the substrate or product classes mentioned above. In principle, it is also possible to react a mixture of the two double bond isomers in a manner according to the invention. This gives a mixture of the two enantiomers of the desired target compound.

[0133] The preparation method according to the invention is carried out in the presence of an optically active iron carbonyl complex of general formula (I) soluble in the reaction mixture or an iron carbonyl complex formed therefrom containing a fragment of formula LFeCO(I') or LFeCO(I").

[0134] The invention also relates to a method for preparing an iron carbonyl complex of general formula (I), which method comprises the reaction of a chiral bidentate bisphosphine ligand L, preferably selected from compounds of formula and their enantiomers, with an iron precursor compound, wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 have the definitions given above.

[0135] The iron precursor compound is preferably a compound of formula Fe(COT)(CO)3 (Va) or Fe(CO)5 (Vb), where COT is cyclooctatetraene. Fe(COT)(CO)3 (Va) is preferably reacted with the chiral bidentate bisphosphine ligand L at a temperature of 20 °C to 120 °C. Fe(CO)5 (Vb) can likewise be reacted directly with the bidentate bisphosphine ligand L. Alternatively, however, an Fe(II) source in the reduced state can also be used. For example, FeBr2 or FeCl2 can be treated with the bidentate bisphosphine ligand L and then reacted with CO, H2 / CO or CO and a reducing agent.

[0136] The iron carbonyl complex can be generated in situ by reaction of an achiral iron precursor compound with a chiral bidentate bisphosphine ligand L and optionally CO before or during hydrogenation.

[0137] In this context, the term "in situ" means that the iron carbonyl complex is produced directly before or at the beginning of the hydrogenation. Preferably, the catalyst is produced before the hydrogenation.

[0138] The iron carbonyl complex (= catalyst) can be pretreated with a gas mixture comprising carbon monoxide and hydrogen before the hydrogenation and / or can be hydrogenated in the presence of carbon monoxide additionally supplied to the reaction mixture.

[0139] This means that the iron carbonyl complex used is pretreated with a gas mixture comprising carbon monoxide and hydrogen before the hydrogenation (i.e., is preformed), or is hydrogenated in the presence of carbon monoxide additionally supplied to the reaction mixture, or is preformed and then hydrogenated in the presence of carbon monoxide additionally supplied to the reaction mixture.

[0140] In this preferred embodiment, the iron carbonyl complex is preferably pretreated with a gas mixture comprising carbon monoxide and hydrogen and is hydrogenated in the presence of carbon monoxide additionally supplied to the reaction mixture.

[0141] In this preferred embodiment, the pretreatment of the iron carbonyl complex mentioned is carried out with a gas mixture comprising 20% to 90% by volume of carbon monoxide, 10% to 80% by volume of hydrogen, and 0% to 5% by volume of additional gas at a pressure of 5 to 100 bar, where the volume percentages mentioned add up to 100% by volume. Furthermore, before being used for the hydrogenation, the excess carbon monoxide is removed from the catalyst thus obtained.

[0142] The term "excess carbon monoxide" should be understood here to mean carbon monoxide present in the reaction mixture obtained in gaseous or dissolved form and not bonded to the iron carbonyl complex. Thus, the excess carbon monoxide not bonded to the iron carbonyl complex is removed at least to a large extent, i.e., to the extent that any residual amount of dissolved carbon monoxide does not cause any significant interference in the subsequent hydrogenation. This is typically ensured when approximately 90%, preferably approximately 95% or more, of the carbon monoxide used for the preformation is removed. Preferably, the excess carbon monoxide is completely removed from the iron carbonyl complex obtained by the preformation.

[0143] The excess carbon monoxide can be removed from the reaction mixture containing the iron carbonyl complex in various ways. Preferably, the iron carbonyl complex obtained by preformation or the mixture containing it is depressurized to a pressure of up to about 5 bar (absolute), preferably, especially when the preformation is carried out in a pressure range of 5 to 10 bar, to a pressure of less than 5 bar (absolute), preferably depressurized to a pressure in the range of about 1 bar to about 5 bar, preferably 1 to less than 5 bar, particularly preferably depressurized to a pressure in the range of 1 to 3 bar, very particularly preferably depressurized to a pressure in the range of about 1 to about 2 bar, and especially preferably depressurized to standard pressure, as a result of which gaseous, unbonded carbon monoxide escapes from the preformed product.

[0144] The above-mentioned depressurization of the preformed catalyst can be carried out, for example, using a high-pressure separator, as is known per se to those skilled in the art. This type of separator (where the liquid is in the continuous phase) is described, for example, in: Perry's Chemical Engineers’ Handbook, 1997, 7th edition, McGraw-Hill, pages 14.95 and 14.96; the prevention of possible droplet entrainment is described on pages 14.87 to 14.90. The preformed iron carbonyl complex can be depressurized in one or two stages until the desired pressure in the range of 1 bar to about 5 bar is reached, during which the temperature typically drops to 10 °C to 40 °C.

[0145] Alternatively, the removal of the excess carbon monoxide can be achieved by so-called stripping of the iron carbonyl complex or the mixture containing the iron carbonyl complex with a gas (advantageously a gas that is inert under the reaction conditions). The term "stripping" is understood by those skilled in the art to mean introducing a gas into the iron carbonyl complex or the reaction mixture containing the iron carbonyl complex, as described, for example, in W.R.A. Vauck, H.A. Müller, Grundoperationen chemischer Verfahrenstechnik [Basic Operations in Chemical Process Technology], Deutscher Verlag für Grundstoffchemie, Leipzig, Stuttgart, 10th edition, 1984, page 800. Examples of suitable inert gases for this purpose include: hydrogen, helium, neon, argon, xenon, nitrogen and / or CO2, preferably hydrogen, nitrogen, argon.

[0146] Then, preferably, hydrogenation is carried out with hydrogen having a carbon monoxide content in the range of 50 to 3000 ppm, particularly in the range of 100 to 2000 ppm, especially in the range of 200 to 1000 ppm, and very especially in the range of 400 to 800 ppm.

[0147] The hydrogenation is advantageously carried out at a pressure of about 5 to about 200 bar, particularly about 10 to about 100 bar, especially at a pressure of about 60 to about 100 bar and at a temperature generally of about 0 °C to about 120 °C, preferably about 20 °C to about 110 °C, especially at about 50 °C to about 100 °C.

[0148] The choice of the solvent to be used for carrying out the hydrogenation is not critical. Suitable solvents that are inert under the reaction conditions are, for example, ethers, alcohols (such as ethanol, methanol, iPrOH, nPrOH, n-BuOH, and cyclohexanol), tetrahydrofuran, methyltetrahydrofuran, toluene, xylene, chlorobenzene, octadecanol, diphenyl ether, Texanol, Marlotherm, Oxo Oil 9N (a hydroformylation product from isooctene, BASF SE), etc. The substrate to be reacted, the product formed in the reaction, or any high-boiling by-products can also be used as the dissolution medium.

[0149] Suitable reaction vessels for carrying out the hydrogenation according to the invention are, in principle, all those vessels that allow the reaction to be carried out under the conditions mentioned (especially pressure and temperature) and are suitable for the hydrogenation reaction, such as autoclaves, tubular reactors, bubble columns, etc.

[0150] If a high-boiling, usually viscous solvent is used, such as those solvents mentioned above (for example, the solvents octadecanol, diphenyl ether, Texanol, Oxo Oil 9N) for the hydrogenation, or if the hydrogenation is carried out without the additional use of a solvent but with the accumulation of a small amount of high-boiling compounds formed as by-products (such as dimers or trimers formed by the reaction of reactants or products and subsequent secondary reactions), it may be advantageous to ensure good gas introduction and good mixing of the gas phase and the condensate phase. This is achieved, for example, by carrying out the hydrogenation step of the process according to the invention in a gas circulation reactor. Gas circulation reactors are known to those skilled in the art and are described, for example, in P. Trambouze, J.-P. Euzen, Chemical Reactors, edited by Technip, 2004, pages 280 - 283, and P. Zehner, R. Benfer, Chem. Eng. Sci. 1996, 51, 1735 - 1744, and are also described, for example, in EP 1 140 349.

[0151] When using the gas circulation reactor mentioned above, it has proven particularly advantageous to introduce the gas or gas mixture to be used (hydrogen gas containing carbon monoxide) and the reactants or catalyst introduced into the reactor and / or the circulating reaction mixture in parallel into the gas circulation reactor through a single nozzle or a two-phase nozzle. What is notable about this two-phase nozzle is the fact that the liquid and gas to be introduced into the reactor pass through two separate tubes (one inside the other) under pressure to reach the nozzle orifice, where they merge with each other.

[0152] The method according to the invention can be successfully carried out with and without the addition of a tertiary amine. An alcoholate, carbonate or hydrogencarbonate can also be added instead of the tertiary amine. Preferably, the method according to the invention is carried out in the absence (i.e., without addition) of an additional tertiary amine or in the presence of only a catalytic amount of an additional tertiary amine. The amount of amine used can be between 0.5 and 500 molar equivalents based on the amount of metal used, but is preferably 1 to 100 molar equivalents based on the amount of metal used. The choice of tertiary amine is not critical. In addition to short-chain alkyl amines such as triethylamine, long-chain alkyl amines such as tri-dodecylamine can also be used. In the context of a preferred embodiment, the hydrogenation method according to the invention is carried out in the presence of a tertiary amine (preferably tri-dodecylamine), the amount of which is about 2 to 30 molar equivalents, preferably about 5 to 20 molar equivalents, and particularly preferably 5 to 15 molar equivalents based on the amount of transition metal used.

[0153] Advantageously, the reaction is terminated when the target compound is present in the reaction mixture in the desired yield and optionally the desired optical activity (i.e., having the desired enantiomeric excess (ee), as can be determined by a person skilled in the art through routine experiments (e.g., by chromatography)). Typically, the hydrogenation is completed after about 1 to about 150 h, often after about 2 to about 24 h.

[0154] The method according to the invention enables the provision of hydrogenated olefins and optically active carbonyl compounds (especially optically active aldehydes) in high yield and enantiomeric excess. Typically, the compound to be asymmetrically hydrogenated is obtained with an enantiomeric excess of at least 80% ee, often with an enantiomeric excess of about 85% to about 99% ee. It should be noted here that the maximum achievable enantiomeric excess can depend on the purity of the substrate used, especially with respect to the isomeric purity of the double bond to be hydrogenated.

[0155] Thus, suitable starting materials are in particular those having an isomer ratio of at least about 90:10, preferably at least about 95:5, with respect to the E / Z double bond isomers.

[0156] Carbon monoxide preformed and / or additionally introduced into the reaction system enables the homogeneous catalyst used to be stabilized, which firstly greatly increases the service life of the catalyst and secondly enables the homogeneous catalyst to be reused.

[0157] For example, the obtained reaction product can be removed from the reaction mixture by methods known per se to those skilled in the art (such as by distillation), and the remaining catalyst can be used in further reactions, optionally after repeated preformation.

[0158] Thus, the process according to the invention can be operated discontinuously (batchwise), semi - continuously or continuously and is particularly suitable for reactions on an industrial scale.

[0159] In a preferred embodiment of the process according to the invention, the organic unsaturated compound is reacted in the presence of an iron precursor compound soluble in the reaction mixture (such as Fe(COT)(CO)3 (Va) or Fe(COT)(CO)3 (Va)) to give the desired organic compound.

[0160] Preferably, the catalyst is preformed under the above - mentioned conditions and then subjected to asymmetric hydrogenation in the presence of hydrogen particularly containing 50 to 3000 ppm of carbon monoxide. In the context of the preferred embodiment, the addition of a solvent is advantageously dispensed with and the reactions mentioned are carried out in the substrate or product to be reacted and optionally in high - boiling by - products as a dissolving medium. A continuous reaction scheme with repeated use or recycling of the homogeneous catalyst stabilized according to the invention is particularly preferred.

[0161] The following examples are used to illustrate the invention without in any way limiting the invention:

[0162] Examples

[0163] Example 1: Preparation of Fe(CO)3(R,R - Chiraphos)

[0164] Under a protective gas atmosphere, Fe(COT)(CO)3 (885 mg, 3.63 mmol) was dissolved in pure toluene (20 mL) at room temperature and mixed with R,R - Chiraphos (1.65 g, 3.87 mmol). The dark red solution was stirred at 105 °C for 96 h. The solution was filtered through silica gel and washed with toluene (20 mL). The filtrate was concentrated under reduced pressure and then redissolved in toluene (10 mL). The solution was cooled to - 20 °C, which caused a yellow solid to precipitate. The precipitate was separated from the solution by decantation. It was washed with pentane (10 mL) and dried under reduced pressure to give Fe(CO)3(R,R - Chiraphos) as a yellow solid (1.02 g, 1.8 mmol, 50% yield).

[0165] 1 1H NMR (500 MHz, CD2Cl2) δ = 7.7 - 7.5 (m, 10H), 7.3 - 7.4 (m, 10H), 2.16 (s, CH, 2H), 0.99 (s, CH3, 6H); 13 13C NMR (125 MHz, C6D6) δ = 221 (CO), 136.7, 134.6, 133.8, 132.0, 130.4, 130.2, 129.1, 128.1 (Ar - C) 40.5 (CH), 15.7 (CH3) ppm; 31 31P NMR (203 MHz, CD2Cl2) δ = 96 ppm; MS (LIFDI) C 31 H 28 FeO3P2([M] + ): Calculated: 566; Found: 566; IR (KBr): δ(CO) = 1977, 1906, 1883 cm -1 ; Optical rotation (Jasco P - 2000 polarimeter): [α] D 25 = -278 (in toluene c = 0.54).

[0166] The iron carbonyl complex A - 1 (Fe(CO)3(R,R - Chiraphos)) crystallizes in an orthorhombic unit cell, space group P212121 (see Figure 1 and 2 ).

[0167] The structure of Fe(CO)3(R,R - Chiraphos) was determined by single - crystal X - ray diffraction:

[0168] Details can be found in Tables 1, 2, and 3.

[0169] Table 1: Incorrect crystal structure data! No reference source found.

[0170] Formula C 31 H 28 FeO3P2

[0171]

[0172] Table 2: Incorrect measurement parameters and structure solution! No reference source found.

[0173]

[0174]

[0175] Table 3: Coordinates and isotropic atomic displacement parameters

[0176]

[0177]

[0178] Example 2: Hydrogenation using Fe(CO)3(R,R-Chiraphos) as the catalyst

[0179] Initially, Fe(CO)3(R,R-Chiraphos) (70 mg, 0.12 mmol) and cyclohexene (5.0 g, 61 mmol) were charged into toluene (10 ml, Sigma-Aldrich) in a 60 ml steel autoclave (V2A steel, manufacturer Premex, magnetic coupling jet stirrer, 1000 rpm), and the hydrogen pressure was set to 60 bar. The temperature was raised to the values given in the table below. After reaching the desired reaction temperature, the hydrogen pressure was set to 80 bar. After 20 h, the mixture was cooled to room temperature and depressurized. The reaction output was analyzed by GC. VF-Wax column (30 m × 0.25 mm / 0.5 μm; 5 min at 60 °C, then to 250 °C at 20 °C / min; flow rate: 2.0 mL / min; H2 as the carrier gas). The conversion was determined by GC area %.

[0180]

[0181] a) Conversion (GC) after 20 h, b) carried out as in Example 2, except that 5 g of another reactant was used instead of 5 g of cyclohexene, c) addition of 1 mol% of KOtBu, d) product: N-(1-phenylethyl)aniline.

Claims

1. An iron carbonyl complex having the following general formula LFe(CO)3 (I), wherein L is a chiral bidentate diphosphine ligand preferably selected from compounds of the formula and its enantiomers, wherein R 1 and R 2 each independently is an unbranched, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, the hydrocarbon group being saturated or may contain one or more, usually 1 to about 4 non-conjugated ethylenic double bonds, and the hydrocarbon group being unsubstituted or bearing one or more, usually 1 to 4 identical or different substituents selected from OR 9 、NR 10 R 11 、halogen, C6-C 10 -aryl and C3-C9-heteroaryl, or R 1 and R 2 together may also be a C2-C10 alkylene or a C3-C10 cycloalkylene group, where one, two, three or four non-adjacent CH2 groups may be replaced by O or N-R 9c substituents, where the alkylene and cycloalkylene groups are saturated or contain one or two non-conjugated olefinic double bonds, and where the alkylene and cycloalkylene groups are unsubstituted or carry one or more identical or different substituents selected from C1-C4-alkyl; R 3 and R 4 each independently is hydrogen or a straight-chain or branched C1-C4-alkyl group, and R 5 、R 6 、R 7 and R 8 are the same or different and are unsubstituted or carry one or more substituents selected from the following C6-C 10 -aryl: C1-C6-alkyl, C3-C6-cycloalkyl, C6-C 10 -aryl, C1-C6-alkoxy and amino; R 9c is hydrogen, C1-C6-alkyl, C6-C 10 -aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl, R 9 , R 10 and R 11 are independently hydrogen, C1-C4-alkyl, C6-C 10 -Aryl, C7-C 12 -aralkyl or C7-C 12 -alkylaryl, wherein R 10 and R 11 together may also be an alkylene chain having 2 to 5 carbon atoms, which may be inserted with N or O.

2. The iron carbonyl complex according to claim 1, wherein R 1 and R 2 each independently is an unbranched, branched or C1-C4-hydrocarbyl group, or R 1 and R 2 together are a C3-C7-alkanediyl, C3-C7-alkenediyl, C5-C7-cycloalkanediyl or C5-C7-cycloalkenediyl group, where the four groups mentioned above are unsubstituted or carry one or more identical or different substituents selected from C1-C4-alkyl groups; R 3 and R 4 each independently is hydrogen or a straight-chain or branched C1-C4-alkyl group; and wherein, in the C3-C7-alkanediyl group, one or two additional non-adjacent CH2 groups may be replaced by O, or the CH2 group may be replaced by N-CH2Ph; and R 5 、R 6 、R 7 and R 8 are phenyl groups.

3. The iron carbonyl complex according to claim 1, wherein The chiral bidentate diphosphine ligand L is selected from compounds having the formulas (1) to (91):

4. The iron carbonyl complex according to claim 1 or 2, wherein The chiral bidentate diphosphine ligand L is a compound having the general formula (II).

5. The iron carbonyl complex according to claim 4, wherein The chiral bidentate diphosphine ligand is selected from those having the general formula A compound, where Ph is phenyl and Bn is benzyl.

6. The iron carbonyl complex according to claim 5, wherein The chiral bidentate diphosphine ligand is the compound having the formula wherein Ph is phenyl.

7. The iron carbonyl complex according to claim 6, namely Fe(CO)3(R,R-Chiraphos), which crystallizes in an orthorhombic unit cell with space group P212121.

8. A method for preparing an organic compound by: hydrogenating an unsaturated organic compound with hydrogen in the presence of at least one iron carbonyl complex according to any one of claims 1 to 7 or an iron carbonyl complex formed therefrom and containing a fragment having the formula LFeCO(I') or LFeCO2(I”).

9. Use of an iron carbonyl complex according to any one of claims 1 to 7 or an iron carbonyl complex formed therefrom and containing a fragment of formula LFeCO(I') or LFeCO2(I”) for the preparation of an organic compound by hydrogenating an unsaturated organic compound with molecular hydrogen.

10. The method according to claim 8 or the use according to claim 9, wherein The unsaturated organic compound is a di- or tri-substituted prochiral or achiral unsaturated organic compound, in particular a prochiral or achiral unsaturated carbonyl compound.

11. The method or use according to claim 8, wherein The unsaturated compound is a prochiral or achiral α,β-unsaturated ketone or a prochiral or achiral α,β-unsaturated aldehyde.

12. The method according to any one of claims 8, 10 and 11, having at least one or all of the following features a–h: a) The hydrogenation is carried out at a hydrogen pressure of 5 to 200 bar, in particular at a hydrogen pressure of 10 to 100 bar; b) The method is carried out batchwise or continuously; c) The iron carbonyl complex is generated in situ by reaction of an achiral iron precursor compound with a chiral bidentate diphosphine ligand L and optionally CO before or during the hydrogenation; d) The catalyst is pretreated with a gas mixture containing carbon monoxide or carbon monoxide / hydrogen before the hydrogenation; e) The hydrogenation is carried out in the presence of carbon monoxide additionally supplied to the reaction mixture; f) The hydrogenation is carried out with hydrogen having a carbon monoxide content in the range of 50 to 3000 ppm, in particular in the range of 100 to 2000 ppm; g) The hydrogenation is carried out in a gas circulation reactor; h) The hydrogenation is carried out in a gas circulation reactor, wherein the unsaturated compound and the hydrogen are introduced into the gas circulation reactor through a two-phase nozzle.

13. A method for preparing an iron carbonyl complex according to any one of claims 1 to 7, the method comprising the reaction of a chiral bidentate diphosphine ligand L, preferably selected from compounds of formula and their enantiomers, with an achiral iron precursor compound and optionally CO, wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 have the definitions given in claim 1.

14. The method according to claim 13, wherein The iron precursor compound is a compound having the formula Fe(COT)(CO)3 (Va) or Fe(CO)5 (Vb), where COT is cyclooctatetraene.

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