Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C403/00—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone
  • C07C403/24—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone having side-chains substituted by six-membered non-aromatic rings, e.g. beta-carotene
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C403/00—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone
  • C07C403/06—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone having side-chains substituted by singly-bound oxygen atoms
  • C07C403/08—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone having side-chains substituted by singly-bound oxygen atoms by hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
  • C07B2200/00—Indexing scheme relating to specific properties of organic compounds
  • C07B2200/07—Optical isomers
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2601/00—Systems containing only non-condensed rings
  • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
  • C07C2601/16—Systems containing only non-condensed rings with a six-membered ring the ring being unsaturated

Definitions

• the present invention relates to a process for preparing cyclic ⁇ -ketoalcohols from cyclic ⁇ -ketoenols or from their tautomeric diketones, in particular comprising a 6-hydroxycyclohexadienone as starting compound. It also includes the use of cyclic ⁇ -ketoenols for the production of astaxanthin in different isomeric forms.
• Astacin has some interest as a potential starting material for the synthesis of astaxanthin, and while no regioselective hydrogenation of 2,3-double bonds has been reported to date, electrochemical reduction under acylating conditions has been reported Astaxanthin in a yield of 10% allowed "[E. A.H. Hall, G.P. Moss, J.H.P. Utley, B.C.L. Weedon, Chem. Commun. (1978) 387]. Astacin has the structural formula L2, which is given below, and can not be compared with a C15 intermediate, ie a building block composed of only 15 C atoms.
• a problem to be solved for the skilled person is to find a way to selectively convert cyclic ⁇ -ketoenols or their tautomeric diketones into cyclic ⁇ -ketoalcohols.
• Selective means that apart from the enol group in the ⁇ -ketoenol - or the corresponding keto group in the diketone - existing functional groups do not react or only to a very limited extent.
• a method is to be established which allows 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethyl -cyclohexa-2,5-diene-1 -one or 6-hydroxy-3 - [(1E / Z, -3E / Z) -5-hydroxy-3-methyl-penta-1,3-dienyl] -2
• This method should be possible with little equipment and possible on an industrial scale.
• Another object is to provide cyclic ⁇ -ketoenols (or diketones) such as 6-hydroxycyclohexadienones, in particular 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl ] -2,4,4-trimethylcyclohexa-2,5-diene-1 -one or 6-hydroxy-3 - [(1E / Z, 3E / Z) -5-hydroxy-3-methyl-penta- 1, 3-dienyl] -2,4,4-trimethyl-cyclohexa-2,5-dien-1 -one stereoselectively implement, that is to say implement so that for the most part and, if possible, in each case only one stereoisomer is formed as the target compound. Also, the stereoselective reactions should be easy to carry out and transferable to a large
• a 6-hydroxycyclohexadienone which is selected from the group consisting of 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1, 4- dienyl] -2,4,4-trimethyl-cyclohexa-2,5-diene-1-one of the formula 2a and 6-hydroxy-3 - [(1 E / Z, 3 E / Z) -5-hydroxy-3- methyl-penta-1,3-dienyl] -2,4,4-trimethyl-cyclohexa-2,5-diene-1-one of the formula (2b) is reacted with a reducing agent stereoinselective or stereoselective.
• Stepselective means that the reaction of the reactant produced by the reducing agent results in a product without any steric preference.
• stereoselective is meant that the reducing agent produces products, namely enantiomers or diastereomers, which predominantly form only one configuration at the site of reduction (at the stereocenter), if possible only one configuration.
• cyclic ⁇ -ketoenols used as starting compounds by the invention in particular the 6-hydroxycyclohexadienones 2a and 2b, can also be understood as tautomeric diketones according to the equilibrium shown below.
• the term "cyclic ⁇ -ketoenol" includes not only the tautomer T1 but also always the tautomer T2
• the tautomers T1 and T2 need not necessarily contain cyclic methyl groups, as previously shown all those compounds which are suitable for converting a cyclic ⁇ -ketoenol into the corresponding alcohol
• the term reducing agent is to be understood as meaning all those compounds which convert a cyclic ⁇ -ketoenol into the corresponding alcohol, without the other functional groups of the starting material, in particular a 6-hydroxycyclohexadienone and very particularly of the compounds 2a, 2b are reacted with.
• the reducing agent is at least one compound selected from the group consisting of hydrogen gas; a secondary alcohol, preferably isopropanol or butan-2-ol;
• Formic acid the salts of formic acid, in particular an alkali metal, alkaline earth metal or ammonium formate or a mono-, di-, tri- or tetra (C 1 -C 4) -alkylammonium formate.
• a secondary alcohol is a compound in which there are two alkyl groups on the ipso-C atom, with alkyl including each group with the molecular formula CnH n + i.
• Secondary alcohols are selected from the group consisting of propan-2-ol, butan-2-ol, 3-methylbutan-2-ol, 3,3-dimethylbutan-2-ol, pentan-2-ol, pentane 3-ol, 2-methylpentan-3-ol, 3-methylpentan-2-ol, 4-methylpentan-2-ol, 2,2-dimethylpentan-3-ol, 2,4-dimethylpentan-3-ol , 3,3-dimethylpentan-2-ol, 4,4-dimethylpentan-2-ol, 2,2,4-trimethylpentan-3-ol, 2,2,4,4-tetramethylpentan-3-ol , Hexan-2-ol, hexan-3-ol, 2-methylhexan-3
• the alcohols are isopropanol and / or butan-2-ol are preferred, since they are available at a low cost and on the other hand in the reduction acetone or methyl ethyl ketone, two solvents that can be easily separated due to their low boiling points .
• the reducing agent is preferably at least one compound which is selected from the group of formic acid and / or salts of formic acid. These links are reasonably priced in procurement.
• carbon dioxide is released, which is continuously released from the reaction vessel without great effort or at the end of the reaction. As a result, an apparatus-simple and targeted reaction is possible. In addition, it simplifies the work-up of the reaction mixture considerably and thus reduces the costs of the manufacturing process.
• Salts of formic acid are all those compounds containing a formate anion and as counterion an organic or inorganic cation.
• a mono-, di- or tri- or tetra (C 1 -C 4) -alkyl ammonium formate contains a formate anion and a nitrogen-bearing cation as counterion.
• the nitrogen-bearing cation is an ammonium ion which contains four hydrogen atoms besides nitrogen or one (mono), two (di), three (tri) or four (tetra) alkyl groups instead of hydrogen.
• the at least one alkyl group is a C1-C4 alkyl group, that is, it is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl.
• Suitable and inexpensive salts of formic acid include trimethylammonium formate, triethylammonium formate, tri-n-butylammonium formate, ethyldiisopropylammonium formate, tetrabutylammonium formate or a mixture of at least two of these salts.
• the reducing agent is particularly preferably an alkali metal salt or an alkaline earth metal salt or an ammonium salt of formic acid or a mixture of at least two of these compounds.
• the gaseous carbon dioxide fall in the reduction with one of these reducing agents to by-products, which are either dissolved in a polar phase or precipitated as a salt. As a result, separation from the reaction product is particularly easy.
• the reducing agent is at least one compound selected from the group consisting of sodium formate, potassium formate, magnesium formate, calcium formate and ammonium salts, that of ammonia, ie ammonium formate.
• these reducing agents have in common that they are very cost-effective. This is because the formates of sodium, potassium, magnesium and calcium, as well as those of ammonia, are readily available and obtainable from various suppliers.
• Ammonium formate also offers the advantage of releasing ammonia at elevated temperatures. From this point of view, excess ammonium formate can be decomposed and separated by heating at the end of the reduction.
• the reducing agent is selected from the group of formates of primary amines, in particular from the formate at least one of the amines methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, sec-butylamine, tert-butylamine, isobutyl lamin, n-pentylamine, aniline, benzylamine.
• the reducing agent is at least one compound selected from the group consisting of secondary or tertiary amines of formic acid.
• Secondary amines of formic acid are composed of an anion and a singly protonated ⁇ , ⁇ -dialkylamine as a cation.
• Secondary amines of formic acid include the formate of dimethylamine, diethylamine, di-n-propylamine, di-n-butylamine or a mixture of at least two of these compounds.
• Tertiary amines of formic acid consist of a formation as anion and a singly protonated ⁇ , ⁇ , ⁇ -trialkylamine as a cation.
• Tertiary amines of formic acid include the formate of trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, ethyldiisopropylamine or a mixture of at least two of these compounds.
• the reducing agent is at least one compound selected from the group of quaternary ammonium salts of formic acid.
• Quaternary ammonium salts of formic acid are compounds consisting of an anion as an anion and a ⁇ , ⁇ , ⁇ , ⁇ -tetraalkylammonium ion as a cation.
• Quaternary salts of formic acid include, for example, tetraethylammonium formate, tetrabutylammonium formate, triisopropylethylammonium formate.
• the reducing agent is preferably at least one compound selected from the group of salts of formic acid, wherein the salts are generated in situ by neutralization of formic acid with a corresponding base.
• This base is selected from the group ammonia and / or primary amines and / or secondary amines and / or tertiary amines. Salts of formic acid generated in this way are always particularly advantageous if salt formation is to take place only slowly or if salt compounds are to be used which are not readily available for sale.
• the reducing agent is preferably at least one compound selected from the group of salts of formic acid, the salts being used as such. Such salts are always found to be favorable if they are readily available and readily storable and a reaction-dependent minimum or maximum concentration of these salts need not be regulated by in situ formation.
• the inventive process is continued by reacting the cyclic a-ketoenol, in particular the 6-hydroxycyclohexadienone with the reducing agent in the presence of a transition metal catalyst, stereoselective or stereoselective; preferably in the presence of an achiral or optically active transition metal catalyst.
• a transition metal catalyst stereoselective or stereoselective; preferably in the presence of an achiral or optically active transition metal catalyst.
• a transition metal catalyst is meant a compound that accelerates a reaction. It contains at least one transition metal, i. at least one metal of the third to twelfth group of the periodic table and at least one ligand.
• An optically active transition metal catalyst is also a compound that accelerates a reaction. It contains at least one transition metal of the third to twelfth group of the periodic table and at least one optically active ligand.
• Optically active ligands are those ligands capable of more or less rotating the plane of polarization of a beam of linearly polarized light.
• the transition metal catalyst has been found to have a transition metal selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag and Au for the inventive method is to be used.
• the transition metals Zr, Nb, Mo, W, Ru, Co, Rh, Ir, Ni, Pd are particularly suitable because of their relative availability and / or their reactivity, especially the transition metals Mo, Ru, Co, Rh, Ir, Ni, Pd , Particularly good results were obtained with the transition metals Ru, Ir, Ni, Pd with appropriate ligand arrangement.
• ruthenium has proved to be particularly suitable for the inventive process in the experiments carried out, since it was possible to obtain high yields of 6-hydroxycyclohexenone, in particular to compound 1 a, 1 b, without the carbonyl group at position 1 and further functional groups of the 6-hydroxycyclohexadienones, in particular the starting compounds 2a, 2b, were noticeably reacted with, if at all not being reacted with.
• the transition metal catalyst suitable for reducing the double bond at the position ⁇ 5 6 (equivalent to a keto group in position 6) of the 6-hydroxycyclohexadienones, especially the compounds 2a, 2b to the corresponding secondary alcohol contains a transition metal atom and at least one optional achiral one or optically active ligands.
• a transition metal atom in principle, all transition metals, such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu , Ag or Au in question, which can form a suitable transition metal catalyst.
• the Mattergangsmetallkatalysa- tor contains at least one ligand selected from amines and / or phosphines.
• the ligand is selected from amines and / or phosphanes and / or aromatic compounds and / or halides.
• the aromatic compounds are complexed to the transition metal and optionally covalently linked to an amine or phosphine ligand. Namely, such species have proven to be particularly suitable when it comes to coordinating with a transition metal.
• the cyclic ⁇ -ketoenol in particular the 6-hydroxycyclohexadienone, is then stereoselective or stereoselective in particular with the reducing agent in the presence of a transition metal catalyst; preferably in the presence of an optically active transition metal catalyst, when the transition metal of the transition metal catalyst is ruthenium (Ru) and the ligand is selected from amines.
• a transition metal catalyst preferably in the presence of an optically active transition metal catalyst, when the transition metal of the transition metal catalyst is ruthenium (Ru) and the ligand is selected from amines.
• the ligand phosphine is preferably a phosphine of the general formula 3,
• R, R 'and R are independently selected from the group consisting of one of the radicals C 1 -C 4 -alkyl, phenyl, one to three C 1 -C 4 -alkyl substituted aryl, preferably a triarylphosphane and most preferably triphenylphosphane.
• C 1 -C 4 Alkyl means a group selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl.
• Aryl includes all aromatic bases, especially phenyl and benzyl.
• C 1 -C 4 alkyl substituted aryl is an aryl as defined previously linked to one, two, three or four or five C 1 -C 4 alkyl radicals as previously defined.
• a particular disclosure of the invention provides for a process for preparing a cyclic ⁇ -ketoalcohol, in particular a 6-hydroxycyclohexenone, which is selected from the group consisting of 6-hydroxy-3 - [(1 E / Z) -3-hydroxy] 3-methyl-penta-1,4-dienyl] -2,4,4-trimethylcyclohex-2-en-1-one of the formula 1 a and 6-hydroxy-3 - [(1 E / Z, 3E / Z) -5-hydroxy-3-methyl-penta-1,3-dienyl] -2,4,4-trimethyl-cyclohex-2-en-1-one of the formula 1 b
• a cyclic ⁇ -ketoenol in particular a 6-hydroxycyclohexadienone, which is selected from the group consisting of 6-hydroxy-3 [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethyl-cyclohexa-2,5-diene-1-one of the formula 2a and 6- Hydroxy-3 - [(1E / Z, 3E / Z) -5-hydroxy-3-methyl-penta-1,3-dienyl] -2,4,4-trimethylcyclohexa-2,5-diene-1 -on the formula 2b
• a transition metal catalyst as a transition metal ruthenium (Ru) and at least one ligand selected from the group consisting of H2N-CH2-CH2-OH, MeHN-CH2-CH2-OH, H2N-CH2-CH2-NH2, TSNH-CH2-CH2-NH2, TsNH-CH2- CH 2 -NH- (CH 2
• the transition metal catalysts required for the racemic mixtures can be prepared, for example, by reacting a suitable ruthenium compound such as [RuX 2 (n 6 -Ar)] 2 with a suitable ligand, where X represents a halogen atom such as fluorine, chlorine, bromine or iodine, and Ar for Benzene or a substituted benzene derivative, in particular a substituted with C1-C4-alkyl radicals benzene derivative.
• a suitable ruthenium compound such as [RuX 2 (n 6 -Ar)] 2
• X represents a halogen atom such as fluorine, chlorine, bromine or iodine
• Ar for Benzene or a substituted benzene derivative, in particular a substituted with C1-C4-alkyl radicals benzene derivative.
• C 1 -C 4 -alkyl has the meaning already mentioned above.
• an optically active transition metal catalyst which contains a transition metal atom and at least one optically active ligand, wherein the transition metal atom is ruthenium (Ru), is particularly preferably used.
• the transition metal catalyst containing a transition metal atom and at least one optically active ligand and the transition metal atom ruthenium (Ru) is.
• Preferred chiral insbesndere optically active ruthenium catalysts can be prepared for example by reacting a suitable ruthenium compound such as [RuX 2 (n 6 - Ar)] produce 2 with a suitable chiral, in particular optically active ligand, wherein X is a halogen atom such as fluorine, chlorine, bromine or iodine and Ar is benzene or a substituted benzene derivative, in particular a C1-C4-alkyl radical-substituted benzene derivative.
• C 1 -C 4 -alkyl has the meaning already mentioned above.
• optically active ruthenium catalyst is preferably characterized in that the optically active ligand is an optically active amine or an optically active amino acid.
• optically active amines which can be reacted with a suitable ruthenium compound, in particular [RuX 2 (n 6 -Ar)] 2, to the catalytically active complex are H 2 IM-CHPh-CHPh-OH, H 2 N-CHMe-CHPh-OH, MeHN-CHMe-CHPh-OH, TsNH-CHPh-CHPh-NH 2 , (1S, 2S) -Np-toulolene-sulfonyl-1,2-diphenylethylenediamine, (1R, 2R) -Np-touluenesulfonyl-1,2-diphenylethylenediamine , N - [(1S, 2S) -1, 2-diphenyl-2- (2- (4-methylbenzyloxy) e
• the transition metal catalyst contains at least one ligand selected from the group consisting of an optically active amine, in particular H 2 N-CHPh-CHPh-OH, H 2 N-CHMe-CHPh-OH , MeHN-CHMe-CHPh-OH, TsNH-CHPh-CHPh-NH 2 , (1S, 2S) -N-p-toluene-sulfonyl-1,2-diphenyl-ethylenediamine, (1R, 2R) -Np-touluolsulfonyl-1, 2-diphenylethylenediamine, N - [(1S, 2S) -1, 2-
• transition metal catalyst according to the invention contains the ligands mentioned in the last paragraph, a simple and efficient route is taken, strongly stereoisomer-enriched or even stereoisomerically pure, cyclic a-ketoalcohols, in particular 6-hydroxycyclohexenones, in good yields from the corresponding cyclic .alpha.-ketoenols in particular to produce the corresponding 6-hydroxycyclohexadienones, as shown below.
• a particularly important forwarding is essential to the invention. It comprises a process for preparing a cyclic ⁇ -ketoalcohol, in particular a 6-hydroxycyclohexenone, which is selected from the group consisting of 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl- penta-1,4-dienyl] -2,4,4-trimethylcyclohex-2-en-1-one of formula 1a and 6-hydroxy-3 - [(1E / Z, 3E / Z) -5 -hydroxy-3-methyl-penta-1,3-dienyl] -2,4,4-trimethylcyclohex-2-en-1-one of the formula 1 b
• a cyclic ⁇ -ketoenol in particular a 6-hydroxycyclohexadienone, which is selected from the group consisting of 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethyl-cyclohexa-2,5-diene-1-one of the formula 2a and 6 -Hydroxy-3 - [(1E / Z, -3E / Z) -5-hydroxy-3-methyl-penta-1,3-dienyl] -2,4,4-trimethylcyclohexa-2,5-diene -1 -one of formula 2b with a reducing agent which is selected from the group consisting of formic acid, the salts of formic acid, isopropanol or butan-2-ol, stereoselect
• the respective other stereoisomers ie the respective other enantiomer or the diastereomers of the ⁇ -ketoalcohol, in particular the stereoisomers of the 6-hydroxycyclohexenone, are obtained in this process only in very small amounts and preferably not at all.
• the compound of the formula (6S-1 a / b) is obtained in high enantiomeric purity, while when using (1 R, 2R) -Np-toluenesulfonyl-1, 2-diphenylethylenediamine as optically active ligand, the compound of formula (6R-1 a / b) is produced. It has been found in the process of the present invention that most of the transition metal catalysts, including most of the chiral transition metal catalysts, are particularly efficient when at least one of their ligands is simply deprotonated.
• a chiral ruthenium catalyst in which the optically active ligand and by simple deprotonation of H 2 N-CHPh-CHPh-OH, H 2 N-CHMe-CHPh-OH, MeHN-CHMe-CHPh-OH or TsNH-CHPh -CHPh-NH 2 , in particular by simple deprotonation of (1 S, 2S) -Np-toluenesulfonyl-1, 2-diphenylethylenediamine or (1 R, 2R) -Np-toluenesulfonyl-1, 2-diphenylethylenediamine is available.
• an embodiment of the method according to the invention provides that the ligand, in particular the ligand selected from amines, is deprotonated, preferably once deprotonated.
• the transition metal catalyst contains at least one ligand selected from the group consisting of an optically active amine, in particular H 2 N-CHPh-CHPh-OH, H 2 N-CHMe-CHPh-OH , MeHN-CHMe-CHPh-OH, TsNH-CHPh-CHPh-NH 2 , (1S, 2S) -N-p-toluene-sulfonyl-1,2-diphenylethylenediamine, (1R, 2R) -Np-touluolsulfonyl-1, 2 diphenylethylenediamine, N - [(1S, 2S) -1, 2-diphenyl-2- (2- (4-methylbenzyloxy) ethylamino) ethyl] -4-methylbenzene sulfonamide, N - [(1R, 2R) -1 , 2-diphenyl-2- (2- (4-methylbenzyloxy) ethylamino
• Transition metal catalysts from a reaction mixture means an additional filtration or extraction step. This step is indispensable in many of these transition-metal catalysts because they would lose some or all of their catalytic activity upon any fixation or immobilization. For some transition metal catalysts, however, such fixation does not matter.
• a very economically designed variant of the inventive method provides that the transition metal is applied to a solid support; preferably on a solid support containing at least one substance selected from the group consisting of carbon, alumina and silica; and most preferably on a solid support made up of at least one substance selected from the group consisting of carbon, alumina and silica.
• a separation of the transition metal catalyst from the reaction product ⁇ -ketoalcohol, in particular from 6-hydroxycyclohexenone and in particular from the compounds 1 a, 1 b is avoided in the sense of a separate process step.
• the reduction of ⁇ -ketoenols, in particular of 6-hydroxycyclohexadienones, such as the compounds 2a, 2b was attempted at very different pH values, with the result that that complete or almost complete conversion to the corresponding ⁇ -keto-alcohol is possible only in a basic environment.
• a further aspect of the invention therefore provides that a-ketoenols, in particular a 6-hydroxycyclohexadienone in the basic, preferably in a pH range of 8 to 12, is reacted with a reducing agent in a stereounselective or stereoselective manner.
• the bases used are either the abovementioned amine ligands and / or additional base is added.
• the base used is ammonia, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, diisopropylethylamine or a mixture of at least two of these compounds.
• a more specific embodiment of the invention determines that ⁇ -ketoenols, in particular a 6-hydroxycyclohexadienone in the basic, preferably in a pH range of 8 to 12, with a reducing agent stereounselektiv or stereoselectively implemented, using bases are selected from the group consisting of ammonia, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, diisopropylethylamine or a mixture of at least two of these compounds.
• asymmetric center in position 6 is racemic, or (S) - or (R) -, in which according to the invention a cyclic ⁇ -ketoenol, in particular a 6-hydroxycyclohexadienone, which is selected from the group consisting of 6-hydroxy-3- [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethyl-cyclohexa-2,5-diene-1-one of the formula 2a and 6- Hydroxy 3 - [(1E / Z, 3E / Z) -5-hydroxy-3-methyl-penta-1,3-dienyl] -2,4,4-trimethylcyclohexa-2,5-diene-1 -on the formula 2b in the basic, preferably in a pH range of 8 to 12, with a reducing agent which is selected from the group consisting of formic acid and / or the salts of formic acid, isopropanol, butan-2-
• a variant for producing enantiomerically / respectively diastereomerically enriched or enantiomeric / diastereomerically pure compounds provides a process for the preparation of a cyclic ⁇ -ketoalcohol, in particular a 6-hydroxycyclohexenone, which is selected from the group consisting of 6-hydroxy-3- [(1 E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethyl-cyclohex-2-en-1-one of the formula Ia and 6-hydroxy 3 - [(1E / Z, 3E / Z) -5-hydroxy-3-methyl-penta-1,3-dienyl] -2,4,4-trimethylcyclohex-2-en-1 -one of Formula 1 b
• a cyclic ⁇ -ketoenol in particular a 6-hydroxycyclohexadienone, which is selected from the group consisting of 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethyl-cyclohexa-2,5-diene-1-one of the formula 2a and 6 -Hydroxy-3 - [(1E / Z, -3E / Z) -5-hydroxy-3-methyl-penta-1,3-dienyl] -2,4,4-trimethylcyclohexa-2,5-diene -1 -one of the formula 2b H in the basic, preferably in a pH range of 8 to 12, with a reducing agent which is selected from the group consisting of formic acid, the salts of formic acid, is
• the process according to the invention is therefore usually carried out in many cases in the liquid phase, ie in at least one solvent or solvent mixture.
• the liquid phase contains at least one organic solvent, wherein the liquid phase usually consists of more than 50% by volume of organic solvents
• a further variant of the invention therefore provides that the cyclic o ketoenol, in particular the 6-hydroxycyclohexadienone is reacted in a liquid medium with a reducing agent stereoinselektiv or stereoselectively, preferably in a liquid medium, the more than 50% by volume of at least an organic solvent.
• a liquid medium any single or multi-phase liquid composition of a solvent or mixture of solvents.
• the liquid medium is therefore selected from the group consisting of dichloromethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, acetonitrile, ethylene carbonate, propylene carbonate, dimethylformamide, dimethyl sulfoxide, ethyl acetate, n-propyl acetate, toluene, xylene, heptane, hexane, pentane, N-methyl - 2-pyrrolidone, dioxane, 2-methyl-tetrahydrofuran, methyl tert-butyl ether, diisopropyl ether, diethyl ether, di-n-butyl ether, water or from a mixture of at least two of these solvents. If the proportion of organic solvent is greater than 50% by volume, reaction educts and reaction products dissolve relatively well.
• the liquid medium may therefore contain water in particular.
• the inventive method determines that the cyclic ⁇ -ketoenol, in particular the 6-hydroxycyclohexadienone is reacted in a liquid medium with a reducing agent stereoinselective or stereoselective, preferably in a liquid medium, which is more than 50% by volume consists of at least one organic solvent and contains water as an inorganic solvent.
• the liquid medium can represent a 1-phase, 2-phase or even multi-phase system. Solubilities and thus reaction rates differ from starting compound to starting compound. However, in a variety of experiments, some solvents or mixtures of them have been found to be particularly suitable.
• the solvents used are in particular mixtures of dichloromethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and also THF and water.
• the organic solvent contains at least one compound which is selected from the group consisting of dichloromethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethylformamide, dimethyl sulfoxide, ethyl acetate, n- Propyl acetate, toluene, xylene, heptane, hexane, pentane, N-methyl-2-pyrrolidone, dioxane, 2-methyl-tetrahydrofuran, methyl tert-butyl ether, diisopropyl ether, diethyl ether, di-n-butyl ether, acetonitrile and preferably from Group consisting of dichloromethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, acetonitrile,
• cyclic ⁇ -ketoenol in particular the 6-hydroxycyclohexadienone, is reacted in a liquid medium with a reducing agent in a stereounselective or stereoselective manner, preferably in a liquid medium which is more than 50% by volume selected from at least one organic solvent consisting of the group consisting of dichloromethane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, acetonitrile, propylene carbonate, ethylene carbonate and contains water as an inorganic solvent.
• a further continuation of the invention leads to high yields after a short reaction time. It comprises a process for preparing a cyclic ⁇ -ketoalcohol, in particular a 6-hydroxycyclohexenone, which is selected from the group consisting of 6-hydroxy-3- [(1E / Z) -3-hydroxy-3-methylpenta- 1,4-dienyl] -2,4,4-trimethylcyclohex-2-en-1-one of the formula Ia and 6-hydroxy-3 - [(1E / Z, 3E / Z) -5-hydroxy 3-methyl-penta-1,3-dienyl] -2,4,4-trimethyl-cyclohex-2-ene-1-ol of formula 1b wherein the asymmetric center in position 6 is racemic, or (S) - or (R) -, in which according to the invention a cyclic ⁇ -ketoenol, in particular a 6-hydroxycyclohexadienone, which is selected from the group consisting of 6-hydroxy-3
• a process for preparing a cyclic ⁇ -ketoalcohol, in particular a 6-hydroxycyclohexenone which is selected from the group consisting of 6-hydroxy-3- [(1E / Z) -3-hydroxy-3-methylpenta- 1,4-dienyl] -2,4,4-trimethylcyclohex-2-en-1-one of the formula Ia and 6-hydroxy-3 - [(1E / Z, 3E / Z) -5-hydroxy 3-methyl-penta-1,3-dienyl] -2,4,4-trimethyl-cyclohex-2-ene-1-ol of formula 1b wherein the asymmetric center is configured in position 6 (S) - or (R) - in which, according to the invention, a cyclic ⁇ -ketoenol, in particular a 6-hydroxycyclo
• the optically active transition metal catalyst as the transition metal ruthenium (Ru) contains and at least one ligand selected from the group consisting of H 2 N-CHPh-CHPh-OH, H 2 N-CHMe-CHPh-OH, MeHN -CHMe-CHPh-OH, TsNH-CHPh-CHPh-NH 2 , (1S, 2S) -Np-toulolene-sulfonyl-1,2-diphenylethylenediamine, (1R, 2R) -N-p-toluene-sulfonyl-1,2-diphenylethylenediamine, N - [(1S, 2
• the inventive method produces high yields of cyclic ⁇ -ketoalcohol or 6-hydroxycyclohexenone, even at low temperatures within a reasonable time. It is therefore the object of a further inventive modification that the cyclic ⁇ -ketoenol, in particular the 6-hydroxycyclohexadienone at a temperature of 10 ° C to 85 ° C; preferably from 20 ° C to 60 ° C, with a reducing agent stereounselektiv or stereoselectively.
• the inventive method can also be carried out under pressure.
• the preferred pressure range is between 0 and 10 bar. Even under pressure, the most preferred temperature range is 20 to 60 ° C.
• the reaction can be carried out batchwise in the batch or semi-batch mode or continuously in the apparatuses customary to the person skilled in the art. As an example may be mentioned, stirred tank, stirred tank cascade and tubular reactor.
• the workup is also carried out under the usual methods. Preference is given to extraction and crystallization.
• Another object of the present invention is a process for the preparation of (3S, 3'S) -Astaxanthin, wherein in a reaction step of the total synthesis of (3S, 3'S) -Astaxan- thin the above-described compound of formula (6S-1 a / b) according to produced by the process according to the invention.
• (3R, 3'R) -astaxanthin can be prepared using a compound of formula (6R-1 a / b).
• the advantage of the method according to the invention lies in the simplified recovery of compounds of the formulas (6S-1 a / b) and (6R-1 a / b) with high enantiomeric purity associated with good yields of these compounds.
• the counting is such that the cyclic OH group is in position 6, the counting method in the compounds of astaxanthin 4a, 4b and 4c so that the cyclic OH group is at position 3 or 3 'in the respective astaxanthin molecule.
• the compounds produced by the inventive process can be used as precursor molecules for different carotenoids, i.a. also for the synthesis of astaxanthin, wherein the term astaxanthin both racemic mixtures, as well as mesoforms and all enantiomerically pure representatives of astaxanthin fall.
• 6-hydroxycyclohexadienone which is selected from the group consisting of the compound 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1, 4-dienyl] -2,4,4-trimethyl-cyclohexa-2,5-diene-1-one of the formula 2a and 6-hydroxy-3 - [(1 E / Z, 3 E / Z) -5-hydroxy-3-methyl- penta-1,3-dienyl] -2,4,4-trimethylcyclohexa-2,5-diene-1-one of the formula 2b as intermediate for the preparation of (3R / S, 3'R / S) -Astaxanthin 4a .
• the catalyst 47 41 mg (0.1 mmol) of chloro ⁇ [2-aminoethyl] (4-toluenesulfonyl) amido ⁇ (p-cymene) ruthenium (II) is dissolved in 1 ml of dichloromethane and added to the reaction mixture at 22 ° C. Subsequently, 2.25 g (48.87 mmol) of formic acid are added dropwise in 12 minutes at 20-27 ° C. The mixture is stirred overnight at 20 ° C. After the addition of 10 ml of water, the phases are separated. The organic phase is washed twice with 10 ml of water and concentrated on a rotary evaporator.
• Example 2 Synthesis of (6S) -hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethylcyclohex-2-one en-1 -one (6S-1 a) with DIGLYME and potassium formate 7.97 g of a 10% sodium hydroxide solution and 10 ml of water and 8.38 g (99.57 mmol) of potassium formate are placed under argon in a 100 ml 3-necked flask and 30.5 g of saturated sodium bicarbonate solution are added.
• the product is obtained by evaporation of the solvent.
• the enantiomeric excess is determined by chiral HPLC. It is 95% in favor of the (S) -enantiomer.
• the mixture is stirred for 195 min at 30 ° C and then cooled to 20 ° C.
• the phases are separated, the aqueous phase is extracted with 50 ml of dichloromethane. Subsequently, the combined organic phases are washed with 100 ml of water.
• the organic phase is mixed with 100 ml of water and adjusted with 10.3 g of formic acid to a pH of 6.6. After phase separation, the organic phase is evaporated.
• Example 4 Synthesis of (6S) -hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethylcyclohex-2-one en-1-one (6S-1a) with dichloromethane and triethylammonium formate and one quarter of the catalyst amount 2.5 g (9.77 mmol) of 6-hydroxy-3 - [(1E / Z) -3-hydroxy-3- Methyl-penta-1,4-dienyl] -2,4,4-trimethylcyclohexa-2,5-diene-1-one 2a are dissolved in 13.36 g of dichloromethane, with 7.42 g (73.3 mmol ) Triethylamine and 15.55 mg (0.02 mmol) of chloro ⁇ [(1S, 2S) - (+) - 2-amino-1,2-diphenyl] ethyl] (4-toluenesulfon
• Example 5 Synthesis of (6S) -hydroxy-3 - [(1E / Z) -3-hydroxy-3-methyl-penta-1,4-dienyl] -2,4,4-trimethylcyclohex-2-one en-1 -one (6S-1a) with N - [(1S, 2S) -1, 2-diphenyl-2- (2- (4-methylbenzyl-oxy) ethylamino) ethyl] -4-methylbenzene sulfonamide (Chloro) ruthenium (II) as a catalyst
• the invention relates to a process for preparing a cyclic ⁇ -ketoalcohol, in particular a 6-hydroxycyclohexenone from a cyclic ⁇ -ketoenol, in particular a 6-hydroxycyclohexadienone using a reducing agent.
• This reducing agent is selected from hydrogen gas; a secondary alcohol, formic acid and the salts of formic acid or a mixture of at least two representatives of these classes of compounds.
• the invention comprises the use of an ⁇ -ketoenol, in particular of a 6-hydroxycyclohexadienone as intermediate for the preparation of astaxanthin.

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• 2015
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