Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
• • 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
  • C07C2601/14—The ring being saturated

Definitions

• the present invention relates to a process for the preparation of (1R, 3R, 6R) -6-dimethylaminomethyl-1- (3-methoxyphenyl) cyclohexane-1, 3-diol or (1S, 3S, 6S) -6-dimethylaminomethyl-1 - (3-methoxyphenyl) cyclohexane-1,3-diol or mixtures thereof.
• EP-A1-0753506 describes 6-dimethylaminomethyl-1- (3-hydroxy- or 3-C r C 4 - alkoxyphenyl) -cyclohexane-1, 3-diols, which are suitable as pharmacologically active analgesics for the treatment of pain. These compounds are chiral and possess three asymmetric C atoms. These 6-dimethylaminomethyl-1- (3-hydroxy or 3-Ci-C 4 -alkoxyphenyl) cyclohexane-1, 3-diols are in a multi-step process by means of protecting group strategy (introduction and cleavage of ketal groups) and subsequent Hydrogenation produced.
• stereoisomers are distinguished by a particularly good pharmacological activity.
• These stereoisomers are the (1R, 3R, 6R) and (1S, 3S, 6S) stereoisomers of the formulas (Va) and (Vb) or mixtures thereof:
• An object of the present invention was to provide a process for the controlled production of the stereoisomers of the formulas (Va) and (Vb) or mixtures thereof, in which the formation of by-products including the unwanted stereoisomers (Vc) and (Vd) and / or is largely suppressed by decomposition products.
• Another object of the present invention was to provide a process for preparing the stereoisomers (Va) and (Vb) which can be carried out without the use of protective groups.
• the object of the present invention is achieved by providing the process according to the invention for the preparation of (1R, 3R, 6R) -6-dimethylaminomethyl-1- (3-methoxyphenyl) cyclohexane-1,3-diol or (1S, 3S, 6S) -6- dimethylaminomethyl-1- (3-methoxyphenyl) cyclohexane-1, 3-diol or mixtures thereof, in each case in the form of the free base or as an acid addition salt, comprising at least the steps
• the method according to the invention further comprises the step
• the method according to the invention further comprises the step (s)
• the compounds of formulas (MIa) and (IMb) are present as a substantially racemic mixture.
• the structural formula of the chiral compound (IV) shown in Scheme 1 represents the enantiomerically pure compounds (3R, 4R) -4-dimethylaminomethyl) -3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IVa), (3S , 4S) -4-Dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IVb), (3R, 4S) -4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IVc ) or (3S, 4R) -4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IVd) or for a mixture of these chiral compounds in any desired ratio (racemates, mixtures of enantiomers, diastereomer mixtures, epimer mixtures) :
• the compounds of formulas (IV) are present as a substantially racemic mixture of compounds (IVa) and (IVb).
• the method described herein is used in particular for the preparation of the chiral compounds (Va) or (Vb) or a mixture thereof, which have a favorable analgesic profile of action.
• the compounds (Va) or (Vb) are present as a substantially racemic mixture.
• synthesis step (a) is carried out as a Mannich reaction.
• 3-methoxyacetophenone (I) can be reacted with tetramethyldiaminomethane and acetyl chloride.
• 3-methoxyacetophenone (I) can be reacted with paraformaldehyde and dimethylamine hydrochloride.
• Eschenmosersalz is preferably understood as meaning the iminium salt obtained by the reaction of tetramethyldiaminomethane and acetyl chloride.
• the Eschenmosersalz can be prepared first and then either undissolved or dissolved 3-methoxyacetophenone (I) to the solution or suspension of Eschenmosersalzes or the solution or suspension of Eschenmosersalzes to undissolved or dissolved 3-methoxyphenone (I) are added ,
• undissolved or dissolved 3-methoxyacetophenone (I) can be added to a solution or suspension of the Eschenmosersalzes.
• the Eschenmosersalz can be prepared in a conventional, known in the art solvent (reaction medium), in particular dimethylformamide, acetonitrile, isopropanol or mixtures of at least two of these solvents can be used.
• solvent reaction medium
• the production of the Eschenmosersalzes in acetonitrile is particularly preferred.
• the molar ratio tetramethyldiaminomethane to acetyl chloride is preferably 10: 1 to 1:10, more preferably em to 1: 8, even more preferably 6: 1 to 1: 6, most preferably 4: 1 to 1: 4 and in particular 2: 1 to 1: 2.
• the molar ratio paraformaldehyde to dimethylamine hydrochloride is preferably 10: 1 to 1:10, more preferably 8: 1 to 1: 8, even more preferably 6: 1 to 1: 6, most preferably 4: 1 to 1: 4 and especially 2: 1 to 1: 2.
• the molar ratio of hydrochloric acid to dimethylamine may preferably be 10: 1 to 1:10, more preferably 6: 1 to 1: 6, even more preferably 4: 1 to 1: 4, more preferably 3: 1 to 1: 3, most preferably 2: 1 to 1: 2 and in particular 1: 1.
• the synthesis of the Eschenmosersalzes regardless of the selected components, which are chosen for the production of Eschenmosersalzes, under reflux. It will be appreciated by those skilled in the art that the reflux temperature will depend on the choice of solvent and environmental variables (e.g., pressure).
• the resulting Eschenmosersalz may preferably be dissolved or suspended in the solvent.
• the Eschenmosersalz is present as a suspension in acetonitrile.
• the reaction time for producing the Eschenmoser salt is preferably 1 minute to 16 hours, more preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours, most preferably 15 minutes to 1 hour, and especially 20 to 40 minutes.
• 3-methoxyacetophenone (I) can be preferably dissolved in a suitable solvent, wherein as a solvent, in particular dimethylformamide, acetonitrile or isopropanol or mixtures of at least two of these solvents can be used.
• a solvent in particular dimethylformamide, acetonitrile or isopropanol or mixtures of at least two of these solvents can be used.
• acetonitrile is used to dissolve the 3-methoxyacetophenone.
• the solvent used for dissolving the 3-methoxyacetophenone (I) is preferably the same solvent as the Eschenmoser salt is prepared, but may be different from it.
• reaction components to effect the Mannich reaction i. bringing the ash molar salt and 3-methoxyacetophenone (I) together, at reflux.
• the Mannich reaction can be started at reflux and after a certain time, preferably after 1 to 16 hours, more preferably after 2 to 14 hours, most preferably after 4 to 10 hours and especially after 6 to 8 hours, the reaction mixture on a temperature of preferably 20 to 25 0 C (room temperature) cooled and for a certain time, preferably for 1 to 30 hours, more preferably for 2 to 24 hours, most preferably for 4 to 20 hours and especially for 8 to 16 hours or 10 be stirred at this temperature for 14 hours.
• a certain time preferably after 1 to 16 hours, more preferably after 2 to 14 hours, most preferably after 4 to 10 hours and especially after 6 to 8 hours
• the reaction mixture on a temperature of preferably 20 to 25 0 C (room temperature) cooled and for a certain time, preferably for 1 to 30 hours, more preferably for 2 to 24 hours, most preferably for 4 to 20 hours and especially for 8 to 16 hours or 10 be stirred at this temperature for 14 hours.
• the total reaction time after combining the reaction components is preferably 1 to 48 hours, more preferably 4 to 40 hours, still more preferably 8 to 32 hours, most preferably 12 to 24 hours and especially 16 to 18 hours.
• the reaction components of the Mannich reaction can be mixed and reacted in a suitable solvent.
• the Eschenmoser salt is formed in situ, which can then react with 3-methoxyacetophenone (I) under Mannich conditions.
• This in-situ reaction can also be carried out under the abovementioned conditions and using the abovementioned solvents.
• the reaction mixture may preferably after completion of the Mannich reaction, preferably at 15 0 C, more preferably cooled to 10 0 C, more preferably Techkartesten to 5 0 C, and to 0 0 C.
• the hydrochloride salt of 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) precipitate from the reaction mixture, which can preferably be isolated by filtration.
• the hydrochloride salt of compound (II) may then be suspended or dissolved in an aqueous base preferably to obtain the free base of the compound (II).
• the bases used may preferably be sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium hydrogencarbonate, magnesium hydroxide, magnesium carbonate, calcium hydroxide or calcium carbonate or mixtures of at least two of these bases.
• aqueous sodium hydroxide solution is used.
• the pH is preferably adjusted to 8 to 14, more preferably 9 to 13, even more preferably 10 to 12, and most preferably 11 to 12.
• the liberated base of 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) can then be extracted from the basic, aqueous solution, preferably with the aid of a suitable organic solvent.
• the extraction may be carried out by conventional organic solvents known to the person skilled in the art (for example chloroform, dichloromethane, diethyl ether, cyclohexane, methylcyclohexane, ethyl acetate, tert-butyl methyl ether or toluene).
• the extraction is carried out with toluene.
• the resulting organic phase can then be dried in particular over anhydrous magnesium or sodium sulfate or a mixture thereof and then filtered.
• the organic solvent may preferably be separated by means of a rotary evaporator, for example at reduced pressure and elevated temperature.
• the resulting 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) can then be further purified, for example by flash chromatography or recrystallization.
• the 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) obtained after removal of the organic phase may also preferably be used for the next reaction step without further purification.
• Reaction step (b) is preferably a Michael addition.
• Reaction step (c) represents a cyclization reaction, preferably an intramolecular aldol reaction.
• the reaction steps (b) and (c) are carried out in a one-pot process (one-pot reaction) in which the product of the Mannich reaction is 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IV) is converted.
• the product of the Mannich reaction is 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one
• II 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone
• IV 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone
• the intermediate 2-dimethylaminomethyl-1- (3-methoxyphenyl) hexane-1,5-dione (IM) which is formed during the one-pot reaction must therefore preferably not be isolated and purified.
• the detection of the formation of the non-isolated intermediate (III) can be carried out, for example, with the aid of LC-MS (liquid chromatography mass spectrometry).
• the one-pot reaction can be carried out after dissolving the educt 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) in a suitable organic solvent, preferably in the presence of a base and an ⁇ , ⁇ -unsaturated ketone.
• a suitable organic solvent preferably in the presence of a base and an ⁇ , ⁇ -unsaturated ketone.
• Typical reaction conditions for this reaction are described in the literature, for example in Turnbull et al., Tetrahedron Lett. 1984 (25) 5449-5452 and DeBoer, J. Org. Chem. 1974 (39) 2426-2427.
• the order of addition of the reagents may vary in the one-pot reaction. Both 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II), the base and the ⁇ , ß-unsaturated ketone can be presented in a suitable solvent. For this solution, the other two reagents can then be added, for example, simultaneously or successively.
• the solvent tetrahydrofuran or toluene or a mixture thereof may be used in any proportion, preferably. Preference is given to tetrahydrofuran.
• the solvents can be used both in anhydrous form.
• the solvent mixture may be 0.10 to 10% by weight, more preferably 0.50 to 7.5% by weight, even more preferably 1.0 to 5.0% by weight, most preferably 1.5 to 4.0 wt .-% and in particular 2.0 to 3.0 wt .-% water.
• the solvent or solvent mixture may contain 2.5 ⁇ 0.4 wt .-% water.
• the reaction can also be carried out under a protective gas atmosphere, preferably under nitrogen gas or argon gas.
• the base is first added to a initially introduced solution of 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) in tetrahydrofuran.
• the solution is then stirred preferably for at least 1 minute, more preferably for at least 5 minutes, even more preferably for at least 10 minutes, most preferably for at least 15 minutes, and most preferably for at least 20 minutes.
• the ⁇ , ⁇ -unsaturated ketone is preferably slowly added to the reaction mixture over a period of preferably ⁇ 10 minutes, more preferably> 30 minutes, more preferably> 1 hour, most preferably> 1.5 hours and especially ⁇ 2 hours, for example by dripping .
• the ⁇ , ⁇ -unsaturated ketone may preferably be dissolved in a suitable solvent prior to addition, for example in tetrahydrofuran, toluene or a mixture of the two solvents in any ratio.
• the ⁇ , ß-unsaturated ketone is dissolved in the same solvent, which is also used for the dissolution of the reactant 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II).
• the amount of substance used in the reaction steps (b) and (c) may vary. These may be 0.01 to 2.0 equivalents, more preferably 0.05 to 1.5 equivalents, even more preferably 0.10 to 1.0 equivalents, most preferably 0.15 to 0.75 equivalents and especially 0.2 to 0, 5 equivalents based on the introduced amount of 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) can be used.
• the amount of ⁇ , ⁇ -unsaturated ketone used for the reaction steps (b) and (c) may also vary.
• preferably 1 to 5 equivalents, more preferably 1 to 4 equivalents, more preferably 1 to 3 equivalents, most preferably 1 to 2 and especially 1 to 1, 5 equivalents based on the amount of 3-dimethylamino-1- (3-methoxyphenyl ) Propan-1-one (II) can be used.
• the ⁇ , ⁇ -unsaturated ketone is methyl vinyl ketone.
• 1, 8-diazabicyclo [5.4.0] undec-7-ene preferably 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU), sodium hydride (NaH), NaOH, KOH, amines, in particular tri-Ci 4- alkylamines such as triethylamine, sodium methoxide or potassium tert-butoxide (KOtBu) or mixtures of at least two of said bases
• DBU 1, 8-diazabicyclo [5.4.0] undec-7-ene
• NaH sodium hydride
• NaOH NaOH
• KOH amines
• tri-Ci 4- alkylamines such as triethylamine, sodium methoxide or potassium tert-butoxide (KOtBu) or mixtures of at least two of said bases
• KOH, potassium tert-butoxide a mixture of at least two of these bases, in particular potassium tert-butoxide, in the process according to the invention as the base.
• the reaction temperature for the one-pot reaction is preferably from -70 to +70 0 C 1 more preferably from -60 to 60 0 C, more preferably -50 to 50 0 C, at Rushzugtesten -40 to 40 0 C and in particular -30 to 20 0 C.
• a solution of 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one (II) in tetrahydrofuran is preferably 0.1 to ⁇ 0.25, more preferably 0.15 to 0, 24, more preferably 0.15 to 0.23, most preferably 0.15 to 0.2 equivalents of potassium tert-butoxide, based on the amount of 3-dimethylamino-1- (3-methoxyphenyl) propan-1-one ( II), and then a dilute solution of methyl vinyl ketone in tetrahydrofuran was slowly added over 1, 2 to 1 for 4 hours to the reaction solution at a temperature of not more than -30 0 C is introduced.
• the reaction mixture may be stirred for preferably up to 12 hours, more preferably up to 10 hours, even more preferably up to 8 hours, most preferably up to 6 hours and most preferably up to 4 hours.
• the temperature may be ⁇ O 0 C, more preferably ⁇ 5 0 C, more preferably ⁇ -15 0 C, at Thompsonzugtesten ⁇ -25 0 C and especially ⁇ -30 ° C in this case preferably. In a preferred embodiment, the temperature is between -30 0 C and -35 0 C.
• the quenching of the reaction can be achieved, for example, by adding an aqueous acid to the reaction solution, preferably by adding aqueous phosphoric acid, whereupon the corresponding acid addition salt precipitates out of the solution. Thereafter, the resulting salt can be separated, for example, by filtration, and the free base of the compound (IV) can be obtained by treatment with an aqueous, alkaline solution, for example sodium hydroxide solution. The liberated base of the compound (IV) can then be extracted from the basic aqueous solution by means of a suitable organic solvent.
• the extraction can be carried out using customary organic solvents known to the person skilled in the art (for example chloroform, dichloromethane, diethyl ether, tert-butyl methyl ether, toluene or ethyl acetate).
• the extraction is carried out with ethyl acetate.
• the organic solvent may then be dried over anhydrous magnesium or sodium sulfate or a mixture thereof and then filtered.
• the organic solvent can then be separated by means of a rotary evaporator, for example at reduced pressure and elevated temperature.
• the resulting crude product of 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IV) can then be further purified, for example by column chromatography or recrystallization.
• the crude product obtained after removal of the organic phase may preferably be used for the next reaction step without further purification because of the high reaction selectivity and the high yield.
• Reaction step (d) is preferably a reduction, more preferably a diastereoselective reduction.
• the educt 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IV) is dissolved in a suitable solvent and then the reducing agent is added to this solution.
• the reducing agent may preferably be dissolved or suspended or added immediately prior to addition in a suitable solvent.
• the reducing agent is dissolved or suspended in a suitable solvent and then the educt is 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IV), which is preferably either in a suitable solvents dissolved or in pure form undissolved, added to the solution or suspension of the reducing agent.
• IV 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone
• Suitable solvents for the reducing agent in particular low molecular weight alcohols such as methanol, ethanol, n-propanol or isopropanol can be used.
• ethanol or methanol, more preferably ethanol is used to dissolve or suspend the reducing agent. Any mixtures of said solvents in any ratio can be used.
• the reducing agent used is a metal hydride, such as, for example, sodium borohydride, lithium borohydride or diisobutylaluminum hydride. Particular preference may be given to using sodium borohydride.
• the diastereomer ratio here is preferably> 55:45, more preferably> 60:40, even more preferably ⁇ 65:35 or> 70:30, most preferably ⁇ 75: 25 and in particular> 80:20.
• the diastereomeric ratio (dr) here is preferably defined as the percentage of diastereomers (Va) and (Vb) to the percentage of undesired diastereomers such as (Vc), (Vd), (Ve), (Vf), (Vg) and ( Vh), in each case based on the total product mixture (cf., for this purpose, IUPAC Compendium of Chemical Terminology, Second Edition, 1997).
• a diastereomeric ratio of, for example, 80:20 means that 80% of the total product mixture consists of the diastereomers (Va) and (Vb).
• the 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IV) is dissolved in tetrahydrofuran and to this solution is subsequently added a solution of sodium borohydride in ethanol.
• the reducing agent sodium borohydride is presented in ethanol and to this ethanolic mixture is then added a solution of 4-dimethylaminomethyl-3-hydroxy-3- (3-methoxyphenyl) cyclohexanone (IV) in tetrahydrofuran.
• Anhydrous tetrahydrofuran can also be used, which can be obtained, for example, by distilling the tetrahydrofuran over benzophenone / sodium in a suitable anhydrous apparatus under a dry protective gas atmosphere.
• the temperature of the reaction solution independently of whether the educt or the reducing agent is initially charged, preferably ⁇ 30 0 C, more preferably ⁇ 20 ° C, more preferably ⁇ 10 0 C, most preferably ⁇ 0 0 C and in particular ⁇ -10 0 C. ,
• the addition of the educt or of the reducing agent can be carried out in such a way that the reaction mixture does not excessively heat due to the exothermic reduction reaction.
• This can preferably be achieved by adequately cooling the reaction mixture.
• the cooling is preferably ensured that the temperature of the reaction mixture in the union of the reactants preferably by a maximum of +20 0 C, more preferably by a maximum of +15 0 C, more preferably by at most +10 ° C and most preferably by at most +5 0 C increased.
• the combination of the reactants may also be such that the reaction temperature does not increase during the addition.
• the reaction may preferably be for ⁇ 24 hours, more preferably for ⁇ 18 hours, more preferably for ⁇ 12 hours, most preferably for ⁇ 8 hours and especially for ⁇ 4 hours be stirred.
• the stirring may preferably be carried out at a higher temperature.
• the temperature may preferably -10 to 0 C to 50 0 C, preferably to -5 ° C to 30 0 C, more preferably 0 to -2 C to 20 ° C, Elliszugtesten on on 0 0 C to 10 0 C and in particular be set at 3 0 C to 6 ° C.
• the quenching of the reduction reaction in which, for example, excess reducing agent is destroyed, is preferably carried out by adding an aqueous acid to the reaction solution, for example of aqueous ammonium chloride solution. Quenching may 0C and more preferably carried out at ⁇ -10 0 C with simultaneous cooling of the reaction mixture preferably ⁇ 10 0 C, more preferably ⁇ O.
• the product solution may first be treated with an aqueous alkaline solution, for example aqueous sodium hydroxide solution, and preferably adjusted to an alkaline pH in order to allow the solvent extraction of the free base of the compound (V).
• an aqueous alkaline solution for example aqueous sodium hydroxide solution
• the organic phase may preferably be dried over anhydrous magnesium or sodium sulfate, filtered and evaporated (e.g., in a rotary evaporator).
• the residue obtained after removal of the solvent can then be purified by column chromatography, for example.
• Separation of the unwanted stereoisomers (Vc) to (Vh) can be carried out, for example, by preparative liquid chromatography, preferably by preparative HPLC (high performance liquid chromatography). Furthermore, preferably, a fractional crystallization of the product mixture may be carried out to separate the unwanted stereoisomers of the compound (V). Further methods for purifying chiral compounds are known to the person skilled in the art.
• the desired enantiomers (1R, 3R, 6R) -6-dimethylamino-methyl-1- (3-methoxyphenyl) cyclohexane-1,3-diol (Va) and (1S, 3S, 6S) -6-dimethylami- nomethyl-1- (3-methoxyphenyl) cyclohexane-1, 3-diol (Vb) are present as a mixture of enantiomers in any ratio after purification.
• the two enantiomers can also be separated from each other, so that after the separation of the enantiomers, both the enantiomer (Va) and the enantiomer (Vb) in each case preferably present enantiomerically pure.
• Methods for the separation of enantiomers are known to the person skilled in the art.
• the compounds (I R.SR.eRJ-.beta.-dimethylaminomethyl) -1-S-methoxyphenylcyclohexane-1,3-diol (Va) and (1S, 3S, 6S) -6-dimethylaminomethyl-1- (3-methoxyphenyl) are disclosed.
• cyclohexane-1,3-diol (Vb) in the form of its substantially racemic mixture.
• the optional reaction step (e) corresponds to the preparation of an acid addition salt, which is preferably carried out by the addition of a suitable acid to the free base of the enantiomerically pure compounds (Va) or (Vb) or the mixture thereof.
• said free base of the enantiomerically pure compounds (Va) or (Vb) or the mixture thereof may preferably be dissolved in a suitable organic solvent.
• Suitable solvents which can be used are customary solvents known to the person skilled in the art, in which the free base is soluble, but the corresponding acid addition salt is only slightly soluble or insoluble.
• the solvents are acetone, benzene, n-butanol, tert-butyl methyl ether, chloroform, cyclohexane, diethyl ether, 1, 4-dioxane, ethyl acetate, ethanol, hexane, heptane, isopropanol, methanol, methylene chloride, pentane, petroleum ether, n-propanol , Tetrahydrofuran or toluene.
• any mixtures of the solvents mentioned here can be used in any ratio. Particularly preferred is the use of ethyl acetate.
• the precipitation or crystallization of the acid addition salt can preferably be initiated or improved by cooling the reaction solution and optionally by additionally concentrating the reaction solution, for example by evaporating part of the solvent in a rotary evaporator.
• the resulting precipitate can then be filtered off and optionally with the aid of a suitable liquid in which the residue is little or even insoluble, washed. Further purification may preferably be carried out by recrystallization.
• the following inorganic and / or organic acids may preferably be used, for example acetic acid, 2,2-dichloroacetic acid, acylated amino acids, preferably acetylated amino acids, such as N-acetylalanine, N-acetylcysteine, N-acetylglycine, N-acetylisoleucine, N-acetylleucine, N-acetylmethionine, N-acetylphenylalanine, N-acetylproline, N-acetylserine, N-acetylthreonine, N-acetyltyrosine, N-acetylvaline, adipic acid, alginic acid, ascorbic acid, L-aspartic acid, Benzene sulfonic acid, benzoic acid, 4-acetamidobenzoic acid, (+) - camphoric acid, (-
• Preferred salts are the hydrochloride, the saccharinate, the dihydrogen phosphate, the hydrogen phosphate and the phosphate. Particularly preferred is the phosphate salt of (1 RS, 3RS, 6RS) -6-dimethylaminomethyl-1- (3-methoxyphenyl) cyclohexane-1, 3-diol.
• the product according to the invention may preferably also be present in any ratio as a mixture of the salts of the abovementioned organic and inorganic acids.
• the Eschenmoser salt was prepared by the reaction of 232 g (2.27 mol, 1 eq.) Of tetramethyldiaminomethane with 187 g (2.14 mol, 0.95 eq.) Of acetyl chloride in 1200 mL of acetonitrile. Subsequently, 328 g (2.17 mol, 0.96 equivalents) of 3-methoxyacetophenone were added over 115 minutes at a temperature of + 3 0 C to + 11 0 C and then at + 20 0 C to + 25 0 C for 20 stirred until 21 hours.
• the resulting hydrochloride salt of 3-dimethylamino-1- (3-methoxyphenyl) -propan-1-one (II) was filtered off. The residue was suspended in 1600 ml of water and 190 ml of sodium hydroxide solution (36% by weight) (pH 11-12) and extracted with 1000 ml of ethyl acetate. The organic phase was separated and dried over 50 g of sodium sulfate. After concentration of the organic solvent, the free base of 3-dimethylamino-1- (3-methoxyphenyl) -propan-1-one (II) was obtained as a colorless oil (93% yield, 96% purity determined by HPLC).
• Ex. Nos. 1-7 To a solution of 3-dimethylamino-1- (3-methoxyphenyl) -propan-1-one (II) in THF or toluene was added 1 equivalent of methyl vinyl ketone. The resulting solution was adjusted to the respective reaction temperature and the base DBU, KOtBu or NaH was added.
• Example No. 10 First of KOtBu was added to the reactant solution at -30 0 C. Only then was the slow addition of 1.2 equivalents of methylvinlyketone, which was previously dissolved in THF, over a period of 1, 5 hours. The quenching of the reaction was carried out by adding aqueous ammonium chloride solution. After a watery work-up, (IV) was recovered as a yellow oil.
• Freshly distilled methyl vinyl ketone (4.1 g,. 0.058 mol, 1, 21 equiv) was then dropwise added dropwise within 110 minutes at -13 ° C to -18 0 C. After complete addition of the methyl vinyl ketone, the starting material (II) could no longer be detected in the reaction mixture. Subsequently, 35 mL of 15% phosphoric acid were added dropwise at -10 0 C to -15 0 C and the reaction mixture warmed to room temperature. The formed precipitate was sucked off with the help of a filter slide (G3). The phosphate salt thus obtained was dissolved in 100 ml of water and converted into the corresponding free base by adding 4 ml of 32% strength sodium hydroxide solution (pH 11-12).

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