Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C59/00—Compounds having carboxyl groups bound to acyclic carbon atoms and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups
  • C07C59/40—Unsaturated compounds
  • C07C59/58—Unsaturated compounds containing ether groups, groups, groups, or groups
  • C07C59/64—Unsaturated compounds containing ether groups, groups, groups, or groups containing six-membered aromatic rings
  • C07C59/66—Unsaturated compounds containing ether groups, groups, groups, or groups containing six-membered aromatic rings the non-carboxylic part of the ether containing six-membered aromatic rings
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/347—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups
  • C07C51/36—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups by hydrogenation of carbon-to-carbon unsaturated bonds

Definitions

• the invention relates to a stereoselective process for the preparation of (R) -2-alkyl-3-phenyl-propionic acids and intermediate products obtained in the process steps.
• EP-A-0 -678 503 ⁇ -amino- ⁇ -hydroxy- ⁇ -aryl-alkanecarbox- amides are described which exhibit renin-inhibiting properties and could be used as antihypertensive agents in pharmaceutical preparations.
• the manufacturing processes described are unsatisfactory in terms of the number of process steps and yields and are not suitable for an industrial process.
• a disadvantage of these processes is also that the total yields of pure diastereomers that are obtainable are too small.
• the 2, 7-dialkyl-8-aryl-4-octenoyl amides may correspond for example to formula A,
• R x and R 2 are, independently of one another, H, C ⁇ -C 6 alkyl , d-C 6 halogenalkyl , C ⁇ C 6 alkoxy, C ⁇ -C 3 alkoxy-C ⁇ - C 6 alkyl , or C ⁇ -C 6 alkoxy-C ⁇ -C 6 alkyloxy, R 3 is C ⁇ -C 6 alkyl, R is C ⁇ -C 6 alkyl , R 6 is C ⁇ -C 6 alkyl , R 5 is C ⁇ C 6 alkyl or C ⁇ -C 6 alkoxy, or R 5 and R 6 together are tetramethylene, pentamethylene, 3-oxa-l , 5-pentylene or -CH 2 CH 2 0-C (0) - substituted if necessary with C ⁇ -C 4 alkyl , phenyl or benzyl .
• Ri to R 4 , R 5 and R ⁇ are as defined above, Y is-Cl, Br or I and Z is Cl, Br or I, in the presence of an alkali metal or alkaline earth metal. Y and Z are preferably Br and especially Cl .
• the compounds of formula B are known from EP-A-0 678 503.
• the compounds of formula C may be prepared from amidation of the corresponding carbonic esters, amides, or halides.
• the formation of carboxamides from carbonic esters and amines in the presence of trialkyl aluminium or dialkyl aluminium halide, for example using trimethyl aluminium or dimethyl aluminium chloride, is described by S. M. einreb in Org. Synthesis, VI, page 49 (1988) .
• the carbonic esters are obtainable by the reaction of trans-1, 3-dihalogenpropene (for example, trans-1, 3-dichlorepropene) with corresponding carbonic esters in the presence of strong bases, for example alkali metal amides.
• the carboxylic acids obtained after saponification can in turn be surprisingly hydrogenated in the presence of homogeneous, asymmetric hydrogenation catalysts to form practically enantiomer-pure 2-alkyl-3-phenylpropionic acids. These acids can then be reduced in a manner known per se to form enantiomer-pure alcohols, from which the compounds of formula B are obtainable by halogenation.
• the object of the invention is a process for the preparation of"compounds of formula I,
• Ri and R 2 are, independently of one another, H, Ci- C 6 alkyl, C ⁇ -C 6 halogenalkyl, C ⁇ C 6 alkoxy, C ⁇ -C 6 alkoxy-C ⁇ -C 6 - alkyl , or C ⁇ -C 6 alkoxy-C ⁇ -C 6 alkyloxy, and R 3 is C ⁇ -C 6 alkyl , comprising a) the reaction of a compound of formula I I
• R 7 is C ⁇ -C ⁇ 2 alkyl, C 3 -C 8 cycloalkyl, phenyl or benzyl, b) the isolation of the crystalline compound of formula IV, the conversion of the OH group to a leaving group, and the reaction of a compound containing a leaving group in the presence of a strong base to form a compound of formula V,
• Ri and R 2 may be a linear or branched alkyl and preferably comprise 1 to 4 C atoms. Examples are methyl, ethyl, n- and i-propyl, n-, i- and t-butyl, pentyl and hexyl .
• Ri and R 2 may be a linear or branched halogenalkyl and preferably comprise 1 to 4 C atoms, 1 or 2 C atoms being especially preferred. Examples are fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloro- methyl, trichloromethyl, 2-chloroethyl and 2, 2, 2-trifluoro- ethyl . Ri and R 2 may be a linear or branched alkoxy and preferably comprise 1 to 4 C atoms. Examples are methoxy, ethoxy, n- and i-propyloxy, n-, i- and t-butyloxy, pentyloxy and hexyloxy.
• Ri and R 2 may be a linear or branched alkoxyalkyl.
• the alkoxy group preferably comprises 1 to 4 and especially 1 or 2 C atoms
• the alkyl group preferably comprises 1 to 4 C atoms. Examples are methoxymethyl, l-methoxyeth-2-yl, l-methoxyprop-3-yl, l-methoxybut-4-yl, methoxypentyl, methoxyhexyl, ethoxymethyl, l-ethoxyeth-2-yl, 1-ethoxyprop- 3-yl, l-ethoxybut-4-yl, ethoxypentyl, ethoxyhexyl, propyloxymethyl, butyloxymethyl, l-propyloxyeth-2-yl and l-butyloxyeth-2-yl .
• Ri and R 2 may be linear or branched C ⁇ -C 6 alkoxy-C ⁇ -C 6 alkylox .
• the alkoxy group preferably comprises 1 to 4 and especially 1 or 2 C atoms, and the alkyloxy group preferably comprises 1 to 4 C atoms.
• Examples are methoxymethyloxy, 1-methoxyeth- 2-yloxy, l-methoxyprop-3-yloxy, l-methoxybut-4-yloxy, methoxypentyloxy, methoxyhexyloxy, ethoxymethyloxy, l-ethoxyeth-2-yloxy, l-ethoxyprop-3-yloxy, l-ethoxybut-4- yloxy, ethoxypentyloxy, ethoxyhexyloxy, propyloxymethyloxy, butyloxy ethyloxy, l-propyloxyeth-2-yloxy and 1-butyloxyeth- 2-yloxy.
• Ri is methoxy-C ⁇ -Calkyloxy or ethoxy-C ⁇ -C 4 alkyloxy, and R 2 is preferably methoxy or ethoxy. Quite especially preferred are compounds of formula I, wherein Ri is l-methoxyprop-3-yloxy and R 2 is methoxy.
• R 3 may be a linear or branched alkyl and preferably comprise 1 to 4 C atoms. Examples are methyl, ethyl, n- and i-propyl, n-, i- and t-butyl, pentyl and hexyl .
• R 3 in compounds of formula I is isopropyl.
• Ri is methoxy-n-propoxy
• R 2 is methoxy
• R 3 is isopropyl.
• R 7 is preferably C ⁇ -C 6 alkyl, C ⁇ -C 4 alkyl being especially preferred; some examples are methyl, ethyl, n-propyl and n- butyl.
• the starting compounds of formulae II and III used in process step a) are known or can be prepared in a manner similar to known processes.
• Compounds of formula II are described in EP-A 0 678 503.
• the reaction is advantageously carried out at low temperatures, for example 0-40°C, in the presence of at least equivalent quantities of strong bases.
• the reaction is further expediently carried out in a solvent, ethers such as diethyl ether, tetrahydrofuran and dioxane being especially suitable.
• Suitable strong bases are in particular alkali metal alcoholates and secondary amides, such as lithium diisopropylamide.
• the desired diastereomer of formula IV is surprisingly formed up to about 75%.
• the compounds of formula IV are surprisingly crystalline and can therefore be readily isolated without any substantial losses by means of extraction and crystallization.
• the conversion of the OH group to a leaving group in reaction step b) is known per se.
• Reaction with carboxylic acids or sulfonic acids, or their anhydrides (acylation) is especially suitable.
• carboxylic acids are formic acid, acetic acid, propionic acid, benzoic acid, benzenesulfonic acid, toluenesulfonic acid, methylsulfonic acid and trifluoromethylsulfonic acid.
• acetic acid anhydride has proved especially successful.
• the elimination is expediently carried out in the presence of strong bases, alkali metal alcoholates such as potassium t- butylate being especially suitable.
• solvents such as ethers is expedient.
• the reaction is advantageously carried out at low temperatures, for example 0-40°C. It is of advantage to conduct the elimination reaction directly in the reaction mixture for acylation.
• the elimination leads to the desired Z iso ers with surprisingly high regioselectivity.
• These isomers are crystalline and can therefore be readily isolated without any substantial losses by means of extraction and crystallization. The yields are above 80%.
• Hydrolysis of the ester of formula V to form the carboxylic acids of formula VI in process step c) is a generally known reaction.
• the hydrolysis may be carried out after isolation and purification of the compound of formula III. It is expedient to add water to the reaction mixture of process step b) , to evaporate off the solvent and then to carry out alkaline or acidic hydrolysis.
• the carboxylic acids of formula VI are crystalline and can be readily isolated in yields of 80% or more.
• the skeletal structures of the chiral ditertiary diphosphines may be acyclic, monocyclic or polycyclic.
• the phosphine groups may be substituted with the same or with different, preferably the same, substituents selected from the group of C ⁇ -C 8 alkyl, C 3 -C 8 cycloalkyl, C 6 - C 12 aryl, and C 6 -C ⁇ aryl- C ⁇ -C 4 alkyl. Cycloalkyl and aryl may be unsubstituted or substituted with C ⁇ -C 4 alkyl, C ⁇ -C 4 alkoxy, C ⁇ -C 4 fluoroalkyl or C-C ⁇ 2 secondary a ino.
• Suitable phosphine groups are also phosphanyl, preferably five-member phosphanyl, which if necessary is substituted in one or both ⁇ -positions with C ⁇ C 4 alkyl or C ⁇ C 4 alkoxy.
• Me is rhodium
• Y stands for two olefins or one diene
• Z is Cl, Br or I
• E ⁇ is the anion of an oxygen acid or a complex acid
• L is a chiral ligand from the group of ditertiary diphosphines, in which the phosphine groups are bonded to a C 2 -C chain of the diphosphine backbone chain, and the diphosphine forms a five to seven-member ring together with the rhodium atom.
• Y stands for two olefins, they may be C 2 -C ⁇ 2 olefins, C 2 -C 6 olefins being preferred and C 2 -C 4 olefins being especially preferred.
• Examples are propene, but-1-ene and especially ethylene.
• the diene may comprise 5 to 12 and preferably 5 to 8 C atoms and may be an acyclic, cyclic or polycyclic diene.
• the two olefin groups of the diene are preferably linked by one or two CH 2 groups.
• Examples are 1, 3-pentadiene, cyclopentadiene, 1, 5-hexadiene, 1, 4-cyclohexadiene, 1,4- or 1, 5-heptadiene, 1,4- or 1, 5-cycloheptadiene, 1,4- or 1,5- octadiene, 1,4- or 1, 5-cyclooctadiene and norbornadiene.
• Y represents preferably two ethylene or 1,5- hexadiene, 1,5- cyclooctadiene or norbornadiene.
• Z is preferably Cl or Br.
• Examples of Ei are C10 4 " , CF 3 S0 3 “ , CH 3 S0 3 “ , HS0 4 ⁇ , BF 4 " , B(phenyl) 4 “ , PF 6 “ , SbCl 6 “ , AsF 6 “ or SbF 6 “ .
• n is 0 or an integer from 1 to 4 and R' represents the same or different substituents selected from the C ⁇ -C 4 alkyl, -CF 3 and C ⁇ -Calkoxy group; and Xi and X 2 are, independently of one another, secondary phosphino.
• R' may preferably comprise 1 to 2 C atoms. Linear alkyl is preferred. Examples of R' as an alkyl are methyl, ethyl, n- and i-propyl, n-, i- and t-butyl. Methyl and ethyl are preferred, and methyl is especially preferred.
• R' may .preferably comprise 1 to 2 C atoms. Linear alkoxy is preferred.
• Examples of R' as an alkoxyl are methoxy, ethoxy, n- and i-propoxy, n-, i- and t-butoxy. Methoxy and ethoxy are preferred and methoxy is especially preferred.
• the Xi and X 2 groups may be different or preferably the same and correspond to formula PR 8 Rs > , wherein R 8 and R 9 are the same or different and represent branched C 3 -C 8 alkyl, C 3 - C 8 cycloalkyl, or unsubstituted or phenyl substituted with one to three C ⁇ -C 4 alkyl, C ⁇ -C-alkoxy, or -CF 3 .
• ligands of formulae VIII and Villa wherein n is 0, and Xi and X 2 are a PR 8 R 9 group, wherein R 8 and R 9 in each case are cyclohexyl, phenyl or phenyl substituted with 1 or 2 methyl, methoxy or CF 3 .
• the new ligands are prepared by means of reactions that are known per se or analogous to known reactions, such as those described in US-A-5, 371, 256, US-A-5, 446, 844 and US-A- 5,583,241.
• Ligands with other phosphine groups may be prepared in a manner analogous to the method described in the example.
• the metal complexes used as catalysts may be added as separately prepared isolated compounds, or also formed in situ before the reaction and then mixed with the substrate to be hydrogenated. It may be advantageous in the reaction using isolated metal complexes to add additional ligands, or in the in situ preparation to use surplus ligands.
• the surplus may for example be up to 10 moles and preferably 0.001 to 5 moles, based on the metal complexes used for the preparation.
• Process step d) may be carried out at low or elevated temperatures, for example at temperatures from -20 to 150°C, preferably from -10 to 100°C, temperatures of 10 to 80°C being especially preferred.
• the optical yields are generally better at low temperatures than at high temperatures.
• the process according to the invention may be carried out at normal pressure or preferably under positive pressure.
• the pressure may for example range from 10 5 to 2xl0 7 Pa (Pascal) .
• Catalysts are preferably used in quantities from 0.0001 to 10 mol-% based on the compound to be hydrogenated, the range
• catalysts as well as process step d) and the other process steps may be carried out in the absence or the presence of an inert solvent, wherein one solvent or a mixture of solvents may be used.
• Suitable solvents are, for example, aliphatic, cycloaliphatic and aromatic hydrocarbons
• the reaction may be carried out in the presence of co- catalysts, for example quaternary ammonium halogenides (tetrabutylammonium iodide) and/or in the presence of protonic acids, for example mineral acids.
• co- catalysts for example quaternary ammonium halogenides (tetrabutylammonium iodide) and/or in the presence of protonic acids, for example mineral acids.
• the intermediate products of formula (B) may be prepared via all process steps in yields of at least 50% by weight, based on the compounds of formula II.
• the high total yields make the process suitable for industrial use.
• a further object of the invention relates to the compounds (intermediates) of formula IX,
• Ri, R 2 and R 3 are as defined hereinbefore and X is the -COOH group.
• a solution of 436 ml diisopropylamine and 2.6 1 tetrahydrofuran is cooled to -20°C, and 1.234 1 n-hexyl lithium (2.5 M in hexane) is added dropwise over a period of 15 minutes.
• a solution of 368 g ethyl isovalerate in 1.7 1 tetrahydrofuran is added dropwise over a period of 15 minutes at -20°C.
• a solution of 584 g 4-methoxy-3- (3-methoxy-propoxy) benzaldehyde EP 0 678 503 in 1.7 1 tetrahydrofuran is added drop by drop and stirred for 40 minutes at -20°C.
• the solution is forced under pressure via a steel capillary tube into a 300 ml steel autoclave under cover of argon.
• argon 20 bar / hydrogen 20 bar the hydrogen pressure is eventually increased to 50 bar.
• Hydrogenation is started by switching on the stirrer and carried out at room temperature. The reaction takes place via hydrogen consumption (fall of pressure in the reservoir of hydrogen) . After a reaction time of 8 hours, a full conversion is measured by HPLC (method 1) .
• the solution is forced under pressure via a steel capillary tube into a 50 ml steel autoclave under cover of argon.
• argon 20 bar / hydrogen 20 bar the hydrogen pressure is eventually increased to 20 bar.
• Hydrogenation is started by switching on the stirrer and carried out at room temperature. The reaction takes place via hydrogen consumption (fall of pressure in the reservoir of hydrogen) . After a reaction time of 20 hours, a full conversion is measured.
• the optical yield amounts to >95% (R) -compound.
• Bl and B2 are derivatized (preparation of the respective methyl esters) : a sample of the residue in diethyl ether is mixed with excess diazo methane in diethyl ether. The solvent is then evaporated off, and the residue obtained is the corresponding methyl ester.
• Method 1 determination of conversion
• Method 2 determination of optical yield: column: Daicel OJ-R 0.45 x 15 cm; solvent 30% acetonitrile and 70% water.

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