CA2619472A1 - Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the new synthesis of (s)-pregabalin - Google Patents

Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the new synthesis of (s)-pregabalin Download PDF

Info

Publication number
CA2619472A1
CA2619472A1 CA002619472A CA2619472A CA2619472A1 CA 2619472 A1 CA2619472 A1 CA 2619472A1 CA 002619472 A CA002619472 A CA 002619472A CA 2619472 A CA2619472 A CA 2619472A CA 2619472 A1 CA2619472 A1 CA 2619472A1
Authority
CA
Canada
Prior art keywords
process according
compound
formula
mixture
organic solvent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002619472A
Other languages
French (fr)
Inventor
Anand Prakash Tiwari
Vinod Kumar Kansal
Brijnath P. Chaurasia
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Teva Pharmaceutical Industries Ltd
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2619472A1 publication Critical patent/CA2619472A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C227/00—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton
    • C07C227/30—Preparation of optical isomers
    • C07C227/32—Preparation of optical isomers by stereospecific synthesis
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C231/00—Preparation of carboxylic acid amides
    • C07C231/16—Preparation of optical isomers
    • C07C231/18—Preparation of optical isomers by stereospecific synthesis
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C233/00—Carboxylic acid amides
    • C07C233/01—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms
    • C07C233/02—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms having nitrogen atoms of carboxamide groups bound to hydrogen atoms or to carbon atoms of unsubstituted hydrocarbon radicals
    • C07C233/04—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms having nitrogen atoms of carboxamide groups bound to hydrogen atoms or to carbon atoms of unsubstituted hydrocarbon radicals with carbon atoms of carboxamide groups bound to acyclic carbon atoms of an acyclic saturated carbon skeleton
    • C07C233/05—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms having nitrogen atoms of carboxamide groups bound to hydrogen atoms or to carbon atoms of unsubstituted hydrocarbon radicals with carbon atoms of carboxamide groups bound to acyclic carbon atoms of an acyclic saturated carbon skeleton having the nitrogen atoms of the carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C237/00—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by amino groups
    • C07C237/02—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by amino groups having the carbon atoms of the carboxamide groups bound to acyclic carbon atoms of the carbon skeleton
    • C07C237/22—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by amino groups having the carbon atoms of the carboxamide groups bound to acyclic carbon atoms of the carbon skeleton having nitrogen atoms of amino groups bound to the carbon skeleton of the acid part, further acylated
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C271/00—Derivatives of carbamic acids, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
    • C07C271/06—Esters of carbamic acids
    • C07C271/08—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms
    • C07C271/10—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms with the nitrogen atoms of the carbamate groups bound to hydrogen atoms or to acyclic carbon atoms
    • C07C271/22—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms with the nitrogen atoms of the carbamate groups bound to hydrogen atoms or to acyclic carbon atoms to carbon atoms of hydrocarbon radicals substituted by carboxyl 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

Abstract

The invention encompasses the synthesis of (S)-(+)-3-(aminomethyl)-5-methylhexanoic acid, (S)-Pregabalin, via the intermediate, (3R)-5-methyl-3-(2-oxo-2{[(lR)- l-phenylethyl]amino} ethyl)hexanoic acid.

Description

CHIRAL 3-CARBAMOYLMETHYL-5-METHYL HEXANOIC ACIDS, KEY
INTERMEDIATES FOR THE SYNTHESIS OF (S)-PREGASALIN

CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to U.S. provisional application Serial Nos. 60/718,689, filed September 19, 2005; 60/754,392, filed December 27, 2005;
60/763,593, filed January 30, 2006; 60/752,434, filed December 20, 2005;
60/753,220, filed Decenlber 21, 2005; 60/763,696, filed January 30, 2006; and 60/839,947, filed August 23, 2006, herein incorporated by reference.

FIELD OF THE INVENTION
[0002] The invention encompasses the synthesis of (S)-(+)-3-(aminomethyl)-5-methylhexanoic acid, (S)-Pregabalin, via the intermediate, (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-phenylethyl] amino } ethyl)hexanoic acid.

BACKGROUND OF THE INVENTION
[0003] (S)-Pregabalin, (S)-(+)-3-(aminomethyl)-5-methylhexanoic acid, a compound having the chemical structure, H2N'-, O

OH
is also known as -y-amino butyric acid or (S)-3-isobutyl GABA. (S)-Pregabalin, marketed under the trade name LYRICA , has been found to activate GAD (L-glutamic acid decarboxylase). (S)-Pregabalin has a dose dependent protective effect on-seizure, and is a CNS-active compound. (S)-Pregabalin is useful in anticonvulsant therapy, due to its activation of GAD, promoting the production of GABA, one of the brain's major inhibitory neurotransmitters, which is released at 30 percent of the brains synapses. (S)-Pregabalin has analgesic, anticonvulsant, and anxiolytic activity.
[0004] Several processes for the syntliesis of (S)-Pregabalin are known. For example, see DRUGS OF THE FUTURE, 24 (8), 862-870 (1999). One such process is illustrated in sclieme 1.

Scheme 1 At'0 1) NH3{a9}. MTBE
HO 3} HCl ~ {R}(4}1-Fitm?~efl~y3tm~e srfb tt 0 OH3 Ghk NH2. CH3 0 O FbIV,, 0, - OH 0 OH
0 laNaoIi Bra ,,..IiCl H2N
a)xC
~JH6 OH3 '. ~ NI1a = CHb CH3 OF~
cl-b cFb (R.)- G Pnegabalin [0005] In Scheme 1, 3-isobutyl glutaric acid, compound 2, is converted into the corresponding anhydride, compound 3, by treatment with refluxing acetic anhydride. The reaction of the anhydride with NH4OH produces the glutaric acid mono-amide, compound 4, which is resolved with (R)-1-phenylethylamine, yielding the (R)-phenylethylamine salt of (R)-3-(carbamoylmethyl)-5-methylhexanoic acid, compound 5. Combining the salt with an acid liberates the R enantiomer, compound 6. Finally, a Hoffinann degradation with Br2/NaOH provides (S)-Pregabalin. A disadvantage of this method is that it requires separating the two enantiomers, thereby resulting in the loss of half the product, such that the process cost is high.
[0006] Several stereoselective processes for the synthesis of (S)-Pregabalin have been disclosed. For example, U.S. Patent No. 5,599,973 discloses the preparation of (S)-Pregabalin using stoichiometric (+)-4-methyl-5-phenyl-2-oxazolidinone as a chiral auxiliary that may be recycled. In general, however, that route is of limited use for scale-up, principally due to the low temperature required for the reactions, the use of pyrophoric reagent, such as, butyl lithium, to side reactions, and due to a low overall yield.
[0007] Another process is disclosed in U.S. Patent Application Publication No.
2003/0212290, which discloses asymmetric hydrogenation of a cyano-substituted olefin, compound 7, to produce a cyano precursor of (S)-3-(aminomethyl)-5-methyl hexanoic acid, compound 8, as seen in scheme 2.

Scheme 2 CN CN
[(R,R)-MeDuPHO S]Rlt(COD)+BF4' CO2R COzR
[0008] Subsequent reduction of the nitrile in compound 8 by catalytic hydrogenation produces (S)-Pregabalin. The cyano hexenoate starting material, compound 7, is prepared from 2-methyl propanal and acrylonitrile (Yamamoto et al, Bull. Chem. Soc.
Jap., 58, 3397 (1985)). However, the disclosed method requires carbon monoxide under high pressure, raising serious problems in adapting this scheme for production scale processes-.
[0009] A process published by G.M. Sammis, et al., J. Am. Chem. Soc., 125(15), 4442-43 (2003), takes advantage of the asymmetric catalysis of cyanide conjugate addition reactions. The method discloses the application of aluminum salen catalysts to the conjugate addition of hydrogen cyanide to c~fl-unsaturated imides as shown in scheme 3.
Reportedly, TMSCN is a useful source of cyanide that can be used in the place of HCN. This process is not practicable for large scale production due to the use of highly poisonous reagents.
Moreover, the last reductive step requires high pressure hydrogen, which only adds to the difficulties required for adapting this scheme for a production scale process.
Scheme 3 O O O O CN
Ph)~N TMSCN iPrOH Cat Ph)~ N
H H

O CN HzN
5%mo1Pt02, NaOH, THF 500 psi HZ
-~ -~
HO HO
11 Pregabalin [0010] In 1989, Silverman reported a conventent synthesis of 3-alkyl-4-amino acids compounds in SrtvTHEsis (1989, 955). Using 2-alkenoic esters as a substrate, a series of GABA analogs were produced by Michael addition of nitromethane to a,P-unsaturated compounds, followed by hydrogenation at atmospheric pressure of the nitro compound to amine moiety as depicted in scheme 4.

Scheme 4 OEt OEt OR
~ -~
O O
OzN HzN
[0011] Further resolution of compound 14 may be employed to resolve Pregabalin.
This, of course, results in the loss of 50 percent of the product.
[0012] Recent studies have indicated that cinchona alkaloids are broadly effective in chiral organic chemistry. A range of nitroalkenes were reportedly treated with dimethyl or diethyl malonate in tetrahydrofuran in the presence of cinchona alkaloids to provide high enantiomeric selectivity of compound 15, >"NO2 RiOOCCOOR2 and its analogues. For example, see H. Li, et al., J. Am. Chefn. Soc., 126(32), 9906-07-(2004). These catalysts are easily accessible from either quinine or quinidine, and are reportedly highly efficient for a synthetically C-C bond forming asymmetric conjugate addition as shown in scheme 5.

Scheme 5 N02 R3 _ R3 \ CH2(CO2Me)2, THF

cat :cinchona alkaloid R1OOC/ COOR2 [0013] R3 represents several alkyl and aryl grbups. The scope of the reaction has been extended to other nitroolefms and applied to prepare ABT-546 employing bis(oxazoline)Mg(OTf)2. See, for example, D.M. Barnes, et al., J Am. C1zem.
Soc., 124(44), 13097-13105 (2002).
[0014] Other groups have investigated a new class of bifunctional catalysts bearing a thiourea moiety and an amino group on a chiral scaffold. See T. Okino, et al., J. Am. Chem.
Soc.,127(1), 119-125 (2005). On the basis of a catalytic Michael addition to the nitroolefin with enantiomeric selectivity, they were able to prepare a series of analogues of compound 15.
[0015] Thus, there is a need in the art for new processes for the preparation of (S)-Pregabalin that do not suffer from the disadvantages mentioned above.
SUMMARY OF THE INVENTION
[0016] In one embodiment, the invention encompasses a compound of formula 24 R

Ar'j,' NH
OH
:r0 wherein Ar is a C6_1o aromatic group selected from the group consisting of naphthyl, phenyl, and substituted phenyl and R is straight or branched Cl-4 alkyl, ester or carboxylic acid.
[0017] Where Ar is phenyl and R is methyl, the compound of formula 24 corresponds to (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-phenylmethyl]amino}ethyl)hexanoic acid of formula Me Ph'It,. NH OH
O v [0018] In another embodiment, the invention'encompasses the compound of formula 24A in crystalline form.
[0019] In another embodiment, the invention encompasses a process for preparing the compound of formula 24 comprising: combining a chiral amine of formula 23, Ar~R

an organic solvent selected from at least one of aromatic hydrocarbons, ethers, halogenated hydrocarbons, alcohols, esters, alkanes, and ketones, and a base to obtain a mixture; cooling the nlixture to a temperature of about 10 C to about -70 C; adding to the mixture 3-isobutyl glutaric anhydride of formula 22, O O O

to obtain the compound of formula 24; and recovering the compound of formula 24 from the mixture, wherein Ar is a C6_1o aromatic group selected from the group consisting of naphthyl, phenyl, and substituted phenyl and R is straight or branched C1_4 alkyl, ester or carboxylic acid.
[0020] In another embodiment, the invention encompasses a process for preparing (S)-pregabalin comprising: combining a chiral amine of formula 23, ArR

an organic solvent selected from at least one of aromatic hydrocarbons, ethers, halogenated hydrocarbons, alcohols, esters, alkanes, and ketones, and a base to obtain a mixture; cooling the mixture to a temperature of about 10 C to about -70 C; adding to the mixture 3-isobutyl glutaric anhydride of formula 22;

O O O

to obtain the compound of formula 24; recovering the compound of formula 24 from the mixture; combining the recovered compound of formula 24, water, an ether, ammonia and an alkali metal, at a temperature of about 10 C to about -78 C to obtain a mixture; recovering the compound of formula 25 from the mixture;

HZN OH
O = 0 y combining the recovered compound of formula 25 with bromine, water, and an alkaline hydroxide to obtain a basic mixture; heating the basic mixture to a temperature of about 60 C
to about 85 C; adding to the basic mixture a strong mineral acid to obtain an acidic mixture;
reacting the acidic mixture with a base to obtain (S)-Pregabalin, and H2N~ O

OH
S-Pregabalin recovering (S)-Pregabalin; wherein Ar is a C6_10 aromatic group selected from the group consisting of naphthyl, phenyl, and substituted phenyl and R is straight or branched C1_4 alkyl, ester or carboxylic acid.
[0021] In another embodiment, the invention encompasses a process for preparing (S)-Pregabalin comprising: combining a chiral amine of formula 23, ArR

an organic solvent selected from at least one of aromatic hydrocarbons, ethers, halogenated hydrocarbons, alcohols, esters, alkanes, and ketones, and a base to obtain a mixture; cooling the mixture to a temperature of about 10 C to about -70 C; adding to the mixture 3-isobutyl glutaric anhydride of formula 22;
to obtain the compound of formula 24; recovering the compound of formula 24 from the mixture; combining the compound of formula 24 with concentrated sulfuric acid to obtain a mixture; maintaining the mixture at a temperature of about 0 C to about 50 C, for about 10 hours to about 30 hours; recovering the compound of formula 25 from the mixture;

HzN OH
O ' O
~

combining the recovered compound of formula 25 with bromine, water, and an alkaline hydroxide to obtain a basic mixture; heating the basic mixture to a temperature of about 60 C
to about 85 C; adding to the basic mixture a strong mineral acid to obtain an acidic mixture;
reacting the acidic mixture with a base to obtain (S)-Pregabalin, and HaN~ 0 OH
S-Pregabalin recovering (S)-Pregabalin; wherein Ar is a C6_10 aromatic group selected from the group consisting of naphthyl, phenyl, and substituted phenyl and R is straight or branched Cl-4 alkyl, ester or carboxylic acid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 illustrates an 1H-NMR spectrum of (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-phenyletliyl] amino} ethyl)hexanoic acid.
[0023] Figure 2 illustrates a 13C-NMR spectrum of (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-phenylethyl] amino } ethyl)hexanoic acid.
[0024] Figure 3 illustrates an IR spectrum of (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-phenylethyl] amino } ethyl)hexanoic acid.
[0025] Figure 4 illustrates a powder X-ray diffraction pattern of (3R)-5-methyl-3-(2-oxo-2 {[(1 [(lR)- 1 -phenylethamino } ethyl)hexanoic acid.

DETAILED DESCRIPTION OF THE INVENTION
[0026] The invention provides a stereoselective synthesis of (S)-Pregabalin according to the following scheme:

Scheme 6 ~ H2N\ O
Ar NH OH O O OH
0 O 0 -~

24 ~ 25 H3C CH3 (S)-Pregabalin [0027] The invention encompasses (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-aryl-alkyl]amino}ethyl)hexanoic acids of formula 24, R
Ar"'~NH OH
O O
24 ~

wherein Ar is a C6_lo aromatic group selected from the group consisting of naphthyl, phenyl, and substituted phenyl, and R is a straight or branched Cl-4 alkyl, ester, or carboxylic acid.
Preferably, Ar is phenyl. Preferably, R is a straight or branched C1-4 alkyl, more preferably, methyl.
[0028] Preferably, the substituted phenyl is a phenyl group substituted with at least one of alkoxy, halogen, alkyl, carboxylic acid, or ester. A preferred alkoxy phenyl is methoxyphenyl. Preferred halogenated phenyls are chlorobenzene, bromobenzene, and fluorobenzene. Preferred alkylated phenyls are either toluene or ethylbenzene.
[0029] Preferably, the C1_4 alkyl is methyl, ethyl, isopropyl, n-butyl, isobutyl or t-butyl. More preferably, the C1_4 alkyl is methyl or ethyl, most preferably, methyl.
[0030] Preferably, the carboxylic acid substittient is -COOH, -CH2COOH, -CH(CH3)COOH or -C(CH3)2COOH. Preferably the ester is a methylester, ethylester, isopropylester, n-butylester, isobutyl or t-butyl derivative of one of the above-listed carboxylic acid substituents.
[0031] When Ar is phenyl and R is methyl, the compound of formula 24 is (3R)-5-methyl-3-(2-oxo-2 {[(1 R)-1-phenylmethyl] amino } ethyl)hexanoic acid 24A
Me Ph /I." NH OH
~ = I
O

which may be characterized by data selected from a 13C-NMR spectrum (CDC13, 75 MHz) having carbon chemical shifts at about 21.74, 22.15, 22.61, 24.12, 24.87, 30:85, 38.1, 40.47, 43.38, 48.88, 126.0, 127.2, 128.49, 143.00, 172.02 and 176.66 ppm; an 1H-NMR
spectrum (CDC13, 300 MHz) having hydrogen chemical shifts at about 0.84, 1.19, 1.44-1.46, 1.63, 2.27, 5.09, 6.89-6.91, 7.28 and 11.65 ppm; an IR spectrum having peaks at about 3323, 3318.8, 2955, 1691.98, 1638, 1617, 1566 and 761 cni 1. The compound of formula 24A may fu.rther be characterized by data selected from a 13C-NMR spectrum substantially as depicted in Figure 2; a 1H-NMR spectrum substantially as depicted in Figure 1; and an IR spectrum substantially as depicted in Figure 3.
[0032] The invention also encompasses isolated (3R)-5-methyl-3-(2-oxo-2{[(1R)-phenylmethyl]amino}ethyl)hexanoic acid 24A, preferably in.a crystalline form.
The crystalline form of 24A may be characterized by a powder X-ray diffraction ("PXRD") pattern having peaks at about 4.3 , 6.2 6.8 , 7.3 , 10.3 , and 17.4 20 0.2 20. The crystalline form of 24A may be further characterized by X-ray powder diffraction peaks at about 7.7 , 8.2 , 9.7 , 11.3 , 12.8 , 13.9 , 15.1 , 15.7 , 18.6 , 19.1 , 19.6 , 20.9 , 21.8 , 22.4 , and 23.3 20 0.2 20.. The crystalline form of 24A may be even further characterized by a powder X-ray diffraction pattern substantially as depicted in Figure 4.
Moreover, the crystalline form of 24A may have a melting range of about 95 C to about 97 C.
[0033] The invention also encompasses (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-phenylmethyl]amino}ethyl)hexanoic acid 24A having an optical purity of at least about 80 percent area by HPLC, preferably of at least about 93 percent area by HPLC, more preferably of about 99 percent to about 100 percent area by HPLC.
[0034] The compound of formula 24 may be prepared by combining a chiral amine of formula 23, NH2 ArR

wherein Ar is a C6_1o aromatic group selected from the group consisting of naphthyl, phenyl, and substituted phenyl, and R is a straight or branched C1-4 alkyl, ester, or carboxylic acid, an organic solvent selected from at least one of aromatic hydrocarbons, ethers, halogenated hydrocarbons, alcohols, esters, alkanes, and ketones, and a base, to obtain a mixture; cooling the mixture to a temperature of about 0 C to about -70 C; and adding 3-isobutyl glutaric anhydride of formula 22 to the mixture to obtain the compound of formula 24, R
Ar-'~NH OH
O = ~
24 ~
which is then recovered from the mixture.
[0035] The 3-isobutyl glutaric anhydride of formula 22 may be prepared according to the process disclosed in U.S. patent No. 5,616,793.
[0036] The chiral amine of formula 23 is commercially available, and is, preferably, a primary amine. Preferably, the primary amine is selected from a group consisting of 1R,2S-ephedrine, naphthyl-a-methyl ethylamine, glycine methylester, methylbenzylamine or a chiral amino acid derivative. Preferably, the primary amine is methylbenzylamine, and more preferably (R)-methylbenzylamine.
[0037] Preferably, the aromatic hydrdcarbon'is a C6_8 aromatic hydrocarbon.
Preferably, C6_8 aromatic aromatic hydrocarbon is toluene, xylene, ethylbenzene, or cumene, more preferably, toluene. Preferably, the ether is a C3_6 ether. Preferably, the C3_6 ether is tert-butyl methyl ether, tetrahydrofuran, diisopropylether, or diethyl ether, more preferably, tetrahydrofuran. Preferably, the halogenated carbon is a Ci_2 halogenated hydrocarbon.
Preferably, the Cl_a halogenated hydrocarbon is dichloroethane, carbon tetrachloride, or chloroform, more preferably, dichloromethane. Preferably, the alcohol is a C1_4 alcohol.
Preferably, the C1_4 alcohol is isopropyl alcohol, ethanol, methanol or n-butanol, more preferably, n-butanol. Preferably, the ester is a C3_6 ester. Preferably, the C3_6 ester is ethyl acetate, isopropyl acetate, or isobutyl acetate, more preferably, ethyl acetate. Preferably, the alkane is a straight, branched or cyclic C5_7 alkane, more preferably, hexane, heptane, or cyclohexane, most preferably, heptane. Preferably, the ketone is a C3_6 ketone. Preferably, the C3_6 ketone is acetone, methyl isobutyl ketone, or methyl ethyl ketone, most preferably, acetone. The more preferred organic solvent is toluene.
[0038] Preferably, the base is an organic base. Preferably, the organic base is a C1_12 amine. Preferably, the C1_12 amine is selected from the group consisting of diethyl amine, triethyl amine, di-n-propyl amine, di-isopropyl amine, tert-butylamine, tri-n-butylamine, morpholine, piperidine, pyridine, and 4-dimethyl aminopyridine, more preferably, the C1_12 amine is 4-dimethyl aminopyridine.
[0039] Preferably, the mixture is cooled to a temperature of about 0 C to about -60 C
before adding the 3-isobutyl glutaric anhydride of formula 22. Preferably, the mixture is maintained at a temperature of about 0 C to about -60 C for at least about one hour, more preferably for about one hour to about two hours, before adding the 3-isobutyl glutaric anhydride of formula 22.
[0040] The order of combining the reacting substances when preparing the compound of formula 24 may influence the purity and the yield of the final product.
Preferably, the chiral amine of formula 23 is combined with the base, prior to the addition of the 3-isobutylglutaric anhydride of formula 22.
[0041] The compound of formula 24 may be recovered by any method known to the skilled artisan. Such methods include, but are not limited to, extracting the organic phase with an aqueous basic solution to convert the acidic product to a salt, and acidifying the aqueous phase with a mineral acid to obtain back the acid product.
[0042] The compound of formula 24,'obtained by the above-described process, has an optical purity of at least about 80 percent area by HPLC, preferably of at least about 93 percent area by HPLC, more preferably of about 99 percent to 100 percent area by HPLC.
[0043] The compound of formula 24 may optionally be further purified by crystallization from an organic solvent selected from at least one of esters, nitriles, ethers, C4_6 straight, branched, or cyclic hydrocarbons, and C6_lo aromatic hydrocarbons. Preferably, the ester is a C3_6 ester. Preferably, the C3_6 ester is ethyl acetate or isopropyl acetate.
Preferably, the nitrile is a C2 nitrile. Preferably, the C2 nitrile is acetonitrile. Preferably, the ether is a C3_6 ether. Preferably, the C3_6 ether is methyl t-butyl ether.
Preferably, the C6_10 aromatic hydrocarbon is a C7_9 aromatic hydrocarbon. Preferably, the C7_9 aromatic hydrocarbon is toluene or xylene. Preferably, the C4_6 straight, branched or cyclic hydrocarbon is cyclohexane or hexane, more preferably, cyclohexane. Preferred mixtures are that of xylene and ethyl acetate, hexane and ethyl acetate, cyclohexane and ethyl acetate and toluene and ethyl acetate. The most preferred mixture is that of toluene and ethyl acetate.
Most preferably, the solvent is toluene.
[0044] The invention fixrther encompasses a process for preparing (S)-Pregabalin by the following scheme:

R H2N~ O

O' o OH
24 ~ 25 H3C CH3 (S)-Pregabalin The process comprises preparing a compound of formula 24, converting the compound of formula 24 into a compound of the following formula 25;

O

converting the compound of formula 25 into (S)-Pregablin; and recovering the (S)-Pregabalin.
[0045] Preferably, the compound of formula'24 is prepared by the processes described above.
[0046] The compound of formula 24 may be converted into the compound of formula 25 by a process comprising combining the compound of formula 24, water, an ether, anlmonia, and an alkali metal at a temperature of about 10 C to about -78 C to obtain a mixture; and recovering the coinpound 25 from the mixture.
[0047] Preferably, the compound of formula 24, water, and ether are combined to form a first mixture, to which ammonia and the alkali metal are then added.
Preferably, combining the compound of formula 24, water and ether provides a first mixture. Preferably, ammonia and the alkali metal, are then added to the first mixture. Preferably, the compound of formula 24, water, and ether are combined at a temperature of about 10 C to about -78 C.
Preferably, the mixture containing the compound of formula 24, water, and ether is combined with ammonia and an alkali metal at a temperature of about -40 C to about 5 C.
[0048] Preferably, the ether is a C3_6 ether. Preferably, the C3_6 ether is tetrahydrofuran or dioxane.
[0049] Preferably, the ammonia is provided in an aqueous solution, i.e., ammonium hydroxide.
[0050] The preferred alkali metal is either lithium or sodium.
[0051] Preferably, the reaction mixture is maintained for about 2 to about 10 hours, more preferably for about 6 to about 10 hours.
[0052] Alternatively, the compound of formula 24 may converted into the compound of formula 25 by a process comprising combining the compound of formula 24 with concentrated sulfuric acid to obtain a mixture; maintaining the mixture at a temperature of about 0 C to about 50 C for about 10 hours to about 30 hours, and recovering the compound of formula 25 from the mixture.
[0053] Preferably, the concentrated sulfuric acid contains about 96 percent to about 100 percent volume of sulfuric acid and about 0 percent to about 4 percent volume of water, more preferably, about 100 percent volume of sulfuric acid.
[0054] The preferred amount of the concentrated sulfuric acid is about 2 to about 70 mole equivalents, more preferably, about 15 to about 25 mole equivalents, and most preferably, about 15 mole equivalents per mole equivalent of the compound of formula 24.
[0055] Preferably, the reaction is maintained at a temperature of about 0 C to about 50 C, when the amount of the concentrated sulfuric acid is about 2 to about 70 mole equivalents per mole equivalent of the compound of formula 24. More preferably, the reaction is maintained at a temperature of about 25 C to about 45 C, when the amount of the concentrated sulfuric acid is about 15 to about 25 mole equivalents per mole equivalent of the compound of formula 24, and most preferably, the reaction is maintained at a temperature of about 35 C to about 40 C, when the amount of the concentrated sulfuric acid is about 15 mole equivalents per mole equivalent of the compound of formula 24.
[0056] The compound of formula 25 may be recovered by any method known to the skilled artisan. Such methods include, but are not limited to extraction, followed by drying over anhydrous sodium sulfate.
[0057] The compound of formula 25 may optionally be purified by crystallization from a polar organic solvent selected from the group consisting of esters, straight and branched C1_4 alcohols, and ethers. Preferably, the ester is a C3_6 ester.
Preferably, the C3_6 ester is ethyl acetate. Preferably, the straight or branched Cl-4 alcohol is ethanol, methanol, isopropanol, or butanol, more preferably, isopropanol, or n-butanol, and most preferably, n-butanol. Preferably, the ether is a C3_6 ether. Preferably, the C3_6 ether is tetrahydrofuran or dioxane. The most preferred polar organic solvent is ethyl acetate.
[0058] ' The (R)-3-(carbamoylmethyl)-5-methyl hexanoic acid 25 is obtained by the above crystallization process having an optical purity of at least about 80 percent area by HPLC, preferably of at least about 93 percent area by HPLC, and more preferably of about of about 99 percent to about 100 percent area by HPLC.
[0059] The (R)-3-(carbamoylmethyl)-5-methyl hexanoic acid 25 may be converted into (S)-Pregabalin by a process comprising combining the (R)-3.-(carbamoylmethyl)-5-methyl hexanoic acid 25 with bromine, water, and an alkali hydroxide to form a basic mixture; heating the basic mixture to a temperature of about 60 C to about 85 C; adding a strong mineral acid to the basic mixture to obtain an acidic mixture; adding a base to the acidic mixture; and recovering (S)-Pregabalin.
[0060] Preferably, the alkali hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide and cesium hydroxide, more preferably, sodium hydroxide.
[0061] Preferably, the alkali hydroxide and water are combined, first, to obtain a solution, followed by addition of compound 25 and bromine.
[0062] Preferably, compound 25 is added to the solution at a temperature of about C to about 10 C. After the addition of compound 25, bromine is added, preferably, at a temperature of about 5 C to about 10 C.
[0063] Preferably, a C4_8 alcohol is added to -the basic mixture prior to the addition of the strong mineral acid. Preferably, the C4_8 alcohol is selected from the group consisting of butanol, iso-butanol, 2-butanol, pentanol and iso-pentanol, more preferably, iso-butanol.
[0064] Preferably, the strong mineral acid is selected from a group consisting of H2SO4, HCI, HBr and H3PO4, more preferably, HCl. Preferably, the addition of the strong mineral acid provides a two-phase system, comprising an organic phase and an aqueous phase.
[0065] Preferably, the base is added to the organic phase. The base may be an organic base. The preferred organic base is a secondary or tertiary amine. Preferably, the secondary amine is diisopropylamine or dipropylamine, more preferably, diisopropylamine.
Preferably, the tertiary amine is tributyl amine or triethyl amine, more preferably, tributyl amine.
[0066] The base may be an inorganic base. Preferably, the inorganic base is an alkali hydroxide or an alkali carbonate. Preferred alkali hydroxides include, but are not limited to, sodium hydroxide, potassium hydroxide, lithium hydroxide, and cesium hydroxide. More preferably, the alkali hydroxide is sodium hydroxide. Preferred alkali carbonates include, but are not limited to, sodium carbonate, sodium bicarbonate, and potassium carbonate. More preferably, the alkali carbonate is sodium carbonate. The more preferred inorganic base is alkali carbonate, most preferably, sodium carbonate.
[0067] The addition of the base induces the precipitation of S-Pregabalin. The precipitate of S-Pregabalin may be recovered by any method known to the skilled artisan.
Such methods include, but are not limited to, filtering the precipitate, followed by drying.
[0068] (S)-Pregabalin is obtained by the above process having an optical purity of about 93 percent to about 100 percent area by HPLC, preferably of about 99 percent to about 100 percent area by HPLC.
[0069] Further, 3-isobutyl glutaric anhydride 22 can be regenerated by a process comprising combining the filtrate obtained from the recovery of (S)-Pregabalin with an acid, to obtain a first mixture; heating the first mixture to obtain 3-isobutyl glutaric acid of the following formula;

O
HO
O OH
3-isobutyl glutaric acid combining the 3-isobutylglutaric acid with acetic anhydride to obtain a second mixture;
heating the second mixture to obtain 3-isobutyl glutaric anhydride 22; and recovering the 3-isobutyl glutaric anhydride 22.
[0070] Preferably, the acid is a strong mineral acid, more preferably either 6N to 12N
hydrochloric acid or 20 percent to 80 percent sulfuric acid.
[0071] Preferably, the first mixture is heated at a temperature of about 100 C
to about 125 C. Preferably, when the mineral acid is hydrochloric acid, the first mixture is maintained at temperature of about 100 C to about 105 C. Preferably, when the mineral acid is sulfuric acid, the first mixture is maintained at a temperature of about 120 C to about 125 C.
[0072] Preferably, the second mixture of 3-isobutylglutaric acid and acetic anhydride is heated at a temperature of about 135 C to about 155 C, more preferably at a temperature about 135 C to about 145 C.
[0073] 3-isobutyl glutaric anhydride of formula 22 may be recovered by any method known to the skilled artisan. Such methods include, but are not limited to, distilling the excess of acetic anhydride and cooling.
[0074] The following non-limiting examples are merely illustrative of the preferred embodiments of the present invention, and are not to be construed as limiting the invention, the scope of which is defined by the appended claims.

EXAMPLES
Chiral HPLC analysis Instrument: Waters-2487 Column: CHIR.AL PACK AD-H, 250 x 4.6 mm, 51in Mobile phase: 2% TFA in n-Hexane/Ethanol -95/5 Flow: 0.5 ml/minute Temperature: 30 C
Wavelength: 210 mn/UV visible spectrophotometer 'H-NMR analysis F2-Acquisition parameters F2-Processing parameters Instrument dpx 300 Probhd 5mm Dual Z5 SI 32768 Pulprog zg SF 300.1300069MHz Solvent CDC13 SSB 0 NS 8 LB 0.01 Hz SWH 8992.806 Hz PC 1.4 FIDRES 0.548877 Hz AQ 0.9110004 sec DW 55.600 sec DE 4.50 gsec TE 300.0 K
Dl 5 seconds Pl 11.35 sec SFOl 300.1342018 MHz PL1 0 dB
13C-NMR analysis F2-Acquisition parameters F2-Processing parameters Instrument dpx 300 Probhd 5mm Dual Z5 SI 16384 Pulprog zgdc SF 75.4677595MHz Solvent CDC13 SSB 0 NS 4959 LB 10.00 Hz SWH 18832.393 Hz PC 1.4 FIDRES 1.149438 Hz AQ 0.4350452 sec RG 9195.2 DW 26.550 sec DE 4.50 gsec TE 300.0 K
D l 1 0.03 second PL12 17.8Db Cpdprg2 waltz 16 PCPD2 90.00 sec SF02 300.1330013 MHz PL2 0 dB
Dl 1 second P1 9.4 gsec DE 4.5 gsec SFO1 75.4767751 MHz PL1 0dB
IR analysis KBr pellets Number of sample scans 16 Number of background scans 16 Scanning parameters 4000-500 cm-1 Resolution 4 Sample gain 8 Mirror velocity 0.6329 Aperture 100 X-ray analysis Instrument SIEMENS " Model : D-5000 Copper radiation 1.5406 A
Scanning parameters 2-50 2B.
Step scan 0.03 Step time 0.5 second Example 1: Preparation of (3R -5-methyl-3-(2-oxo-2{[(1R)-l-phenylethyl]aminolethyl) hexanoic acid compound (24) [0075] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with toluene (400 ml), (R)-(+)-phenylethylamine (38.59 g, 0Ø319 mole) and 4-diniethylaminopyridine (0.358 g, 0.0029 mole). The mixture was cooled to a temperature of -50 C to -60 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (50 g, 0.294 mole) in toluene (100 ml), over a period of 45-60 minutes, and stirring for additional 1.5-2 hours, at a temperature of -50 C to -60 C.
The mixture was then.extracted with 3.5-4.0 percent aqueous solution of NaOH
(1000 ml), and the aqueous phase was washed with toluene (1 x 250 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a solution hydrochloric acid (1-12N). The aqueous phase was further extracted with ethyl acetate (1 x 300 ml and 1 x 100 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 66 g (77.2 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl) hexanoic acid with an optical purity of 99.91 percent, as measured by chiral HPLC.

Example 2: Preparation of (3R -5-methyl-3-(2-oxo-2{[(lR)-1-phenylethyllamino ethyl) hexanoic acid compound (24) [0076] A three-necked flask equipped with an addition funnel, thermometer pocket , drying tube and mechanical stirrer, was charged with ethyl acetate (100 ml), (R)-(+)-phenylethylamine (26.69 g, 0Ø22mole) and 4-dimethylaminopyridine (2.69 g, 0.15.mole).
The mixture was cooled to a temperature of -50 to -60 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in ethyl acetate (50 ml), over a period of 25-30 minutes, and stirring for additional 1.5-2 hours, at a temperature of -50 to -60 C. The mixture was then extracted with 5-4 percent aqueous solution of NaOH (500 ml), and the aqueous phase was separated. The pH of the aqueous phase was adjusted to 2-2.5 by adding a solution hydrochloric acid (1-12N). The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 100 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvent to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 35.43 g (82.87 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl) hexanoic acid with an optical purity of 99.4 percent, as measured by chiral HPLC.

Example 3: Preparation of (3R)-5-methyl-3-(2-oxo-2 f f(1R)-1-phenylethvl]amino ethyl) hexanoic acid compound (24) [0077] A three-necked flask equipped with an addition funnel, thennometer pocket, drying tube and a mechanical stirrer, was charged with toluene (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.294 mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in toluene (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0 -5 C.
The mixture was then extracted with 2.5-3.0 percent aqueous solution of NaHCO3 solution (500 ml), and the aqueous phase was washed with toluene (1 x 100 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 28.4g (66.4 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.6 percent, as measured by chiral HPLC.

Example 4: Preparation of (3R)-5-methyl-3-(2-oxo-2{[(1R)-1-phenylethyl ]aminolethyl) hexanoic acid compound (24) [0078] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer), was charged with tert-butyl methyl ether (100 ml), (R)-(+)-phenylethylamine (43.05 g, 0.355 mole) and 4-diinethylaminopyridine (0.258 g, 0.0021 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (40 g, 0.235 mole) in tert-butyl methyl ether (100 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C. The mixture was then extracted with 5 percent aqueous solution of NaHCO3 solution (700 ml), and the aqueous phase was washed with tert-butyl methyl ether (1 x 100 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 200 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 44.5 g (70 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.19 percent, as measured by chiral HPLC.

Example 5: Preparation of (3R -5-methyl-3-(2-oxo-2{f(1R)-1-phen Elethyll amino}ethyl) hexanoic acid compound (24) [0079] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with methylene chloride (100 ml), (R)-(+)-phenylethylamine (53.38 g, 0.44 mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole).
The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in methylene chloride (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C. The mixture was then extracted with 2.5-3 percent aqueous solution of NaHCO3 solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution Of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 26.2 g (61.3 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.41 percent, as measured by chiral HPLC.

Example 6: Prgparation of (3R -5-meth yl-3 -(2-oxo-2{r(1R)-1-phenylethyl]amino ethyl) hexanoic acid compound (24):
[0080] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with IPA (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in IPA (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C.
The solvent was stripped off and the residue was extracted with 2.5-3 percent aqueous solution of NaHCO3 solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue.
The residue was crystallized from ethyl acetate and toluene mixture to get 25.2 g (58.9 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino} ethyl)hexanoic acid with an optical purity of 99.34 percent, as measured by chiral HPLC.

Example 7: Preparation of (3R)-5-methyl-3-(2-oxo-2{[(1R)-l-phenYlethyIlaminolethyl) hexanoic acid compound (24) [0081] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with ethyl acetate (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in ethyl acetate (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C. The solvent was stripped off and the residue was extracted with 2.5-3 percent aqueous solution of NaHCO3 solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and l x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12 N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 26.6 g (61.5 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.3 percent, as measured by chiral HPLC.

Example 8: Preparation of (3R)-5-methyl-3-(2-oxo-2{[(1R)-l-phenylethyl]aminolethyl) hexanoic acid compound (24) [0082] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with acetone (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in acetone (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C.
The solvent was stripped off and the residue was extracted with 2.5-3'percent aqueous solution of NaHCO3 solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue.
The residue was crystallized from ethyl acetate and toluene mixture to get 24 g (56 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethy.l)hexanoic acid with an optical purity of 99.32 percent, as measured by chiral HPLC.

Example 9: Preparation of (3R -5-meth yl-3-(2-oxo-2{[(1R)-1-phenylethyllamino}ethyl) hexanoic acid compound (24) [0083] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with hexane (100 ml), (R)-(+)-phenylethylanline (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in hexane (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C.
The mixture was then extracted with 2.5-3 percent aqueous solution of NaHCO3 solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 22.2 g (51.9 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.27 percent, as measured by chiral HPLC.

Example 10: Preparation of (3R -5-methyl-3-(2-oxo-2{[(1R)-1-phenYlethyI
]amino}ethyl) hexanoic acid compound 24) [0084] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with a mixture of cyclohexane and toluene (100 ml) in a ratio of 1 to 1, (R)-(+)-phenyle~hylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in mixture of cyclohexane and toluene (100 ml) in a ratio of 1 to 1, (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C.
The mixture was then extracted with 2.5-3 percent aqueous solution of NaOH
solution (500 ml), and the aqueous phase was washed with toluene (1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid.
The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 28.7 g (67 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]aminoI ethyl)hexanoic acid with an optical purity of 99.34 percent, as measured by chiral HPLC.

Example 11: Preparation of (3R)-5-methyLI-3-(2-oxo-2{L(1R)-1-phen lethyl]amino}eth~) hexanoic acid compound (24) [0085] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with methyl isobutyl ketone (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in methyl isobutyl ketone (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C. The solvent was stripped off and the residue was extracted with 2.5-3 percent aqueous solution of NaHCO3 solution (500 ml), followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 25.2 g (58.9 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.3 percent, as measured bychiral HPLC.

Example 12: Preparation of (3R)-5-methyl-3-(2-oxo'2 {[(1R)-Itphen l~
ethyl]aminoethyl) hexanoic acid compound (24) [0086] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with toluene (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) aiid 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in toluene (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C.
The mixture was then extracted with 2.5-3 percent aqueous solution of NaOH solution (500 ml), and the aqueous phase was washed with toluene (1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 29.3 g (68.5 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.34 percent, as measured by chiral HPLC.

Example 13: Preparation of (3R)-5-methyl-3-(2-oxo-2{L(1R)-1-phenylethYIlamino lethyl) hexanoic acid compound (24) [0087] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with methanol (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in methanol (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C. The solvent was stripped off and the residue was extracted with 2.5-3 percent aqueous solution of NaHCO3 solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue. The residue was crystallized from ethyl acetate and toluene mixture to get 22.2 g (51.76 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.1 percent, as measured by chiral HPLC.

Example 14: Preparation of (3R -5-methyl-3-(2-oxo-2{[(1R)-1-phenylethLllamino}ethyl) hexanoic acid compound (24) [0088] A three-necked flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with ethanol (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in ethanol (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C.
The solvent was stripped off and the residue was extracted with 2.5-3 percent aqueous solution of NaOH
solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric acid. The aqueous phase wa's further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue.
The residue was crystallized from ethyl acetate and toluene mixture to get 22.7 g (53.09 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.17 percent, as measured by chiral HPLC:

Example 15: Preparation of (3R)-5 -methyl-3 -(2-oxo-2 [(1R)- 1 phenylethyl1amino}ethyl) hexanoic acid compound (24) [0089] A three-neck-flask equipped with an addition funnel, thermometer pocket, drying tube and a mechanical stirrer, was charged with n-butanol (100 ml), (R)-(+)-phenylethylamine (35.58 g, 0.147mole) and 4-dimethylaminopyridine (0.18 g, 0.00147 mole). The mixture was cooled to a temperature of 0-5 C, followed by addition of a solution of 3-isobutyl glutaric anhydride (25 g, 0.147 mole) in n-butanol (25 ml), over a period of 15-20 minutes, and stirring for additional 1.5-2 hours, at a temperature of 0-5 C. The solvent was stripped off and the residue was extracted with 2.5-3 percent aqueous solution of NaOH
solution (500 ml), and diluted with water (1000 ml) followed by washing the aqueous phase with toluene (1 x 100 ml and 1 x 50 ml). The pH of the aqueous phase was adjusted to 2-2.5 by adding a 1-12N solution of hydrochloric ar,id. The aqueous phase was further extracted with ethyl acetate (1 x 150 ml and 1 x 50 ml), followed by drying the combined ethyl acetates extracts over anhydrous sodium sulfate, and stripping off the solvents, to obtain a residue.
The residue was crystallized from ethyl acetate and toluene mixture to get 23.1 g (54.03 percent yield) of a white solid of (3R)-5-methyl-3-(2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)hexanoic acid with an optical purity of 99.16 percent, as measured by chiral HPLC.

Examble 16: Preparation of (R)-3-carbamo lniethyl-5methyl hexanoic acid compound (25) [0090] A 2 liter four-necked flask, equipped with a mechanical stirrer, thermometer pocket and a liquid ammonia inlet, was charged with 24 (7.5 g, 0.0257 mole) from examples 1-13, tetrahydrofuran (112.5 ml) and water (7.5 ml). The reaction mixture was cooled to -40 C and liquid ammonia (700 ml) was added followed by addition of small pieces of sodium metal (2.5 g). The resultant reaction mixture was stirred vigorously for 6-10 hours, until the ammonia had evaporated. Water (100 ml) was added to the reaction mass under N2 atmosphere at 5-10 C, followed by separating the phases. The pH of the aqueous phase was adjusted to 1.5-1.7 using hydrochloric acid, followed by extractions with methylene dichloride (2 x 250 ml). The combined methylene dichloride layers were dried over anhydrous sodium sulfate and the solvent was stripped off. The residue was crystallized from ethyl acetate to get 1.89 g (39.37 percent yield) of (R)-3-carbamoylmethyl-5-methy.lhexanoic acid with optical purity of 99.81 percent as measured by chiral HPLC.
[0091] Compound 25 is characterized by: 1. IR (KBr) :3436.17, 1712.53, 1644.29 cm 1. 2.1H NMR (CDCl3) : 8 0.89-0.90 (d, 6H), 1.24-1.26 (t, 2H), 1.63-1.72 (septet, 1H), 2.04-2.11 (d, 2H), 2.26-2.32 (d, 2H),, 6.50 (s,1H), 6.94 (s,1H). 3. 13C NMR
(CDC13): S
21.79, 22.02, 22.61, 24.27, 29.62, 37.86, 38.82, 39.48, 42.71, 174.39, 174.83.

Example 17: Preparation of (R)-3-carbamo .l~yl-5methyl hexanoic acid compound (25) [0092] A 2 liter four neck-flask, equipped with a mechanical stirrer, tliermometer pocket and a liquid ammonia inlet, was charged with 24 (7.0 g, 0.024 mole) from examples 1-13, tetrahydrofuran (70 ml) and water (5 ml). The reaction mixture was cooled to -40 C
and liquid ammonia (400 ml) was added followed by addition of small pieces of lithium metal (0.667 g, 0.0962 mole). The resultant reaction mixture was stirred vigorously for 6-10 hours until the ammonia had evaporated. Water (50 ml) was added to the reaction mass under N2 atmosphere at 5-10 C, followed by separating the phases. The pH of the aqueous phase was adjusted to 1.5-1.7 using hydrochloric acid, foll6wed by extractions with ethyl acetate (1 x 150 ml and 1 x 100 ml). The combined ethyl acetate layers were dried over anhydrous sodium sulfate and the solvent was stripped off. The residue was crystallized from ethyl acetate to get 2.66 g (59.37 percent yield) of (R)-3-carbamoylmethyl-5-methylhexanoic acid witli optical purity of 99.8 percent as measured by chiral HPLC.

Exainple 18: Preparation of (R)-3-carbamo l~yl-5methyl hexanoic acid compound (25) [0093] A 250 ml four-necked flask, equipped with thermometer pocket and drying tube, was charged concentrated sulfuric acid (36.4 g, 0.37 mole) and 24 (2.0 g, 0.0068 mole).
The reaction mixture was stirred over night at 25-30 C, and then quenched with crushed ice (150 g) and stirred. The aqueous phase was extracted with ethyl acetate (1 x 150 ml and 1 x 150 ml), followed by washing the ethyl acetate layer with water, and finally drying over anhydrous sodium sulfate. The solvent was stripped off, and the product was crystallized from ethyl acetate obtaining 0.5 g (39 percent yield) of (R)-3-carbamoylmethyl-methylhexanoic acid with optical purity of 99.5 percent as measured by chiral HPLC.
Example 19: Regeneration of 3-isobutylglutaric acid [0094] A 0.51iter four necked-flask, equipped with a mechanical stirrer, thermometer pocket, and condenser, was charged with a residue of the secondary amide after crystallization (5 g) from examples 1-13 and concentrated hydrochloric acid (100 ml). The reaction mixture was refluxed at 100-105 C for 20-24 hours, and then cooled to 20-25 C.
The pH of the mixture was adjusted to 10-11 with a 20 percent solution of sodium hydroxide.
The aqueous layer was extracted with toluene (2 x 50 ml) and the pH of the aqueous layer was adjusted to 1.5-2 with concentrated hydrochloric acid, followed by,extractions with methylene chloride (2 x 50 ml). The combined methylene chloride layers were dried over anhydrous sodium sulfate and the solvent was stripped off to obtain 3-isobutyl glutaric acid (3.39 g) in purity of 88.48 percent as measured by GC.
[0095] 3-isobutylglutaric acid is characterized by: 1. IR (KBr) : 1713.27 cm 1. 2. 1H
NMR (CDCl3): 6 0.89-0.92 (d, 6H), 1.25 (t, 2H), 1.6-1.69 (septet, 1H), 2.42 (s, 4H), 11.96 (s,2H). 3. 13C NMR (CDC13): 822.39,25.06,28.11,29.50,38.45,43.38,179.17.

Example 20: Regeneration of 3-isobutylglutaric acid [0096] A 0.5 liter four-necked flask, equipped with a mechanical stirrer, thermometer pocket and a condenser, was charged with the residue of the secondary amide after crystallization (5 g) from example 1-13, and 70 perc~nt of sulfuric acid (100 ml). The reaction mixture was refluxed at 120-125 C for 1-2 hours, and then it was cooled to 20-25 C, followed by adjusting the pH to 10-11 with a 20 percent solution of sodium hydroxide solution. The aqueous layer was extracted with toluene (2 x 50 ml) and the pH
of the aqueous layer was adjusted to 1.5-2 with concentrated. Hydrochloric acid, and then it was extracted with methylene chloride 92 x 50 ml). The combined methylene dichloride layers were dried over anhydrous sodium sulfate and the solvent was stripped off to obtain 3-isobutyl glutaric acid (3.3 g).

Example 21: Converting 3-isobutylglutaric acid to 3-isobutylglutaric anhydxide, compound [0097] A 1 liter four-necked flask equipped with a mechanical stirrer, thermometer pocket and condenser, was charged with 3-isobutyl glutaric acid (250 g) and acetic anhydride (62.7 g).The reaction mixture was refluxed at 135 -145 C for 2.5-3 hours, followed by distilling out the unreacted acetic anhydride at 147 -155 C, and then the distillation was continued under vacuum to ensure removal of traces of unreacted acetic anhydride. The residue was cooled to 25 -30 C to obtain 220-225 g of 3-isobutylglutaric anhydride.
Example 22: Preparation of (S)-Pre ag balin [0098] A 0.21iter reactor was loaded with 60 ml of water and 17.65 g of NaOH.
The solution was cooled to from 10 to 15 C, and 15 g of 25 were added. Then, 15 g, of Br2 were added drop-wise over a period of 15 minutes, while maintaining the temperature at less than 20 C. The mixture was heated to 80 C for 15 minutes, and then cooled to room temperature, i.e., about 20 to about 25 C. An aqueous 32 percent solution of HC1 was added in an amount sufficient to provide a pH of 1. The solution was then divided to two portions.
[0099] Portion I was extracted with 37 ml of iso-butanol, the organic layer was separated, and Bu3N was added in an amount sufficient to provide a pH of 4.
The (S)-Pregabalin was precipitated, filtered, and washed with 10 ml of iso-butanol. After drying at 55 C under vacuum, (S)-Pregabalin was obtained as white crystals in a 71 percent yield.
Optical purity: 97.2 percent area by HPLC.
[00100] Portion II was extracted with 37 ml of pentanol, the organic layer was separated, and Bu3N was added in an amount sufficient to provide a pH of 4.
The (S)-Pregabalin was precipitated, filtered, and washed with 10 ml of pentanol.
After drying at 55 C under vacuum, (S)-Pregabalin was obtained aswhite crystals in a 73 percent yield.
Optical purity: 93.1 percent area by HPLC.

Example 23: Preparation of (S)-Pregabalin [00101] A 0.1 liter reactor was loaded with 60 ml of water and 17.6 g of NaOH.
The solution was cooled to from 10 to 15 C, and 15 g of 25 were added. The mixture was stirred, and 15 g of Br2 were added drop-wise over a period of 45 minutes, while maintaining the temperature at less than 20 C. The mixture was heated to 85 C for 15 minutes, and then was cooled to about 20 to about 25 C. Then, 12.4 ml of HaSO4 were added drop-wise in an amount sufficient to lower the pH to 1, and the .resulting solution was divided to two portions.
[00102] Portion I was extracted with 37 ml of iso-butanol. The organic layer was separated, and Bu3N was added in an amount sufficient to provide a pH of 4, precipitating (S)-Pregabalin, which was filtered, and washed with 10 ml of iso-butanol.
After drying at 55 C under vacuum, (S)-Pregabalin was obtained as white crystals in a 63 percent yield.
Optical purity: 99.1 percent area by HPLC.
[00103] Portion II was extracted with 37 ml of pentanol, the organic layer was separated; and Bu3N was added in an amount sufficient to provide a pH of 4.
The precipitated (S)-Pregabalin was filtered, and washed with 10 ml of pentanol.
After drying at 55 C under vacuum, (S)-Pregabalin was obtained as white crystals in a 61 percent yield.
Optical purity: 96.6 percent area by HPLC.

Example 24: Preparation of (S -Pre a~ balin [00104] A 0.2 liter reactor was loaded with 60 ml of water and 17.65 g of NaOH. The resulting solution was cooled to from 10 to 15 C, and 15 g of 25 were added.
Then, 15 g of Br2 were added drop-wise over 15 minutes, while maintaining the temperature at less than 20 C. The mixture was heated to 80 C for 15 minutes, and then cooled to room temperature, i.e., about 20 to about 25 C. Then, 75 ml of iso-butanol were added, and an aqueous 32 percent solution of HCl was added in an amount sufficient to provide a pH of 2. The organic phase was separated, and (S)-Pregabalin was precipitated after the addition of 14 ml of Bu3N.
The mixture was cooled to 2 C, and the solid was filtered, washed, and dried at 55 C under vacuum, providing a 61 percent yield. Optical purity: 98.7 percent area by HPLC.

Example 25: Preparation of (S)-Pregabalin [00105] A 0.2 liter reactor was loaded with 60 ml of water and 17.65 g of NaOH. The solution was cooled to from 10 to 15 C, and 15 g of 25 were added. Then, 15 g of Br2 were added drop-wise over 15 minutes, while maintaining the temperature at less than 20 C. The mixture was heated to 80 C for 15 minutes, and then cooled to room temperature, i.e., about 20 to about 25 C. Then 75 ml of pentanol were added, followed by an aqueous 32 percent of HC1 in an amount sufficient to provide a pH of 2. The orgaiuc phase was separated, and (S)-Pregabalin was precipitated after the addition of 14 ml of Bu3N. The mixture was then cooled to 2 C, and the solid was filtered, washed, and dried at 55 C under vacuum, providing a 52 percent yield. Optical purity: 96.9 percent area by HPLC.

Example 26: Preparation of (S)-Pre ag balin [00106] A 0.2 liter reactor was loaded with 110 ml of water and 27.65 g of NaOH.
The solution was cooled to from 10 to 15 C, and 23.5 g of 25 were added.
Then, 23.5 g of Br2 were added drop-wise over 15 minutes, while maintaining the temperature at less than 20 C. The mixture was heated to 80 C for 15 minutes, and then cooled to room temperature, i.e., about 20 to about 25 C. An aqueous 32 percent solution of HCl was added in an amount sufficient to provide a pH of 2. The mixture was then extracted with 138 ml of iso-butanol, and the organic phase was separated. (S)-Pregabalin precipitated after the addition of diisopropylethyl amine in an amount sufficient to provide a pH of 4. The mixture was cooled to 2 C, and the solid was filtered, washed, and dried at 55 C under vacuum, providing a 43 percent yield. Optical purity: 98.4 percent area by HPLC.

Example 27: Preparation of (S)-Pre ag balin [00107] A reactor (0.2 liter) was loaded with water (50 ml), NaOH (14.7 g).
The solution was cooled to 10-15 C and 25 (12.5 g) was added. Br2 (12.5 g) was added dropwise (15 min) while keeping the temperature below 20 C. The mixture was heated to 80 C for 15 and then cooled to room temperature. Iso-butanol was added (75 ml) then a 66 percent solution of H2SO4 was added to obtain a pH of 2. The organic phase was separated, distilled (to a volume of 50 ml), (S)-Pregabalin was precipitated after addition of Bu3N
(11.6 ml). The mixture was cooled to 2 C, and then the solid was filtered, washed, and dried at 55 C under vacuum, providing a 81 percent yield. Optical purity: 98.9 percent area by HPLC.
[00108] While it is apparent that the iriventioil disclosed herein is well calculated to fulfill the objects stated above, it will be appreciated that numerous modifications and embodiments may be devised by those skilled in the art. Therefore, it is intended that the appended claims cover all such modifications and embodiments as falling within the true spirit and scope of the present invention.

Claims (106)

1. A compound of formula 24 wherein Ar is a C6-10 aromatic hydrocarbon group, preferably selected from the group consisting of naphthyl, phenyl, and substituted phenyl; and R is straight or branched C1-4 alkyl, ester or carboxylic acid.
2. A compound according to claim 1, wherein Ar represents unsubstituted phenyl.
3. A compound according to claim 1 or 2, wherein the R is straight or branched alkyl.
4. A compound according to claim 3, wherein R represents methyl, ethyl, isopropyl, n-butyl, isobutyl or t-butyl.
5. A compound according to claim 4, wherein R represents methyl or ethyl.
6. A compound according to claim 5, wherein R represents methyl.
7. A compound according to any preceding claim, wherein Ar represents phenyl substituted with at least one of alkoxy, halogen, alkyl, carboxylic acid, and ester.
8. A compound according to claim 7, wherein Ar represents methoxyphenyl.
9. A compound according to claim 7, wherein Ar represents chlorophenyl, bromophenyl or fluorophenyl.
10. A compound according to claim7, wherein Ar represents toluene or ehtylbenzene.
11. A compound according to claim 7, wherein Ar represents phenyl substituted with at least one of -COOH, -CH2COOH, -CH(CH3)COOH and -C(CH3)2COOH.
12. A compound according to claim 7, wherein Ar represents phenyl substituted with at least one of methylester, ethylester, isopropylester, n-butylester, isobutyl ester, and t-butyl ester derivatives of -COOH, -CH2COOH, -CH(CH3)COOH or -C(CH3)2COOH.
13. A compound according to any preceding claim, having optical purity of at least about 93% area by HPLC.
14. A compound according to claim 13, having optical purity of about 99% to 100% area by HPLC.
15. A compound oaccording to claim 13, wherein Ar is phenyl, and R is methyl (Formula 24A).

16. A compound according to claim 15, characterized by data selected from a group consisting of: a 13C- NMR spectrum (CDC13, 75 MHz) having carbon chemical shifts at about 21.74, 22.15, 22.61, 24.12, 24.87, 30.85, 38.1, 40.47, 43.38, 48.88, 126.0, 127.2, 128.49, 143.00, 172.02 and 176.66 ppm; a 13C- NMR spectrum substantially as depicted in Figure 2; an 1H-NMR spectrum (CDC13, 300 MHz) having hydrogen chemical shifts at about 0.84, 1.19, 1.44-1.46, 1.63, 2.27, 5.09, 6.89-6.91, 7.28 and 11.65 ppm; a 1H- NMR spectrum substantially as depicted in Figure 1; an IR

spectrum having peaks at about 3323, 3318.8, 2955, 1691.98, 1638, 1617, 1566 and 761 cm-1, and an IR spectrum substantially as depicted in Figure 3.
17. A compound according to claim 15 or 16 in a crystalline form.
18. A compound according to any of claims 15 to 17, characterized by a PXRD
pattern having peaks at about 4.3°, 6.2° 6.8°, 7.3°, 10.3°, and 17.4° 2.THETA. ~ 0.2° 2.THETA..
19. A compound according to claim 18, further characterized by data selected from a group consisting of: X-ray powder diffraction peaks at about 7.7°, 8.2°, 9.7°, 11.3°, 12.8°, 13.9°, 15.1°, 15.7°, 18.6°, 19.1°, 19.6°, 20.9°, 21.8°, 22.4°, and 23.3° 2.THETA. ~ 0.2°
2.THETA.; a PXRD pattern substantially as depicted in Figure 4; a melting range of about 95°C to about 97°C.
20. A process for the preparation of the compound of formula 24, comprising:
(a) combining a chiral amine of formula 23, an organic solvent selected from at least one of aromatic hydrocarbons, ethers, halogenated hydrocarbons, alcohols, esters, alkanes, and ketones, and a base to obtain a mixture;
(b) cooling the mixture to a temperature of about 10°C to about -70°C;
(c) adding to the mixture 3-isobutyl glutaric anhydride of formula 22, to obtain the compound of formula 24, (d) recovering the compound of formula 24 from the mixture; wherein Ar is a C6-aromatic group selected from the group consisting of naphthyl, phenyl, and substituted phenyl and R is straight or branched C1-4 alkyl, ester or carboxylic acid.
21. The process according to claim 20, wherein Ar represents phenyl.
22. The process according to any of claims 20 to 21 wherein R represents straight or branched C1-4 alkyl.
23. The process according to claim 22, wherein R represents methyl, ethyl, isopropyl, n-butyl, isobutyl or t-butyl.
24. The process according to claim 23, wherein R represents methyl or ethyl.
25. The process according to claim 24, wherein R represents methyl.
26. The process according to any of claims 20 to 25 wherein Ar represents phenyl substituted with at least one of alkoxy, halogen, alkyl, carboxylic acid, and ester.
27. The process according to claim 26, wherein Ar represents methoxyphenyl.
28. The process according to claim 26, wherein Ar represents chlorophenyl, bromophenyl or fluorophenyl.
29. The process according to claim 26, wherein Ar represents toluene or ethylbenzene.
30. The process according to claim 26, wherein Ar represents phenyl substituted with at least one of -COOH, -CH2COOH, -CH(CH3)COOH and -C(CH3)2COOH.
31. The process according to claim 26, wherein Ar represents phenyl substituted with at least one of methylester, ethylester, isopropylester, n-butylester, isobutyl ester, and t-butyl ester derivatives of -COOH, -CH2COOH, -CH(CH3)COOH or -C(CH3)2COOH.
32. The process according to any of claims 20 to 31 wherein the chiral amine is a primary amine.
33. The process according to any of claims 20 to 32 wherein the chiral amine is selected from a group consisting of: 1R,2S-Ephedrine, naphthyl-.alpha.-methyl ethylamine, Glycine methylester, methylbenzylamine and a chiral amino acid derivative.
34. The process according to claim 33 wherein the chiral amine is methylbenzylamine.
35. The process according to claim 34, wherein the chiral amine is (R)-methylbenzylamine.
36. The process according to any of the claims 20 to 35 wherein the organic solvent is a C6-8 aromatic hydrocarbon.
37. The process according to claim 36 wherein the organic solvent is toluene or xylene.
38. The process according to any of claims 20 to 35, wherein the organic solvent is a C3-6 ether.
39. The process according to claim 38, wherein the organic solvent is selected from the group consisting of tert-butyl methyl ether, THF, Diisopropylether, and Diethyl ether.
40. The process according to any of the claims 20 to 35 wherein the organic solvent is a C1-2 halogenated hydrocarbon.
41. The process according to claim 40 wherein the organic solvent is dichloromethane.
42. The process according to any of the claims 21 to 35, wherein the organic solvent is a C1-4 alcohol selected from a group consisting of isopropyl alcohol, ethanol, methanol and n-butanol.
43. The process according to any of claims 21 to 35 wherein the organic solvent is a C3-6 ester.
44. The process according to claim 43, wherein the organic solvent is selected from the group consisting of ethyl acetate, isopropyl acetate, and isobutyl acetate.
45. The process according to any of the claims 21 to 35, wherein the organic solvent is a straight, branched, or cyclic C5-C7 alkane.
46. The process according to claim 45, wherein the organic solvent is hexane or cyclohexane.
47. The process according to any of claims 21 to 35 wherein the organic solvent is a C3-6 ketone.
48. The process according to claim 47, wherein the organic solvent is selected from the group consisting of acetone, methyl isobutyl ketone, and methyl ethyl ketone.
49. The process according to claim 48, wherein the organic solvent is acetone.
50. The process according to any of claims 20 to 49 wherein the base is an organic base.
51. The process according to claim 50, wherein the base is a C1-12 amine.
52. The process according to claim 51, wherein the C1-12 amine is selected from the group consisting of diethyl amine, triethyl amine, di-n-propyl amine, di-isopropyl amine, tert-butylamine morpholine, piperidine, pyridine, and 4-dimethyl aminopyridine.
53. The process according to claim 52, wherein the organic base is 4-dimethyl aminopyridine.
54. The process according to any of claims 20 to 53 wherein the mixture is cooled to a temperature of about 0°C to about -60°C.
55. The process according to claim 54 wherein the mixture is maintained at a temperature of about 0°C to about -60°C for about one hour to about two hours, prior to the addition of 3-isobutyl glutaric anhydride.
56. The process according to any of claims 20 to 55 wherein the recovered compound of formula 24 has an optical purity of at least about 93%.
57. The process according to claim 56, wherein the recovered compound of formula 24 has an optical purity of about 99% to about 100% area by HPLC.
58. The process according to any of claims 20 to 57 further comprising purifying the recovered compound 24 by a process of crystallization from an organic solvent selected from the group consisting of esters, nitriles, ethers, C4-6 straight, branched or cyclic hydrocarbons, C6-10 aromatic hydrocarbons and mixtures thereof.
59. The process according to claim 58, wherein the organic solvent is C3-6 ester.
60. The process according to claim 59, wherein the C3-6 ester is ethyl acetate.
61. The process according to claim 58, wherein the organic solvent is acetonitrile.
62. The process according to claim 58, wherein the organic solvent is a C2-6 ether.
63. The process according to claim 62, wherein the C2-6 ether is methyl t-butyl ether.
64. The process according to claim 61, wherein the organic solvent is a C7-9 aromatic hydrocarbon.
65. The process of claim 64 wherein the C7-9 aromatic hydrocarbon is either toluene or xylene.
66. The process according to claim 58, wherein the mixtures are that of xylene and ethyl acetate, hexane and ethyl acetate, cyclohexane and ethyl acetate and toluene and ethyl acetate.
67. The process according to claim 66, wherein the mixture is that of toluene and ethyl acetate.
68. The process according to any of claims 20 to 67, further comprising converting the compound of formula 24 to (S)-Pregabalin.
69. A process according to claim 71 wherein the compound of formula 24 is converted to a compound of formula 25, and the compound of formula 25 is subsequently converted to (S)-pregabalin
70. A process according to claim 69 wherein the compound of formula 24 is converted to the compound of formula 25 by a process comprising: combining the compound of formula 24, water, an ether, ammonia and an alkali metal at a temperature of about 10°C to about -78°C to obtain a mixture; and recovering the compound of formula 25 from the mixture.
71. The process according to claim 70 wherein the compound of formula 24, water and ether are combined, prior to the addition of ammonia and an alkali metal.
72. The process according to claim 72, wherein the ammonia and alkali metal are added to the compound of formula 24, water, and ether at a temperature of about 5°C to about -40°C.
73. The process according to any of claims 70 to 72 wherein the ether is C2-6 ether.
74. The process according to claim 73 wherein the ether is tetrahydrofuran or dioxane.
75. The process according to any of claims 70 to 74 wherein the ammonia is an aqueous solution of ammonia.
76. The process according to any of claims 70 to 75 wherein the alkali metal is either lithium or sodium.
77. The process according to claim 69 wherein the compound of formula 24 is converted to the compound of formula 25 by a process comprising:
a) combining the compound of formula 24 with concentrated sulfuric acid to obtain a mixture;
b) maintaining the mixture at a temperature of about 0°C to about 50°C, for about 10 hours to about 30 hours, and c) recovering the compound of formula 25 from the mixture.
78. A process according to any of claims 69 to 77 wherein the conversion of the compound of formula 25 to (S)-pregabalin comprises combining the compound of formula 25 with bromine, water, and an alkaline hydroxide to obtain a basic mixture; heating the basic mixture to a temperature of about 60°C to about 85°C; adding to the basic mixture a strong mineral acid to obtain an acidic mixture; reacting the acidic mixture with a base to obtain (S)-Pregabalin, and recovering (S)-Pregabalin;
79. The process according to claim 83, wherein the alkaline hydroxide and water are combined to obtain a solution, prior to the addition of the compound of formula 25 and bromine.
80. The process according to any of claims 78 to 79 wherein the alkaline hydroxide is selected from a group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide and cesium hydroxide.
81. The process according to claim 80, wherein the alkaline hydroxide is sodium hydroxide.
82. The process according to any of claims 78 to 81, wherein the compound of formula 25 is added to the solution at a temperature of about 5°C to about 10°C.
83. The process according to claim 82, wherein the bromine is added to the solution of alkaline hydroxide and water after the addition of the compound of formula 25.
84. The process according to claim 83, wherein the compound of formula 25 is added to the solution of alkaline hydroxide and water at a temperature of about 5°C
to about 10°C.
85. The process according to any of claims 78 to 84, wherein a C4-8 alcohol is added prior to the addition of the strong mineral acid.
86. The process according to claim 85 wherein the C4-8 alcohol is selected from the group consisting of butanol, iso-butanol, 2-butanol, pentanol and iso-pentanol.
87. The process according to claim 86, wherein the C4-8 alcohol is iso-butanol.
88. The process according to any of claims 78 to 87, wherein the strong mineral acid is selected from a group consisting of H2SO4, HCl, HBr and H3PO4.
89. The process according to claim 88, wherein the strong mineral acid is HCl.
90. The process according to any of claims 78 to 89, wherein the addition of the strong mineral acid provides a two-phase system comprising an organic phase and an aqueous phase.
91. The process according to claim 90, wherein the base is added to the organic phase.
92. The process according to any of claims 78 to 91 wherein the base is an organic base.
93. The process according to claim 92, wherein the organic base is either a secondary or tertiary amine.
94. The process according to claim 93, wherein the secondary amine is diisopropylamine or dipropylamine.
95. The process according to claim 94, wherein the secondary amine is diisopropylamine.
96. The process according to claim 93, wherein the tertiary amine is tributyl amine or triethyl amine.
97. The process according to claim 96, wherein the tertiary amine is tributyl amine.
98. The process according to any of claims 78 to 91 wherein the base is an inorganic base.
99. The process according to claim 98, wherein the inorganic base is either an alkali hydroxide or an alkali carbonate.
100. The process according to claim 99, wherein the alkali hydroxide is sodium hydroxide, potassium hydroxide, lithium hydroxide, or cesium hydroxide.
101. The process according to claim 100, wherein the alkali hydroxide is sodium hydroxide.
102. The process according to claim 99, wherein the inorganic base is alkali carbonate.
103. The process according to claim 102, wherein the alkali carbonate is sodium carbonate, sodium bicarbonate, or potassium carbonate.
104. The process according to claim 103, wherein the alkali carbonate is sodium carbonate.
105. Use of a process as defined in any of claims 20 to 67 in the manufacture of (S)-pregabalin.
106. Use of an intermediate as defined in any of claims 1 to 19 in the manufacture of (S)-pregabalin.
CA002619472A 2005-09-19 2006-09-19 Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the new synthesis of (s)-pregabalin Abandoned CA2619472A1 (en)

Applications Claiming Priority (15)

Application Number Priority Date Filing Date Title
US71868905P 2005-09-19 2005-09-19
US60/718,689 2005-09-19
US75243405P 2005-12-20 2005-12-20
US60/752,434 2005-12-20
US75322005P 2005-12-21 2005-12-21
US60/753,220 2005-12-21
US75439205P 2005-12-27 2005-12-27
US60/754,392 2005-12-27
US76359306P 2006-01-30 2006-01-30
US76369606P 2006-01-30 2006-01-30
US60/763,593 2006-01-30
US60/763,696 2006-01-30
US83994706P 2006-08-23 2006-08-23
US60/839,947 2006-08-23
PCT/US2006/036576 WO2007035789A1 (en) 2005-09-19 2006-09-19 Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the new synthesis of (s)-pregabalin

Publications (1)

Publication Number Publication Date
CA2619472A1 true CA2619472A1 (en) 2007-03-29

Family

ID=37671245

Family Applications (2)

Application Number Title Priority Date Filing Date
CA002619472A Abandoned CA2619472A1 (en) 2005-09-19 2006-09-19 Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the new synthesis of (s)-pregabalin
CA2619473A Expired - Fee Related CA2619473C (en) 2005-09-19 2006-09-19 An asymmetric synthesis of (s)-(+)-3-(aminomethyl)-5-methylhexanoic acid

Family Applications After (1)

Application Number Title Priority Date Filing Date
CA2619473A Expired - Fee Related CA2619473C (en) 2005-09-19 2006-09-19 An asymmetric synthesis of (s)-(+)-3-(aminomethyl)-5-methylhexanoic acid

Country Status (9)

Country Link
US (11) US7563923B2 (en)
EP (2) EP1841726B1 (en)
KR (2) KR20080034205A (en)
BR (1) BRPI0606118A2 (en)
CA (2) CA2619472A1 (en)
ES (1) ES2398579T3 (en)
IL (2) IL186279A0 (en)
MX (1) MX2007005936A (en)
WO (2) WO2007035890A1 (en)

Families Citing this family (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6687187B2 (en) * 2000-08-11 2004-02-03 Phonak Ag Method for directional location and locating system
US20070043241A1 (en) * 2005-05-10 2007-02-22 Lilach Hedvati Optical resolution of 3-carbamoylmethyl-5-methylhexanoic acid
US7763749B2 (en) 2005-05-10 2010-07-27 Teva Pharmaceutical Industries Ltd. Method for the preparation of Pregabalin and salts thereof
US7563923B2 (en) 2005-09-19 2009-07-21 Teva Pharmaceutical Industries Ltd. Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the synthesis of (S)-Pregabalin
EP1904486A2 (en) * 2006-04-24 2008-04-02 Teva Pharmaceutical Industries Ltd Processes for the synthesis of 3-isobutylglutaric acid
WO2007143113A2 (en) * 2006-05-31 2007-12-13 Teva Pharmaceutical Industries Ltd. The use of enzymatic resolution for the preparation of intermediates of pregabalin
TW200846308A (en) 2007-03-22 2008-12-01 Teva Pharma Synthesis of (s)-(+)-3-(aminomethyl)-5-methyl hexanoic acid
EP1992609A1 (en) * 2007-05-14 2008-11-19 Dipharma Francis S.r.l. A process for the preparation of a (S)(+)-3-(aminomethyl)-5-methylhexanoic acid
WO2009001372A2 (en) * 2007-06-25 2008-12-31 Manne Satyanarayana Reddy A novel process for the preparation of pregabalin
WO2009046309A2 (en) * 2007-10-03 2009-04-09 Teva Pharmaceutical Industries Ltd. Pregabalin -4-eliminate, pregabalin 5-eliminate, their use as reference marker and standard, and method to produce pregabalin containing low levels thereof
US20100312010A1 (en) * 2007-12-18 2010-12-09 Watson Pharma Private Limited Process for the Preparation of (S)-Pregabalin
US20110144383A1 (en) * 2008-02-18 2011-06-16 Matrix Laboratories Limited Process for preparing (s)-3-(aminomethyl)-5-methylhexanoic acid
EP2110372A1 (en) * 2008-04-16 2009-10-21 Chemo Ibérica, S.A. Intermediates for the preparation of Pregabalin and process for their preparation
SG157299A1 (en) * 2008-05-09 2009-12-29 Agency Science Tech & Res Diagnosis and treatment of kawasaki disease
CN102099482B (en) 2008-05-21 2014-04-16 桑多斯股份公司 Process for the stereoselective enzymatic hydrolysis of 5-methyl-3-nitromethyl-hexanoic acid ester
US20100087525A1 (en) * 2008-06-23 2010-04-08 Lilach Hedvati Stereoselective enzymatic synthesis of (s) or (r)-iso-butyl-glutaric ester
CA2888877C (en) 2012-11-07 2021-07-27 Hikal Limited A process for the preparation of pregabalin
WO2014080345A2 (en) * 2012-11-20 2014-05-30 Shasun Pharmaceuticals Limited Improved process for the preparation of pregabalin
WO2016075082A1 (en) 2014-11-10 2016-05-19 Sandoz Ag Stereoselective reductive amination of alpha-chiral aldehydes using omega-transaminases for the synthesis of precursors of pregabalin and brivaracetam
WO2017019791A1 (en) 2015-07-27 2017-02-02 Teva Pharmaceuticals International Gmbh Synthesis of (s)-pregabalin

Family Cites Families (55)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0258183B1 (en) * 1986-08-13 1993-03-17 Ciba-Geigy Ag Process for the preparation of 5-amino-4-hydroxyvaleric-acid derivatives
US6197819B1 (en) * 1990-11-27 2001-03-06 Northwestern University Gamma amino butyric acid analogs and optical isomers
US5616793A (en) * 1995-06-02 1997-04-01 Warner-Lambert Company Methods of making (S)-3-(aminomethyl)-5-methylhexanoic acid
US5637767A (en) * 1995-06-07 1997-06-10 Warner-Lambert Company Method of making (S)-3-(aminomethyl)-5-methylhexanoic acid
DE19530637A1 (en) * 1995-08-21 1997-02-27 Bayer Ag Process for the preparation of 2,2-difluorobenzo [1.3] dioxolcarbaldehydes
WO1998003167A1 (en) * 1996-07-24 1998-01-29 Warner-Lambert Company Isobutylgaba and its derivatives for the treatment of pain
ES2130079B1 (en) * 1997-07-10 2000-01-16 Esteve Labor Dr AMINE RESOLUTION
ATE311867T1 (en) * 1997-09-08 2005-12-15 Warner Lambert Co ANALGESIC COMPOSITION CONTAINING ANTEPILEPTIC DRUGS AND USES THEREOF
WO1999031074A2 (en) * 1997-12-16 1999-06-24 Warner-Lambert Company ((cyclo)alkyl substituted)-.gamma.-aminobutyric acid derivatives (=gaba analogues), their preparation and their use in the treatment of neurological disorders
GB9812413D0 (en) * 1998-06-10 1998-08-05 Glaxo Group Ltd Compound and its use
FR2781793B1 (en) * 1998-08-03 2001-07-20 Prographarm Lab PROCESS FOR PRODUCING COATED GABAPENTINE GRANULES
US6642398B2 (en) * 1999-06-10 2003-11-04 Warner-Lambert Company Mono-and disubstituted 3-propyl gamma-aminobutyric acids
BRPI0107863B8 (en) 2000-01-27 2017-04-25 Warner-Lambert Company method for preparing a 3-cyano-5-methylhexanoic acid derivative (s), intermediate compound, its preparation method and method for preparing pregabalin
JP2003529571A (en) * 2000-04-04 2003-10-07 ブランデイス ユニヴァーシティー Catalytic chiral asymmetry of meso-form compounds
US6833458B2 (en) * 2000-06-05 2004-12-21 Development Center For Biotechnology Practical syntheses of chiral trans-3, 4-disubstituted piperidines and the intermediates
WO2002070653A2 (en) * 2001-03-01 2002-09-12 Smithkline Beecham Corporation Peptide deformylase inhibitors
US7022678B2 (en) * 2001-03-30 2006-04-04 Warner-Lambert Company Pregabalin lactose conjugates
WO2003020273A2 (en) 2001-09-03 2003-03-13 Newron Pharmaceuticals Spa Pharmaceutical composition comprising gabapentin or an analogue thereof and an $g(a)-aminoamide and its analgesic use
DE10203122A1 (en) * 2002-01-25 2003-07-31 Gruenenthal Gmbh Process for the preparation of substituted acrylic acid esters and their use for the production of substituted gamma-amino acids
WO2003077902A1 (en) * 2002-02-19 2003-09-25 Xenoport, Inc. Methods for synthesis of prodrugs from 1-acyl-alkyl derivatives and compositions thereof
US20030225149A1 (en) * 2002-04-30 2003-12-04 Blazecka Peter G. Process for preparing highly functionalized gamma-butyrolactams and gamma-amino acids
WO2003099338A2 (en) * 2002-05-17 2003-12-04 Xenoport, Inc. Amino acid conjugates providing for sustained systemic concentrations of gaba analogues
CA2519582A1 (en) * 2003-03-21 2004-09-30 H. Lundbeck A/S Substituted p-diaminobenzene derivatives
CA2466393A1 (en) * 2003-05-06 2004-11-06 Patheon Inc. In vitro method for determining drug permeability using immobilized artificial membrane chromatography
BRPI0414819A (en) * 2003-09-25 2006-11-14 Warner Lambert Co affinity amino acid prodrugs for alpha2delta protein
AU2005221401A1 (en) * 2004-03-12 2005-09-22 Warner-Lambert Company Llc C1-symmetric bisphosphine ligands and their use in the asymmetric synthesis of pregabalin
WO2005095424A1 (en) * 2004-04-01 2005-10-13 Warner-Lambert Company Llc Preparation of p-chirogenic phospholanes and their use in asymetric synthesis
UA82292C2 (en) 2004-04-14 2008-03-25 Пфайзер Продактс Инк. A method for stereoselective byconversion of aliphatic dinitriles into cyanocarboxylic acids (variants)
BRPI0510598A (en) * 2004-05-04 2007-11-20 Pfizer substituted aryl or heteroaryl amide compounds
JP4054368B2 (en) * 2004-05-04 2008-02-27 ファイザー株式会社 Substituted methylaryl or heteroarylamide compounds
CN102102114B (en) 2004-06-21 2013-08-14 沃尼尔·朗伯有限责任公司 Preparation of pregabalin and related compounds
WO2006008640A1 (en) 2004-07-15 2006-01-26 Pharmacia & Upjohn Company Llc Non-aqueous suspension containing a drug having an unpleasant taste
CN1634869A (en) 2004-12-06 2005-07-06 北京阜康仁生物制药科技有限公司 Novel pregabalin crystalline form and its preparing process
US20060128765A1 (en) * 2004-12-10 2006-06-15 Wood Michael R 2-(Bicyclo)alkylamino-derivatives as mediators of chronic pain and inflammation
MX2007012606A (en) 2005-04-11 2008-01-11 Teva Pharma Process for making (s)-pregabalin.
US7763749B2 (en) * 2005-05-10 2010-07-27 Teva Pharmaceutical Industries Ltd. Method for the preparation of Pregabalin and salts thereof
BRPI0605833A (en) 2005-05-10 2007-12-18 Teva Pharma isobutylglutaric acid free pregabalin and a process for its preparation
EP1879852A1 (en) 2005-05-10 2008-01-23 Teva Pharmaceutical Industries Ltd Pregabalin free of lactam and a process for preparation thereof
US20060270871A1 (en) * 2005-05-30 2006-11-30 Khanduri Chandra H Polymorphic form i of pregabalin and processes for its preparation
CN100410242C (en) 2005-06-23 2008-08-13 江苏恩华药业股份有限公司 Pregabalin intermediate and process for preparing same
CZ297970B6 (en) 2005-08-10 2007-05-09 Zentiva, A. S Process for preparing (S)-3-(aminomethyl)-5-methyl-hexanoic acid (pregabalin)
US7563923B2 (en) 2005-09-19 2009-07-21 Teva Pharmaceutical Industries Ltd. Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the synthesis of (S)-Pregabalin
EP1995250A4 (en) 2006-03-03 2011-09-14 Univ Tokyo Ligand, method for producing the same, and catalyst using the ligand
CA2649115A1 (en) * 2006-05-24 2007-12-06 Teva Pharmaceutical Industries Ltd. Processes for the preparation of r-(+)-3-(carbamoyl methyl)-5-methylhexanoic acid and salts thereof
WO2007143113A2 (en) 2006-05-31 2007-12-13 Teva Pharmaceutical Industries Ltd. The use of enzymatic resolution for the preparation of intermediates of pregabalin
ITMI20061297A1 (en) 2006-07-04 2008-01-05 Laboratorio Chimico Int Spa PROCEDURE FOR THE PREPARATION OF ACID (R) - (-) - 3- (CARBAMYLMETHYL) -5-METHYLESANOIC AND PREGABALIN AND INTERMEDIATE OF SYNTHESIS
CA2657544C (en) 2006-07-12 2013-05-28 Generics [Uk] Limited Process for preparing pregabalin
GB0614133D0 (en) 2006-07-15 2006-08-23 Pliva Istrazivanje I Razvoj D Process for preparing a pharmaceutical compound
US20080014280A1 (en) * 2006-07-17 2008-01-17 Glenmark Pharmaceuticals Limited Amorphous pregabalin and process for the preparation thereof
WO2008062460A2 (en) 2006-10-06 2008-05-29 Cadila Healthcare Limited Crystalline forms of pregabalin
GB0619888D0 (en) 2006-10-07 2006-11-15 Pliva Istrazivanje I Razvoj D New polymorphic forms of pregabalin
TW200846308A (en) 2007-03-22 2008-12-01 Teva Pharma Synthesis of (s)-(+)-3-(aminomethyl)-5-methyl hexanoic acid
EP1992609A1 (en) 2007-05-14 2008-11-19 Dipharma Francis S.r.l. A process for the preparation of a (S)(+)-3-(aminomethyl)-5-methylhexanoic acid
EP2017273A1 (en) 2007-07-18 2009-01-21 Laboratorios del Dr. Esteve S.A. Process for the enantioselective preparation of pregabalin
ITMI20072262A1 (en) * 2007-12-03 2009-06-04 Dipharma Francis Srl PROCEDURE FOR THE PREPARATION OF ACID (S) (+) - 3- (AMINOMETHYL) -5-METHYLESANOIC

Also Published As

Publication number Publication date
US7470812B2 (en) 2008-12-30
US7923575B2 (en) 2011-04-12
US20100081841A1 (en) 2010-04-01
MX2007005936A (en) 2007-07-04
US20090069578A1 (en) 2009-03-12
US20090069593A1 (en) 2009-03-12
EP1841726A1 (en) 2007-10-10
US7465826B2 (en) 2008-12-16
US7973196B2 (en) 2011-07-05
US8212071B2 (en) 2012-07-03
KR20080034205A (en) 2008-04-18
US7586005B2 (en) 2009-09-08
US20070191636A1 (en) 2007-08-16
US20090062562A1 (en) 2009-03-05
IL186280A0 (en) 2008-01-20
ES2398579T3 (en) 2013-03-20
CA2619473A1 (en) 2007-03-29
US20090069596A1 (en) 2009-03-12
CA2619473C (en) 2012-04-17
US7687656B2 (en) 2010-03-30
EP1841726B1 (en) 2012-10-31
EP1802568A1 (en) 2007-07-04
US20070197827A1 (en) 2007-08-23
US7960583B2 (en) 2011-06-14
US20080051602A1 (en) 2008-02-28
US20080045747A1 (en) 2008-02-21
BRPI0606118A2 (en) 2009-06-02
US7851651B2 (en) 2010-12-14
US7446220B2 (en) 2008-11-04
US20090069600A1 (en) 2009-03-12
US20100324307A1 (en) 2010-12-23
KR20070087596A (en) 2007-08-28
WO2007035789A1 (en) 2007-03-29
US7563923B2 (en) 2009-07-21
WO2007035890A1 (en) 2007-03-29
IL186279A0 (en) 2008-01-20

Similar Documents

Publication Publication Date Title
US7465826B2 (en) Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the synthesis of (S)-pregabalin
CA2649115A1 (en) Processes for the preparation of r-(+)-3-(carbamoyl methyl)-5-methylhexanoic acid and salts thereof
CA2681313C (en) Synthesis of (s)-(+)-3-(aminomethyl)-5-methyl hexanoic acid
CN101282924A (en) Chiral 3-carbamoylmethyl-5-methyl hexanoic acids, key intermediates for the new synthesis of (S)-pregabalin
US8168828B2 (en) Process for the preparation of pregabalin
US20100286442A1 (en) Novel method for preparing pregabalin

Legal Events

Date Code Title Description
EEER Examination request
FZDE Discontinued