WO2004087703A1 - Process for the preparation of n,n,6-trimethyl-2-(4-methylphenyl)-imidazo[1,2-a]pyridine-3-acetamide - Google Patents

Process for the preparation of n,n,6-trimethyl-2-(4-methylphenyl)-imidazo[1,2-a]pyridine-3-acetamide Download PDF

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WO2004087703A1
WO2004087703A1 PCT/IN2004/000057 IN2004000057W WO2004087703A1 WO 2004087703 A1 WO2004087703 A1 WO 2004087703A1 IN 2004000057 W IN2004000057 W IN 2004000057W WO 2004087703 A1 WO2004087703 A1 WO 2004087703A1
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compound
formula
preparation
mixed anhydride
formula iii
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WO2004087703A8 (en
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Samir Rameshchandra Shah
Kartik Shantilal Patel
Rajeev Budhdev Rehani
Rajamannar Thennati
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Sun Pharmaceutical Industries Limited
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D471/00Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
    • C07D471/02Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed system contains two hetero rings
    • C07D471/04Ortho-condensed systems

Definitions

  • the present invention relates to a process for the preparation of N,N,6-trimethyl-2-(4- methylphenyl)-imidazo[l,2-a]pyridine-3-acetamide, commonly known as zolpidem (INN name), compound of formula I.
  • N,N,6-trimethyl-2-(4-methylphenyl)-imidazo[l,2- a]pyridine-3-acetamide is indicated for the short term treatment of insomnia.
  • United States patent number 4382938 (referred to herein as '938, Indian reference not available) exemplifies a process for the preparation of compound of formula I, by reacting compound of formula II with dimethyl amine in the presence of carbonyldiimidazole.
  • the amidation reaction can also be carried out by reacting compound of formula II with thionyl chloride followed by reaction with dimethyl amine. It has been reported that the reaction product of compound of formula II with thionyl chloride gives a black tar which requires additional purification steps, thus making the process unsuitable for industrial scale production.
  • the process of the present invention prepares compound of formula I through a novel mixed anhydride, compound of formula III, without the use of carbonyldiimidazole.
  • patent number 4794185 (Indian reference not available) describes a process for the preparation of compound of formula I by reacting ⁇ -hydroxy-N,N- dimethyl-acetamide derivative with thionyl chloride followed by reduction with sodium borohydride.
  • the drawback of this process is that the intermediate used to prepare ⁇ - hydroxy-N,N-dimethyl-acetamide viz., N,N-dimethyl-2.2-dimethoxy-acetamide is less stable as it is sensitive towards traces of water and acid.
  • the process of the present invention prepares compound of formula I using novel mixed anhydride, compound of formula III.
  • the stability of mixed anhydride, compound of formula III, of the present invention has been found to be superior to the intermediates reported in prior art.
  • An object of the present invention is to provide a novel process for the preparation of compound of formula I, from stable mixed anhydride, compound of formula III.
  • Another object of the present invention is to provide stable mixed anhydride, compound of formula III, and its process of preparation.
  • the present invention provides a process for the preparation of N,N,6- trimethyl-2-(4-methylphenyl)-imidazo [l,2-a]pyridine-3-acetamide,compound of formula
  • R is selected from Cito C 6 linear or branched alkyl groups and substituted phenyl groups.
  • compound of formula I may be converted to an acid addition salt such as hemitartrate or tartrate.
  • the present invention also provides mixed anhydride, compound of formula III,and its process of preparation, comprising reacting compound of formula II, with RCOX;
  • N,N,6-trimethyl-2-(4-methylphenyl)- imidazo[l,2-a]pyridine-3-acetamide, compound of formula I is obtained by reacting mixed anhydride, compound of formula III, with dimethylamine.
  • novel mixed anhydride, compound of formula III, of the present invention may be prepared by reaction of compound of formula II with RCOX wherein R is selected from Cito C 6 linear or branched allcyl and substituted phenyl groups, preferably pivaloyl and isobutyl groups and X is a halo group, such as chloro, bromo, fluoro & iodo, preferably chloro.
  • RCOX wherein R is selected from Cito C 6 linear or branched allcyl and substituted phenyl groups, preferably pivaloyl and isobutyl groups and X is a halo group, such as chloro, bromo, fluoro & iodo, preferably chloro.
  • the mixed anhydride, compound of formula III may be isolated followed by nucleophilic addition reaction with dimethylamine to yield compound of formula I.
  • compound of formula I may be prepared by reacting compound of formula II with RCOX followed by insitu addition of dimethylamine.
  • the reaction of mixed anhydride, compound of formula III, with dimethylamine may be carried out at about -10 to 100 °C, preferably the reaction is carried out at about -10 to 50°C.
  • reaction of mixed anhydride, compound of formula III, with dimethylamine may be carried out in an organic solvent in the presence of base.
  • the organic solvent may be selected from non-polar, polar, polar aprotic or polar protic solvents, preferably polar aprotic to non-polar solvent(s).
  • the polar aprotic to non-polar solvent(s) may be selected from ethers such as diethylether, di-isopropylether, diphenylether, dioxane, tetrahydrofuran and the like; linear or cyclic aliphatic or aromatic hydrocarbons such as n-hexane, n-heptane, cyclohexane, methylcyclohexane, toluene, ethylbenzene, xylene and the like; aliphatic or aromatic halogenated hydrocarbons such as methylene dichloride, ethylene dichloride, tetrachloroethane, trichloroethane, chlorobenzene, dichlorobenzene and the like; amides such as acetamide
  • the base is preferably non-nucleophilic base selected from organic and inorganic bases such as linear and cyclic amines selected from C ⁇ -4 lower alkyl tertiary amines e.g. trimethylamine triethylamine, l,8-diazabicyclo[5.4.0] undec-7-ene, tetramethylguanidine, pyridine, substituted pyridine, dimethylamino pyridine, lutidine and the like; and carbonates or bicarbonates of alkali or alkaline earth metals such as sodium, potassium, lithium, calcium, barium and the like.
  • organic and inorganic bases such as linear and cyclic amines selected from C ⁇ -4 lower alkyl tertiary amines e.g. trimethylamine triethylamine, l,8-diazabicyclo[5.4.0] undec-7-ene, tetramethylguanidine, pyridine, substituted pyridine, dimethylamino
  • mixed anhydride, compound of formula III may be prepared from compound of formula II with RCOX followed by reaction of mixed anhydride, compound of formula III, with dimethylamine insitu at about -10 to 100 °C, preferably at about -10 to 50°C.
  • the process for the preparation of mixed anhydride, compound of formula III may be carried out by treating compound of formula II with RCOX wherein R is selected from Cito C 6 linear or branched alkyl groups and substituted phenyl groups and X is a halo group; in an organic solvent in the presence of base.
  • the organic solvent may be selected from non-polar, polar, polar aprotic or polar protic solvents, preferably polar aprotic to non-polar solvent(s).
  • the polar aprotic to non-polar solvent(s) may be selected from ethers such as diethylether, di-isopropylether, diphenylether, dioxane, tetrahydrofuran and the like; linear or cyclic aliphatic or aromatic hydrocarbons such as n-hexane, n-heptane, cyclohexane, methylcyclohexane, toluene, ethylbenzene, xylene and the like; aliphatic or aromatic halogenated hydrocarbons such as methylene dichloride, ethylene dichloride, tetrachloroethane, trichloroethane, chlorobenzene, dichlorobenzene and the like; amides such as acetamide
  • the base is preferably non-nucleophilic base selected from organic and inorganic bases such as linear and cyclic amines selected from C ⁇ -4 lower alkyl tertiary amines e.g. trimethylamine triethylamine, l,8-diazabicyclo[5.4.0] undec-7-ene, tetramethylguanidine, pyridine, substituted pyridine, dimethylamino pyridine, lutidine and the like; and carbonates or bicarbonates of alkali or alkaline earth metals such as sodium, potassium, lithium, calcium, barium and the like.
  • organic and inorganic bases such as linear and cyclic amines selected from C ⁇ -4 lower alkyl tertiary amines e.g. trimethylamine triethylamine, l,8-diazabicyclo[5.4.0] undec-7-ene, tetramethylguanidine, pyridine, substituted pyridine, dimethylamino
  • Compound of formula II used in the preparation of compound of formula III may be prepared as per any prior art method such as United States patent number 4382938. Further, the compound of formula I may be converted to acid addition salts such as acetic, citric, malic, succinic, maleic, fumaric, oxalic, tartaric, alkyl or aryl sulfonic, pamoic, xinafoic, ascorbic and the like or mineral acids such as hydrochloric, hydrobromic, sulfuric and the like.
  • acid addition salts such as acetic, citric, malic, succinic, maleic, fumaric, oxalic, tartaric, alkyl or aryl sulfonic, pamoic, xinafoic, ascorbic and the like or mineral acids such as hydrochloric, hydrobromic, sulfuric and the like.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Nitrogen Condensed Heterocyclic Rings (AREA)

Abstract

A process for the preparation of N,N,6-trimethyl-2-(4-methylphenyl)-imidazo [1,2-a]pyridine-3-acetamide, compound of formula (I), comprising reacting mixed anhydride, compound of formula (III), with dimethylamine; wherein R is selected from C1 to C6 linear or branched alkyl groups and substituted phenyl groups.

Description

PROCESS FOR THE PREPARATION OF N,N,6-TRIMETHYL-2-(4- METHYLPHENYL) -IMroAZO[l,2-a]PYRIDINE-3-ACETAMIDE
FIELD OF THE INVENTION
The present invention relates to a process for the preparation of N,N,6-trimethyl-2-(4- methylphenyl)-imidazo[l,2-a]pyridine-3-acetamide, commonly known as zolpidem (INN name), compound of formula I. N,N,6-trimethyl-2-(4-methylphenyl)-imidazo[l,2- a]pyridine-3-acetamide is indicated for the short term treatment of insomnia.
Figure imgf000003_0001
Formula I
BACKGROUND OF THE INVENTION
United States patent number 4382938 (referred to herein as '938, Indian reference not available) exemplifies a process for the preparation of compound of formula I, by reacting compound of formula II with dimethyl amine in the presence of carbonyldiimidazole.
Figure imgf000003_0002
Formula II
Large scale production with carbonyldiimidazole is not viable as carbonyldiimidazole is a very expensive, toxic, allergenic and hygroscopic compound. Further, the decomposition products of carbonyldiimidazole would contaminate the compound of formula I thereby reducing the purity. Thus, purification steps are required to obtain zolpidem of acceptable purity.
The amidation reaction can also be carried out by reacting compound of formula II with thionyl chloride followed by reaction with dimethyl amine. It has been reported that the reaction product of compound of formula II with thionyl chloride gives a black tar which requires additional purification steps, thus making the process unsuitable for industrial scale production.
The process of the present invention prepares compound of formula I through a novel mixed anhydride, compound of formula III, without the use of carbonyldiimidazole.
Figure imgf000004_0001
Formula III
United states patent number 6407240 (Indian reference not available) describes a process for the preparation of compound of formula I by reducing α-hydroxy ester, compound of formula IV, followed by reaction with dimethylamine in a polyhydroxylated solvent medium. The process of the present invention prepares compound of formula I using a different route via novel mixed anhydride, compound of formula III.
Figure imgf000005_0001
Formula IV
United states patent number 4794185 (Indian reference not available) describes a process for the preparation of compound of formula I by reacting α-hydroxy-N,N- dimethyl-acetamide derivative with thionyl chloride followed by reduction with sodium borohydride. The drawback of this process is that the intermediate used to prepare α- hydroxy-N,N-dimethyl-acetamide viz., N,N-dimethyl-2.2-dimethoxy-acetamide is less stable as it is sensitive towards traces of water and acid.
PCT publication 0138327 (Indian reference not available) describes a process for the preparation of compound of formula I by reacting an ester, compound of formula V, in a polar protic or aprotic solvent with dimethylamine.
Figure imgf000005_0002
The process of the present invention prepares compound of formula I using novel mixed anhydride, compound of formula III. The stability of mixed anhydride, compound of formula III, of the present invention has been found to be superior to the intermediates reported in prior art. OBJECT OF THE INVENTION
An object of the present invention is to provide a novel process for the preparation of compound of formula I, from stable mixed anhydride, compound of formula III.
Another object of the present invention is to provide stable mixed anhydride, compound of formula III, and its process of preparation.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a process for the preparation of N,N,6- trimethyl-2-(4-methylphenyl)-imidazo [l,2-a]pyridine-3-acetamide,compound of formula
Figure imgf000006_0001
Formula I comprising reacting mixed anhydride, compound of formula III, with dimethylamine,
Figure imgf000007_0001
Formula III wherein R is selected from Cito C6 linear or branched alkyl groups and substituted phenyl groups.
Optionally compound of formula I may be converted to an acid addition salt such as hemitartrate or tartrate.
The present invention also provides mixed anhydride, compound of formula III,and its process of preparation, comprising reacting compound of formula II, with RCOX;
Figure imgf000007_0002
Formula II
DETAILED DESCRIPTION OF THE INVENTION
According to the process of the present invention, N,N,6-trimethyl-2-(4-methylphenyl)- imidazo[l,2-a]pyridine-3-acetamide, compound of formula I, is obtained by reacting mixed anhydride, compound of formula III, with dimethylamine.
The novel mixed anhydride, compound of formula III, of the present invention may be prepared by reaction of compound of formula II with RCOX wherein R is selected from Cito C6 linear or branched allcyl and substituted phenyl groups, preferably pivaloyl and isobutyl groups and X is a halo group, such as chloro, bromo, fluoro & iodo, preferably chloro. The mixed anhydride, compound of formula III, may be isolated followed by nucleophilic addition reaction with dimethylamine to yield compound of formula I.
Optionally compound of formula I may be prepared by reacting compound of formula II with RCOX followed by insitu addition of dimethylamine.
According to one embodiment of the process of the present invention the reaction of mixed anhydride, compound of formula III, with dimethylamine may be carried out at about -10 to 100 °C, preferably the reaction is carried out at about -10 to 50°C.
The reaction of mixed anhydride, compound of formula III, with dimethylamine may be carried out in an organic solvent in the presence of base.
The organic solvent may be selected from non-polar, polar, polar aprotic or polar protic solvents, preferably polar aprotic to non-polar solvent(s). The polar aprotic to non-polar solvent(s) may be selected from ethers such as diethylether, di-isopropylether, diphenylether, dioxane, tetrahydrofuran and the like; linear or cyclic aliphatic or aromatic hydrocarbons such as n-hexane, n-heptane, cyclohexane, methylcyclohexane, toluene, ethylbenzene, xylene and the like; aliphatic or aromatic halogenated hydrocarbons such as methylene dichloride, ethylene dichloride, tetrachloroethane, trichloroethane, chlorobenzene, dichlorobenzene and the like; amides such as acetamide, dimethylformamide, dimethylacetamide and the like; nitriles such as acetonitrile, benzonitrile and the like; sulphoxides such as dimethylsulfoxide, sulfolane and the like.
The base is preferably non-nucleophilic base selected from organic and inorganic bases such as linear and cyclic amines selected from Cι-4 lower alkyl tertiary amines e.g. trimethylamine triethylamine, l,8-diazabicyclo[5.4.0] undec-7-ene, tetramethylguanidine, pyridine, substituted pyridine, dimethylamino pyridine, lutidine and the like; and carbonates or bicarbonates of alkali or alkaline earth metals such as sodium, potassium, lithium, calcium, barium and the like. According to another embodiment of the process of the present invention mixed anhydride, compound of formula III, may be prepared from compound of formula II with RCOX followed by reaction of mixed anhydride, compound of formula III, with dimethylamine insitu at about -10 to 100 °C, preferably at about -10 to 50°C. Accordingly, the process for the preparation of mixed anhydride, compound of formula III, may be carried out by treating compound of formula II with RCOX wherein R is selected from Cito C6 linear or branched alkyl groups and substituted phenyl groups and X is a halo group; in an organic solvent in the presence of base.
The organic solvent may be selected from non-polar, polar, polar aprotic or polar protic solvents, preferably polar aprotic to non-polar solvent(s). The polar aprotic to non-polar solvent(s) may be selected from ethers such as diethylether, di-isopropylether, diphenylether, dioxane, tetrahydrofuran and the like; linear or cyclic aliphatic or aromatic hydrocarbons such as n-hexane, n-heptane, cyclohexane, methylcyclohexane, toluene, ethylbenzene, xylene and the like; aliphatic or aromatic halogenated hydrocarbons such as methylene dichloride, ethylene dichloride, tetrachloroethane, trichloroethane, chlorobenzene, dichlorobenzene and the like; amides such as acetamide, dimethylformamide, dimethylacetamide and the like; nitriles such as acetonitrile, benzonitrile and the like; sulphoxides such as dimethylsulfoxide, sulfolane and the like.
The base is preferably non-nucleophilic base selected from organic and inorganic bases such as linear and cyclic amines selected from Cι-4 lower alkyl tertiary amines e.g. trimethylamine triethylamine, l,8-diazabicyclo[5.4.0] undec-7-ene, tetramethylguanidine, pyridine, substituted pyridine, dimethylamino pyridine, lutidine and the like; and carbonates or bicarbonates of alkali or alkaline earth metals such as sodium, potassium, lithium, calcium, barium and the like.
Compound of formula II used in the preparation of compound of formula III may be prepared as per any prior art method such as United States patent number 4382938. Further, the compound of formula I may be converted to acid addition salts such as acetic, citric, malic, succinic, maleic, fumaric, oxalic, tartaric, alkyl or aryl sulfonic, pamoic, xinafoic, ascorbic and the like or mineral acids such as hydrochloric, hydrobromic, sulfuric and the like.
The invention is illustrated but not restricted by the description in the following examples.
Examples:
Example-1
Preparation of 2-(4-methylphenyl)-6-methyl-imidazo(l_,2-a)pyridine-3-acetic acid, compound of formula II Charge 150 It of cone, hydrochloric acid along with 15 kg of 2-(4-methylphenyl)-6- methyl-imidazo(l,2-a)pyridine-3 -acetonitrile into a reaction vessel under stirring at 25 to 30 deg.C. Heat the reaction mixture upto 97-100 deg.C. Maintain at reflux temperature for 12 hrs. Cool the reaction mixture to 30 to 35 deg.C and then further cool to 15 to 20 deg.C for an hour and filter. Wash with chilled demin. water, chilled acetone to obtain crude compound of formula II. Treat with 18%w/v of aqueous potassium hydroxide solution at 25 to 30 deg.C and heat to 100 to 105 deg.C for 2-3 hrs. Cool to 30 to 35 deg.C and add demin. water and cool. Then charge glacial acetic acid and adjust pH between 5 to 5.2 at 30 to 40 deg.C, further cool to 25 to 30 deg.C and maintain for an hour and filter. Wash the cake with chilled demin. water, acetone and dry to obtain compound of formula II.
Example-2
Preparation of N,N,6-Trimethyl-2-(4-methylphenylHmidazoFL2-a1pyridine-3- acetamide (Formula I) Charge 13 kg of 2-(4-methylphenyl)-6-methyl -imidazo[l,2-a]pyridine-3-acetic acid, compound of formula II, followed by methylene dichloride 195 Its to the reaction vessel, stir and cool the contents to 10 to 15° C under nitrogen atmosphere. Charge triethylamine 9.23 It to the chilled contents and further cool to 0 to 2 deg.C. Add Pivaloyl chloride 7.28 kg to the above reaction mixture slowly at 0 to 10°C.The compound of formula III is obtained in the reaction mass.
Add 40% aqueous dimethyl amine solution (15.6 kg) to the above mentioned reaction mass within 20 to 30 minutes at 0 to 2 ° C and stir for 30 mins at 0 to 5 deg.C. Charge 52 Its of 4% aqueous sodium hydroxide solution into the reaction mixture and maintain temperature at 25 to 30 deg C for 15 minutes and separate the organic layer. Then charge 52 Its of 4% aqueous sodium hydroxide solution into the separated organic layer in a reactor. Stir at 25 to 30 deg C for 15 mins. Allow the phases to separate and repeat the washing with aqueous sodium hydroxide twice. Then wash with demin water twice. Dry the organic layer over anhydrous sodium sulfate and distill off methylene dichloride below 60 deg.C. Charge 26 Its of ethyl acetate to the residue and heat to distillation temperature to distill off 19 Its of ethyl acetate and repeat the addition and distillation of ethyl acetate Then charge 39 l;ts of ethyl acetate in to the reactor. Cool the reaction mixture to 30 to 35 deg. C, further cool to 20 to 25 deg. C, stir for 60 minutes and filter. Wash the solids with ethyl acetate and dry to yield compound of formula I.
Example-3 Preparation of N_,N,6-Trimethyl-2-(4-methylphenyl)-imidazo [l_,2-alpyridine-3- acetamide hemitartrate
Charge 100 Its of methanol and 10 kg of compound of formula I obtained from example 2 into a reactor and stir for 10 mins. Add a solution of 2.43 kg L(+) tartaric acid to 50 Its of methanol to the reactor. Gradually raise the temp of reaction mixture to 30 to 35 deg.C and maintain the temp for 2 hrs. Cool to 0 to 2 deg.C and stir for 1 hr and filter. Wash the solids with methanol and dry to yield hemitartrate of compound of formula I.

Claims

WE CLAIM :
1. A process for the preparation of N,N,6-trimethyl-2-(4-methylphenyl)-imidazo [l,2-a]pyridine~3-acetamide,compound of formula I,
Figure imgf000013_0001
Formula I comprising reacting mixed anhydride, compound of formula III, with dimethylamine;
Figure imgf000013_0002
Formula III wherein R is selected from Cito C6 linear or branched alkyl groups and substituted phenyl groups.
2. A process as claimed in 1 wherein the mixed anhydride, compound of formula III is prepared by reacting compound of formula II with RCOX;
Figure imgf000013_0003
Formula II wherein R is selected from Cito C6 linear or branched alkyl groups and substituted phenyl groups and X is a halo group
3. A process for the preparation of compound of formula I as claimed in claim 1 further comprising converting compound of formula I to its hemitartrate or tartrate salt.
4. A process for the preparation of compound of formula I as claimed in claim 1 wherein R is selected from pivaloyl and isobutyl groups.
5. A process for the preparation of compound of formula I as claimed in claim 2 wherein X is chloro.
6. A process for the preparation of compound of formula I as claimed in claim 1 wherein the reaction is carried out in polar aprotic to non-polar solvent(s).
7. A process for the preparation of compound of formula I as claimed in claim 1 wherein the reaction is carried out in the presence of non-nucleophilic base.
8. A process for the preparation of compound of formula I as claimed in claim 1 wherein the reaction is carried out at about -10 to 100°C.
9. Mixed anhydride, compound of formula III,
Figure imgf000014_0001
Formula III wherein R is selected from Cito C6 linear or branched alkyl groups and substituted phenyl groups.
10. Mixed anhydride, compound of formula III, as claimed in claim 9 wherein R is selected from pivaloyl and isobutyl groups.
11. A process for the preparation of mixed anhydride, compound of formula III, comprising reacting compound of formula II, with RCOX;
Figure imgf000015_0001
Formula II wherein R is selected from Cito C6 linear or branched alkyl and substituted phenyl groups and X is a halo group.
12. A process for the preparation of mixed anhydride, compound of foraiula III, as claimed in claim 11 wherein R is selected from pivaloyl and isobutyl groups.
13. A process for the preparation of mixed anhydride, compound of formula III, as claimed in claim 11 wherein X is Chloro.
14. A process for the preparation of mixed anhydride, compound of formula III, as claimed in claim 11 wherein the reaction is carried out in polar aprotic to non-polar solvent.
15. A process for the preparation of mixed anhydride, compound of formula III, as claimed in claim 11 wherein the reaction is carried out in the presence of non-nucleophilic base.
16. A process for the preparation of mixed anhydride, compound of formula III, as claimed in claim 11 wherein reaction is carried out at about -10 to 100 C.
7. A process for the preparation of compound of formula I as claimed in claims 1 to 16 substantially as herein described and illustrated by examples 1,2 and 3.
PCT/IN2004/000057 2003-03-12 2004-03-11 Process for the preparation of n,n,6-trimethyl-2-(4-methylphenyl)-imidazo[1,2-a]pyridine-3-acetamide WO2004087703A1 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007040995A1 (en) * 2005-10-03 2007-04-12 Mallinckrodt Inc. Process for preparing zolpidem hemitartrate and tartrate polymorphs
WO2009007995A1 (en) * 2007-07-09 2009-01-15 Suven Life Sciences Limited Process for preparing zolpidem and its intermediate
WO2010122576A1 (en) 2009-04-20 2010-10-28 Matrix Laboratories Ltd Improved process for the preparation of 6-methyl-2-[4-methyl phenyl] imidazo [1, 2-a] pyridine-3-n, n-dimethyl acetamide.

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001038327A2 (en) * 1999-11-22 2001-05-31 EGIS Gyógyszergyár Rt. Process for the preparation of 6-methyl-2-(4-methyl-phenyl)-imidazo[1,2-a]pyrimidine-3-(n,n-dimethyl-acetamide) and intermediates
WO2001080857A1 (en) * 2000-04-24 2001-11-01 Teva Pharmaceutical Industries Ltd. Zolpidem hemitartrate
EP1172364A1 (en) * 2000-07-14 2002-01-16 Dinamite Dipharma S.p.A. (in abbreviated form Dipharma S.p.A.) A process for the preparation of 2-phenyl-imidazo[1,2-A]pyridine-3-acetamides

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001038327A2 (en) * 1999-11-22 2001-05-31 EGIS Gyógyszergyár Rt. Process for the preparation of 6-methyl-2-(4-methyl-phenyl)-imidazo[1,2-a]pyrimidine-3-(n,n-dimethyl-acetamide) and intermediates
WO2001080857A1 (en) * 2000-04-24 2001-11-01 Teva Pharmaceutical Industries Ltd. Zolpidem hemitartrate
EP1172364A1 (en) * 2000-07-14 2002-01-16 Dinamite Dipharma S.p.A. (in abbreviated form Dipharma S.p.A.) A process for the preparation of 2-phenyl-imidazo[1,2-A]pyridine-3-acetamides

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007040995A1 (en) * 2005-10-03 2007-04-12 Mallinckrodt Inc. Process for preparing zolpidem hemitartrate and tartrate polymorphs
JP2009510163A (en) * 2005-10-03 2009-03-12 マリンクロッド・インコーポレイテッド Process for producing hemitartaric acid and zolpidem tartrate polymorph
WO2009007995A1 (en) * 2007-07-09 2009-01-15 Suven Life Sciences Limited Process for preparing zolpidem and its intermediate
WO2010122576A1 (en) 2009-04-20 2010-10-28 Matrix Laboratories Ltd Improved process for the preparation of 6-methyl-2-[4-methyl phenyl] imidazo [1, 2-a] pyridine-3-n, n-dimethyl acetamide.

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