IES64896B2 - Process for the resolution of racemic 3-(2-pyridyl)-3-phenyl-N,N-dimethylpropylamines - Google Patents

Process for the resolution of racemic 3-(2-pyridyl)-3-phenyl-N,N-dimethylpropylamines

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Publication number
IES64896B2
IES64896B2 IES950207A IES64896B2 IE S64896 B2 IES64896 B2 IE S64896B2 IE S950207 A IES950207 A IE S950207A IE S64896 B2 IES64896 B2 IE S64896B2
Authority
IE
Ireland
Prior art keywords
compound
pyridyl
formula
acid
pharmaceutically acceptable
Prior art date
Application number
Inventor
Brian Brady
Maurice Fitzgerald
Original Assignee
Dunconor Limited
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.)
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Publication date
Application filed by Dunconor Limited filed Critical Dunconor Limited
Priority to IES950207 priority Critical patent/IES64896B2/en
Publication of IES950207A2 publication Critical patent/IES950207A2/en
Publication of IES64896B2 publication Critical patent/IES64896B2/en

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  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

Abstract

A process for preparing in essentially pure form the d-isomer of a compound of the formula I wherein X is chlorine and n is 0 or 1, or a pharmaceutically acceptable addition salt thereof, comprises reacting the dl-form of a compound formula I with a 3,5-disubstituted benzoic acid as resolving agent and, if desired, converting the compound thus obtained into a pharmaceutically acceptable acid addition salt thereof. These compounds have strong anti-histamine activity.

Description

APPLICATION Nc...............—« Process for the Resolution of Racemic 3-(2-Pvridvl)-3-phenvl-N.IV- dimethvlpropvlamines.
This invention relates to a process for the resolution of racemic 3-(2-pyridyl)-3-phenylΝ,Ν-dimethylpropylamines. In particular, it relates to a process for the preparation of the tZ-isomers of compounds of the formula I wherein X is chlorine, and n is 0 or 1, and salts thereof.
These compounds are well known and have strong anti-histamine activity.
U.S. Patent Specification No. 3,061,517 describes a process for the separation of the disomers of phenyl-(2-pyridyl)-alkyl substituted tertiary amines and halogen substituted derivatives thereof from a racemic mixture of same. However, the resolving agent, dphenylsuccinic acid is difficult to manufacture and is therefore expensive. The process must be carried out in an organic solvent. Furthermore, successive purification steps by multiple recrystallisation are required with consequent low yields and high costs of the desired products.
It is the object of the invention to provide a superior process for preparing the rf-isomer of a compound of the formula I as defined above.
According to the invention there is provided a process for preparing, in essentially pure form, the d-isomer of a compound of the formula I wherein X and n are as already defined, or a pharmaceutically acceptable addition salt thereof, which process comprises reacting the (//-form of a compound of the formula I with a 3,5-disubstituted benzoic acid -2and, if desired, converting the compound thus obtained into a pharmaceutically acceptable acid addition salt thereof.
The {/-isomers obtained according to the process of the invention are essentially optically pure and can be reacted with suitable mineral and organic acids to form pharmaceutically ¢: acceptable acid addition salts thereof. Examples of suitable acids are hydrochloric acid, hydrobromic acid, tartaric acid, citric acid, succinic acid, maleic acid and fumaric acid. » The substituents on the benzene radical of the resolving agent may be methyl, bromo or nitro. Preferably, the resolving agent is 3,S-dinitrobenzoic acid.
The separation of the {/and /-isomers of the compound of the formula I is accomplished in a continuous cyclic process using the achiral disubstituted benzoic acid as the resolving agent. The process is designed on the basis that addition salts of the compound of the formula I with the disubstituted benzoic acid crystallise in a form in which individual crystals are comprised entirely of pure {/- or pure /-isomer. Seeding a saturated solution, for example, with pure {/-isomer affords a crop greatly enriched in that isomer. The /isomer is then obtained by appropriate seeding of the mother liquor. The balance of the mother liquor is restored after each cycle by the addition of the appropriate quantities of racemate and resolving agent.
The reaction of the dl-form of a compound of the formula I with the resolving agent is preferably carried out in water in the presence of a mineral acid, preferably hydrochloric acid. The undesired /-isomer, after conversion back to the {//-form, and the resolving agent are cycled back into the process.
The mole ratio of racemate to resolving agent is not critical but is preferably in the range of from 2:1 to 3 :1.
Following the reaction between the racemate and resolving agent, the product can be removed and washed with water. Following extraction of the resulting product into a ,.
V solvent, the pure {/-isomer of the formula I can be obtained by distillation of the solvent. -3The reaction is typically performed at a temperature of 20 to 90°C, the preferred temperature being 60 to 80°C.
The invention is illustrated by the following Example.
EXAMPLE (a) d'-3-(2-Pyridyl)-3-(p-chJorophenyl)-NJV-dimethyIpropylamine A mixture of 105 g of d, /-3-(2-pyridyl)-3-(p-chlorophenyl)-N,N-dimethylpropylamine, 31 g of /-3-(2-pyridyl)-3-(p-chIorophenyl)-N,N-dimethylpropyIamine 3,5-dinitrobenzoate, 11 g of 3,5-dinitrobenzoic acid, 26.5 mi of concentrated hydrochloric acid and 200 ml of water is agitated at a temperature or about 70° C for about 12 hours. The precipitated /-3(2-pyridyl)-3-(p-chlorophenyl)-N,N-dimethylpropylaniine 3,5-dinitrobenzoate is removed by filtration at about 20°C.
To the mother liquor is added 25 g of 4/-3-(2-pyridyl)-3-(p-chlorophenyl)-N,N-dimethyIpropylamine, and 28 g of 3,5-dinitrobenzoic add (alternately the 3,5-dinitrobenzoate salt of the cff-form may be used) and the mixture is agitated at a temperature of about 70° C for about 12 hours. The predpitated The 23* +49° to +53° (cone., 5% in dimethylformamide). The yield from each cycle is about 33% but overall is essentially quantitative. -4The /-3-(2-pyridyl)-3-(p-chlorophenyl)-N,N-dimethylpropylamine 3,5-dinitrobenzoate, isolated on alternate cycles of the process, is converted back to the d7-form by heating in aqueous hydrochloric add in the presence of a catalytic amount Of maleic add. The d7-3(2-pyridyl)-3-(p-chlorophenyl)-N,N-dimethylpropylamine 3,5-dinitrobenzoate so obtained is recycled back into the process. (b) d-3-(2-Pyridyl>3-(p-chIorophenyl)-N,N- Fifty grams of the above base, ef-3-(2-pyridyl)-3-(p-chlorophenyl)-N,N- The d-3-(2-pyridyl)-3-(p-chlorophenyl)-N,N-dimethylpropylamine maleate so obtained is filtered, washed with ethyl acetate and dried.
M.P. 112-115°, [ajo25’ +39.5 to +43.0® (cone., 5% in dimethylformamide).

Claims (5)

1. A process for preparing in essentially pure form the rf-isomer of a compound of the formula I wherein X is chlorine and n is 0 or 1, or a pharmaceutically acceptable addition salt thereof, which process comprises reacting the d/-form of a compound of formula I with a 3,5-disubstituted benzoic acid as resolving agent and, if desired, converting the compound thus obtained into a pharmaceutically acceptable acid addition salt thereof.
2. A process according to claim 1, wherein the resolving agent is 3,5-dinitrobenzoic acid, and the reaction is carried out in water.
3. A process according to claim 1 or 2 wherein the /-form of the compound of formula I, obtained in alternate cycles of the process, is converted back to the d/-form by heating in aqueous hydrochloric acid in the presence of a catalytic amount of maleic acid.
4. A process according to any preceding claim, wherein the compound prepared is d-3-(2-pyridyl)-3-(p-chlorophenyl)-N,N-dimethylpropylamine or d-3-(2-pyridyl)-3-phenyl-N,N-dimethylpropylamine or a pharmaceutically acceptable acid addition salt thereof.
5. A pharmaceutical composition containing a compound prepared by a process claimed in any preceding claim.
IES950207 1995-03-23 1995-03-23 Process for the resolution of racemic 3-(2-pyridyl)-3-phenyl-N,N-dimethylpropylamines IES64896B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
IES950207 IES64896B2 (en) 1995-03-23 1995-03-23 Process for the resolution of racemic 3-(2-pyridyl)-3-phenyl-N,N-dimethylpropylamines

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IES950207 IES64896B2 (en) 1995-03-23 1995-03-23 Process for the resolution of racemic 3-(2-pyridyl)-3-phenyl-N,N-dimethylpropylamines

Publications (2)

Publication Number Publication Date
IES950207A2 IES950207A2 (en) 1995-09-20
IES64896B2 true IES64896B2 (en) 1995-09-20

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Family Applications (1)

Application Number Title Priority Date Filing Date
IES950207 IES64896B2 (en) 1995-03-23 1995-03-23 Process for the resolution of racemic 3-(2-pyridyl)-3-phenyl-N,N-dimethylpropylamines

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Publication number Publication date
IES950207A2 (en) 1995-09-20

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