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Preparation of paroxetine involving novel intermediates

a technology of intermediates and paroxetine, which is applied in the field of intermediate synthesis processes, can solve the problems of large quantities of phenol as undesirable by, low yield of paroxetine, and long time required for the conversion of me-prx to paroxetin

Inactive Publication Date: 2005-12-15
TEVA PHARMA IND LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among the disadvantages of this process are the low conversion of Me-PRX to the phenyl carbamate, resulting in low yields of paroxetine.
This process also results in large quantities of phenol as an undesirable by-product.
A significant disadvantage of this process is the long time required for the conversion of Me-PRX to paroxetine under the conditions disclosed in, for example, Examples 6 and 7 of the '723 patent.

Method used

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  • Preparation of paroxetine involving novel intermediates
  • Preparation of paroxetine involving novel intermediates
  • Preparation of paroxetine involving novel intermediates

Examples

Experimental program
Comparison scheme
Effect test

example 1

Reaction with 2-Cl-ethylchloroformate (CECF) in dry conditions

[0050] Me-PRX (3 g) and extra dry toluene (40 ml, less than 0.001% water) are charged into dried equipment under a dry N2 stream. The reaction mixture is cooled to 4° C. with an ice bath. CECF (2.7 mL, 3 eq., purchased from SNPE) is added dropwise for several minutes. The mixture is heated to reflux for 7 hours providing the substantially complete conversion of Me-PRX (HPLC) to the carbamate. Water (50 mL) is added to cool the reaction mixture to room temperature. The organic layer is separated, washed with water, dried with Na2SO4 and evaporated to dryness to give 1-(2-chloroethoxycarbonyl)-4-fluorophenyl-3-[5-(1,3-dioxaindanyl)oxymethyl]piperidine, i.e., the 2-chloroethyl carbamate of paroxetine (CECB).

example 2

Reaction with CECF in the presence of Bu3N

[0051] The same procedure as described in Example I is repeated, except that the equipment is not previously dried, technical grade toluene (less than 0.10% water) is used instead of extra dry toluene, and the reactants are not charged under a dry N2 stream. The reaction mixture, before addition of CECF, also contains 2.05 g (1.2 eq.) of Bu3N. After 1.5 hours of reflux, substantially complete conversion of Me-PRX to the corresponding carbamate takes place. The carbamate, i.e., the 2-chloroethyl carbamate of paroxetine (CECB) is separated from the reaction mixture using the same procedures as described in Example 1.

example 3

Reaction with CECF in the presence of Et3N

[0052] The same procedure as described in Example 2 is repeated, but with 1.1 g Et3N (1.2 eq.) used in place of Bu3N. After 4 hours of reflux, conversion of the Me-PRX to the corresponding carbamate is 74% (reaction stopped).

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Abstract

Disclosed are processes for preparing novel carbamate intermediates of paroxetine comprising dealkylating N-alkylparoxetine by reaction thereof with a haloalkyl ester of a haloformic acid, in a suitable organic solvent. Also disclosed are processes for preparing paroxetine comprising hydrolyzing the novel carbamate intermediates in a suitable solvent. Paroxetine prepared by the above processes can be neutralized with hydrogen chloride and crystallized as paroxetine hydrochloride anhydrous, hemihydrate or as a solvate of isopropanol. The invention is further directed to the novel carbamate intermediates formed by the disclosed processes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 137,087, filed on May 1, 2002, which claims the benefit of provisional application Ser. No. 60 / 360,760, filed Mar. 1, 2002. The disclosure of application Ser. Nos. 10 / 137,087 and 60 / 360,760 are is incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention relates to processes for the synthesis of intermediates useful in preparing paroxetine (PRX); processes for preparing paroxetine using such intermediates; and, to intermediates of the disclosed processes. More particularly, the present invention relates to a novel process for the preparation of paroxetine by dealkylation of N-alkylparoxetine, such as N-methylparoxetine (Me-PRX), and to novel intermediates of this process. BACKGROUND OF THE INVENTION [0003] Paroxetine (PRX), (−)-trans-3-[(1,3-benzodioxol-5-yloxy)methyl]-4-(4-fluorophenyl)piperidine; (3S, 4R)-3-[5-(1,3-dioxaindanyl)oxymeth...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C07D405/12
CPCC07D405/12
Inventor PILARSKI, GIDEONAVRUTOV, ILYA
Owner TEVA PHARMA IND LTD
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