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Racemisation of enantiomers of nefopam and analogues

A racemization, enantiomer technology, applied in the field of racemization and recycling, can solve the problems of inappropriateness, chemical instability, etc.

Inactive Publication Date: 2009-06-03
SOSEI R&D LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The literature on the accelerated stability of the Nefopam molecule shows that it is chemically unstable under both acidic and basic conditions, suggesting that racemization of Nefopam may not be appropriate under these conditions

Method used

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  • Racemisation of enantiomers of nefopam and analogues
  • Racemisation of enantiomers of nefopam and analogues

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Treatment of (-)-nefopam free base (obtained from the mother liquor in the resolution process) with dilute hydrochloric acid (1.5 vol) in ethanol (5 vol) resulted in racemization even at low temperatures. The results are shown in the table below. The conversion was from an initial ee (enantiomeric excess) of 95.6 to 2.4 at 80°C and 13.0 at 20-25°C.

Embodiment 2

[0017] The mother liquor from the resolution of 300 g of Nefopam racemate (WO2005 / 056539) was treated in the following manner:

[0018] The mother liquor from the formation of the hydrochloride salt was placed in a suitable container and the isopropanol was distilled off under vacuum. To the concentrate was added the liquid from the recrystallization of Nefopam dibenzoyl tartrate and the ethanol was distilled off under vacuum. The mother liquor from the initial dibenzoyl tartrate formation was added to the concentrate and the ethanol was distilled off under vacuum. Water (100ml) and toluene (300ml) were added to the concentrate. The mixture was heated at 50-55°C for at least 1 hour and potassium carbonate solution (50% w / w in water) was added over a period of at least 1 hour. The lower aqueous layer was separated. The upper organic layer was washed with water (100ml) and the lower aqueous layer was separated. Toluene was distilled off under vacuum to obtain a concentrate. ...

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Abstract

The present invention discloses a process for the racemisation of a compound which is nefopam or an analogue thereof in the form of a single enantiomer or non-racemic mixture, which comprising contacting the compound with an acid.

Description

technical field [0001] The present invention relates to racemization and recycling processes, in particular to the racemization of the enantiomers of Nefopam and its analogs. Background technique [0002] Nefopam (available as the hydrochloride salt) is a centrally acting non-narcotic analgesic. Nefopam and its analogs are described in GB1148717 and WO2004 / 056788. The use of the single isomer of Nefopam, namely (+)-Nefopam, is disclosed in WO03 / 105832 and WO03 / 105833. Furthermore, single enantiomers of nefopam analogues and their use are described in WO2006 / 095187. [0003] (+)-Nefopam hydrochloride monohydrate can be prepared by resolution as described in WO2005 / 056539, see Scheme 1. Currently, the (-)-nefopam enantiomer has no defined use and is discarded as waste. [0004] plan 1 [0005] [0006] To date, there is no evidence of chemical racemization of optically pure Nefopam in the literature, nor any evidence of racemization in API stability studies performed o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D267/22
CPCC07D267/22A61P25/04
Inventor 马克-亨利·穆托埃尔夫·莱尔米特安德鲁·道格拉斯·巴克斯特肯尼思·沃尔特·辛登
Owner SOSEI R&D LTD
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