Reaction equation
CN1CCN(C([O:10][CH:11]2[N:20]([C:21]3[CH:26]=[CH:25][C:24]([Cl:27])=[CH:23][N:22]=3)[C:18](=[O:19])[C:17]3[C:12]2=[N:13][CH:14]=[CH:15][N:16]=3)=O)CC1.Cl>>[Cl:27][C:24]1[CH:25]=[CH:26][C:21]([N:20]2[CH:11]([OH:10])[C:12]3[C:17](=[N:16][CH:15]=[CH:14][N:13]=3)[C:18]2=[O:19])=[N:22][CH:23]=1Participants
Procedure
In another embodiment, the invention provides a process to recycle the (R)-zopiclone, which remains in solution as waste product. (R)-zopiclone is recovered from the solution by any known conventional methods, for example, by solvent distillation, evaporation, or precipitation by adding a non-polar solvent, etc. This is followed by neutralization with base, extraction using methylene chloride followed by removal of the solvent. The (R)-isomer isolated is subjected to acid hydrolysis using aqueous HCl, obtaining 6-(5-chloropyrid-2-yl)-5-hydroxy-7-oxo-5,6-dihydropyrrolo-[3,4-b]pyrazine. The compound, 6-(5-chloropyrid-2-yl)-5-hydroxy-7-oxo-5,6-dihydropyrrolo-[3,4-b]pyrazine, is reacted with 1-chlorocarbonyl-4-methylpiperazine hydrochloride in a suitable organic solvent in the presence of triethyl amine and N,N-dimethylamino pyridine to obtain zopiclone in high yields. The racemate thus obtained is further resolved to obtain eszopiclone by the above stated method.
Workup
- customIn another embodiment, the invention provides a process
- additionby adding a non-polar solvent, etc.
- extractionThis is followed by neutralization with base, extraction
- customfollowed by removal of the solvent
- customThe (R)-isomer isolated
- customis subjected to acid hydrolysis
Sources & evidence
- ORD record
- ord-f75ff59fbe9c40b9b045366d96b9a834
- Source dataset
- uspto-grants-2010_08
- Patent number
- US07786304B2
Linked notes
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