PROCESS FOR PREPARATION OF DEXTROROTATORY ISOMER OF 6-(5-CHLORO-PYRID-2-YI)-5-(4-METHYL -1-PIPERAZINYL) CARBONYLOXY-7-OXO-6,7-DIHYDRO-5H-PYRROLO 3,4-B PYRAZINE (ESZOPICLONE)

摘要

Disclosed herein is the process for preparation of 6-(5-chloro-pyrid-2-yl)-5-[(4-methyl-1-piperazinyl) carbonyloxy]-7-oxo-6,7-dihydro-5H-pyrrolo [3,4-b] pyrazine (Zopiclone), its resolution to get the dextrorotatory isomer of formula (I) substantially free of R (-) enantiomer and recovery of key raw material i.e. 6-(5-chloro pyrid-2-yl)-5-hydroxy-7-oxo-5,6-dihydropyrrolo [3,4-b] pyrazine from the R-isomer of Zopiclone followed by conversion of the recovered compound to get pure Eszopiclone (I) in high yield and high purity.