6-(5-chloropyridin-2-yl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazin-5-one;Zopiclone specified impurity C [EP];Eszopiclone Impurity C;6-(5-chloropyridin-2-yl)-6,7-dihydro-5h-pyrrolo[3,4-b]pyrazin-5-one;6-(5-chloropyridin-2-yl)-7H-pyrrolo[3,4-b]pyrazin-5-one
