Zopiclone (CAS: 43200-80-2) & intermediates

i.  6-(5-chloro-2-piperidinyl)-6,7-dihydro-7-hydroxy-5H-pyrrolo[3,4-b]pyrazin-5 -one (CAS: 43200-81-3)

 ii. 6-(5-chloro-2-piperidinyl)-5H-pyrazine-5,7(6H,7H)-dione (CAS: 43200-82-4)

2,3-Pyrazinecarboxylic anhydride(CAS No.: 4744-50-7)

2,3-Pyrazinedicarboxylic acid(CAS No.: 89-01-0)