Zopiclone → Eszopiclone

Participants

Reaction Conditions

Reaction Steps

Mixture of dichloromethane 300 ml, 6-(5-chloropyridin-2-yl)-5-(4-methylpiperazin-1-yl)-carbonyloxy-7-oxo-5,6-dihydropyrrolo-[3,4-b]-pyrazine D (+)-O,O′-dibenzoyltartaric acid salt 100 g (Chiral purity 97%) and water 250 ml was warmed to 35-37° C. Sodium bicarbonate (28.1 g) was added to the mixture and maintained at 35-37° C. Reaction mixture was stirred for 30-60 min and cooled to 25-30° C. Organic layer was separated. The organic layer was washed with 200 ml water and then with activated carbon (5 g) for 30 min at 20-25° C. Carbon was filtered over hyflo and washed with 100 ml dichloromethane. The filtrate was concentrated to 150 ml at atmospheric pressure. Cyclohexane (600 ml) was added to residual solution at 25-30° C. in 60 min. The slurry was slowly cooled to 0 to 5° C. and stirred for 60 min at same temperature. The solid was filtered and washed with chilled 50 ml Cyclohexane (10° C.) and then dried at 50-60° C. to obtained 44 g Eszopiclone with chiral purity ˜97%

Provenance & Evidence