508169-19-5

Upstream product

• 627-11-2 2-Chloroethyl chloroformate 
• 43200-81-3 6-(5-chloropyridin-2-yl)-7-hydroxy-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazin-5-one 
• 508169-17-3 (+/-)-7-(2-chloroethyloxycarbonyloxy)-6-(5-chloropyridin-2-yl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazin-5-one 

Relevant academic research and scientific papers

Enzymatic resolution of new carbonate intermediates for the synthesis of (S)-(+)-zopiclone

The lipase from Candida antarctica B catalyzes the enantioselective hydrolysis of (±)-6-(5-chloropyridin-2-yl)-7-chloromethyloxycarbonyloxy-6,7- dihydro-5H-pyrrolo[3,4-b]pyrazin-5-one, a useful intermediate in the synthesis of (S)-(+)-zopiclone. This enzyme also catalyzes the resolution of the corresponding 2-chloroethylcarbonate derivative.

Resolution of (±)-5-substituted-6-(5-chloropyridin-2-yl)-7-oxo-5,6-dihydropyrrolo [3,4b]pyrazine derivatives-precursors of (S)-(+)-Zopiclone, catalyzed by immobilized Candida antarctica B lipase in aqueous media

The enzymatic resolution of different cyclopyrrolone compounds has been performed in aqueous systems using different immobilized preparations of lipase from Candida antarctica (fraction B). The relevance of the immobilization protocol in the results has been shown: lipase immobilized on octadecyl-Sepabeads gave the highest stability and enantioselectivity. Commercial Novozym 435 was scarcely enantioselective in the hydrolytic process. On the other hand, the structure of the cyclopyrrolone was also found to be very important to the outcome of the reaction, the best results being achieved with compounds (±)-1 and (±)-2. Thus, using compound (±)-2, a ees of >95% can be achieved under conditions in which the enzyme preparation can be utilized in 10 recycles without any significant detriment to the enzymatic properties (activity, enantioselectivity). Moreover, this enzyme catalyzes the hydrolytic resolution of chloromethyl carbonate (±)-5, a useful intermediate for the synthesis of the hypnotic agent (S)-(+)-Zopiclone.