Intermediate and process for preparing of beta-anomer enriched 21-deoxy-21, 21 - difluoro-D-ribofuranosyl nucleosides

摘要

The present invention provides a highly stereoselective, simple and economical glycosylation process for preparation of beta-anomer enriched 2¹-deoxy-2¹,2¹-D-ribofuranosyl difluoronucleosides of formula (II), and physiologically acceptable salts thereof, in particular, the beta-enriched anomer of gemcitabine hydrochloride of formula (IIb) in purity of >99% is provided through utilization of a novel trichloroacetimidate of formula (I).