The present invention provides a highly stereoselective, simple and economical glycosylation process for preparation of .beta.-anomer enriched 2.sup.1-deoxy-2.sup.1,2.sup.1-D-ribofuranosyl difluoronucleosides of formula (II), and physiologically acceptable slats 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).