2-Deoxy-2-iodo- and 2-Deoxy-2-bromo-α-glucopyranosyl Trichloroacetimidates: Highly Reactive and Stereoselective Donors for the Synthesis of 2-Deoxy-β-glycosides

[formula: see text] 2-Deoxy-2-iodo- and 2-deoxy-2-bromoglucopyranosyl trichloroacetimidates 8-10 and 22 are extremely useful precursors of 2-deoxy-beta-glycosides. These reactive glycosyl donors undergo highly stereoselective glycosidation reactions at -78 degrees C with a range of glycosyl acceptors using TBS-OTf as the activating agent. beta-Glycosides are obtained with > or = 19:1 selectivity in six of the seven examples reported herein.