Chemoselective glycosylations using 2,3-unsaturated-4-keto glycosyl donors

2,3-Unsaturated-4-keto glycosyl acetates were found to exhibit low reactivity under several glycosylation conditions. Chemoselective glycosylations were effectively performed using 2,3-unsaturated glycosyl and 2,3-dideoxy glycosyl acetates as armed glycosyl donors, and 2,3-unsaturated-4-keto glycosyl acetates as disarmed glycosyl donors.