Abstract
Despite advances in synthetic carbohydrate chemistry, the 1,2-cis-selective glycosylation reaction of 2-deoxy-2-amino sugars has not progressed during the last three decades. For such glycosylations, 2-azide glycosyl donors have been extensively employed, notwithstanding difficulties in their preparation and moderate selectivities. Herein, we report on a highly 1,2-cis-selective trans-carbamate sugar donor, which can be readily prepared in high yields. Furthermore, the utility of the novel cis-selective glycosyl donor for preparing complex oligosaccharides is demonstrated through the effective synthesis of an anti-Helicobacter pylori hexasaccharide.