Stereoselective -Glycosylation with GlcN₃ Donors Enabled Collective Syntheses of Acinetobacter baumannii Capsular Polysaccharides K43, K47 and K88 Repeating Units

Collective syntheses of A. baumannii CPS K43, K47 and K88 repeating units have been accomplished via a new alpha-glycosylation method with GlcN3 as donors, which features: 1) mild reaction conditions, 2) good to high yields, 3) excellent stereoselectivities. The synthetic route also highlights an orthogonal one-pot coupling strategy on the basis of glycosyl ortho-(1-phenylvinyl)benzoates for stereoselective constructions of both 1,2-trans and 1,2-cis glycosidic bonds, precluding the issues of aglycone transfer. A synergistic alpha-glycosylation method with GlcN3 as donors has been developed, which enjoys mild reaction conditions, good to high yields, and high stereoselectivities. Furthermore, collective syntheses of A. baumannii CPS K43, K47 and K88 repeating units 1-3 have been achieved for the first time via applications of this alpha-glycosylation method.dagger image