title: Convergent synthesis of 4-O-phosphorylated L-glycero-D-manno-heptosyl lipopolysaccharide core oligosaccharides based on regioselective cleavage of a 6,7-O-tetraisopropyldisiloxane-1,3-diyl protecting group.
abstract: The structurally conserved lipopolysaccharide core region of many Gram-negative bacteria is composed of trisaccharides containing 4-O-phosphorylated L-glycero-D-manno-heptose (L,D-Hep) units, which act as ligands for antibodies and lectins. The disaccharides Glc-(1→3)-Hep4P Hep-(1→3)-Hep4P and Hep-(1→7)-Hep4P and the branched trisaccharide Glc-(1→3)-[Hep-(1→7)]-Hep4P, respectively, have been synthesized from a methyl heptopyranoside acceptor in less than 10 steps. The synthetic strategy was based on the early introduction of a phosphotriester at position 4 of heptose followed by a regioselective opening of a 6,7-O-(1,1,3,3-tetraisopropyl-1,3-disiloxane-1,3-diyl) group allowing for a straightforward access to glycosylation at position 7. Perbenzylated N-phenyl trifluoroacetimidate glucosyl and heptosyl derivatives served as α-selective glycosyl donors.
authors.affiliation: Department of Chemistry, University of Natural Resources and Life Sciences , A-1190 Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Stanetty
authors.forename: Martin
authors.initials: M
authors.lastname: Walter
authors.forename: Paul
authors.initials: P
authors.lastname: Kosma
mesh_terms: D008070:Lipopolysaccharides / Q000737:chemistry*; D008968:Molecular Conformation; D009844:Oligosaccharides / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D008070:Lipopolysaccharides; D009844:Oligosaccharides; D012833:Siloxanes