72858-55-0Relevant articles and documents
Glycosidic linkage, N-acetyl side-chain, and other structural properties of methyl 2-acetamido-2-deoxy-β-d-glucopyranosyl-(1→4)-β-d-mannopyranoside monohydrate and related compounds
Carmichael, Ian,Meredith, Reagan J.,Oliver, Allen G.,Serianni, Anthony S.,Zhang, Wenhui
, p. 287 - 297 (2020/03/17)
The crystal structure of methyl 2-acetamido-2-deoxy-β-d-glycopyranosyl-(1→4)-β-d-mannopyranoside monohydrate, C15H27NO11·H2O, was determined and its structural properties compared to those in a set of mono- and disaccharides bearing N-acetyl side-chains in βGlcNAc aldohexopyranosyl rings. Valence bond angles and torsion angles in these side chains are relatively uniform, but C - N (amide) and C - O (carbonyl) bond lengths depend on the state of hydrogen bonding to the carbonyl O atom and N - H hydrogen. Relative to N-acetyl side chains devoid of hydrogen bonding, those in which the carbonyl O atom serves as a hydrogen-bond acceptor display elongated C - O and shortened C - N bonds. This behavior is reproduced by density functional theory (DFT) calculations, indicating that the relative contributions of amide resonance forms to experimental C - N and C - O bond lengths depend on the solvation state, leading to expectations that activation barriers to amide cis-trans isomerization will depend on the polarity of the environment. DFT calculations also revealed useful predictive information on the dependencies of inter-residue hydrogen bonding and some bond angles in or proximal to β-(1→4) O-glycosidic linkages on linkage torsion angles φ and ψ. Hypersurfaces correlating φ and ψ with the linkage C - O - C bond angle and total energy are sufficiently similar to render the former a proxy of the latter.
Synthesis of building blocks for an iterative approach towards oligomers of the Streptococcus pneumoniae type 1 zwitterionic capsular polysaccharide repeating unit
Ní Cheallaigh, Aisling,Oscarson, Stefan
, p. 940 - 960 (2016/11/17)
Zwitterionic capsular polysaccharide extracts, 8 kDa in mass, from Streptococcus pneumoniae type 1 (Spt1) have shown unique T-cell activating properties. Oligomers of the trisaccharide repeating unit of the Spt1 capsular polysaccharide [3)-4-NH2-α-d-QuipNAc-(14)-α-d-GalpA-(13)-α-d-GalpA-(1-]n of defined length are needed to further investigate this response. An approach towards iteratively extendable trisaccharide building blocks of the zwitterionic capsular polysaccharides of Spt1 is described. Key elements include the comparison of pre-glycosylation oxidation and post-glycosylation oxidation approaches using thioglycoside donors to the target trisaccharide, the optimisation of the post-glycosylation oxidation approach, and the conversion of the trisaccharide to building blocks tailored for iterative glycosylation. The construction and evaluation of stereotunable 2-N-3-O-oxazolidinone donors for the common bacterial 2-acetamido-4-amino-2,4,6-trideoxy-α-d-galactopyranoside motif is also described, as is a key intermediate for their efficient synthesis.
An efficient synthesis of the protected carbohydrate moiety of Brasilicardin A
Jung, Michael E.,Koch, Pierre
, p. 3710 - 3713 (2011/09/14)
A synthesis of the protected carbohydrate moiety 2 of Brasilicardin A starting from l-rhamnose and d-glucosamine is described. The disaccharide was synthesized using a TMSOTf-mediated glycosylation of the 2-phthalimido-2- deoxyglucose donor 5 and the 3-hydroxyl group of the protected l-rhamnose derivative 4, which already bears the 3-hydroxybenzoate unit. The imidate 2 was coupled via TMSOTf-mediated glycosidation with cholesterol as a model aglycone followed by the selective cleavage of all the acetate groups to give the Brasilicardin A analogue 16.
