Synthesis and Conformational Analysis of the T-Antigen Disaccharide (β-D-Gal-(1→3)-α-D-GalNAc-OMe)

Abstract

We report an improved synthesis of the T-antigen disaccharide [β-D-Gal-(1Ǟ3)-α-D-GalNAc-OMe], incorporating recycling of the undesired β-glycosyl acceptor [methyl 2-azido-4,6-benzylidene-2-deoxy-β-D-galactopyranoside (9β)] through anomerization by treatment with FeCl 3 . The conformational analysis of the disaccharide made use of high quality NOE data in combination with extensive Metropolis Monte-Carlo (MMC) and molecular dynamic (MD) simulations. To sample the conformational space sufficiently, 9.5·10 6[a]

Concise synthesis of the pentasaccharide O-antigen of Escherichia coli O83:K24:H31 present in the Colinfant vaccine

“…Glycosylation of ethyl 6-Obenzyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (5) [20] with trichloroacetimidate donor (6) [21] in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) [22] furnished disaccharide thioglycoside derivative 7, which on conventional acetylation gave disaccharide thioglycoside donor (8) in over all 76% yield in two steps. Presence of signals at δ [5.44 (d, J=10.6 Hz, H-1 D ) and 4.49 (d, J=8.0 Hz, H-1 E )] in the 1 H NMR and at δ [100.3 (C-1 E ) and 80.9 (C-1 D )] in the 13 C NMR spectra supported its formation.…”

Chemoenzymatic synthesis of glycosyl-deoxyinositol derivatives. First example of a fagopyritol β-analogue containing an aminoinositol unit

“…Compound 5 was prepared according to the established literature procedures. 16 The glycosylation of acceptor 4 with donor 5 in the presence of a catalytic amount of TMSOTf at À15°C yielded glycoside 6 in excellent yield, and no additional products were detected in the reaction (Scheme 2). The structure of compound 6 was corroborated by means of 2D NMR spectroscopy (COSY, HSQC) which identified the anomeric proton (d = 4.8 ppm, J = 8.0 Hz) and confirmed the downfield shift of the carbon bearing the glycosidic moiety.…”

Enzymatic Glycosylation Strategies in the Production of Bioactive Compounds

“…Functional oligosaccharides and glycans such as galacto-N-biose (GNB) and lacto-Nbiose (LNB) glycoconjugates are important carbohydrates derivatives that are present in a wide scope of bioactive compounds. Thus, straightforward access to this type of scaffolds is crucial, with versatile applications in medicinal chemistry and biology [61][62][63][64][65][66]. So, Y-W. Kim et al [66] studied a new route to access D-Lacto-and D-Galacto-N-bioside glycans (D-LNB and D-GNB, respectively) involving an enzymatic pathway.…”