中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
苯基-2,3,4-三-O-苄基-1-硫代-β-L-岩藻吡喃糖苷 | 2,3,4-tri-O-benzyl-1-thio-β-L-fucopyranoside | 167612-35-3 | C33H34O4S | 526.697 |
—— | phenyl 6-deoxy-1-thio-β-L-galactopyranoside | 187233-24-5 | C12H16O4S | 256.323 |
The conformations of a series of derivatives of the disaccharide α-L-fucopyranosyl-(1[Formula: see text]3)-2-acetamido-2-deoxy-D-glucopyranoside, part of the Lex determinant, were studied by molecular modelling using the MM3* forcefield and by 1H NMR spectroscopy. Unusually shielded O-benzyl protons were observed in the 1H NMR spectrum of phenyl 2,3,4-tri-O-benzyl-α-L-fucopyranosyl-(1[Formula: see text]3)-2-deoxy-2-phthalimido-1-thio-α-D-glucopyranoside and assigned to the 2-O-benzyl group. This observation was explained by a shift in the population of the conformational mixture present about the glycosidic linkage from the positive Ψ region in the unsubstituted disaccharide to the negative Ψ region induced by π-stacking between the phthalimide and the 2-O-benzyl phenyl ring. The experimental nuclear Overhauser enhancements confirm the accuracy of the calculations.Key words: disaccharide, conformation, π-stacking, Lex determinant, NOE measurements, MM3 calculations.