摘要:
Diastereoselective deuteration and H-1 NMR spectroscopy were applied in a conformational study of the C5-C6 bond in four stereoisomeric methyl N-acetylneuraminyl(2-6)-beta-D-hexopyranosides [NeuNAc-alpha(2-6)Gal, NeuNAc-beta-(2-6)Gal, NeuNAc-alpha-(2-6)Glc, and NeuNAc-beta-(2-6)Glc]. In aqueous solution, NeuNAc-alpha-(2-6)Gal prefers a gt conformer (gg:gt:tg = ca. 20:60:20), NeuNAc(2-6)Glc isomers prefer a gg (gg:gt:tg = ca. 60:40:0), and NeuNAc-beta-(2-6)Gal exists equally in the three conformers.