Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
Org Biomol Chem. 2013 Sep 7;11(33):5465-72. doi: 10.1039/c3ob40991k.
The predominantly populated conformation of carbohydrates in solution does not necessarily represent the biologically active species; rather, any conformer accessible without too large an energy penalty may be present in a biological pathway. Thus, the conformational preferences of a naphthyl xyloside, which initiates in vivo synthesis of antiproliferative glycosaminoglycans, have been studied by using NMR spectroscopy in a variety of solvents. Equilibria comprising the conformations (4)C1, (2)SO and (1)C4 were found, with a strong dependence on the hydrogen bonding ability of the solvent. Studies of fluorinated analogues revealed a direct hydrogen bond from the hydroxyl group at C2 to the fluorine atom at C4 by a (1h)JF4,HO2 coupling. Hydrogen bond directionality was further established via comparisons of fluorinated levoglucosan molecules.
碳水化合物在溶液中的主要构象并不一定代表具有生物活性的物种；相反，任何没有太大能量惩罚的构象都可能存在于生物途径中。因此，通过使用 NMR 光谱在各种溶剂中研究了起始体内合成抗增殖糖胺聚糖的萘基木糖苷的构象偏好。发现包含构象（4）C1、（2）SO 和（1）C4 的平衡，并且强烈依赖于溶剂的氢键形成能力。氟化类似物的研究表明，通过（1h）JF4,HO2 偶联，C2 上的羟基与 C4 上的氟原子直接形成氢键。通过比较氟化莱苏糖分子进一步确定了氢键的方向性。
