Some Aspects of Selectivity in the Reaction of Glycosyl Donors*
摘要:
Some advantages, disadvantages, and anomalies of various donors in glycosidations are discussed. By studying several two-component donor/acceptor-diol reactions, it is shown that regiopreferences are not very sensitive to the type of donor used. However, in competitive glycosidations within a given type of donor and between different types of donor, it is shown that regio- and chemoselectivities must be indexed to donor reactivity.
The cycloalkane-based thermomorphic (CBT) system is a convenient and practical method for oligosaccharide synthesis, and hydrophobically modified oligosaccharides have a remarkable affinity for CBT solutions composed of methylcyclohexane and propionitrile.
Conformation-Controlled Hydrogen-Bond-Mediated Aglycone Delivery Method for α-Xylosylation
作者:Deqin Cai、Ya Bian、Shengjie Wu、Kan Ding
DOI:10.1021/acs.joc.1c00187
日期:2021.8.6
α-xyloside-containing molecules was full of challenges. Herein, a robust method is presented for selective α-xylosylation via combination of a rare conformation-controlled strategy and the hydrogen-bond-mediated aglycone delivery method. Various native branched α-xyloside structures necessitate an orthogonally protected xyloside, and a three-pot preparation method of the xylosyl donor was developed for this novel
α-木糖基化聚糖和木糖基衍生物是生物医学上重要的分子,它们显示出许多抗感染、癌症、炎症等生物活性。由于缺乏有效的α-木糖基化方法,含α-木糖苷分子的合成充满挑战。在此,通过结合罕见的构象控制策略和氢键介导的苷元递送方法,提出了一种用于选择性 α-木糖基化的稳健方法。各种天然支链 α-木糖苷结构需要正交保护的木糖苷,为此新的 α-木糖基化方法开发了木糖基供体的三锅制备方法,并进一步应用于木葡聚糖侧链 N 的首次合成。这项工作提供了一种有效的 α-木糖基化方法,可以实现各种 α-木糖苷结构。构象控制策略对五碳吡喃糖的化学也有重要参考。
<i>n</i>-Pentenyl-Type Glycosides for Catalytic Glycosylation and Their Application in Single-Catalyst One-Pot Oligosaccharide Assemblies
We have developed a new type of n-pentenyl-type glycosides that can be activated by catalytic amounts of promoter, Hg(NTf2)2 or PPh3AuCl/AgNTf2, at room temperature. The mild activation conditions and outstanding stability of common protection/deprotection manipulations enable the enynyl donors to have broad applications in constructing various glycosidic bonds. Furthermore, under the Hg(NTf2)2-catalyzed
Some Aspects of Selectivity in the Reaction of Glycosyl Donors*
作者:Clara Uriel、Ana M. Gomez、J. Cristóbal López、Bert Fraser‐Reid
DOI:10.1080/07328300500176528
日期:2005.8
Some advantages, disadvantages, and anomalies of various donors in glycosidations are discussed. By studying several two-component donor/acceptor-diol reactions, it is shown that regiopreferences are not very sensitive to the type of donor used. However, in competitive glycosidations within a given type of donor and between different types of donor, it is shown that regio- and chemoselectivities must be indexed to donor reactivity.