Mimics of the sialyl Lewis X tetrasaccharide. Replacement of the N-Acetylglucosamine sugar with simple C2-symmetric 1,2-diols
摘要:
Analogues of sialyl Lewis X have been synthesized that feature replacement of the N-acetylglucosamine residue with C-2-symmetric diols. The diols used contain different levels of torsional constraint and various functional groups. The cyclohexyl derived compound 27 was equipotent to sLex in vitro (IC50 0.5 mM). Copyright (C) 1996 Elsevier Science Ltd
Assembly of a Complex Branched Oligosaccharide by Combining Fluorous-Supported Synthesis and Stereoselective Glycosylations using Anomeric Sulfonium Ions
作者:Wei Huang、Qi Gao、Geert-Jan Boons
DOI:10.1002/chem.201501844
日期:2015.9.7
reliable strategies for the rapid assembly of complex oligosaccharides. This paper presents a set of strategically selected orthogonal protecting groups, glycosyl donors modified by a (S)‐phenylthiomethylbenzyl ether at C‐2, and a glycosyl acceptor containing a fluorous tag, which makes it possible to rapidly prepare complex branched oligosaccharides of biological importance. The C‐2 auxiliary controlled
迫切需要开发可靠的策略来快速组装复杂的寡糖。本文提出了一组战略性选择的正交保护基团、C-2 处 ( S )-苯硫基甲基苄基醚修饰的糖基供体以及含有氟标签的糖基受体,这使得快速制备具有生物学重要性的复杂支链寡糖成为可能。C-2辅助剂控制各种半乳糖基化的1,2-顺式异头选择性。正交保护基团2-萘甲基醚(Nap)和乙酰丙酸酯(Lev)使得生成糖基受体并允许安装拥挤的支化点成为可能。糖基化后,可以使用酸性条件去除手性辅助剂,这与正交保护基团 Lev 和 Nap 的存在相容,从而可以有效安装 1,2 连接糖苷。轻氟标签使得使用碳氟化合物改性的硅胶通过简单的过滤方法纯化化合物成为可能。该组构件已成功用于制备布氏锥虫 GPI 锚的碳水化合物部分,该寄生虫是一种导致人类昏睡病和家畜类似疾病的寄生虫。
Steric effects on the formation of isolable products in the reactions of dibutyltin oxides with carboxylic acids
作者:V.B. Mokal、V.K. Jain
DOI:10.1016/0022-328x(92)83381-q
日期:1992.12
(CH3)2CH (iPr) and (CH3)3C (tBu)] in 1:1 and 1:2 stoichiometry were investigated. The products formed in these reactions were characterized by elemental analyses, IR and NMR (1H, 13C and 119Sn) data. Reactions in 1:2 stoichiometry afforded dibutyltin dicarboxylates which have six-coordinate tin atom. Stericeffects of the butyl group and the R group of the carboxylate ligand play an important role in
氧化二丁基锡,x Bu 2 SnO [ x = n(正态),i(异),s(仲)和t(叔)]与羧酸[RCOOH; řCH 3,(Me)时,CH 3 CH 2(ET),(CH 3)2 CH(我PR)和(CH 3)3 C(吨丁基)]在1:1和1:2的化学计量进行了研究。在这些反应中形成的产物通过元素分析,IR和NMR(1 H,13 C和119Sn)数据。以1:2化学计量比的反应得到具有六配位锡原子的二羧酸二丁基锡。丁基和羧酸酯配体的R基团的立体效应在1:1反应中起重要作用。与n Bu 2 SnO形成二羧基四有机锡氧烷类,而[ t Bu 2 Sn(μ-OH)(OOCR)] 2羟基配合物是唯一与t Bu 2 SnO形成的产物。所有这些配合物的立体化学都基于NMR数据进行了讨论。
Cationic organotin cluster [
<i>t</i>
‐Bu
<sub>2</sub>
Sn(OH)(H
<sub>2</sub>
O)]
<sub>2</sub>
<sup>2+</sup>
2OTf
<sup>−</sup>
‐catalyzed one‐pot three‐component syntheses of 5‐substituted 1
<i>H</i>
‐tetrazoles and 2,4,6‐triarylpyridines in water
作者:Hongshe Wang、Weixing Zhao、Juan Du、Fenyan Wei、Qi Chen、Xiaomei Wang
DOI:10.1002/aoc.5132
日期:2019.10
The cationicorganotincluster [t‐Bu2Sn(OH)(H2O)]22+2OTf− is easy to prepare and stable in air. The catalytic activity of [t‐Bu2Sn(OH)(H2O)]22+2OTf− as a neutralorganotin Lewis acid catalyst is probed through the one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles from aldehydes, hydroxylamine hydrochloride and sodium azide, and of 2,4,6‐triarylpyridines from aromatic aldehydes, substituted
A New Class of Eight-Membered Sn<sub>2</sub>P<sub>2</sub>O<sub>4</sub> Heterocycles. Crystal Structure and Electrolytic Dissociation in Solution of <i>c</i><i>yclo</i>-[R<sub>2</sub>Sn(OPPh<sub>2</sub>O)<sub>2</sub>SnR<sub>2</sub>](O<sub>3</sub>SCF<sub>3</sub>)<sub>2</sub> (R = Me, <i>t</i>-Bu)
In the solid state, 1 and 2 were investigated by 119Sn MAS and 31P MAS NMR spectroscopy as well as X-ray crystallography and appear to exist as ion pairs of cyclo-[R2Sn(OPPh2O)2SnR2]2+ dications and triflateanions. In solution, 1 and 2 are involved in extensive equilibria processes featuring cationic diorganotin(IV) species with Sn−O−P linkages, as evidenced by 119Sn and 31P NMR spectroscopy, electrospray
通过R 2 SnO(R的连续反应)合成环-[R 2 Sn(OPPh 2 O)2 SnR 2 ](O 3 SCF 3)2(R = Me(1),t -Bu(2))给出了具有三氟甲磺酸和二苯基次膦酸的= Me,t- Bu)。在固态下,通过119 Sn MAS和31 P MAS NMR光谱以及X射线晶体学研究了1和2,它们似乎以环-[R 2的离子对形式存在。Sn(OPPh 2 O)2 SnR 2 ] 2+离子和三氟甲磺酸根阴离子。在溶液中,1和2涉及广泛的平衡过程,其特征是带有Sn-O-P键的阳离子二有机锡(IV)物种,如119 Sn和31 P NMR光谱,电喷雾质谱和电导率测量所证明的。
Structure Characterization of the Products of the Reaction between Racemic 1,2,4-Butane Triol and Di-<i>tert</i>-butyltin Oxide
作者:Monique Biesemans、Guy Buytaert、Luk Van Lokeren、José C. Martins、Rudolph Willem、Edward R. T. Tiekink
DOI:10.1021/om020864o
日期:2003.4.1
a model compound mimicking the tetra-tert-butyldistannoxane derivative of erythromycine A, affords two novel compounds, 1 and 2. Compound 1, which cannot be isolated as a pure product, was characterized in situ in C6D6 solution by two-dimensional, multinuclear (1H, 13C, 119/117Sn) NMR and proven to exhibit the same structural organooxotin moiety as the tetra-tert-butyldistannoxane derivative of erythromycine
二叔丁基氧化锡与外消旋1,2,4-丁烷三醇的反应旨在合成模仿红霉素A的四叔丁基二恶烷衍生物的模型化合物,提供了两种新化合物1和2。不能分离为纯产物的化合物1在C 6 D 6溶液中通过二维多核(1 H,13 C,119/117 Sn)NMR进行了原位表征,并证明具有相同的结构有机氧磷素部分作为四-叔红霉素A的叔丁基二恶烷衍生物,但是现在可以明确定义可交换羟基质子的位置。通过X射线衍射分析,将分离为结晶产物的化合物2表征为二聚体的RS异构体,该二聚体由手性相反的两个单体单元生成,该单体单元是由二叔丁基氧化锡与外消旋体1 :1缩合而成的。 2,4-丁烷三醇; 碳原子C(1)和C(2)的OH基团的羟基质子已被消除,形成了五元环状1,3,2二氧黄环烷样结构,其中碳C(1的配体与相邻分子的锡原子络合,形成中心对称的Sn 2 O 2。核; 所述配体的碳原子C(4)的OH基的羟基质子与C(2)的氧原子形成分子内氢桥。化合物2的C