Highly Efficient Regio- and Stereoselective Synthesis of β-（1 →6）-Branched β-（1 →3）-Linked Glucohexaose and Its Analogue

A β-（1→）6）-branched β-（1→）3）-linked glucohexaose （1） and its lauryl glycoside （2）, present in many biologically active polysaccharides from traditional herbal medicines such as Ganoderma lucidum, Schizophyllum commune and Lentinus edodes, were highly efficiently synthesized. Coupling of 2,3,4,6-tetra-O-benzoyl-β-D-glucopyranosyl- （1--）3）-2-O-benzoyl-4,6-O-benzylidene-a-D-glucopyranosyl trichloroacetimidate （7） with 3,6-branched acceptors 8 and 12 gave β-（1→）3）-linked pentasaccharides （9） and （13）, then via simple chemical transformation 4＇,6＇-OH pentasaccharide acceptors 10 and 14 were obtained. Regio- and stereoselective coupling of 3 with 10 and 14 gave β-（1→）3）-linked hexasaccharides （11） and （15） as the major products. Deprotection of 11 and 15 provided the target sugar 1 and 2. Thus, a new method for the preparation of this kind of compounds was developed.     

Synthesis and Crystal Structure of a Heptanuclear Trigonal Prismatic Cluster {PrCu_6} with Glycine and Imidazole as Ligands

A new heptanuclear trigonal prismatic cluster [PrCu6(μ3-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of Pr^3 , Cu^2 , glycine and imidazole in aqueous solution and characterized by X-ray structure analysis. The compound belongs to the trigonal R3 space groupwith a=b=15.8761(2), c=23.4943(5) A, V=5128.4(1)A^3, Z=3, Dc=1.965 g/cm^3,μ=2.869mm^-1 F(000)=3012, the final R=0.0332 and wR=0.0844 for 3596 independent reflections. In the cation, the Pr3 ion is situated at the center of a prism formed by six copper atoms and coordinates to nine oxygen atoms with a tricapped trigonal prismatic coordination polyhedron. Six glycine ligands and six imidazole terminal ligands participate in constructing the cluster.     

Synthesis and Crystal Structure of a Novel Aminothiourea Derivative Bearing Sugar Moiety

5-O-Benzoyl-1,2-O-isopropylidene-α-D-erythro-ketofuranose-3-ulose-3-aminothiose 3 was synthesized and characterized by spectral analysis, and its crystal structure was determined by X-ray diffraction analysis. The crystal belongs to orthorhombic, space group P212121 with a = 6.6276(13), b = 10.993(2), c = 25.027(5) , β = 90°, V = 1823.4(6)3, Z = 4, C16H20N3O5S, Mr = 366.41, Dc = 1.335 g/cm3, μ = 0.208 mm-1, F(000) = 772, S = 1.007, the final R = 0.0465 and wR = 0.1061 for 3251 observed reflections (I > 2σ(I)). Four hydrogen bonds are observed. The absolute configuration of this molecule was confirmed by comparing with that of the original material.     

基于可见近红外光谱的糖类别快速鉴别研究

提出了一种用近红外光谱技术快速鉴别糖类别的新方法.采用近红外光谱获取白砂糖、木糖醇、双歧糖和葡萄糖等四种糖类别的光谱反射特征曲线,采用偏最小二乘法进行模式特征分析,经过交互验证法判别,确定最佳主成分数为11.完成特征提取后,将11种主成分作为神经网络的输入变量,建立了3层BP神经网络.四个类别的糖样本数均为40,共计160个样本,将其分成训练集样本120个和预测集样本40个,对40个未知样本进行预测,准确率为100%.说明所提出的方法对于糖类别具有很好的分类和鉴别能力.     

糖簇分子和糖树状分子的合成进展

糖簇分子和糖树状分子是为了模拟天然存在的“多价效应”而发展起来的一类糖缀合物 .从糖簇分子和糖树状分子的骨架结构特点出发 ,综述了近几年来多价糖簇分子和糖树状分子的各种合成方法及其特点     

降压活性成分淫羊藿甙的HMQC和HMBC谱研究

首次对中药淫羊藿中降压活性成分淫羊藿甙的HMQC和HMBC谱进行了深入研究,结合¹H-¹H COSY谱,确切归属了全部碳氢信号,并直接从HMBC谱上确认了异戊烯基,甲氧基,鼠李糖和葡萄糖在黄酮母核上的连接位置,并修正了文献中关于该化合物某些碳信号归属的错误.显示这两种2D NMR新技术对结构复杂的黄酮甙类化合物的结构研究具有重要意义.     

紫外分光光度法测定红枣中总糖的含量

采用浓盐酸使红枣中总糖发生脱水反应,紫外分光光度法在284nm处直接测定红枣中总糖的吸光度.在0.78-2.34mg/mL的范围内总糖的浓度与吸光度呈现良好的线性关系(r=0.9990,n=5),平均回收率为99.8%(RSD=2.5%,n=6).本法简单,明确,可用于红枣中总糖的含量测定.