三种保护的二糖苯丙素苷的合成研究

本文采用先成苷法，从已合成的2-对烯丙氧苯乙基-4,6-O-亚苄基-β-D-葡萄糖苷(1)出发，经2位选择性乙酰化、3位引入三乙酰基保护的鼠李糖基、4，6位脱去亚苄基，得到了关键的中间体4；在化合物4的葡萄糖4、6位分别引入对位取代的肉桂酰基，便得到了保护的二糖苯丙素苷5、7、8。与后成苷法相比，路线缩短一步，收率有所提高。     

环糊精葡萄糖基转移醇的固化定及其应用研究.Ⅱ.壳素糖作载…

使用经戊二醛处理过的壳素糖作载体固定化环糊精葡萄糖基转移酶，研究了酶量，吸附时间等对固定化效果的影响。考察了固定化后酶学性质的变化。实验表明，酶经固定化后，热稳定性提高，最适ｐＨ值向前移１个单位。１０ｍｍｏｌ／Ｌ的ＣａＣｌ２可以使酶活力有较大提高。     

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.     

高效液相色谱中流动相的pH对麦迪霉素保留行为的影响

This paper reports the influence of pH value of mobile phase on retention and resolution of mydecamycinanalysed by HPLC. Many tests have been made to prove that the effective components,mydecamycin A_1,A_2,A_3and A_4, are separated very well when the pH values of mobile phase(CH_3 OH :0. 067mol/L NH_4 Ac= 6:4) arebetween 5.90 and 6.90 on ODS column.     

气相气谱测定土壤中的糖

气相气谱测定土壤中的糖王彦中,穆惠玲,仇津苹（南开大学中心实验室天津３０００７１）１前言糖是土壤有机质的重要组成,它的测定对认识土壤质量无疑是重要的。以往大多仅测定土壤有机质总量,而单独测定其中糖含量的报道甚少￣［１～３］,在国内尚未见到。近年来气相...     

硅元素对甘蔗的增产和增糖作用

<正> 我校化学系以季明德同志为首的含硅植物生长素课题组于1985年研究成功8501含硅植物生长素(简称8501),在盆栽试验的基础上进行了三年连续的田间小区试验。研究结果表明、8501可使甘蔗含糖分提高8%左右、产量增加10%左右。根据小区试验结果估算、每亩净增