生物素中间体内酯合成进展

简述了生物素合成方法,并综述了有关生物素中间体内酯(3aS,6aR)-1,3-二苄基一六氢-1H-呋喃并[3,4-d]咪唑-2,4-二酮的合成进展。     

一种吸附荧光素的生物素化聚苯乙烯微球的制备

合成的聚苯乙烯乳胶微球经氯甲基化和胺化后，在碱性条件下用生物素－ε－氨基己酸－Ｎ－羟基琥珀酰亚胺酯生物素化，制备了生物素化微球。制备的微球对荧光素钠具有良好的吸附能力。     

气相色谱法测定不对称催化合成反应液中手性1,1-二苯基-2-丙醇含量

(S)-(+)-1,1-二苯基-2-丙醇是一种很有用的医药中间体,用它可以合成生物素,此物质广泛应用于医学各领域。近年来大量研究证实,生物素-亲和素(BAS)系统几乎可与目前研究成功的各种标记物结合。在生物素-亲和素(BAS)系统中,借助所形成的生物素-亲和素-酶复合物,追踪生物素标记的抗原或抗体,通过酶催化底物显色,可检出相应的抗体或抗原。由于抗原或抗体分子可偶联多个生物素,     

6-羧甲硫基-7-硝基庚酸甲酯二环己基铵盐的合成

生物素（即维生素Ｈ）是重要的维生素，对人体及家禽的生长起着重要的作用［１］。现在国内所用生物素均从日本进口，而且未见国内有合成及应用方面的报道，因此进行生物素合成的研究是非常必要的。我们采用了由己内酯出发经中间体６－羧甲硫基－７－硝基庚酸甲酯二环己基...     

d,l-2,3,4,6-四氢-2-氧-1氢噻吩并[3,4-d]咪唑-4-戊酸的合成

生物素(即维生素H或维生素B7)是人体及家禽体内主要代谢中所必需的,对生物生理具有不可替代的作用[1].它还是配合饲料的关键组份之一,能改善饲料效率,提高家禽的生长速度,以较少的投入产生较大的经济效益.由于生物素不能直接从自然界获得,而我国目前所用生物素均从日本进口,且国内尚无生物素合成方面的研究.     

新型生物素标记的苦杏仁苷活性探针的合成

以苦杏仁苷结构中的糖羟基作为反应位点进行生物素化修饰,经酯化、缩醛化、Sonogashira偶联等反应合成了一个新型的生物素标记的苦杏仁苷活性探针,其结构经1H NMR,13C NMR,IR和HR-ESI-MS表征。     

基于生物素的荧光有机小分子及其应用

生物素是一种水溶性维生素,在人体中作为一种重要的羧酸酶辅酶起作用,近年来受到化学家和生物学家的广泛青睐。此外,其在各种生理和病理过程中表现出低毒性,可以被设计成具有靶向选择性的药物载体,能将抗癌药物有效地传递给肿瘤细胞。如今含生物素的小分子已发展成一类具有显著应用价值的生物功能分子。该类化合物具有合成简便、易功能化和特异性强等优点。本文综述了生物素及其衍生物在生物传感、药物释放和其他领域的研究进展,并对其发展趋势做出了展望。     

生物素标记试剂的合成方法改进及其在DNA合成中的应用

以生物素,4,4’-二甲氧基三苯基氯甲烷,6-氨基-1-己醇,2-氰基乙氧基-双(N,N-二异丙基)亚磷酰胺等为原料,采用改进方法合成了生物素标记试剂——[1-N-(4,4’-二甲氧基三苯甲基)-生物素-6-氨基己基]-2-氰乙氧基-N,N-二异丙基亚磷酰胺(3),总收率51.0%,其结构经1H NMR,13C NMR,31P NMR和MS确证。通过固相亚磷酰胺三酯法,应用3合成了一段含有十个碱基的5’-端生物素标记的寡核苷酸链,其结构经MS确证。     

含生物素的赖氨酸衍生物的合成

以赖氨酸为原料，合成了两种含生物素的赖氨酸衍生物Boc-Lys(Biotin)-OH和Fmoc-Lys(Biotin)-OH。     

11-巯基十一酸-(8-生物素酰胺基-3,6-二氧辛基)酰胺的合成

以溴十一酸、苄硫醇、生物素和长醚链二胺为原料,通过活化酯法,设计并合成了一种新型长链含巯基的生物素衍生物--11-巯基十一酸-(8-生物素酰胺基-3,6-二氧辛基)酰胺,其结构经<'1>H NMR和IR表征.     

Densities,speeds of sound,excess volumes and viscosities of binary mixtures of mtbe with tetralin and decalin at 303.15 k

Measurements of densities, speeds of sound, excess volumes and viscosities of binary mixture of methyl tert-butyl ether with tetralin and decalin are reported at 303.15?K over the entire range of composition. Excess volumes are measured using batch dilatometer technique. Sound speeds are obtained using ultrasonic interferometer. Densities are computed from excess volume data. Isentropic compressibilities are derived from density and sound speed data. Speeds of sound are evaluated on the basis of Jacobson's free length theory and Schaff's collision factor theory. The predicted values are in good agreement with the experimental results. The viscosity data are analysed on the basis of corresponding states approach. Excess volumes and deviation in isentropic compressibilities are negative and deviation in viscosities are positive over the entire composition range. The experimental results are discussed in terms of possible molecular interactions between unlike molecules.     

Review of Analytical Methods for Atmospheric Oxidants Measurements

Abstract

Instrumental and manual methods currently available for the measurement of atmospheric oxidants are surveyed. Techniques used in the United States are emphasized and their advantages and disadvantages are discussed. Commercial systems are evaluated in terms of general operating principles rather than of specific instruments. The ability of these techniques to meet the measurement requirements defined by U.S. Federal air quality oxidant criteria are discussed. Alternative chemical techniques that may have some advantages over the neutral, buffered KI procedure are discussed. Also some attractive, alternative instrumental procedures that are ozone-specific are presented. These systems are based on chemiluminescence and ultraviolet absorption photometry. Electrochemical and colorimetric methods for total oxidant measurements are compared. Finally, some data are presented on relationships of ozone and total oxidants.     

若干含多硫基的配合物的合成方法及结构特征

本文综述了近年来我们合成的十二种多硫基的配合物，这些配合物含有Ｓ＾２－２，Ｓ＾２－４，Ｓ＾２－５，Ｓ＾２－６，Ｓ＾２－７等多硫革配体，总结了这些配合物中的金属配位构型，比较了各种多硫基的Ｓ－Ｓ键长及有关键角，归纳了配合物外光谱，并阐述了其中几个配合物与ＮＨ２ＮＨ２的反应性能。     

Some Strategies for the Refinement of Disordered Structures with the SHELXL-97 Refinement Program

1 INTRODUCTION finement stage. The person performing the crysta- llographic manipulations works on numerical data The high degree of order in the arrangement of that are quite different from the diffraction images atoms in a crystal is a fundamental characteristic of on a computer terminal, and most often does not even the crystalline state, an ideal crystal being envisaged see the images. to be constructed of regularly-stacked unit cells, each The refinement program, SHELXL-97[1], has …     

Inorganic electrides

Inorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low-density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced-dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite.     

The Application of NMR Spectroscopy and Chemometrics in Authentication of Spices

Spices and herbs are among the most commonly adulterated food types. This is because spices are widely used to process food. Spices not only enhance the flavor and taste of food, but they are also sources of numerous bioactive compounds that are significantly beneficial for health. The healing effects of spices are connected with their antimicrobial, anti-inflammatory and carminative properties. However, regular consumption of adulterated spices may cause fatal damage to our system because adulterants in most cases are unhealthy. For that reason, the appropriate analytical methods are necessary for quality assurance and to ensure the authenticity of spices. Spectroscopic methods are gaining interest as they are fast, require little or no sample preparation, and provide rich structural information. This review provides an overview of the application of NMR spectroscopy combined with chemometric analysis to determine the quality and adulteration of spices.     

Nitrenium Salts in Lewis Acid Catalysis

Molecular compounds featuring nitrogen atoms are typically regarded as Lewis bases and are extensively employed as donor ligands in coordination chemistry or as nucleophiles in organic chemistry. By contrast, electrophilic nitrogen‐containing compounds are much rarer. Nitrenium cations are a new family of nitrogen‐based Lewis acids, the reactivity of which remains largely unexplored. In this work, nitrenium ions are explored as catalysts in five organic transformations. These reactions are the first examples of Lewis acid catalysis employing nitrogen as the site of substrate activation. Moreover, these compounds are readily accessed from commercially available reagents and exhibit remarkable stability toward moisture, allowing for benchtop transformations without the need to pretreat solvents.     

Alternate multi-layered adsorption of macro-cations and -anions on the colloidal spheres. Influence of the deionization of the complexation mixtures with coexistence of the ion-exchange resins

The alternate multiple adsorption layers of macrocations and macroanions on the surfaces of colloidal spheres, in which the complexation mixtures are deionized with ion-exchange resins are studied with help of the electrophoretic light-scattering, dynamic light-scattering and transmitted electron-microscopy techniques. The results are compared with those without resins. Colloidal silica spheres (110 nm in diameter) and monodispersed polystyrene spheres (220 nm) are used as colloidal spheres. The macrocations used are poly (4-vinyl-N-n-butyl pyridinium bromide) and poly (allylamine hydrochloride). Sodium poly (styrene sulfonate) and sodium polyacrylate are used as macroanions. The macroion-colloid complexations are formed firmly when the complexation suspensions are deionized with the resins.     

钼、钨系过氧化物在Sharpless烯烃环氧化反应中的应用*

钼、钨系过氧化物是非常重要的Sharpless烯烃环氧化催化剂,有着非常广泛的工业发展前景。本文综述了钼、钨系过氧化物的种类,结构,合成方法及催化活性,分析了各种钼、钨系过氧化物的特点以及在催化环氧化领域的发展现状。同时,本文还讨论了钼、钨系过氧化物催化烯烃环氧化反应的机理。评述了在催化环氧化领域中两种主要理论——Mimoun机理与Sharpless机理的争论焦点及发展现状,以及计算化学对两种理论中间过渡态的研究进展,并且重点分析了Sharpless机理的过渡态结构。此外,本文还综述了影响钼、钨系过氧化物催化剂反应活性的各种因素以及质子所产生的副反应。最后,本文对应用于催化环氧化领域的钼、钨系过氧化物未来的研究方向提出了建议。