羟基磺酸、氨基磺酸和磺酰肽的合成

具有四面体结构的磺酸衍生物可用于模拟酯键和酰胺键水解的过渡态，特别是 含有四面体结构磺酰胺键的磺酰肽作为天然肽的硫类似物，广泛用于作为酶抑制剂 以及用来诱导抗体酶的半抗原。综述了羟基磺酸、氨基磺酸和磺酰肽的合成。重点 介绍了消旋的和手性的α－和β－取代的β－氨基磺酸及其酰氯和亚磺酰氯，γ－ 氨基－α，β－不饱和磺酸及其酰氯的合成，以及由它们作为基元分子通过液相和 固相方法来合成α－和β－取代的β－磺酰肽、亚磺酰肽及乙烯磺酰肽。     

叔丁基二甲硅氧基苯硼酸及羟基苯硼酸的制备

以邻、间、对三种溴酚为原料, 经叔丁基二甲基氯硅烷保护酚基后制成格氏试剂, 然后与硼酸酯反应, 选择性水解得到了邻、间、对-叔丁基二甲硅氧基苯硼酸, 收率分别为51%, 44%和40%. 将对位、间位的硼酸酯中间体3a, 3b用强酸水解可得到间羟基苯硼酸(产率65%)和对羟基苯硼酸(产率14%), 但发现它们极难纯化, 这是由于羟基硼酸极易生成苯二酚之故.     

Microwave-Assisted Esterification of Diverse Carboxylic Acids and Chiral Amino Acids

A facile and efficient synthetic method of esters from their corresponding carboxylic acids and amino acids is described. The esterification reaction of carboxylic acids and amino acids could be greatly accelerated under microwave irradiation because the reactions described in this article took place in only 5 min with almost quantitative yields, and distinct acidity of catalytic acids was well tolerated. Unlike the racemation problem in microwave-assisted N-acylation reactions, the esters of chiral amino acids could be achieved with retention of configuration under this condition.     

Thin-Layer Chromatography of Bile Alcohols,Bile Acids and Conjugated Bile Acids

Abstract

Thin-layer chromatography of bile alcohols, bile acids and bile acid conjugates has been reviewed. Particular emphasis has been placed on the separation of the glycine and taurine conjugated bile acids as a class and as individual compounds, and on the isolation of bile alcohols and C₂₇ bile acids diastereo-isomeric at C-25.     

Pentafluoroethylsilicic Acids

Pure anhydrous hexafluorosilicic acid (H₂[SiF₆]) is a still elusive species, although its existence in aqueous solutions is well documented. Desiccation inevitably leads to decomposition to form tetrafluorosilane and hydrogen fluoride. An oxonium hexafluorosilicate turned out to not be stable at room temperature. Partial substitution of the fluorine atoms with strong electron‐withdrawing perfluoroalkyl groups results in substantial stabilization of the corresponding fluorosilicic acids. Mono‐ and bis(pentafluoroethyl)‐substituted fluorosilicic acids were prepared through conversion of the respective halosilanes (Si(C₂F₅)_nX_4?n, with X=Cl, Br) with aqueous HF, and were obtained as colorless solids. They can be stored at room temperature for several months without decomposition, and thus are the first examples of stable fluorosilicic acids.     

手性羟酸和氨基酸类化合物的构效关系研究

构造了用于手性参数衍生的距离矩阵和扩展的距离矩阵, 并且观察了与羟酸类和氨基酸类化合物手性薄层色谱保留指数的相关性, 得到了具有启示性的结果. 引进了扩展的eAm指数和连乘指数, 以及综合运用了三种算法. 所得参数进行了多元回归分析, 得到了单一变量和变量组合的分析结果. 与多元回归分析相比较, 运用人工神经网络法, 使结果得到了较大的改善. 所引进的方法对于化合物构效关系研究具有普遍可用性.     

Efficient and Convenient Method for Synthesis of Benzofuran-3-acetic Acids and Naphthafuran-acetic Acids

Herein, we report an efficient and convenient method for synthesis of benzofuran-3-acetic acids and naphthafuran-acetic acids 5a–p by the reaction of substituted-4-bromomethylcoumarins with aqueous sodium hydroxide at refluxing temperature. The obtained products are characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectral data. Structures 5a and 5e are confirmed by their single x-ray diffraction studies. The advantages of this method are good yields, easy workup, and no chromatographic purifications.     

离子排斥色谱法分析有机酸和无机弱酸

用非抑制型电导检测的离子排斥色谱法,以对甲苯磺酸为淋洗液,研究了柠檬酸、苹果酸、抗坏血酸、乙醇酸、甲酸、乙酸、丙酸及氢氟酸和碳酸的色谱分离及定量检测条件。     

Chalcogenocarbonic Acids and Their Anions

Carbonic acids in which the oxygen has been wholly or partly replaced by sulfur, selenium, and/or tellurium are known as “chalcogenocarbonic acids”. The aim of the present article is to review existing knowledge of these acids and so establish a basis for further systematic syntheses. The anions required for the synthesis of chalcogenocarbonic acids will also be briefly characterized.     

基于哌嗪与二羧酸/羟基羧酸的二元体系的超分子自组装

本文选择哌嗪 (pip) 为研究中心,分别和1,4-环己二甲酸 (H2chda)、间苯二甲酸(H2mpda)、6-羟基-2-萘甲酸 (Hohna)、1-羟基-2-萘甲酸 (Hshna) 进行超分子自组装,得到了四种新的氢键超分子体系：H2pip·chda (1), H2pip·2Hmpda (2), H2pip·ohna·2H2O (3),H2pip·shna (4)。单晶结构分析表明：1-3为三维氢键超分子结构,而 4为一维链状氢键结构。     

Determination of L- and D-2-Halopropanoic Acids and 2-Halobutanoic Acids with Bacterial Dehalogenases

Abstract

A simple method for the enantioselective determination of 2-halopropanoic acids and 2-halobutanoic acids with two bacterial 2-halo acid dehalogenases has been developed. L-2-Halo acid dehalogenase acts specifically on L-2-haloalkanoic acids, and DL-2-halo acid dehalogenase acts on both enantiomers of the acids. The dehalogenation was followed by determination of halogen ions released. Linear relationship was established between the absorbance at 460 nm, and the amounts of L-2-haloalkanoic acids (0.025-0.5 μmol) or the racemates (0.05-1.0 μmol). The D-isomers were estimated by subtracting the amounts of L-isomers from those of DL-2-haloalkanoic acids.     

Phosphonic Aminocarboxylic Acids

Methods of synthesis of phosphonic aminocarboxylic acids, ω-phosphonic analogs of monoaminodicarboxylic acids, are reviewed. Many of such compounds are ligands of ionotropic and metabotropic glutamate receptors determining the phenomenon of information processing and communication in central nervous system, important in view of prevention and treatment of Alzheimer, Huntington, and Parkinson diseases and other socially important neurodegenerative and psychoneurological diseases as well as learning and memory processes.     

Sunlight- or UVA-Light-Mediated Synthesis of Hydroxamic Acids from Carboxylic Acids

The development of light-mediated methods for synthetic applications is increasingly attracting high interest. We present herein a new photochemical protocol for the synthesis of hydroxamic acids, which constitute an important class of medicinal agents, mainly due to their anticancer properties. The method is mediated by UVA-light or sunlight and its key point is the generation of a charge transfer complex by the interaction of 4-dimethylaminopyridine with a halomethane. Various carboxylic acids were directly coupled with O-protected hydroxylamines, upon irradiation with either LED 370 nm or solar light. A detailed study of the mechanism was carried out by the employment of direct infusion–high resolution mass spectrometry (DI-HRMS), providing experimental evidence for the formation of various activated species, which may lead to the desired product. The light-mediated protocol was applied in the synthesis of the drugs Vorinostat and Bufexamac.     

Synthesis of Levulinic Acids From Muconic Acids in Hot Water

Levulinic acid is a key biorenewable platform molecule. Its current chemical production from sugars is plagued by limited yields, char formation and difficult separations. An alternative and selective route starting from muconic acid via simple heating in water at high temperature (180 °C) has been developed. Muconic acid can be obtained from sugars or catechol fermentation. Chemical oxidation of catechol is another possibility which advantageously can also be applied on substituted catechols, hereby providing substituted muconic acids. When applying the disclosed hydrothermal protocol on these substrates hitherto unknown substituted levulinic acids were accessed. In particular, 3-propyllevulinic acid has been synthesized from 4-propylcatechol, prepared from pine wood. This propylated derivative has been used for the synthesis of a 3-propyllevulinate diester, i.e. butane-1,4-diyl bis(4-oxo-3-propylpentanoate), via esterification with 1,4-butanediol. The diester showed superior performance as plasticizer in comparison to the corresponding levulinate diester in both PVC (polyvinyl chloride) and PLA (polylactic acid). It plasticizes equally effective as the notorious commercial phthalate-based benchmark DEHP (di-2-ethylhexyl phthalate) in PVC.     

Homopolymerization of Four New Hydroxyamic Acids and Polycondensation of Glycerol With Dibasic Amic Acids

During the past 15 years or so, research in our laboratory has been mainly directed toward the synthesis of cyclic imides and isoimides for different purposes [1–4]. Thus a large number of substituted amic acids and bis-amic acids were prepared as intermediates. These amic acids were readily purified, crystallized, and obtained in excellent yields. In the present paper two types of amic acids are prepared. The first type is hydroxyamic acids of formula A, while the second type consisted of dibasic amic acids such as B:     

Fluorinated N-Arylaminoarylmethanephosphonic Acids and Bisfunctional Derivatives

Abstract

Aminophosphonic acids and corresponding derivatives are of widespread biological and biochemical interest. Especially fluorinated and aromatically substituted compounds ac-ting as antibacterial agents and showing fbngicidal activities are important for medicine and agriculture.     

Reaction Between Oxophosphorus Acids and Glycine

2-Hydroxyesters of oxophosphorus acids (hypophosphorous, phosphorous and phosphoric) react with glycine to give amidoglycine-H-phosphinate, cyclic phospho-amidoanhydrideglycine-H-phosphonate and cyclic phosphoamidoanhydrideglycinephosphate. The reaction proceeds easily and in high yields under mild conditions because of the effect of vicinally hydroxy group as intramolecular catalyst on the reactivity of the ester bonds.     

N-Glucosides of Aminobenzoic Acids and Aminophenols

N-o-, -m-, and -p-carboxyphenyl-D-glucosylamines and N-o-, -m-, and -p-hydroxyphenyl-D-glucosylamines were synthesized by reaction of D-glucose with o-, m-, and p-aminobenzoic acids and o-, m-, and p-aminophenols. It was demonstrated that both - and -anomers were formed by N-glycosylation of o-, m-, and p-aminobenzoic acids; only -anomers, by N-glycosylation of o-, m-, and p-aminophenols.