聚乙二醇支载的杂环化合物库的液相合成

随着组合化学的迅速发展, 兼容固相合成和溶液相合成优点的液相合成方法已成为实现组合化学的一条重要途径. 综述了近年来聚乙二醇为可溶性聚合物载体支载的杂环化合物库的研究, 并展望了其今后的发展方向.     

Intramolecular C-H...Ccarbene hydrogen bonds and competing interactions in monoprotonated tripodal carbenes

The anionic tripodal N-heterocyclic carbene (C3N2H3)3BH- first prepared by Fehlhammer, together with three neutral variants, (C3N2H3)3CH, (C3N2H3)3P, and (C3N2H3)3SiH, have been studied using quantum chemical methods. Isodesmic reactions are used to deduce that the phosphine-bridgehead species in particular has a large-resonance stabilization energy. All the podands undergo substantial conformational change on excitation to the lowest triplet electronic state, with effective localization of the excitation on one of the heterocyclic rings, dearomatizing it. On monoprotonation of the ground states, three of these species display intramolecular C-H...Ccarbene hydrogen bonding: The nature and strength of these interactions is explored using model (intermolecularly hydrogen-bonded) complexes, isodesmic reactions, and GIAO calculations of chemical shifts. One surprising result is that C-H...Ccarbene hydrogen bonds involving ethenic hydrogens can be almost as strong as those involving the imidazolium proton (first identified by Arduengo). The case of the monoprotonated carbon bridgehead species is in particular intriguing. It is stabilized by a competitive Ccarbene...N interaction of sufficient strength to override the C-H...Ccarbene bonding motif observed in the other structures.     

3-氯-4-氰基-5-取代苯氧基异噻唑的合成及生物活性

有些醚化合物如早期出现的商品化品种草枯醚、间草醚等二苯醚类除草剂 ,其结构相对简单、在土壤中易于降解且易于合成 ,因而引起了人们的广泛[1 - 3] 兴趣。最近的研究表明很可能从异噻唑杂环中找到生物活性独特的新型化合物[4] 。为此 ,我们设计合成了含异噻唑杂环的醚类化合物3ａ～ 3ｋ ,合成路线见下图 .所有产物经1 ＨＮＭＲ、ＩＲ和元素分析证实 ,并对大部分化合物的除草活性和杀菌活性进行了测定。1　实验部分所有溶剂为分析纯 ,用前经纯化处理。试剂为化学纯或分析纯。硅胶为青岛海洋化工厂产品。元素分析用ＹａｎａｃｏＣＨＮＣＯＲ…     

A MOLECULE LIKE SODIUM

The use of neutral π-radicals as building blocks for molecular conductors holds both appeal and challenge. Such systems obviate the need for counterions, as charge transfer is not required to generate charge carriers. Essentially an array of π-radicals should function like atoms in an elemental metal, e.g., sodium, affording a half-filled energy band. Most radicals, however, tend to dimerize, and even when association can be suppressed the resulting low bandwidth W, coupled with a high on-site Coulomb repulsion U, leads to a Mott insulating state. We are pursuing the design and synthesis of stable heterocyclic thiazyl radicals, with a view to generating stable, crystalline materials with a high W/U ratio. The search for these new radicals, the molecular analogues of sodium, is the subject of this presentation.     

Copper‐catalyzed/mediated aromatic C?H bond functionalization

The C? H functionalization strategy has received substantial attention because of its economic, sustainable and environmentally benign features. Most reports are on palladium, rhodium or ruthenium catalysis, and reports on copper catalysis are relatively fewer. Recently, many reports on copper‐catalyzed/mediated C? H functionalization have been published. Copper salts bear properties of cheapness and relatively low toxicity. This review introduces an advance on copper‐catalyzed/mediated aromatic C? H functionalization. The content includes aromatic ring C? H bond functionalization and heteroaromatic C? H bond functionalization forming new carbon–carbon or carbon–heteroatom bonds. Copyright © 2010 John Wiley & Sons, Ltd.     

无溶剂反应在杂环合成中的应用进展

杂环化合物在药物和农药领域具有多种优良的生物活性,其合成方法是目前药物和农药研究的热点领域之一.以绿色合成为主题,介绍了无溶剂杂环有机合成在产率高、选择性好、操作简便、成本低及环境友好等绿色化学方面的优点,综述了近四年无溶剂反应在杂环合成方面研究的最新进展.     

Intramolecular diels-alder reactions of diester-tethered trienes. synthesis of medium ring-containing carbocycles and heterocycles

Intramolecular Diels-Alder reactions of cyclohexane-1,2-dicarboxylic anhydride-derived diester-tethered trienes are described. The stereoselectivities of most of the cycloaddition processes studied may be rationalised in terms of an preferred ‘inside’-oriented diene giving rise to an endo-transition state.     

A Simple One-pot Synthesis of 3,5-Dicyano-1,2-dihydropyrid-2-ones in Aqueous Media

A simple and clean synthesis of 3,5-dicyano-1,2-dihydropyrid-2-ones by a one-pot three-component reaction of malononitrile, aromatic aldehydes and 2-cyanoacetamide or 2-cyanothioacetamide has been achieved in an aqueous solution with potassium carbonate as a base under microwave irradiation without a phase transfer reagent. This protocol has the advantages of short reaction time （5-8 min） and convenient work-up.     

3-位苯并含氮杂环取代的焦脱镁叶绿酸-a甲酯的合成

以焦脱镁叶绿酸-a甲酯(MPP-a)(1)为起始原料，在二氯甲烷中与醋酸锌共回流得锌配合物2，在四氯钯锂催化下，通过与苯基氯化汞的偶联反应生成3b-苯基焦脱镁叶绿酸-a甲酯(3)．分别选用四氧化锇、高钌酸四丙基铵(TPAP)和N-甲基吗啉N-氧化物将环外烯键氧化成邻二酮(4)．在酸性条件下，4与邻苯二胺的缩合形成了3-位喹喔啉取代的焦脱镁叶绿酸-a甲酯(5)．用四氧化锇和高碘酸钠将1的3-位碳碳双键氧化，则生成焦脱镁叶绿酸-d甲酯(6)．所得卟吩醛与环己二酮和萘胺进行一锅法反应，得到3-位苯并吖啶取代的焦脱镁叶绿酸-a甲酯(7)．所合成的新卟吩化合物均经UV，IR，^1H NMR及元素分析证明其结构．     

Cytotoxic,Apoptosis-Inducing Activities,and Molecular Docking of a New Sterol from Bamboo Shoot Skin Phyllostachys heterocycla var. pubescens

Phytochemical screening of nonpolar fractions from the methanol extract of the Bamboo shoot skin Phyllostachys heterocycla var. pubescens resulted in the isolation of a new sterol-glucoside-fatty acid derivative (6’-O-octadeca-8″,11″-dienoyl)-sitosterol-3-O-β-d-glucoside (1), together with six known compounds. The chemical structures of the pure isolated compounds were deduced based on different spectral data. The isolated compounds were assessed to determine their cytotoxic activity, and the results were confirmed by determining their apoptotic activity. Compound 1 was more cytotoxic against the MCF-7 cells (IC₅₀ = 25.8 µM) compared to Fluorouracil (5-FU) (26.98 µM), and it significantly stimulated apoptotic breast cancer cell death with 32.6-fold (16.63% compared to 0.51 for the control) at pre-G1 and G2/M-phase cell cycle arrest and blocked the progression of MCF-7 cells. Additionally, RT-PCR results further confirmed the apoptotic activity of compound 1 by the upregulation of proapoptotic genes (P53; Bax; and caspases 3, 8, and 9) and downregulation of the antiapoptotic genes (BCL2). Finally, the identified compounds, especially 1, were found to have high binding affinity towards both tyrosine-specific protein kinase (TPK) and vascular endothelial growth factor receptor (VEGFR-2) through the molecular docking studies that highlight its mode of action.