B环取代基对黄酮类化合物缩合,关环的影响

黄酮类化合物广泛存在于自然界中,是药用植物的有效成分之一,黄烷酮和查耳酮是黄酮类化合物的主要结构之一,一般可通过2-羟基苯乙酮和芳香醛在酸或碱的催化下进行羟醛缩合后脱水而制得。     

在不同介质中合成黄烷酮的最新研究进展

黄烷酮化合物是一类具有多种生物活性的天然产物,在诸多的黄烷酮合成方法中,经查尔酮环化的合成路线是一条合成黄烷酮的经典线路,方法主要是在环化剂的作用下使2'-羟基查耳酮闭环生成黄烷酮;并介绍了近几年来在不同介质中合成黄烷酮的研究进展.     

7,3'',5''-三取代黄烷酮和黄酮醇类化合物的合成

以3,5-二羟基苯甲酸和间苯二酚为原料,分别经酯化、乙酰化、甲氧甲氧基保护或甲基化、酰肼化、氧化、醛酮缩合、环化、Algar-Flynn-Oyamada反应以及脱保护基等步骤,以21%~32%的总收率合成了7,3’,5’-三取代黄烷酮1a~1b和黄酮醇类化合物2a~2b,所有合成产物通过1H NMR,IR,MS进行了结构确证.其中黄烷酮1b是从药用植物中间锦鸡儿Caragana intermedia Kang etH.C.Fu中分离得到的新天然有机化合物,此次为首次全合成.     

7，3＇，5＇-三取代黄烷酮和黄酮醇类化合物的合成

以3，5-二羟基苯甲酸和间苯二酚为原料，分别经酯化、乙酰化、甲氧甲氧基保护或甲基化、酰肼化、氧化、醛酮缩合、环化、Algar—Flynn-Oyamada反应以及脱保护基等步骤，以21％～32％的总收率合成了7，3’，5’-三取代黄烷酮1a～1b和黄酮醇类化合物2a～2b，所有合成产物通过0HNMR，IR，MS进行了结构确证．其中黄烷酮1b是从药用植物中间锦鸡儿Caragana intermedia KangetH．C．Fu中分离得到的新天然有机化合物，此次为首次全合成．     

黄烷酮烯醇硅醚的合成及其与氧化银反应

应用Me_2NSiMe_3为试剂合成了4个黄烷酮烯醇硅醚,收率很高。黄烷酮烯醇硅醚用氧化银氧化主要发生脱氢反应,生成黄酮,同时有少量3,3″-偶联反应产物双黄酮生成。     

Claisen-Schmidt反应合成的查耳酮类化合物及其生物活性研究进展

查耳酮类化合物是一类自然分布广泛、药理活性多样的重要物质,一直是化学及药物学家研究的热点之一.Claisen-Schmidt反应作为合成及修饰查耳酮小分子的主要方法被广泛运用,以简单的芳香醛和芳香酮缩合即可得到结构多样的查耳酮分子,该方法具有操作简便、反应条件温和等特点.以查耳酮活性为分类,综述了近年来以Claisen-Schmidt反应合成的查耳酮类化合物及其生物活性研究进展.整理了该类化合物抗癌、抗炎、抗菌、抗氧化等生物活性,并发掘提出了其生物活性构效关系,为后续查耳酮类化合物研究开发提供参考.     

对甲氧苯炔基取代黄酮以及橙酮衍生物的合成

以2,4,6–三羟基苯乙酮为原料,通过保护、羟醛缩合、环化、碘代以及Sonogashira反应合成了2个新的8位对甲氧苯炔基取代黄酮化合物.同时,从4,6–二羟基橙酮和金鱼草素出发,通过保护、碘代以及Sonogashira反应合成了2个新的7位对甲氧苯炔基取代橙酮化合物.以常见黄酮和橙酮为母核,探讨8位对甲氧苯炔基取代黄酮和7位对甲氧苯炔基取代橙酮衍生物的合成方法.这些化合物的合成为进一步对黄酮化合物8位以及橙酮的7位进行化学修饰奠定了良好的基础.     

3,5-二芳基吡唑类化合物合成及结构的测定

在微波-超声波辐射条件下,以芳香醛和芳香酮为起始原料合成了六种3,5-二芳基吡唑类化合物,并通过核磁共振氢谱测定了其结构.同时发现只有在乙酸介质中该反应才能生成主要产物.这为标题化合物的合成提供了一个快速、高产率、简便的方法.     

合成查尔酮化合物新方法的研究进展

查尔酮化合物是芳香醛酮发生交叉羟醛缩合的产物,它不仅是一种重要的有机合成中间体,还具有多种药理作用和生物活性;综述了最近几年来合成查尔酮化合物的反应体系、合成方法,并介绍了各种反应体系的优点及其合成查尔酮化合物的产率范围,认为查尔酮化合物的合成将以新技术、新方法和无污染的绿色合成为发展方向.     

5-取代-4-氨基-1,2,4-三唑-3-硫酮席夫碱的合成

目的 研究5位有芳香基取代的4-氨基-1,2,4-三唑-3-硫酮席夫碱化合物.方法 以自制的5-邻硝基苯氧甲基-4-氨基-1,2,4-三唑-3-硫酮与取代芳香醛为原料,以醋酸为溶剂,回流反应.结果 合成了未见文献报道的7个三唑硫酮席夫碱类化合物,各化合物通过IR,1H NMR和元素分析确定了其分子结构.结论 该合成方法 简便、易行、收率高.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the