顺反异构键参数拓扑指数及其在相关顺反异构分子性质中的应用

顺反异构键参数拓扑指数及其在相关顺反异构分子性质中的应用张宏光，辛厚文（中国科技大学近代化学系，合肥２３００２６）关键词：顺反异构分子，键参数拓扑指数分子的拓扑指数是近几十年来发展起来的一种重要的分子图不变量。自１９４７年Ｗｉｎｎｅｒ提出第一个分子拓...     

乙炔氧化羰基化合成丁烯二酸二丁酯的反应动力学和机理

在常压下,考察了在PdC1_2-FeCl_3-H_2SO_4-BuOH催化体系中乙炔氧化羰基化合成丁烯,二酸二丁酯的反应动力学。所得结果验证了乙炔形成双金属络合活化机理的合理性,提出了因分子岐化反应而得到顺反异构体产物的反应历程。     

1—间甲氧苯基—2—二甲胺甲基环己醇的合成与结构研究

通过间溴苯甲醚与２－二甲胺甲基环己酮反应制得１－间甲氧苯基－２－二胺甲基环己醇，对其分离得到相应的顺反异构体，对反应的立体化学进行了分析，并对＾１３Ｃ ＮＭＲ谱确定了顺反异构体的构型。     

钯催化的烯烃异构化反应

烯烃异构反应可以从简单烯烃出发,通过对碳碳双键立体选择性或者位置选择性调控,实现内烯烃化合物尤其其他方法难以构建的多取代烯烃的高效合成,原子经济性高.详细介绍了钯催化烯烃异构化反应的反应机制,系统总结了钯催化的烯烃顺反异构和位置选择性异构反应,以及其在药物分子和天然产物合成中的应用.     

硝基苯乙烯基芳香化合物光谱性质的研究

本文通过9-对-硝基苯乙烯基蒽和1-对-硝基苯乙烯基芘在不同溶剂中的光谱数据,利用Lippert-Mataga公式估算了它们在激发态与基态时偶极矩的差值,计算了1-对-硝基苯乙烯基芘在不同溶剂中的辐射与非辐射速率常数,讨论了溶剂极性和温度对分子内光致电子转移和电荷分离的影响。文中还初步探讨了光诱导顺反异构化反应与分子内电荷转移的关系。     

新型3－取代－6－芳偶氮香豆素化合物的合成及结构表征

合成了一系列新型偶氮香豆素化合物，通过^1H NMR,IR,MS和元素分析对其结 构进行了确认，同时用X射线单晶衍射测定了化合物2a的晶体结构，其特殊的双功 能分子键连，偶氮基的顺反异构和苯环与香豆素环平面间的扭转平角，使之可能成 为有效的分子器件材料。     

单分子反应理论的启发式教学实践

将启发式教学理念应用到单分子反应理论的教学中。本文针对单分子反应RRKM理论的教学难点，通过在课堂上引入科研实例，再设计问题，一点点启发学生思考，激发课堂讨论，让学生更加容易地理解知识难点，同时提高学生分析问题和解决问题的能力。     

结构受阻对取代苯乙烯基吡嗪光物理行为的影响

有关藻类化合物衍生物的荧光发光及其顺反异构化是长期来一直受到广泛注意的问题［’，2］，近年来特别在发现了街的两侧苯环联有推、拉电子能力基团、构成了分子内共轭的电行转移化合物后，其荧光发射有了较大幅度的增长［3，4］，使人们对这一问题的研究更加关切．由于荧光的增长会导致异构化反应的减少，促使人们提出所谓的激发态多衰变通道的观点［5，6］以激发的英分子为例；已认识到其中的双键扭转应为异构化（无辐射衰变的一种）的主要通道，而蔑分子的平面态或双键二侧单键的扭转态则是荧光发射（辐射衰变）的主要途径·所有这些看…     

偶氮液晶在光学材料中的应用进展

偶氮液晶是一类分子中含有偶氮苯结构的液晶,其偶氮基团在光照射下,能发生可逆的顺反异构反应。由于偶氮苯的顺式结构不能形成稳定的液晶相,因此,偶氮液晶在具有向列液晶温敏性质的同时,也具有特有的光敏性质,其相变与分子取向能够通过光照进行控制。这种特性使得偶氮液晶在光学功能材料方面具有广泛的应用。本文介绍了偶氮液晶的基本特性,结合作者自身的研究工作阐述了其在光学材料应用方面的研究进展。     

白藜芦醇、白皮杉醇和赤松素的合成

研究了白藜芦醇、赤松素和白皮杉醇的一种简便合成方法.二苯乙烯类化合物在铝和碘的作用下实现双键顺反异构和芳甲醚甲基的脱除,实现白藜芦醇、赤松素和白皮杉醇的高效合成,反应的总收率分别为68%,78%和56%.反应溶剂过滤后可以再次使用.通过量子化学计算和控制实验认为碘自由基可能是脱甲基过程中导致双键顺反异构的关键因素.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.