五元杂环分子超极化率的电子相关效应

用有限场方法在HF和MP4水平上计算呋喃、吡咯和噻吩的极化率、一阶和二阶超极化率.结果表明,电子相关效应对各阶极化率,尤其是高阶极化率影响较大.MP2计算值较HF有显著改善,一阶超极化率的MP2,MP3和MP4计算值依次增大,二阶超极化率的MP2和MP4值相近,而MP3值小于MP2.呋喃、吡咯和噻吩的各阶极化率在各级微扰中均具有与HF水平上一致的相对大小顺序.     

五元芳杂环的芳香性和亲电取代活性顺序

本文简要介绍了五元芳杂环芳香性强弱顺序和它们进行芳香族亲电取代反应的难易顺序是两种不同性质的顺序，并指出应怎样来判断这两种顺序。     

新型含膦五元杂环类化合物的合成

以1-苯基磷杂环戊烷硼烷络合物为起始原料,经羧基化、酯化、格氏反应以及硅基化反应合成了两个新型的含膦五元杂环化合物——顺式-二[3,5-二-(三氟甲基苯基)](1-苯基磷杂环戊烷-2)-甲醇硼烷络合物和顺式-二[3,5-二-(三氟甲基苯基)](1-苯基磷杂环戊烷-2)-三甲基硅氧甲烷硼烷络合物,其结构经1H NMR,13C NMR,31P NMR和HR-EI-MS表征。     

五元杂环类茂金属配合物研究进展

综述了五元杂环类茂金属配合物的研究进展及其在烯烃聚合中的应用.     

苯并五元杂环系列分子的结构与非线性光学性质

采用AM1方法优化分子构型，用ZINDO方法研究了氨基，硝基取代的2－苯基苯并噻唑系列分子的光谱，并在此基础上用自编程序计算了这些分子的二阶非线性光学系数，对取代2－苯基苯并噻唑系列分子的二阶非线性光学系数的影响因素进行了探讨，并在微观上给予解释。     

含五元杂环的聚酰亚胺的合成与性能研究

以多聚磷酸为溶剂,4-氨基苯甲酸与硫代氨基脲反应制得一种含噻二唑环的二胺单体4-(5-对氨基苯基)-1,3,4-噻二唑苯胺(2); 2与均苯四酸二酐反应合成了含五元杂环的聚酰亚胺(3),其结构和性能经¹H NMR, FT-IR和TGA表征,并研究了3的溶解性能。结果表明：3的热稳定性较好,T_5%为402 ℃。 3在二甲基亚砜、DMF和N-甲基吡咯烷酮等溶剂中溶解性较好。     

一类α-五元杂环氨基酸的合成研究进展

杂环位于氨基酸C-末端羧基与α-碳之间的α-五元杂环氨基酸是一类主要来源于海洋多肽的高度修饰的氨基酸,分子中杂环的存在对化合物的生物活性有着重要的影响.综述了此类氨基酸的合成方法,这些方法针对不同的底物在操作简便性、收率、产物光学纯度、适用范围上有着明显差别.     

双二茂铁基吡咯衍生物电荷交互通道

以二茂铁炔烃为原料通过“一锅法”环加成反应合成了一系列2,5-双二茂铁基-1-苯基-吡咯衍生物, 包括: 2,5-双二茂铁基-1-(3-三氟甲基苯基)-吡咯(1), 2,5-双二茂铁基-1-(4-氟苯基)-吡咯(2), 2,5-双二茂铁基-1-苯基-吡咯(3), 2,5-双二茂铁基-1-(4-乙基苯基)-吡咯(4)和2,5-双二茂铁基-1-(4-乙氧基苯基)-吡咯(5), 使用元素分析, 傅里叶变换红外(FTIR)光谱, 质谱(MS)和核磁共振(NMR)等手段对化合物进行了结构表征. 采用循环伏安法(CV), 密度泛函理论(DFT)模拟计算研究了苯基上取代基对双二茂铁间电荷交互的影响. 研究发现第一氧化电位(E_a1), 峰电位差(ΔE)与取代基的哈米特常数(σ), 吡咯¹H NMR的化学位移(δ), 吡咯N原子自然轨道(NBO)电荷之间存在显著线性关联; 同时发现, N原子电荷密度升高, 双二茂铁间电荷交互能力减弱, N原子电荷密度降低, 双二茂铁间电荷交互能力提高. 因此这类双二茂铁基吡咯衍生物中N原子电荷密度对双二茂铁间电荷交互起着关键的影响作用.     

含氮五元杂环酮的拟除虫菊酯的合成、结构和生物活性

以1-对乙氧基-2,2-二氯环丙烷甲酸(1a)和3-(2-氯-3,3,3-三氟-1-丙烯)-2,2-二甲基环丙烷甲酸(1b)为原料, 经酰氯化反应得到酰氯, 再以三乙胺为缚酸剂, 分别与2-烷酮、2-噻唑烷酮、2-噻唑硫酮、1-乙酰基-2-咪唑烷酮、1-甲磺酰 基-2-咪唑烷酮反应, 得到10个新的含氮五元杂环酮的拟除虫菊酯. 化合物结构经¹H NMR, IR, MS和元素分析进行表征. 并用X-ray单晶衍射测定了化合物3-(1-对乙氧基-2,2-二氯环丙烷甲酰)-2-噁唑烷酮(4a-1)的晶体结构. 对合成的化合物进行了初步的生物活性测试, 结果表明, 在试验浓度下部分目标化合物对黄瓜灰霉病菌具有一定得防效作用; 其中, 化合物(4a-1)和3-(3-(2-氯-3,3,3-三氟-1-丙烯)-2,2-二甲基环丙烷甲酰)-2-噻唑烷酮(4b-3)对粘虫也分别有50%及90%的杀虫活性.     

α-重氮羰基化合物在合成五元杂环化合物中的新应用

本文综述了α-氮羰基化合物在合成五元杂环化合物方面新的研究成果，分为四大类：类卡宾对X－H键的插入反应；类卡宾时π键的反应；经由isomnchnone的反应；经由叶利德的反应．     

Three types of reactions with intramolecular five-membered ring compounds in organic synthesis

There are three types of reactions with intramolecular five-membered ring compounds in organic syntheses: The first type is reactions involving intramolecular five-membered ring compounds which are utilized for the ease of synthesis of these compounds and the stability of the products. The second is reactions performed via intramolecular five-membered ring intermediates, because such intermediates are very reactive and labile compounds. The third is the metal-catalyzed reactions with the intramolecular five-membered ring compounds because these metal compounds have catalytic activities. The third type reactions involving intramolecular five-membered ring pincer compounds are also provided.The first type reactions include carbonylations, alkenylations, alkynylations, acylations, isocyanations, Diels-Alder reactions, etc. The second type reactions include carbonylations, cross-coupling reactions, hydroacylations, ring expansion reactions, carbocyclizations, etc. The third type reactions include cross-coupling reactions, rearrangements, metatheses, reductions, Michael reactions, dehydrogenations, Diels-Alder reactions, etc.     

Synthesis of fused bicyclic pyridines with microwave-assisted intramolecular hetero-Diels-Alder cycloaddition of acetylenic pyrimidines

A series of acetylenic pyrimidines was synthesized and subjected to microwave irradiation. In contrast to conventional heating, the microwave irradiations generally gave clean conversion to fused bicyclic pyridines for all substrates reported with shorter reaction time. This method has been successfully applied to the synthesis of both fused lactones and lactams.     

Stereocontrolled intramolecular nitrile oxide cycloaddition reaction using a gauche-gauche interaction

A gauche-gauche interaction is proposed as a powerful controlling factor for the stereochemistry in the intramolecular nitrile oxide cycloaddition reaction derived from N-protected 3-(N-allylamino)propionaldehyde and 2-(N-homoallylamino)acetaldehyde oximes. High levels of stereoselectivity (76% de to perfect) were obtained from the reaction involving nitrile oxides with substituents at the adjacent carbon atom to the tether nitrogen.     

Direct observation of intramolecular coplanarity regulated polymorph emission of a tetraphenylethene derivative

Polymorphism makes it possible to clarify the relationship between emission property and crystal structure. However, based on the exact molecular conformation in tetraphenylethene polymorphisms, it is still challenging to evaluate the difference of intramolecular coplanarity without the support of calculation because of the complex combination of four different torsion angles between four peripheral benzenes and the central ethylene plane. Here, by using a di-formyl-functionalized tetraphenylethene derivative, two ideal polymorphisms with a consistent trend of the corresponding torsion angles have been obtained. For the first time, we explicitly demonstrated that intramolecular coplanarity is the underlying cause of the polymorphism-dependent emission of tetraphenylethene derivatives.     

系列杂氮钛三环中的分子内弱相互作用的紫外光电子能谱和理论研究

首次报道了四种杂氮钛三环的紫外光电子能谱,结合量子化学从头算和和电子密度拓扑分析方法对这些化合物的电子结构和分子内存在的弱相互作用进行了分析研究。通过优化STO-6G(d)基组(C:1s=5.66,ζ2s=1.675,ζ2p=1.66;O:ζ1s=7.67,ζ2s=2.25,ζ2p=2.20;N:ζ1s=6.66,ζ2s=1.91,ζ2p=1.89;H:ζ1s=1.24)对所研究的化合物进行了分子轨道计算,结合计算结果对化合物的紫外光电子能谱进行了解析和指认。实验得到的体现分子内弱相互作用σN-Ti的轨道电子的电离能表明了N,Ti间相互作用的弱成键特性,电子密度拓扑分析显示N,Ti原子间存在体现成键作用的键鞍点,键鞍点处电子密度的拓扑性质也进一步支持了N,Ti间弱成键作用的特性。     

The enantioselective intramolecular Morita-Baylis-Hillman reaction catalyzed by amino acid-derived phosphinothiourea

A series of chiral bifunctional phosphinothioureas derived from l-amino acids have been developed to promote the enantioselective intramolecular Morita-Baylis-Hillman reaction. The process afforded the cyclic hydroxyl enones with up to 84% ee and good yields under mild conditions.     

The intramolecular hydrogen bond in 2-hydroxy-benzamides

The two crystal structures of 5-chloro-2-hydroxy-benzamide and 2-hydroxy-N,N-diethyl-benzamide were determined by X-ray diffraction at 100 K. The intramolecular and intermolecular hydrogen bonds were found in these structurally similar 2-hydroxy-benzamides. Analysis of the hydrogen bonding was carried out on the basis of X-ray data, infrared spectra, and DFT calculations. Disruption of the intramolecular hydrogen bonding in the solid state by a steric effect is shown. Conformational analysis and potential energy calculations as functions of the turning angle around the C_aryl–C_alkyl bond were conducted. The values obtained for the HOMA index indicate mutual compensation of the amide and hydroxyl groups (due to the high degree aromaticity of the phenyl ring).     

The subtle electronic effects of alkyl groups on the conformational equilibria and intramolecular hydrogen-bond strength in cis-3-alkoxycyclohexanols

(1)H NMR data for cis-3-n-propoxycyclohexanol (cis-3-PCH) and cis-3-isopropoxy-cyclohexanol (cis-3-ICH) show that a concentration increase shifts the conformational equilibrium from the diaxial (aa) conformer, stabilized by an intramolecular hydrogen bond (IAHB), to the diequatorial (ee) conformer [X(ee)=42% and 21% (at 0.01molL(-1)) to 58% and 56% (at 0.40molL(-1)), in CCl(4,) respectively] due to intermolecular hydrogen bonds (IEHB), as confirmed by IR data. The Deltanu values, obtained by IR spectra, indicated that increasing the size of the OR group [R=CH(3), CH(2)CH(2)CH(3) and CH(CH(3))(2)], increases the IAHB strength, due to an increase in the inductive effect of R group, which makes the oxygen lone pairs more available for an IAHB with OH group, in opposition to the steric effect. The percentage of ee conformer increases with the solvent basicity for cis-3-PCH and cis-3-ICH, from 48% and 36% in CCl(4) to 97% and 96% in DMSO, respectively. Values of 4.58, 6.06 and 6.33kcalmol(-1) for the IAHB strength in cis-3-PCH, cis-3-ICH and cis-3-TCH (cis-3-tert-butoxycyclohexanol), respectively, were obtained, from the theoretical data through the CBS-4M method, confirming the experimental results and indicating that the IAHB strength increases with the increasing bulk of OR substituent in this series of compounds.     

Towards the total synthesis of tangutorine by intramolecular Diels-Alder reaction

The syntheses of 3,5-disubstituted-2-sulfolenes, and their participation in Pictet-Spengler reactions to give precursors of tangutorine, are described.