α-V、Ⅵ主族正离子取代的甲苯和苯乙酮系列中碳-氢键均裂及异裂能量的研究

合成了α-位有第V、Ⅵ主族元素杂正离子取代基的甲苯系列（1）和苯乙酮系列（2）共11个Ylide前体化合物，用重迭指示剂法首次测定了其在二甲亚矾（DMSO）溶剂中的酸性解离常数PKa，同时结合碳负离子（即Ylide）氧化电位的测定，通过热力学循环估测了它们的气相均裂键能（BDE）．根据这些PKa和BDE数据，对16个Ylide前体化合物的C－H键的均裂能和异裂能进行了比较，并讨论了a-杂正离子取代基对相关的Ylide和类-Ylide自由基的热力学稳定性的影响及结构效应     

磷叶立德CH2PH3和类磷叶立德自由基∙CHPH3优势构型和C—P键结构的研究

采用MP4/6-311++G(d,p)和B3LYP/6-311++G(d,p)对磷叶立德CH₂PH₃和类磷叶立德自由基∙CHPH₃进行构型优化，从电子密度拓扑分析的角度对C—P键的键结构进行了探讨。得到如下结论：类磷叶立德自由基和磷叶立德的C—P键性质类似，但磷叶立德中π键由两个电子形成，类磷叶立德自由基中π键由一个电子形成，所以前者的π性明显，而后者的π性不明显。类磷叶立德自由基中的这个单电子在碳原子附近，垂直于对称面的方向上运动，有p_(C→P)配键的特征，所以类磷叶立德自由基∙CHPH₃中的C—P键比相应的产物∙CH₂PH₂中的C—P键要弱一些。     

全氟萘烷的化学还原与电化学还原

全氟碳化合物 ( PFCs)是分子中与碳原子相连的氢 (官能团中的除外 )全部被氟原子取代的有机氟化合物 .由于氟元素的电负性最大 ,所以 C— F键的键能很大 ( 4 80～ 5 30 k J/mol) ;PFCs与相应的碳氢化合物相比 ,C— F键的键长 ( 0 .1 3nm)与 C— H键的键长 ( 0 .1 nm)接近 ,而且氟原子的范德华半径( 0 .1 5 nm)与氢原子的范德华半径 ( 0 .1 2 nm)也非常接近 ,所以当碳氢化合物中的氢原子被氟原子取代而形成全氟碳化合物后 ,结构上不会发生太大的变化 [1] ;但是全氟碳化合物的物理化学性质与原来碳氢化合物的物理化学性质有显著差异 ,表…     

利用邻-碳硼烷可变的C-C键实现发光分子从ACQ到AIE转变（英文）

利用邻-碳硼烷骨架中可变的C-C键,将在聚集态会发生猝灭(ACQ)的传统发光分子和具有振动自由度的碳硼烷基团连接起来,合成了带有聚集诱导发光(AIE)效应的邻-碳硼烷基发光分子。通过紫外可见吸收光谱、DFT计算、发射光谱及晶体结构测定等手段,研究了邻-碳硼烷可变的C-C键对化合物性质的影响。结果表明,在邻-碳硼烷骨架的碳原子上引入不同的取代基可以改变C-C键的振动特性,从而能够调控化合物的发光性质,并有效实现从ACQ到AIE的转变。     

环境污染物中碳氯键离解能的理论研究

利用六种密度泛函理论方法（B3LYP, B3P86, MPW1K, TPSS1KCIS, X3LYP, BMK）对碳氯键离解能进行理论计算,结果发现几种新发展的密度泛函(DFT)方法用于碳氯键离解能的计算比传统的B3LYP有较大的改善,其中对能量估算相对准确的B3P86方法对碳氯键离解能的计算精度最高,对17个分子中碳氯键离解能计算的平均绝对偏差为6.58 kJ/mol。最后运用B3P86方法对一系列环境危害较大,但可通过光化学降解和生物降解的氯代有机物的碳氯键离解能值进行预测,并讨论了影响碳氯键离解能的结构性质关系。     

基于磷杂菲基团化合物的构建与性能*

由于磷杂菲基团具有杂环含磷特性、非共平面性、与分子内或分子间基团的相互作用性、分子极性等特点,能够作为改性基团引入到化合物中用于构建具有新结构和新性能的材料。本文综述了磷杂菲基团衍生物的构建方法和含有磷杂菲基团功能材料的性能以及磷杂菲基团对材料性能的影响规律。介绍了利用9,10-二氢-9-氧杂-10-磷杂菲 10-氧化物（DOPO）的P-H键与不饱和基团醌、醛、酮、碳碳双键、碳氮双键、碳氮三键等进行加成反应获得磷杂菲衍生物的方法和原理。重点总结了含磷杂菲基团的环氧树脂、聚酯、涂料和助剂等化合物的阻燃性能以及磷杂菲基团提高材料阻燃性能的原理;介绍了磷杂菲基团易于与分子内和分子间基团相互作用的性质以及对热致液晶高分子材料液晶性质的影响规律,这一性质也导致了一些磷杂菲化合物的聚集诱导发光现象的发生。此外,磷杂菲基团的极性提高了聚酯和聚酰胺等化合物的分子极性,使这类化合物获得了良好的有机溶解性。     

碳-碳重键的新合成方法学研究

本研究工作包括下列8方面:(1)一种不同于Wittig反应的新的烯化方法,含氟β-酮基磷盐在有机合成中的应用。(2)"一锅"法的碳-碳双键形成反应。(3)一种新的叶立德阴离子的形成方法。(4)消去三苯基胂形成碳-碳双键的合成方法学。(5)立体选择性地控制合成(Z)或(E)-碳-碳双键化合物的新方法。(6)亲核试剂对全氟酰基膦酸酯进攻为基础的新合成方法学。(7)还原烯化反应的合成方法学。(8)含氟碳-碳叁键的合成方法学。     

含砷、磷、氟有机化合物中碳、氢的微量测定

在碳、氢分析中,含砷、磷、氟有机化合物的碳、氢分析存在许多困难。如有机砷化合物灼烧后生成的氧化物会毒化填充剂并进入吸收管而使碳、氢分析失败。有机磷和氟化合物由于C-P键和C-F键的稳定性不易裂解和定量氧化;此外,在燃烧过程中磷生成五氧化二磷易在高温挥发,大部分被氧气带走或沉渍在燃烧管的出口冷却部分或进入水吸收管;氟则与有机物中的氢作用生成氟化氢,再与石英管中的二氧化硅反应生成挥发性的四氟化硅和     

异丙基溴化镁催化脱氧反应

格氏试剂通常以碳负离子形式对亲电试剂进行加成。但是有催化量的Cp_2TiCl_2存在时,具有β质子的烷基格氏试剂往往能发生还原反应或氢镁化反应。例如,使环氧键、碳氧双键、硅氧键、硅卤键、碳卤键、碳氮双键、碳氮三键、碳碳双键、碳碳三键等还原或氢镁化的反应已有报道。但是,对硫氧双键、氮氧键、磷氧双键和砷氧双键的     

钯催化的Grignard型反应

对钯催化的Grignard类型反应作了论述.总结了钯催化的有机卤化物或炔烃与C=O键或C≡N键的二组分反应和有机卤化物、烯烃或炔烃与C=O键或C≡N键的三组分反应.在这些反应中的C-Pd键是通过C-X键与Pd(0)的氧化加成或通过碳碳双键或叁键的碳/亲核钯反应生成,C-Pd键与C=O键或C≡N键之间的反应一般为分子内反应.当然,人们也观察到了通过芳香C-H键活化产生的芳基碳钯键与腈基的分子间反应.在这些反应中催化剂的再生是关键.本工作对反应的机理也作了一些探讨.     

Cyclic phosphonium ylides

Synthetic approaches to cyclic phosphonium ylides are reviewed and the syntheses are classified according to reaction type rather than ring size. Particular attention is paid to syntheses leading to isolable or easily characterizable cyclic ylides and a number of other reactions in which cyclic phosphonium ylides are postulated as transient intermediates are discussed. There is also a brief discussion regarding structure and bonding in certain of the more stable cyclic ylides such as the 1,1-disubslituted phosphorins and certain diphosph(V)orins.     

1,2]- or [2,3]-rearrangement of onium ylides of allyl and benzyl ethers and sulfides via in situ-generated iodonium ylides

Iodonium ylides, generated in situ with bisacetoxyiodobenzene, are converted to allyl- or benzyl-substituted oxonium or sulfonium ylides via rhodium- or copper-catalyzed carbene transfer. Except for the S-benzyl example, the resulting ylides undergo rearrangement to the corresponding 2-substituted heterocycles. This demonstrates the first use of iodonium ylides as diazoketone surrogates for the generation and rearrangement of onium ylide intermediates. This abbreviated one-step method proceeds in comparable yields relative to the corresponding two-step route employing diazoketone intermediates.     

Decomposition of diazoketones in organic sulfides and sulfoxides: Cyclopropane formation from diazoketones via sulfonium ylides

The catalytic decomposition of diazoketones in the presence of organic sulfides and sulfoxides, gives sulfonium and sulfoxonium ylides as the primary reaction products, the final products isolated depending upon the relative nucleophilicity of the sulfides compared to that of the corresponding ylides, and on the stability of the ylides. The mechanism, scope and limitations of a new method of cyclopropane formation from diazoketones are discussed. Some circumstantial evidence supporting a concerted process for Wolff rearrangement is presented.     

Reactivity and selectivity in the Wittig reaction: a computational study

The salt-free Wittig reaction of non-, semi-, and stabilized ylides has been investigated on realistic systems using density functional theory (DFT) calculations, including continuum solvation. Our results provide unequivocal support for the generally accepted mechanism and are in very good agreement with experimental selectivities. This study shows that E/Z selectivity of non- and semi-stabilized ylides cannot be fully understood without considering the energy of the elimination TS. The influence of ylide stabilization and the nature of phosphorus substituents on reversibility of oxaphosphetane formation is clarified. Unexpectedly, the puckering ability of addition TSs is shown not to depend on ylide stabilization, but the geometry of the TS is decided by an interplay of 1,2; 1,3; and C-H...O interactions in the case of non- and semi-stabilized ylides, whereas a dipole-dipole interaction governs the addition TS structures for stabilized ylides. The well-known influence of ylide stabilization on selectivity of PPh(3) derivatives is explained as follows: in non- and semi-stabilized ylides reactions, cis and trans addition TSs have, respectively, puckered and planar geometries, and selectivity is governed by an interplay of 1,2 and 1,3 interactions. For stabilized ylides, the high E selectivity is due to a strong dipole-dipole interaction at the addition TS. The influence of the nature of phosphorus substituents on selectivity is also detailed, the different behavior of (MeO)(3)PCHCO(2)Me ylides being explained by their lower dipole. This novel picture of the factors determining TS structures and selectivity provides a sound basis for the design of new ylides.     

An efficient method to prepare sulfoxonium ylides and their reactivity studies using copper powder and Sc(III) as catalysts: Molecular and electronic structure analysis

Sulfoxonium ylides are the viable alternatives for diazo compounds as carbene precursors. Unlike diazo compounds, these are bench-stable and crystalline solids. However, the existing methods for the synthesis of sulfoxonium ylides have disadvantages related to the yields, substrate scope, and usage of expensive catalysts. Therefore, it is necessary to develop efficient and competitive protocols for the preparation of sulfoxonium ylides. In this study, we developed an economically affordable protocol for the synthesis of sulfoxonium ylides from diazo compounds using copper powder as a catalyst. This protocol leads to the efficient multigram-scale synthesis of a wide range of sulfoxonium ylides in good yields. Further, we demonstrated scandium triflate–catalyzed carbene insertion into the N−H bond from sulfoxonium ylide. A variety of anilines and sulfoxonium ylides with various functional groups reacted well and produced the corresponding α-amino esters in good yields. All the synthesized compounds were characterized using various standard spectroscopic and analytical techniques. We also used computational methods to understand the electronic structure of all the sulfoxonium ylides using geometry optimization, frequency calculation, molecular orbital and natural bond orbital analysis, and energy decomposition analysis. Our computational results revealed that the interaction between carbene and dimethyl sulfoxide is covalent in nature and stable enough to handle in the absence of any catalyst.     

Rhodium(I)/Zn(OTf)2‐Catalyzed Asymmetric Ring Opening/Cyclopropanation of Oxabenzonorbornadienes with Phosphorus Ylides

The strong binding ability of P‐ylides with transition metals limits the utilization of stabilized P‐ylide as nucleophiles in asymmetric organometallic catalysis. Herein we describe the first rhodium‐catalyzed asymmetric ring‐opening reaction of P‐ylides utilizing oxabicyclic alkenes as the electrophilic partner. Various P‐ylides including ester‐, ketone‐ and amide‐style P‐ylides are all applicable. This asymmetric reaction occurs through the cleavage of two bridgehead C?O bonds and the formation of two C?C bonds, and oxabenzonorbornadienes are used as 1,4‐biselectrophiles, thus providing access to benzonorcaradienes in good yields with high enantioselectivity and perfect diastereoselectivity. The present protocol also constitutes the first highly enantioselective direct catalytic asymmetric cyclopropanation of stabilized P‐ylide nucleophiles.     

Density functional theory investigations on sulfur ylide promoted cyclopropanation reactions: insights on mechanism and diastereoselection issues

The mechanism and diastereoselectivity of synthetically useful sulfur ylide promoted cyclopropanation reactions have been studied using the density functional theory method. Addition of different substituted ylides (Me2S+CH-R) to enone ((E)-pent-3-en-2-one, MeHC=CH-COMe) has been investigated. The nature of the substituent on the ylidic carbon brings about subtle changes in the reaction profile. The stabilized (R=COMe) and semistabilized (R=Ph) ylides follow a cisoid addition mode, leading to 1,2-trans and 1,2-cis cyclopropanes, respectively, via syn and anti betaine intermediates. The simplest and highly reactive model ylide (R=H) prefers a transoid addition mode. Diastereoselectivity is controlled by the barrier for cisoid-transoid rotation in the case of stabilized ylides, whereas the initial electrophilic addition is found to be the diastereoselectivity-determining step for semistabilized ylides. High selectivity toward trans cyclopropanes with stabilized ylides are predicted on the basis of the relative activation energies of diastereomeric torsional transition states. The energy differences between these transition states could be rationalized with the help of weak intramolecular as well as other stereoelectronic interactions.     

Triphenylphosphine Mediated Simple Synthesis of Vinyl-Substituted Benzimidazoles

N -isopropenylbenzimidazolone undergoes a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates to produce highly functionalized salt-free phosphorus ylides in good yields. These stabilized phosphorus ylides exist as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. These ylides are converted to dialkyl 2-(1-isopropenyl-1H-benzimidazol-2-yl)-but-2-enedioates in boiling toluene.     

Bonding properties and bond activation of ylides: recent findings and outlook

The interaction of phosphorus and nitrogen ylides with metallic precursors has been examined from different points of view. The first one is related to the bonding properties of the ylides. Ylides with a unique stabilizing group bond through different atoms (the Calpha or the heteroatoms); while ylides with two stabilizing groups never coordinate through the Calpha atom. In the second section we examine the cause of the stereoselective coordination of bisylides of phosphorus, nitrogen and arsenic, and of mixed bisylides. We describe here the very interesting conformational preferences found in these systems, which have been determined and characterized. The DFT study of these bisylides has allowed for the characterization of strong intramolecular PO and AsO interactions, as well as moderate CHO[double bond, length as m-dash]C hydrogen bonds as the source of these conformational preferences. The third topic is related to the amazing reactivity of phosphorus ylides in bond activation processes. Depending on the nature of the metallic precursors, ylides can behave as sources of carbenes, of phosphine derivatives, of other ylides or of orthometallated complexes through P[double bond, length as m-dash]C, P-C or C-H bond activation reactions.     

Immonium ylides derived from halocarbenes in the synthesis of nitrogen-containing compounds

Reactions of halocarbenes with imines, ketenimines, and aromatic azaheterocycles, which proceed through the corresponding azomethine ylides, keteneimine ylides, and cycloimmonium ylides, are reviewed. New routes for the synthesis of halo- and nitrogencontaining compounds using the transformations of halosubstituted immonium ylides are discussed.The paper is based on an invited lecture at the fifth Conference on Carbene Chemistry (Moscow, September 16–18, 1992).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 646–654, April, 1993.