SiO2在CH3ONO→CH3O+NO解离中作用的理论研究

利用B3LYP方法,在6-31 G^ 基组下研究了在SiO2存在下的CH3ONO→CH3O NO解离反应．计算了全优化下的解离反应,以及固定SiO2的键长和键角做部分优化下的解离反应．在反应中SiO2与CH3ONO相接近,O-N键逐渐伸长,生成复合物,放出热量,进一步促进了CH3ONO中NO的解离．     

Metal‐Free σ‐Bond Metathesis in 1,3,2‐Diazaphospholene‐Catalyzed Hydroboration of Carbonyl Compounds

The first metal‐free catalytic hydroboration of carbonyl derivatives has been developed in which a catalytic amount of 1,3,2‐diazaphospholene effectively promotes a hydroboration reaction of aliphatic and aromatic aldehydes and ketones. The reaction mechanism involves the cleavage of both the P? O bond of the alkoxyphosphine intermediate and the B? H bond of pinacolborane as well as the formation of P? H and B? O bonds. Thus, the reaction proceeds through a non‐metal σ‐bond metathesis. Kinetic and computational studies suggest that the σ‐bond metathesis occurred in a stepwise but nearly concerted manner.     

Cu(I)-assisted carbon---carbon bond forming reactions of γ,γ-dialkoxyallylic zirconium species: a new versatile homoenolate equivalent of propionate

In the presence of CuCN, reaction of γ,γ-dialkoxyallylic zirconium species 1 with acyl chloride or allylic phosphates proceeded at the -position of 1 to give alkanoates 3 after aqueous work-up. The ketene dialkylacetal moiety in the coupling products 2 can be used for further bond forming reaction with electrophiles such as nitrosobenzene, nitrostyrene or trichloroacetylisocyanate.     

Asymmetric Disulfonimide‐Catalyzed Synthesis of δ‐Amino‐β‐Ketoester Derivatives by Vinylogous Mukaiyama–Mannich Reactions

An organocatalytic asymmetric synthesis of δ‐amino‐β‐ketoester derivatives has been developed. A chiral disulfonimide (DSI) serves as a highly efficient precatalyst for a vinylogous Mukaiyama–Mannich reaction of readily available dioxinone‐derived silyloxydienes with N‐Boc‐protected imines, delivering products in excellent yields and enantioselectivities. The synthetic utility of this reaction is illustrated in various transformations, including a new C? C bond‐forming reaction, which provide useful enantioenriched building blocks. The methodology is applied in a formal synthesis of (?)‐lasubin.     

Direct N‐Methylation Reaction Using DMSO as One‐Carbon Bridge: Convenient Access to Heterocycle‐Containing β‐Amino Ketones

A novel oxidative C? S bond cleavage reaction of DMSO for dual C? C and C? N bond formation is described. A series of acetyl heteroarenes could be selectively converted into the corresponding β‐amino ketones, which are frequently found in biologically active compounds and pharmaceuticals. DMSO acted in this reaction not only as the solvent but also as a one‐carbon bridge.     

Copper‐Catalyzed Oxidative Reaction of β‐Keto Sulfones with Alcohols via C−S Bond Cleavage: Reaction Development and Mechanism Study

A Cu‐catalyzed cascade oxidative radical process of β‐keto sulfones with alcohols has been achieved by using oxygen as an oxidant. In this reaction, β‐keto sulfones were converted into sulfinate esters under the oxidative conditions via cleavage of C?S bond. Experimental and computational studies demonstrate that a new pathway is involved in this reaction, which proceeds through the formation of the key four‐coordinated Cu^II intermediate, O?O bond homolysis induced C?S bond cleavage and Cu‐catalyzed esterification to form the final products. This reaction provides a new strategy to sulfonate esters and enriches the research content of C?S bond cleavage and transformations.     

On the NH3+HCO3H→HCOOH+H3NO mechanism: a density functional theory study

The B1LYP, B3LYP and MPW1PW91 density functional theory methods combined with the 6-311G(2d, 2p) basis set were used to carry out a density functional theory study of the NH₃+HCO₃H→HCOOH+H₃NO reaction. The purpose of this work is to study the reaction mechanism from the viewpoint of bond order transformations throughout the course of the reaction, and propose the reasons for the apparent differences in activation barriers.     

Gold‐Catalyzed [3+2]/Retro‐[3+2]/[3+2] Cycloaddition Cascade Reaction of N‐Alkoxyazomethine Ylides

A novel cascade reaction has been developed for the synthesis of 2,6‐methanopyrrolo[1,2‐b]isoxazoles based on the gold‐catalyzed generation of an N‐allyloxyazomethine ylide. This reaction involves sequential [3+2]/retro‐[3+2]/[3+2] cycloaddition reactions, thus providing facile access to fused and bridged heterocycles which would be otherwise difficult to prepare using existing synthetic methods. Notably, this reaction allows the efficient construction of three C−C bonds, one C−O bond, one C−N bond and one C−H bond, as well as the cleavage of one C−C bond, one C−O bond and one C−H bond in a single operation. The intermolecular cycloaddition of an N‐allyloxyazomethine ylide and the subsequent application of the product to the synthesis of tropenol is also described.     

钛铁矿型六方相ZnTiO3的电子结构和光学性质

分别采用基于密度泛函理论(DFT)的局域密度近似(LDA)和广义梯度近似(GGA)方法对钛铁矿型六方相ZnTiO₃的电子结构进行了第一性原理计算, 并在局域密度近似下计算了六方相ZnTiO₃的光学性质, 并将计算结果与实验数据进行了对比. 结果表明, 在局域密度近似下计算得到的结构参数更接近实验数据. 理论预测六方相ZnTiO₃属于直接带隙半导体材料, 其禁带宽度(布里渊区Z 点)为3.11 eV. 电子态密度和Mulliken 电荷布居分析表明Zn―O键是典型的离子键而Ti―O键是类似于钙钛矿型ATiO₃ (A=Sr, Pb, Ba)的Ti―O共价键. 在50 eV的能量范围内研究了ZnTiO₃的介电函数、吸收光谱和折射率等光学性质, 并基于电子能带结构和态密度对光学性质进行了解释.     

Formal Aminocyanation of α,β‐Unsaturated Cyclic Enones for the Efficient Synthesis of α‐Amino Ketones

Installation of amino functionality on organic molecules through direct C N bond formation is an important research objective. To achieve this goal, a 1,2‐aminocyanation reaction was developed. The reaction occurs through the formation of pyrazolines by means of a formal dipolar cycloaddition of cyclic α,β‐unsaturated ketones with lithium trimethylsilyldiazomethane followed by novel protonolytic N N bond cleavage under mild conditions. This two‐step process provides a diverse array of structurally complex free and mono‐alkylated α‐amino ketones in excellent yields.     

A study on feasibility of insect—control with γ-ray

Insect-control with Co-γ-ray is a method for conserving archives, books, cotton textiles, historical relics, wood structured houses and furniture, which are called irradiated objects later on. The temporary and residual effects of γ-ray on irradiated objects and the biological effects on insects are presented in this report.

Our study shows that there is no obvious harmful effect on irradiated objects when the ray is below 870 Gy, while there is obvious deterioration on the objects when the ray is above 870 Gy. On the other hand, the ray below 870 Gy is strong enough for the insects. In fact, at the dose of 43.5–130.5 Gy, the irradiated insects could be damaged on reproductive function, even sterilized, or killed.     

A Mild Isomerization Reaction for β,γ‐Unsaturated Ketone to α,β‐Unsaturated Ketone

A series of β,γ‐unsaturated ketones were isomerized to their corresponding α,β‐unsaturated ketones by the introduction of DABCO in iPrOH at room temperature. The endo‐cyclic double bond (β,γ‐position) on ketone was rearranged to exo‐cyclic double bond (α,β‐position) under the reaction conditions.     

Chemical Bond Parameters in Sr_3MRhO_6(M=Rare earth)

over tile years, tile collcept of bolld covalellcy or ionicity has been proved to be a veryilllpol'tallt quantity in classifyillg and explaining many basic properties of molecules andsolids from the viewpoint of the electronic structure. Nevertheless, previous study in thisaspect was only on binary crystals, which limited the usefulness of the theory. Therecently proposed method I for the evaluation of chemical bond parameters includingbond covalency has made the study on crystals with multipl…     

Pd-catalyzed synthesis of 3-(diarylmethylene)-2-oxindoles and 3-(arylmethylene)-2-oxindoles

An efficient method for the stereoselective synthesis of 3-(diarylmethylene)-2-oxindoles and 3-(arylmethylene)-2-oxindoles via carbopalladation is described. In this approach, an Ugi-4-component reaction (4-CR) adduct was used as the starting material. A one-pot sequence involving intermolecular carbopalladation C-H activation/C-C bond formation efficiently afforded the oxindole derivatives.     

Trajectory of Approach of a Zinc–Hydrogen Bond to Transition Metals

Through a dramatic advance in the coordination chemistry of the zinc–hydride bond, we describe the trajectory for the approach of this bond to transition metals. The dynamic reaction coordinate was interrogated through analysis of a series of solid state structures and is one in which the TM‐H‐Zn angle becomes increasingly acute as the TM–Zn distance decreases. Parallels may be drawn with the oxidative addition of boron–hydrogen and silicon–hydrogen bonds to transition metal centers.     

8-甲氧基呋喃并[3′,2′:6,7]香豆素与烯烃的光环合加成反应的量子化学研究

我们用CNDO/Ⅱ方法UI对四甲基乙烯,偏甲基乙氧基乙烯,三甲基乙烯和丙烯睛等四个烯烃分子作了量子化学计算,它们的几何参数均采用pople标准数据。     

Palladium(II)‐catalyzed cyclization of W‐(2′,4′‐dienyl)‐2‐alkynamides to α‐alkylidene‐γ‐butyrolactams

In the presence of CuCl₂, N‐(2′, 4′‐dienyl)‐2‐alkynamides can be converted to α‐alkylidene‐σ‐butyrolactams under the catalysis of palladium(II). In this reaction, CuCl₂ is used to oxidize Pd(0) to regenerate Pd(II), or the carbon‐palladium bond is quenched by the oxidative cleavage reaction of CuCl₂.     

K2CO3促进苯并呋喃单元3-位与硫酚构建C-S键

本文在前期工作基础上进一步考察了2-位支链酮苯并呋喃单元在3位与硫酚构建C-S键的反应。研究发现,以K₂CO₃作碱,苯并呋喃单元2-位官能团为不同链长的脂肪酮时能高效地合成各种不同取代基的3-芳硫基苯并呋喃衍生物,所得产物经核磁共振、HRMS等方法进行了表征。该反应具有条件温和、底物适用范围广、操作简单、产率高、环境友好等优点,可为含有芳香烃硫基取代的天然产物及复杂药物分子的合成提供潜在的合成途径。     

Introduction of functionalized C1, C2, and C3 units to imines through the dimethylzinc-air-initiated radical addition

Introduction of functionalized C1, C2, and C3 units to imines was achieved by using the dimethylzinc-air-initiated alpha-alkoxyalkyl radical addition as a key reaction. The addition to a C[double bond]N double bond chemoselectively occurred in the presence of a C[double bond]O double bond, which is one of the advantages of this radical addition reaction over ionic addition reactions.     

Selective synthesis of 3‐Selanylindoles from Indoles and Diselenides using IK/mCPBA system

In the presence of a catalytic amount of KI combined with oxidant m CPBA, a convenient catalytic procedure is developed for the preparation of 3‐selanylindoles from indoles and diselenides. In this protocol, KI is first oxidized by m CPBA into hypoiodous acid, which reacts with diselenide to cleave Se‐Se bond. The in situ generated active electrophilic selenium species then reacts with indole, affording 3‐selanylindole via an electrophilic substitution mechanism. This catalytic selenation of indoles has mild reaction conditions and is a simple procedure, which extends the synthetic application of KI in organic synthesis.