Palladium-catalyzed one-pot synthesis of polysubstituted furans from alkynoates and 2-yn-1-ols

Easily accessible propargyl vinyl ethers are found to be acyclic precursors to construct furan derivatives. According to the reactive behavior of the substrates and the regulation of reaction conditions, three synthetic routes to polysubstituted furans via palladium-catalyzed reactions of propargyl vinyl ethers in situ-prepared from alkynoates and 2-yn-1-ols are presented herein. These methods could have potential application in synthetic and pharmaceutical chemistry for its facilitation and accessible starting materials.     

Seed-mediated growth approach to shape-controlled synthesis of Cu2O particles

With glucose as reducing agent, Cu2O particles with different size and morphology were synthesized selectively by a seed-mediated growth approach. The major advantage of this process is that Cu(II) cannot be reduced to Cu metal. The size of the Cu2O particles can be controlled by changing the Cu(II) concentration in colloid solution. Square-shaped Cu2O particles (20-700 nm in diameter) were obtained in the presence of PEG 400, and polygonal-shaped Cu2O particles (approximately 1000 nm) were observed upon using triblock copolymer as modifier, while sphere-shaped Cu2O particles with a diameter of 400-700 nm were obtained in the absence of a modifier.     

Photocycloaddition of acetylacetonatoboron derivatives with simple olefins

Acetylacetonatoboron difluoride (AABF₂) and oxalate (AABO) undergo cycloaddition from their singlet excited state with cyclic and terminal olefins to give stereospecific but non-regiospecific products; the latter oxalate reacted slightly faster than the former difluoride. A conjugated diene, 1,3-cyclooctadiene, and methyl substituted benzenes also reacted similarly but with slower rates owing to electron transfer at the encounter stage. The resulting radical ion pairs may undergo radical ion type reactions and/or reverse electron transfer, which leads to the partial waste of the photoenergy. For the same reasons, the reaction occurs more efficiently in non-polar solvents, such as ether, dioxane and methylene chloride than in acetonitrile.     

常温常压下光促进烯烃与一氧化碳的羰基化反应

 报道了烯烃（环己烯和1－辛烯）与一氧化碳通过光促进实现常温常压非贵金属（钴配合物）催化的羰基化反应．研究发现，以Co（OAc）2为催化剂时，不需要加入光敏剂丙酮就能发生反应；CoSalen，吡啶－2－羧酸钴和大环配合物［Co（14）4，11－diene－N4］I2是较好的催化剂，其催化活性比Co（OAc）2高．其中，吡啶－2－羧酸钴与Co（OAc）2相同，反应中不需要光敏剂存在，其选择性很高．通过氘代丙酮和氘代甲醇同位素实验，进一步证实了反应中双键异构的存在和副产物的分析结果．     

离子交换树脂催化合成丙烯酸—β—羟乙酯的动力学研究

对732~#强酸型离子交换树脂催化合成丙烯酸-β-羟乙酯进行了动力学研究。测定并推算出反应级数、反应速率常数及活化能,提出了反应机理。     

Hydrothermal-induced assembly of colloidal silver spheres into various nanoparticles on the basis of HTAB-modified silver mirror reaction

Small colloidal silver spheres (diameter < 10 nm) were found to assemble into various silver nanoparticles including cubes, triangles, wires, and rods in water in the presence of HTAB (n-hexadecyltrimethylammonium bromide) at 120 degrees C, while the colloids were generated in situ on the basis of a HTAB-modified silver mirror reaction during the synthesis process. Adjustment of the synthesis parameters, in particular the concentrations of HTAB and [Ag(NH3)2]+, led to an obvious shape evolution of silver nanoparticles, thus resulting in the shape-selective formation of the silver nanoparticles. The monodisperse nanocubes with a well-defined crystallographical structure (a single crystal bounded by six {200} facets) have a strong tendency to assemble into two-dimensional arrays on substrates. The nanowires with uniform diameter usually existed in the form of two-dimensional alignments. The findings suggested that hydrothermal-induced assembly of small silver colloidal particles should be a convenient and effective approach to the preparation of various silver nanoparticles.     

Design and synthesis of palladium (II) OCO pincer type complexes and their catalytic role towards the α-arylation of ketones

Twelve OCO bisacetamide ligands 4aa-4dc were synthesized after condensation of isophenylenediamines 1a-1d and anhydride/acyl chlorides. The corresponding Pd(II)–OCO–H(5aa-5ac), Pd(II)–OCO–Me(5ba-5bc), Pd(II)–OCO–OMe(5ca-5?cc), Pd(II)–OCO–NO₂(5da-5dc) pincer complexes were prepared via C-H activation of precursors and Pd(OAc)₂, and characterized by IR, ¹H NMR, ¹³C NMR and elemental analysis. The α-arylation of ketones and aryl bromides catalyzed by 5 under low catalyst loadings (0.1?mol%) show that 5da exhibits the highest catalytic activity, resulting in a 98% isolated yield.     

光促进下环己烯与二氧化碳羰基化反应中副产物的气相色谱-质谱分析

应用气相色谱-质谱法（GC-MS）研究了光促进温和条件下环己烯与CO2羰基化反应中与丙酮有关的副产物,这有助于对反应进行深入的研究和优化。在光促进温和条件下环己烯与CO2进行羰基化反应的同时,环己烯也可以与反应体系中的CH3COCH3发生光化学反应,生成副产物。分别用CH3COCH3和CD3COCD3进行实验,对反应产物进行GC-MS分析,通过对不同反应情况下的MS图中同位素效应的比较,可以分析出副产物中是否有来自CH3COCH3中的—CH3。研究表明丙酮与底物环己烯之间生成了环氧丁烷衍生物、cyclo-C6H9-C(CH3)2OH和cyclo-C6H11-C(CH3)2OH等3种副产物。     

Four classes of linear codes from cyclotomic cosets

This paper presents four classes of linear codes from coset representatives of subgroups and cyclotomic coset families of certain finite field, and determines their weight enumerators. These linear codes may have applications in consumer electronics, communications and secret sharing schemes.     

A Low-Emittance Lattice for the ESRF

In the framework of its upgrade, the ESRF is designing a new lattice to replace the present double-bend achromat structure. This new lattice fulfills the following constraints and requirements:

• It fits in the present tunnel and keeps the insertion device source points at the same location;

• Its target horizontal emittance is around 150 pm;

• It keeps the electron energy at 6 GeV in order to preserve the spectral properties of the present beamlines;

• It minimizes the radiation losses and the magnet electrical consumption in order to decrease operating costs;

• The present injector complex is re-used with minor changes.