有机磷催化γ-甲基联烯酸酯[3+2]环化反应

在有机磷催化下,γ-甲基联烯酸酯和烯基茚二酮经过[3+2]环加成反应,以中等到较好的产率、高化学选择性和非对映选择性形成一系列官能团化的螺环化合物.该反应具有操作简单、反应条件温和和底物适用性广等优点.需要指出的是,使用简单易得的PPh_3作为催化剂,就能实现完全的α-区域选择性加成的环化产物.     

3-(三氟甲基)吡唑类化合物的合成

探索了三氟甲基溴代腙与炔酮、炔酯和炔酰胺的[3+2]环加成反应,以中等至优异的产率得到了一系列3-(三氟甲基)吡唑类化合物.该方法具有区域选择性高、官能团兼容性强、操作简单和反应条件温和等特点,为合成3-(三氟甲基)吡唑类化合物提供了一种高效的新方法.     

2,2,6,6-四甲基哌啶氧化物催化的高选择性羟基氧化反应

次氯酸钠在2,2,6,6-四甲基哌啶氧化物(TEMPO)的催化下,可在温和的条件下选择性氧化胆酸类化合物的C3位羟基.该方法提供了与常规的氧化剂相反的区域选择性,为胆酸类化合物的结构改造提供了简洁的路线.     

专一选择性反应策略合成2′-O-甲基腺嘌呤核苷

2′-O-烷基核糖核苷由于其在赋予寡核苷酸高度的目标特异性、代谢稳定性以及优良的药代动力学和药效动力学特征上所展现的重要作用,成为了反义药物研究领域的热点,尤其是2′-O-甲基腺嘌呤核苷,作为第二代反义寡核苷酸的关键原料药,其的高效合成研究具有重要意义。现有合成方法存在的成本高和选择性不足等问题,本文基于专一选择性反应思路设计了一条新的合成路线,即以腺嘌呤核苷为起始物,经过缩醛化实现2′-和3′-位羟基选择性地保护、环状缩醛保护基可控区域选择性还原开环、2′-位羟基选择性甲基化及氢化脱苄反应,成功实现了2′-O-甲基腺嘌呤核苷的高效合成,单程总产率为36.7%。此策略不仅每一步反应表现出高选择性以及温和的反应条件,而且使用的试剂更加廉价易得,合成步骤也相对简短,为核苷类化合物核糖骨架上羟基的区域选择性功能化提供了新的思路。     

一种简单、高效合成α-卤代甲基酮化合物的新方法

发展了一种简单、高效、温和的卤代炔烃水合反应体系.在阳离子金催化剂的催化作用下,以二氯乙烷为溶剂,室温下卤代炔烃发生水合反应,高收率、高区域选择性地得到单一的α-卤代甲基酮化合物(收率≥91%).该方法具有底物适用范围广、反应条件温和和环境友好等优点,为含α-卤代甲基酮结构单元的天然产物及复杂药物分子的合成提供了新方法.     

过渡金属催化合成吡咯-2-甲酸酯的研究进展

吡咯-2-甲酸酯广泛存在于生物活性分子中,在医药领域具有十分重要的应用,因此吡咯-2-甲酸酯类化合物的合成研究受到了广泛关注.过渡金属催化的环加成反应在合成吡咯骨架方面应用广泛,具有区域选择性专一的优点.且过渡金属配体导向的C—N键构筑方法具有原子步骤经济性较高、效率高、反应条件温和以及选择性高等优点.按照过渡金属催化...     

电氧化合成2-吡啶甲酸

以2-甲基吡啶为原料,用电化学方法合成了2-吡啶甲酸.研究了反应温度、硫酸浓度、反应物2-甲基吡啶浓度和阳极电位对选择性和电流效率的影响.结果表明,在最佳反应条件下,以电化学方法合成2-吡啶甲酸的选择性高达95.3%,电流效率可达到45.3%.     

银催化2-芳基吲哚与马来酰亚胺C—H键烷基化反应

发展了一种银催化高效高区域选择性的2-芳基吲哚C-3位烷基化反应.在温和条件下,能以高达97%的收率得到目标化合物,且该方法操作简单,不需要外加氧化剂.     

银催化2-芳基吲哚与马来酰亚胺C—H键烷基化反应（英文）

发展了一种银催化高效高区域选择性的2-芳基吲哚C-3位烷基化反应.在温和条件下,能以高达97%的收率得到目标化合物,且该方法操作简单,不需要外加氧化剂.     

2-巯基嘧啶与碳酸Morita-Baylis-Hillman酯的选择性S-烯丙基烷基化

发展了一种1,4-二氮杂二环[2.2.2]辛烷(DABCO)催化2-巯基嘧啶与碳酸Morita-Baylis-Hillman(MBH)酯的S-烯丙基烷基化反应新方法.一系列碳酸MBH酯与2-巯基嘧啶反应并以55%~99%的产率得到S-烯丙基烷基化产物.具有专一的化学选择性和良好的区域选择性,反应条件温和,反应时间短,底物适用广泛,有良好的应用前景.     

Sc2MgGa2 and Y2MgGa2

Scandium magnesium gallide, Sc₂MgGa₂, and yttrium magnesium gallide, Y₂MgGa₂, were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo₂FeB₂‐type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc₂MgGa₂ was determined from single‐crystal diffraction intensities and the isostructural Y₂MgGa₂ was identified from powder diffraction data.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

The alkali hypophosphites KH2PO2, RbH2PO2 and CsH2PO2

The structures of the hypophosphites KH₂PO₂ (potassium hypophosphite), RbH₂PO₂ (rubidium hypophosphite) and CsH₂PO₂ (caesium hypophosphite) have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of alkali cations and hypophosphite anions, with the latter bridging four cations within the same layer. The Rb and Cs hypophosphites are isomorphous.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Formal [(2+2)+2] and [(2+2)+(2+2)] nonconjugated dienediyne cascade cycloadditions

[reaction: see text] Fluoranthene 2 and heptacycle 3 are easily accessible from the reaction of diyne 1 and norbornadiene (NBD) in the presence of the rhodium catalyst. The unusual [(2+2)+(2+2)] adduct 3 was confirmed by the X-ray crystal structure analysis.     

Crystal Structures of [Bu2Sn(O2PPh2)2], [Ph2Sn(O2PPh2)2], and [PhClSn(O2PPh2)OMe]2. Raman Spectra of [Ph2Sn(O2PPh2)2] and [PhClSn(O2PPh2)OMe]2

[(n‐Bu)₂Sn(O₂PPh₂)₂] ( 1 ), and [Ph₂Sn(O₂PPh₂)₂] ( 2 ) have been synthesized by the reactions of R₂SnCl₂ (R=n‐Bu, Ph) with HO₂PPh₂ in Methanol. From the reaction of Ph₂SnCl₂ with diphenylphosphinic acid a third product [PhClSn(O₂PPh₂)OMe]₂ ( 3 ) could be isolated. X‐ray diffraction studies show 1 to crystallize in the monoclinic space group P2₁/c with a = 1303.7(1) pm, b = 2286.9(2) pm, c = 1063.1(1) pm, β = 94.383(6)°, and Z = 4. 2 crystallizes triclinic in the space group , the cell parameters being a = 1293.2(2) pm, b = 1478.5(4) pm, c = 1507.2(3) pm, α = 98.86(3)°, β = 109.63(2)°, γ = 114.88(2)°, and Z = 2. Both compounds form arrays of eight‐membered rings (SnOPO)₂ linked at the tin atoms to form chains of infinite length. The dimer 3 consists of a like ring, in which the tin atoms are bridged by methoxo groups. It crystallizes triclinic in space group with a = 946.4(1) pm, b = 963.7(1) pm, c = 1174.2(1) pm, α = 82.495(6)°, β = 66.451(6)°, γ = 74.922(6)°, and Z = 1 for the dimer. The Raman spectra of 2 and 3 are given and discussed.     

Die Photoionenspektren von SCl2, S2Cl2 und S2Br2

Photoionization Mass Spectra of SCl₂, S₂Cl₂, and S₂Br₂ Photoionization mass spectra of SCl₂, S₂Cl₂, and S₂Br₂ have been measured. Heats of formation, bond energies, and ionization potentials of fragments have been calculated from appearance potentials.