4-亚甲基-1,2-氧-异丙叉-3-甲氧基-α-D-呋喃戊糖的合成和聚合

本文报道了4-亚甲基-1,2-氧-异丙叉-3-甲氧基-α-D-呋喃戊糖的合成和在自由基和阳离子引发剂存在下的聚合反应.通过研究聚合物的结构,提出了聚合反应机理.比较了该单体在阳离子和自由基聚合反应中的聚合活性,聚合物的结构和聚合机理上的差别.     

寡糖的立体选择性合成策略

研究寡糖及缀合物的生物活性日益显现出重要的生物学意义, 采用化学合成方法研究特定的或糖苷键的构建对复杂寡糖及缀合物的合成极其重要. 到目前为止, 寡糖及其缀合物化学偶联立体选择性设计与合成策略是糖化学领域中十分活跃和引人注目的热点, 受到特别的关注. 综述了多年来高立体选择性寡糖的合成的研究进展.     

Cu-催化炔丙醇酯与β-酮酸酯的不对称[3+2]环加成反应合成手性2,3-二氢呋喃化合物

正手性2,3-二氢呋喃骨架广泛存在于天然产物和药物中,因此不对称构建这些手性骨架具有十分重要的意义.但利用不对称催化的方法来合成手性2,3-二氢呋喃类化合物仍然是一项极具挑战性的工作,特别是手性2-亚甲基-2,3-二氢呋喃类化合物的不对称合成,目前尚未有文献报道.中国科学院大连化学物理研究所胡向平课题组通过发展新     

多取代呋喃合成最新研究进展

呋喃是一类重要的五元含氧杂环化合物,其不仅是许多天然产物、药物和生物活性分子的核心结构,而且还是重要的有机合成中间体,具有广泛的应用价值.因此,呋喃及其衍生物的合成一直是有机化学家关注的研究热点之一.对2013年以来多取代呋喃的合成新方法进行了综述,包括二取代、三取代、四取代呋喃和苯并呋喃等.     

基于可再生资源含呋喃环聚酯

2,5-呋喃二甲酸（2,5-FDCA）是基于可再生资源的二酸,来源广泛,可由果糖和半乳糖制得。近年来以2,5-呋喃二甲酸为起始原料合成聚合物的研究引起了人们的广泛关注。本文对基于可再生资源含呋喃环均聚酯及共聚酯的合成、结构和性能等方面的研究作了综述,着重阐述了以2,5-呋喃二甲酸及其衍生物为起始原料制备聚酯的新进展,并讨论了基于可再生资源含呋喃聚酯的应用及发展前景。     

寡糖合成中的“预活化”策略

寡糖及其缀合物因其重要的生物学功能而日益受到人们的关注,由于糖链结构的复杂性与多样性,寡糖的化学合成具有很大的挑战性。为了减少合成及分离步骤,提高寡糖合成的效率,糖基化策略十分重要。"一釜合成法"由于进行多个连续的糖基化反应但不需分离中间体而具有很大优势,但传统"一釜法"在设计单糖模块时需要进行精细复杂的保护基操作和离去基调整而影响其合成效率。"预活化"寡糖合成策略不依赖于糖基供体与糖基受体的活性差异,无需复杂的保护基操作,所有偶联反应在同一条件下一釜完成,实现了寡糖的高效、快速合成。本文在简要介绍传统"一釜合成法"的基础上,对"预活化"策略的研究进展进行综述,重点介绍"预活化"策略的基本原理,发展过程及其在生物活性寡糖合成上的应用。     

基于末端炔烃一锅法合成取代噻吩和呋喃化合物

噻吩和呋喃衍生物是许多天然产物、药物和发光材料的核心骨架,因此发展一种从简单易得的原料高效合成呋喃和噻吩衍生物的方法具有非常重要的应用价值.该研究实现了一锅法高产率合成2,5-二取代呋喃、2,5-二取代噻吩、苯并呋喃和苯并噻吩化合物.首先通过铜催化末端炔烃Glaser偶联反应合成1,4-二取代丁二炔化合物,接着硫化钠(氢氧化钾)参与水解和环化反应得到2,5-二取代噻吩和呋喃化合物.该合成策略同样适用于合成苯并呋喃和苯并噻吩化合物,通过末端炔与邻氟碘苯的Sonogashira偶联反应,然后硫化钠(或氢氧化钾)参与碳氟键的水解和环化反应得到相应的苯并噻吩和苯并呋喃化合物.该合成方法具有反应条件温和、操作简便和高产率等优点,可为该类呋喃和噻吩的合成提供简便的途径.     

糖苷和寡糖的立体选择性合成研究进展

精苷、寡糖的立体选择性合成是一个十分重要的课题. 本文结合作者的研究工作介绍了糖苷、寡糖的立体选择合成的方法学进展,主要涉及近年来合成寡糖的新方法,并对这些方法的优势及不足进行了评述.     

用不保护或少保护的糖基受体合成寡糖*

用不保护或少保护的葡萄糖、甘露糖、鼠李糖作为糖基受体,经由糖原酸酯的中间体,能高区选和立体选地合成寡糖. α-(1→6)-连接的甘露寡糖、β-(1→6)-连接的葡萄寡糖、3,6-支化的甘露寡糖及葡萄寡糖用此方法能用很简单步骤合成,如具有重要生物活性的寡糖植保素激活剂葡萄六糖、具有抗肿瘤活性的香菇多糖的活性片段,以及一些具有重要生理功能的多糖的重复单元等.本文同时简述了用少保护的半乳糖和氨基葡萄糖为糖基受体合成寡糖的进展.     

含有2'-O-甲基伪胞苷的寡核苷酸合成用于DNA三链的合成

三绞脱氧核糖核酸生成的可能性已知对双绞DNA的结构和功能有直接的影响,为增长三重态DNA生成的稳定性。我们设计并合成了2-氨基-5-(2-O-甲基-β-D-呋喃核糖基)-4(1H)-嘧啶酮或2'-O-甲基拟异胞嘧啶并取代第三股上的原来的碳。     

Furyl- and thienyl-silatranes and germatranes

We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992.     

Review and patents and literature

The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed.     

Ground- and excited-state aromaticity and antiaromaticity in benzene and cyclobutadiene

The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei.     

Hard and soft acids and bases: structure and process

Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

Syntheses and structures of P-anilino-P-chalcogeno- and P-anilino-P-iminodiazasilaphosphetidines and their group 12 and 13 metal compounds

The P-anilino-P-chalcogeno(imino)diazasilaphosphetidines [Me(2)Si(mu-N(t)Bu)(2)P=E(NHPh)] (E = O (3), S (4), Se (5), N-p-tolyl (6)) were synthesized by oxidizing the P-anilinodiazasilaphosphetidine [Me(2)Si(N(t)Bu)(2)P(NHPh)] (2) with cumene hydroperoxide, sulfur, selenium, and p-tolyl azide, respectively. The lithium salt of 4 reacted with thallium monochloride to produce ([Me(2)Si(mu-N(t)Bu)(2)P=S(NPh)-kappaN-kappaS]Tl)(7), which features a two-coordinate thallium atom. Treatment of 4-6 with AlMe(3) gave the monoligand dimethylaluminum complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE]AlMe(2)) (E = S (8), Se (9), N-p-tolyl (10)), respectively. In these complexes the aluminum atom is tetrahedrally coordinated by one chelating ligand and two methyl groups, as a single-crystal X-ray analysis of 8 showed. A 2 equiv amount of 4-6 reacted with diethylzinc to produce the homoleptic diligand complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE](2)Zn)(E = S (11), Se (12), N-p-tolyl (13)). A crystal-structure analysis of 11 revealed a linear tetraspirocycle with a tetrahedrally coordinated, central zinc atom.