二氧化碳与1,3-二烯的不对称催化偶联构建全碳季碳手性中心

二氧化碳(CO2)是自然界中储量丰富且可再生的碳一资源,将其转化为高附加值化学品具有重要的理论研究意义和应用价值.采用金属催化CO2的高效转化近年来受到广泛关注,并取得了显著的研究进展[1].比如,丁奎岭等[2]实现了钌催化CO2的高效催化氢化转化为N,N-二甲基甲酰胺(DMF),获得了非常高的催化活性和效率.     

乙酰丙酸催化加氢制备γ-戊内酯的研究进展

正植物通过光合作用将CO2和水转化为生物质,利用生物质我们可以得到能源原料、化工中间体等有用的产品.从生物质获得可再生能源与资源方面研究得较多的是纤维素和木质素的转化[1-5].纤维素由D-葡萄糖单体通过β-糖苷键连接而形成,水解打开β-糖苷键可以得到寡聚葡萄糖和葡萄糖单体,寡聚葡萄糖可以进一步水解为葡萄糖单体.葡萄糖单体能作为合成众多能源、化工成品的前体,例如5-羟甲基糠醛(5-HMF)[6],乙二醇[7-9],丙     

关于[Co(NH3)5NO2]Cl2键合异构体相互转化的研究

[Co(NH_3)_5NO_2]Cl_2是最早发现和首先分离得到的第一个键合异构体。长期被认为只有氧配位的[Co(NH_3)_5ONO]Cl_2异构体会向氮配位的[Co(NH_3)_5NO_2]Cl_2异构体转化。本文认为氮配位的异构体也会向氧配位的异构体转化,并测定和报导了这种转化的速率常数。     

抗积炭CH_4/CO_2重整用Ni/Al_2O_3催化剂

甲烷转化制备的合成气是合成液体燃料和含氧有机化合物的原料 .甲烷转化制合成气的方法有甲烷蒸汽重整、甲烷部分氧化和甲烷、二氧化碳重整 3种 [1～ 3] .对于 CH4/CO2 重整反应 ,调节进料比可制备出 H2 /CO≤ 1、富含 CO的合成气 ,它适于羰基合成和 F- T合成 .这种方法一方面充分利用碳资源 ,缓解能源危机 ;一方面可减少温室气体的排放 ,改善人类的居住环境 .目前倍受关注 .CH4/CO2 重整制合成气 ,Rh、Ru、Pd、Ir等贵金属有很高的活性和稳定性 [4] .但其价格昂贵 ,高温易流失 ,商业化困难 .Ni基催化剂的活性与贵金属相当 ,但它易积…     

超声波下 2",3"-二溴化三尖杉宁碱的高效还原研究

2",3"-二溴化三尖杉宁碱(DIBROCs)是紫杉醇纯化过程中溴与三尖杉宁碱加成反应产生的副产物[1],其结构如下: DIBROCs具有与紫杉醇相当的抗肿瘤活性[2],但这两种手性异构体的分离非常困难[3],且毒性比紫杉醇大,缺乏应用价值.三尖杉宁碱对人体鼻咽癌(KB)有细胞毒活性,配合地塞米松对粒细胞性白血病的疗效较好[4],已作为白血病治疗的临床制剂.因此将DIBROCs还原成三尖杉宁碱后加以利用具有特别重要的意义.Kingston等[5]用锌粉将DIBROCs还原成三尖杉宁碱,然而该方法无法实现反应物的完全转化,反应时间过长,容易引起反应物分解,造成资源的浪费.本文利用超声波作用,以金属粉末还原DIBROCs,使反应物在较短的时间内充分转化为三尖杉宁碱.同时对超声辐射作用下影响DI-BROCs还原的因素进行了探讨.     

自然光照下PEG/PAA 凝胶在Fe3+/CA溶液中的 凝胶-溶胶转化行为的研究

本文将PEG/PAA凝胶浸入铁/柠檬酸（Fe3+/CA）溶液中,在自然光照一定的时间可实现凝胶-溶胶的相互转化,而且转化行为受溶液的组成及其pH值的影响。只有当溶液中[Fe3 ]0: [CA]0≤1:2,且溶液的pH在1-6之间,该转化才会发生,通过改变溶液中[Fe3 ]0: [CA]0的值或溶液的pH可以有效地控制其转化速率。此外,实验结果表明,当凝胶转化为溶胶后,在其中加入高价金属阳离子,例如Fe3 、 Al3 、Ce4 、Cu2 等,溶胶又会再次转化为凝胶。由于这种新颖的特性,该凝胶有望应用于药物释放、细胞培养等领域。     

非活化的非共轭二烯与CO2的电还原双羧化反应合成环状二元羧酸

<正>CO₂是一种温室气体,也是一种储量丰富、无毒、廉价、可再生的理想C1资源,然而CO₂具有较高的热力学稳定性和动力学稳定性.因此将CO₂通过化学手段转化为具有高附加值的精细化学品,是近年来研究的热点^[1].二元羧酸及其衍生物在材料科学和生物医学领域有着诸多应用^[2],通过亲核试剂与CO₂发生羧化反应可以高效合成二酸^[3].     

自然光照下PEG/PAA凝胶在Fe~(3+)/CA溶液中的凝胶-溶胶转化行为

将PEG/PAA凝胶浸入铁/柠檬酸(Fe3+/CA)溶液中,自然光照一定时间可实现凝胶-溶胶的相互转化,而且转化行为受溶液的组成及其p H影响。只有当溶液中[Fe3+]0∶[CA]0≤1∶2,且溶液的p H在1~6之间,该转化才会发生,通过改变溶液中[Fe3+]0∶[CA]0的值或溶液的p H可以有效地控制其转化速率。此外,结果还表明,当凝胶转化为溶胶后,向其中加入高价金属阳离子,例如Fe3+、Al3+、Ce4+、Cu2+等,溶胶又会再次转化为凝胶。由于这种新颖的特性,该凝胶有望应用于药物释放、细胞培养等领域。     

纤维素在离子液体中的降解转化

随着社会对能源资源的需求越来越大,生物质资源得到了广泛的重视,世界上存储量最大的生物质资源--纤维素在新兴溶剂离子液体中的降解转化受到了越来越多的关注。本文简要介绍了近几年来纤维素在离子液体中的溶解、单糖(果糖、葡萄糖)在离子液体中脱水转化为5-HMF(5-羟甲基糠醛)和纤维素在离子液体中一步降解转化为5-HMF的研究。指出目前研究存在的缺点与不足,并提出了可能的解决方法。     

天然气化学转化新途径

21世纪初将迎来天然气能源时代,作为石油的替代资源,由天然气间接转化(经由合成气)和直接转化为液体燃料或重要化工品原料已成为人们关注的热点。本文简要介绍了80年代以来世界各国和我国有关天然气转化的各种新过程。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.