Pd-N-杂环卡宾化合物催化的Heck反应、Suzuki反应进展

Pd催化的C—C键偶联反应是形成碳—碳单键的重要反应之一.传统上,使用膦化合物为配体来调整催化活性及选择性.但大多数Pd-膦化合物对空气稳定性差,容易被氧化;在溶液中易于解离出膦配体而降低催化剂稳定性,通常需要给反应体系中加入较多的膦配体以保持催化剂的稳定性和活性.1991年发现的稳定N-杂环卡宾(NHC)类配体具有富含电子、给电子能力强,对金属配位能力强,结构易修饰等特点,使得金属-NHC化合物成为金属有机化学、催化等领域研究新的焦点.Pd-NHC化合物已经可催化多类有机反应,是继传统Pd-膦催化剂外的又一类高效催化剂.综述了近年来不同结构的NHC如单齿简单NHC、双齿NHC、含其它配位原子的NHC等配体与Pd的配合物在Heck反应、Suzuki反应等偶联反应中的应用.     

有机催化不对称Henry加成反应

有机催化不对称合成反应是目前国内外研究最为活跃的领域之一.不对称Henry反应是合成光学活性硝基化合物的有效手段,目前报道的催化不对称Henry反应的有机催化剂主要有手性胍、手性(硫)脲衍生物、金鸡纳碱衍生物等,取得了良好的催化活性和对映选择性.对各类有机催化剂在有机催化不对称Henry反应中的应用研究进展,以及不对称诱导反应的机理、催化剂的分子结构及反应条件对其催化活性和不对称诱导活性的影响进行了评述.     

廉价过渡金属催化烯烃异构反应研究进展

过渡金属催化的烯烃异构反应在有机化合物合成、日用化学品合成、原料油应用和天然产物合成中都有着举足轻重的作用。廉价过渡金属由于其在资源、价格、后处理等方面的优势,日益受到研究者的重视。本文主要综述了近几十年来廉价过渡金属铁、钴、镍在催化烯烃异构反应方面的研究进展,详细阐述了不同的催化体系在催化活性、反应选择性、底物适用性及反应机理方面的特点。虽然目前的催化体系已经表现出优异的性能与应用价值,但在烯烃异构的立体选择性、区域选择性机制等方面,仍然需要更深入的研究。     

PPh3衍生准多孔有机笼在Rh/PPh3体系催化氢甲酰化反应中的应用:增强活性和选择性及可回收利用

多孔有机笼(POCs)由英国利物浦大学的Cooper教授在2009年首次合成,这种多孔小分子材料的出现具有两方面重要意义:(1)开拓了多孔材料领域的一个全新分支,改变了人们对多孔材料的传统认知;(2)由于POCs材料由离散的小分子堆积而成,可溶解于一些常用的有机溶剂中,因此其在材料制备方面具有很好的"溶液成型"性能,该优势是三维延伸网状多孔材料所不具备的.POCs本质上是一种"中心带孔"的有机小分子,由刚性有机分子砌块收敛堆叠而成,其特殊结构在气体吸附与分离等方面表现出很好的应用前景.不同于传统空间延伸网状框架材料(如金属-有机框架材料和共价有机框架材料)及多孔有机聚合物(POPs)材料,POCs是一种在大多数有机溶剂中可溶解的小分子材料,因此在均相催化领域也有很好的应用前景.作为最为经典的有机配体,三苯基膦(PPh3)在金属有机化学和均相催化领域应用十分广泛,如目前均相催化工业应用最成功的典范之一氢甲酰化反应,大多数情况下使用的是PPh3与Rh形成的络合物催化剂.本文首先将PPh3进行醛基官能团化,通过醛基和氨基的收敛缩合形成POCs材料,合成了基于PPh3配体的准多孔有机笼(POC-DICP),利用得到的多孔有机笼制备出类Rh/PPh3均相催化体系的Rh/POC-DICP络合催化体系,并将其应用于氢甲酰化反应.相比于经典的Rh/PPh3均相催化体系,该Rh/POC-DICP催化体系在氢甲酰化反应中不仅展示出了更高的活性和目标产物醛的选择性(醛的化学选择性为97％,醛的正异构比为1.89),而且可以很方便地从均相反应体系中沉淀回收(通过调整溶剂体系极性).在氢甲酰化反应中,Rh/POC-DICP体系显示出了良好的底物适用性,在己烯、庚烯、辛烯和苯乙烯的氢甲酰化反应中均表现出良好的催化活性和醛选择性,同时催化剂回收使用4次,未见催化性能明显下降.X射线单晶衍射、同步辐射及DFT计算等结果表明,Rh/POC-DICP催化体系在氢甲酰化反应中具有较高活性和选择性的原因是POC-DICP多孔有机笼分子的有利的空间咬合角(123.88o)和P原子上相对的缺电子效应.本文设计合成的PPh3衍生的多孔有机笼不仅拓宽了多孔有机笼材料在催化领域的应用,而且为新型配体及络合催化剂的设计、合成及修饰提供了新的思路.     

PPh3衍生准多孔有机笼在Rh/PPh3体系催化氢甲酰化反应中的应用:增强活性和选择性及可回收利用

多孔有机笼(POCs)由英国利物浦大学的Cooper教授在2009年首次合成,这种多孔小分子材料的出现具有两方面重要意义:(1)开拓了多孔材料领域的一个全新分支,改变了人们对多孔材料的传统认知;(2)由于POCs材料由离散的小分子堆积而成,可溶解于一些常用的有机溶剂中,因此其在材料制备方面具有很好的"溶液成型"性能,该优势是三维延伸网状多孔材料所不具备的.POCs本质上是一种"中心带孔"的有机小分子,由刚性有机分子砌块收敛堆叠而成,其特殊结构在气体吸附与分离等方面表现出很好的应用前景.不同于传统空间延伸网状框架材料(如金属-有机框架材料和共价有机框架材料)及多孔有机聚合物(POPs)材料,POCs是一种在大多数有机溶剂中可溶解的小分子材料,因此在均相催化领域也有很好的应用前景.作为最为经典的有机配体,三苯基膦(PPh3)在金属有机化学和均相催化领域应用十分广泛,如目前均相催化工业应用最成功的典范之一氢甲酰化反应,大多数情况下使用的是PPh3与Rh形成的络合物催化剂.本文首先将PPh3进行醛基官能团化,通过醛基和氨基的收敛缩合形成POCs材料,合成了基于PPh3配体的准多孔有机笼(POC-DICP),利用得到的多孔有机笼制备出类Rh/PPh3均相催化体系的Rh/POC-DICP络合催化体系,并将其应用于氢甲酰化反应.相比于经典的Rh/PPh3均相催化体系,该Rh/POC-DICP催化体系在氢甲酰化反应中不仅展示出了更高的活性和目标产物醛的选择性(醛的化学选择性为97％,醛的正异构比为1.89),而且可以很方便地从均相反应体系中沉淀回收(通过调整溶剂体系极性).在氢甲酰化反应中,Rh/POC-DICP体系显示出了良好的底物适用性,在己烯、庚烯、辛烯和苯乙烯的氢甲酰化反应中均表现出良好的催化活性和醛选择性,同时催化剂回收使用4次,未见催化性能明显下降.X射线单晶衍射、同步辐射及DFT计算等结果表明,Rh/POC-DICP催化体系在氢甲酰化反应中具有较高活性和选择性的原因是POC-DICP多孔有机笼分子的有利的空间咬合角(123.88o)和P原子上相对的缺电子效应.本文设计合成的PPh3衍生的多孔有机笼不仅拓宽了多孔有机笼材料在催化领域的应用,而且为新型配体及络合催化剂的设计、合成及修饰提供了新的思路.     

铜-手性氮杂环卡宾化合物催化的不对称1,4-共轭加成反应

近年来,利用金属-手性氮杂环卡宾(NHC)化合物进行不对称催化反应已取得了快速发展.相关报道越来越多,一些反应已获得良好的对映异构体选择性,这显示出金属-NHC化合物在催化合成手性化合物中的潜在用途.按NHC为单齿、双齿配体总结了金属-手性NHC化合物对"α,β-不饱和酮的共轭加成反应的不对称催化,以期对发现高立体选择性金属-NHC催化剂提供一些启发.     

碘作为Lewis酸催化剂在合成中的应用进展

碘催化的有机反应具有价廉易得、操作简单、温和、清洁、高效及高选择性等优点,广泛应用于亲电反应、亲核反应、多组份反应以及其它涉及复杂官能团化合物的合成反应中,在环境友好化学合成、复杂化合物合成及选择性合成领域具有应用价值.     

碘作为Lewis酸催化剂在合成中的应用

碘催化的有机反应具有价廉易得、操作简单、温和、清洁、高效及高选择性等优点, 广泛应用于亲电反应、亲核反应、多组份反应以及其它涉及复杂官能团化合物的合成反应中, 在环境友好化学合成、复杂化合物合成及选择性合成领域具有应用价值.     

手性(硫)脲衍生物在不对称有机催化反应中的应用

手性(硫)脲衍生物是各种亲核试剂对亚胺、醛、缺电子烯烃加成反应的非常有效的有机催化剂之一, 已成功应用于对映选择性催化Strecker反应、Michael加成反应、Mannich反应、Baylis-Hillman反应、Henry反应等一系列重要的有机合成反应. 手性(硫)脲衍生物具有催化活性高、对映选择性和功能基相容性好、易于制备和修饰、适用范围广等优点, 成为近年来研究较多的不对称反应有机催化剂. 对手性(硫)脲衍生物在有机催化不对称合成中的应用研究进展进行了评述.     

有机小分子催化的不对称Strecker反应研究进展

有机小分子催化的不对称合成反应是目前研究最为活跃的领域之一. 不对称Strecker反应是合成光学活性α-氨基酸衍生物的有效手段. 目前报道的催化不对称Strecker反应的有机催化剂主要有手性胍类、手性(硫)脲衍生物、氮-氧偶极化合物、手性Brønsted酸等, 取得了良好的催化活性和对映选择性. 对各类有机小分子催化剂在有机催化不对称Strecker反应中的应用研究进展, 以及催化剂结构与反应条件对催化活性和不对称诱导作用的影响进行了简要评述.     

Nickel and palladium <Emphasis Type="Italic">N</Emphasis>-heterocyclic carbene complexes. Synthesis and application in cross-coupling reactions

N-Heterocyclic carbenes (NHCs) are widely used as ligands in catalysis by transition metal complexes. The catalytic activity of transition metal NHC complexes is much higher than that of the transition metal complexes bearing the phosphine and nitrogen-containing ligands. They show excellent catalytic performance in different transformations of the organic compounds, especially in the carbon—carbon and carbon—element bond forming reactions. Palladium NHC complexes are very efficient catalysts for the cross-coupling reactions. On the other hand, nickel is less expensive and regarded as a promising alternative to palladium and, therefore, it attracts increasing attention from the researches. The present review is focused on the recent advances in the synthesis of N-heterocyclic carbene complexes of nickel and palladium and their application in catalysis of cross-coupling reactions of organic, organoelement and organometallic compounds with organic halides.     

离子液体功能化金属/共价-有机框架材料在催化反应中应用

离子液体（ILs）功能化的金属有机框架（MOFs）和共价有机框架（COFs）材料兼具离子液体和MOFs/COFs的优点，是一种极具潜力的复合催化材料。MOFs和COFs材料固定的孔结构及较大的比表面积为负载高分散催化中心提供了天然的物理空间；多孔结构促使催化剂与反应物充分接触；丰富的孔道有利于运输催化反应底物和产物，进而实现催化反应的高效进行。特别是离子液体片段的引入，可以作为催化活性中心的配体（稳定剂）或分散剂，同时能够有效改善MOFs和COFs材料孔道和活性中心周围的微环境。此外，还可以充分利用离子液体片段在适当的反应条件下转化为氮杂环卡宾配体的特点，在MOFs和COFs材料中引入氮杂环卡宾有机金属配合物。因此，我们对近几年来离子液体功能化的MOFs或COFs催化体系在CO2环加成、CO2还原、C-C偶联、羰基化以及其它有机转化反应中的研究应用进行简要综述。并对复合材料在催化领域的发展进行总结和展望。     

Gold and Carbene Relay Catalytic Enantioselective Cycloisomerization/Cyclization Reactions of Ynamides and Enals

The combined use of gold as transition metal catalyst and N‐heterocyclic carbene (NHC) as organic catalyst in the same solution for relay catalytic reactions was disclosed. The ynamide substrate was activated by gold catalyst to form unsaturated ketimine intermediate that subsequently reacted with the enals (via azolium enolate intermediate generated with NHC) effectively to form bicyclic lactam products with excellent diastereo‐ and enantio‐selectivities. The gold and NHC coordination and dissociation can be dynamic and tunable events, and thus allow the co‐existence of both active metal and carbene organic catalysts in appreciable concentrations, for the dual catalytic reaction to proceed.     

N‐Heterocyclic Carbene Mediated Activation of Tetravalent Silicon Compounds: A Critical Evaluation

An overview of the recent bibliography concerning the N‐heterocyclic carbene (NHC)‐mediated activation of tetravalent silicon compounds is presented. Diverse reactions are discussed, such as the NHC‐mediated addition of silyl pronucleophiles to a variety of electrophiles, NHC‐promoted organic and inorganic polymerisation and the reduction of CO₂ by hydrosilanes as facilitated by NHCs. The review concludes with a discussion of the current knowledge regarding the role of Lewis acid–base NHC–Si interactions in the mechanistic course of these reactions.     

The first N-heterocyclic carbene-based nickel catalyst for C-S coupling

We have developed the first N-heterocyclic carbene (NHC)-based transition metal catalysts for C-S coupling reactions. Ni-NHC catalysts showed good to excellent activities toward various aryl halides in C-S coupling reactions. The catalytic activities were greatly affected by the electronic and steric properties of the NHC ligands. The new catalysts were inexpensive, easy to synthesize, and environmentally friendly. They could be excellent candidates to replace Pd-organophosphanes for C-S coupling catalysis.     

Transamidation of Amides and Amidation of Esters by Selective N–C(O)/O–C(O) Cleavage Mediated by Air- and Moisture-Stable Half-Sandwich Nickel(II)–NHC Complexes

The formation of amide bonds represents one of the most fundamental processes in organic synthesis. Transition-metal-catalyzed activation of acyclic twisted amides has emerged as an increasingly powerful platform in synthesis. Herein, we report the transamidation of N-activated twisted amides by selective N–C(O) cleavage mediated by air- and moisture-stable half-sandwich Ni(II)–NHC (NHC = N-heterocyclic carbenes) complexes. We demonstrate that the readily available cyclopentadienyl complex, [CpNi(IPr)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), promotes highly selective transamidation of the N–C(O) bond in twisted N-Boc amides with non-nucleophilic anilines. The reaction provides access to secondary anilides via the non-conventional amide bond-forming pathway. Furthermore, the amidation of activated phenolic and unactivated methyl esters mediated by [CpNi(IPr)Cl] is reported. This study sets the stage for the broad utilization of well-defined, air- and moisture-stable Ni(II)–NHC complexes in catalytic amide bond-forming protocols by unconventional C(acyl)–N and C(acyl)–O bond cleavage reactions.     

Force field parametrization and molecular dynamics simulation of flexible POSS-linked (NHC; phosphine) Ru catalytic complexes

In recent years, N-heterocyclic carbene (NHC) or phospine groups have been put forward as candidate catalysts ligands for olefin metathesis reactions to be performed using multistep methods. Some of these proposed ligands contain polyhedral oligomeric silsesquioxane (POSS) structures linked to NHC rings by means of alkyl chains. Some important properties for the prediction of catalytic activity, such as the theoretically defined buried volume, are related to the conformational characteristics of these complex ligands that can be studied through molecular dynamics simulations. However, the chemical structure of resulting catalytic complexes usually contains atoms or groups that are not included in the common forcefields used in simulations. In this work we focus on complexes formed by a catalytic metal center (Ru) with both phospine and POSS-linked NHC groups. The central part of the complexes contain atoms and groups that have bonds, bond angles, and torsional angles whose parameters have not been previously evaluated and included in existing force fields. We have performed basic ab initio quantum mechanical calculations based on the density functional theory to obtain energies for this central section. The force field parameters for bonds, bond angles, and torsional angles are then calculated from an analysis of energies calculated for the equilibrium and different locally deformed structures. Nonbonded interactions are also conveniently evaluated. From subsequent molecular dynamics simulations, we have obtained results that illustrate the conformational characteristics most closely connected with the catalytic activity.     

Synthesis and catalytic activity of pyrazolyl-functionalized N-heterocyclic carbene palladium complexes

Three pyrazolyl-functionalized N-heterocyclic carbene (NHC) palladium complexes based on 1-[2-(pyrazol-1-yl)phenyl]imidazole have been synthesized and characterized by physico-chemical and spectroscopic methods, and the structures of two of the complexes have been confirmed by single-crystal X-ray diffraction. The pyrazolyl-functionalized NHCs act as chelating N,C-bidentate ligands in these three complexes. Catalytic tests have proved that these complexes exhibit highly effective catalytic activity for the Suzuki–Miyaura and Mizoroki–Heck coupling reactions in water or aqueous/organic media under air. The substituents on the pyrazolyl ring exert different influences on the catalytic activity of the complexes in these coupling reactions.     

Pyrazole-3-carboxylates assisted N-heterocyclic carbene palladium complexes: synthesis,characterization, and catalytic activities towards arylation of azoles with arylsulfonyl hydrazides

Four mononuclear and dinuclear pyrazole-3-carboxylates assisted NHC–Pd complexes have been synthesized and characterized. Notably, the bridge-cleavage reactions of [Pd(μ-Cl)(Cl)(NHC)]₂ with 1H-pyrazole-3-carboxylic acid afforded dinuclear complexes [(NHC)Pd(μ-1H-pyrazolato-3-carboxylate)]₂, in which the 1H-pyrazolato-3-carboxylate was employed as a N^N^O dianionic chelating and bridging ligand. To further explore the structural features and catalytic properties of the complexes, 1-methyl-1H-pyrazole-3-carboxylic acid was introduced into the coordination with [Pd(μ-Cl)(Cl)(NHC)]₂ and the corresponding mononuclear complexes (NHC)PdCl(1-methyl-1H-pyrazole-3-carboxylate) were obtained. The catalytic properties of the complexes in desulfitative arylation of azoles with arylsulfonyl hydrazides were initially investigated.