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1.
烯烃复分解反应是形成碳碳双键的重要反应之一,其发展与结构明确的钌催化剂[L2X2Ru=CHR]中配体的创制密切相关.1999年,环二氨基卡宾配体的引入极大提高了催化剂的活性、稳定性以及官能团适用性.2005年,Bertrand等发展了一种比环二氨基卡宾具有更强给电子能力的配体──环(烷基)(氨基)卡宾(CAACs)配体,且卡宾中心α位为一季碳原子,这使得其空间环境与其他类型卡宾配体有很大差异.首先概述了CAACs配体的合成及性质,紧接着讨论了其在烯烃复分解催化反应中的研究进展,最后对该领域所存在的问题进行简要分析并对其发展作了展望. 相似文献
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Dr. Gaël Ung Jonathan Rittle Dr. Michele Soleilhavoup Prof. Guy Bertrand Prof. Jonas C. Peters 《Angewandte Chemie (International ed. in English)》2014,53(32):8427-8431
The CAAC [CAAC=cyclic (alkyl)(amino)carbene] family of carbene ligands have shown promise in stabilizing unusually low‐coordination number transition‐metal complexes in low formal oxidation states. Here we extend this narrative by demonstrating their utility in affording access to the first examples of two‐coordinate formal Fe0 and Co0 [(CAAC)2M] complexes, prepared by reduction of their corresponding two‐coordinate cationic FeI and CoI precursors. The stability of these species arises from the strong σ‐donating and π‐accepting properties of the supporting CAAC ligands, in addition to steric protection. 相似文献
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Pei Ling Chiu 《Journal of organometallic chemistry》2005,690(6):1682-1687
Reactions of the ethylene- and methylene-bridged bis(imidazolium) salts with an equivalent amount of silver oxide in dichloromethane at room temperature produced readily the silver NHC compounds [Ag2LBr2]. These compounds are partially soluble in DMF. The X-ray structure determination on 3d (L = 1,1′-dibenzyl-3,3′-ethylenediimidazolin-2,2′-diylidene) reveals the formation of bromide bibridged (Ag2LBr2)n chains and a unique supramolecular motif with weak Ag?Ag interactions of 3.429 Å. Similar to monomeric silver(I) NHC complexes, the silver coordination polymers can also act as carbene transfer reagents for the formation of chelating palladium NHC complexes in excellent yields. 相似文献
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Organocatalytic Enantioselective Higher‐Order Cycloadditions of In Situ Generated Amino Isobenzofulvenes 下载免费PDF全文
Dr. Bjarke S. Donslund Dr. Alicia Monleón Dr. Teresa A. Palazzo Mette Louise Christensen Anne Dahlgaard Dr. Jeremy D. Erickson Prof. Karl Anker Jørgensen 《Angewandte Chemie (International ed. in English)》2018,57(5):1246-1250
The [8+2] cycloaddition of indene‐2‐carbaldehydes and nitro olefins is described to provide benzonorbornene scaffolds in a highly peri‐, diastereo‐, and enantioselective fashion in the presence of a C2‐symmetric aminocatalyst. This reaction, which proceeds through a transient semi‐aromatic amino isobenzofulvene, represents the first example of catalytic formation and transformation of these species. Quantum chemical calculations suggest a kinetically controlled stepwise mechanism where the stereochemistry is determined in the first bond‐forming event. Beyond the useful [8+2] cycloadducts, [10+4] cycloadducts have been identified in silico as potential off‐pathway intermediates. 相似文献
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YongQiangMA XiaoCHEN JingLI QingLanXIE HongGenWANG 《中国化学快报》2003,14(4):413-416
The synthesis,the crystal structure and the reaction of the hetero-binuclear complex[MnRe(CO)6(μ-SH)(μ-SC(H)PPr^i3)(PPh3)] are reported.The results of single crystal X-ray structure analysis showed that the fragments Mn(CO)3 and Re(CO)3 were bridged by SH and SC(H)PPr^i3.The title complexes can react with Bu^nLi and RX forming complexes MnRe(CO)6(μ-SR)(μ-SC(H)PPr^i3)(PPh3)](R=Me,CH2CH=CH2,SnBu3^n). 相似文献
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《化学:亚洲杂志》2017,12(17):2304-2310
A dinuclear ruthenium complex [RuII(NCNHC O)(pic)2]22+ ( 2 ) was firstly prepared and characterized spectroscopically and electrochemically. Instead of the conventional ligand exchange, complex 2 dissociates in situ to afford two single‐site Ru aqua complexes, [RuII(OH2)(NCNHC O)(pic)2]+, which mediates water oxidation through proton‐coupled electron transfer events. In electrokinetic studies, complex 2 demonstrated a TOF of 150.3 s−1 comparable to those state‐of‐the‐art catalysts at neutral conditions. TONs of 2173 and 217 were attained in chemical and photochemical water oxidation when 2 was used as a catalyst, exhibiting good stability. Notably, a TOF of 1.3 s−1 was achieved at CAN‐driven water oxidation, which outperformed most of the reported single‐site Ru complexes, indicating that complex 2 is one of most active water oxidation catalysts (WOCs) to date. The unique coordination configuration and outstanding catalytic performance of complex 2 might shed light on the design of novel molecular WOCs. 相似文献
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Agnes Bittermann Eberhardt Herdtweck Wolfgang A. Herrmann 《Journal of organometallic chemistry》2008,693(12):2079-2090
Rhodium(I) complexes of acceptor substituted N-heterocyclic carbenes were obtained either by transmetalation from the corresponding Ag(I) complexes or by thermal decomposition of corresponding pentafluorobenzene carbene adducts. All complexes were fully characterized by means of NMR- and mass spectroscopy. Compounds 5, 6, 7 and 11 were although characterized by single-crystal X-ray analysis. The relative σ-donor/π-acceptor strength of the NHC ligands was determined by means of IR spectroscopy. Dimerisation behaviour of Rh carbonyl complexes was studied. 相似文献
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A blue photoluminescent coordination polymer [Ag4Cl4(dppe)2]n has been prepared solvothermally and characterized structurally. The crystal structure was determined by single-crystal X-ray diffraction. The crystal is of tetragonal, space group I41/a, a=b=1.936 03(6) nm, c=1.465 63(8) nm, V=5.493 5(4) nm3, Z=4, Dcalcd=1.657 Mg·m-3, μ=1.749 mm-1. Reflections collected: 17 147, independent reflections: 3 247, Rint=0.021 1. Final R indices [I> 2σ(I)]: R1=0.044 8, wR2=0.111 0. The structure of [Ag4Cl4(dppe)2]n is a 3D-diamond highly symmetrical polymeric network containing Ag4Cl4 cubane-like clusters connected by 1,2-bis(diphenylphosphino)ethane (dppe). Each Ag4Cl4 cluster is composed of four silver and four chlorine atoms situated at alternate vertexes of a highly distorted cube with each silver atom being further coordinated to one phosphorus atom from a dppe ligand. The stripping of chloride ions from CHCl3 provides the source for chlorine in the formation of Ag(Ⅰ) clusters. In addition, the emission spectrum of the complex 1 in solid state has been studied. CCDC: 288080. 相似文献
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The Copper(Ⅰ) supramolecular complexes of 4,5-bis(methylthio)-1,3-dithiole-2-thione (C5H6S5), [Cu(C5H6S5)(SCN)]∞ 1 and [Cu(C5H6S5)I]∞ 2, have been prepared and characterized. X-ray structure analysis for complex 1 reveals that the infinite chain structure with polymeric stairs of different lengths is formed through the coordination mode (μ3) of the thiocyanate bridges. The shorter interchain S…S contacts give rise to a three-dimensional network structure. CCDC: 215668. 相似文献
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Dr. Ning Sun Xin Xie Haoyi Chen Prof. Yuanhong Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14175-14180
Gold‐catalyzed cyclization of various furan‐ynes with a propargyl carbonate or ester moiety results in the formation of a series of polycyclic aromatic ring systems. The reactions can be rationalized through a tandem gold‐catalyzed 3,3‐rearrangement of the propargyl carboxylate moiety in furan‐yne substrates to form an allenic intermediate, which is followed by an intramolecular Diels–Alder reaction of furan and subsequent ring‐opening of the oxa‐bridged cycloadduct. It was found that the steric and electronic properties of phosphine ligands on the gold catalyst had a significant impact on the reaction outcome. In the case of 1,5‐furan‐yne, the cleavage of the oxa‐bridge in the cycloadduct with concomitant 1,2‐migration of the R1 group occurs to furnish anthracen‐1(2H)‐ones bearing a quaternary carbon center. For 1,4‐furan‐yne, a facile aromatization of the cycloadduct takes place to give 9‐oxygenated anthracene derivatives. 相似文献
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Cyclic (Amino)(aryl)carbenes (CAArCs) as Strong σ‐Donating and π‐Accepting Ligands for Transition Metals 下载免费PDF全文
Bin Rao Huarong Tang Prof. Dr. Xiaoming Zeng Liu Liu Dr. Mohand Melaimi Prof. Dr. Guy Bertrand 《Angewandte Chemie (International ed. in English)》2015,54(49):14915-14919
Cyclic (amino)(aryl)carbenes (CAArCs) result from the replacement of the alkyl substituent of cyclic (alkyl)(amino) carbenes (CAACs) by an aryl group. This structural modification leads to enhanced electrophilicity of the carbene center with retention of the high nucleophilicity of CAACs, and therefore CAArCs feature a small singlet–triplet gap. The isoindolium precursors are readily prepared in good yields, and deprotonation at low temperature, in the presence of [RhCl(cod)]2 and [(Me2S)AuCl] lead to air‐stable rhodium and gold CAArC‐supported complexes, respectively. The rhodium complexes promote the [3+2] cycloaddition of diphenylcyclopropenone with ethyl phenylpropiolate, and induce the addition of 2‐vinylpyridine to alkenes by CH activation. The gold complexes allow for the catalytic three‐component preparation of 1,2‐dihydroquinolines from aniline and phenyl acetylene. These preliminary results illustrate the potential of CAArC ligands in transition‐metal catalysis. 相似文献
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Synthesis of Difluoromethyl Thioethers from Difluoromethyl Trimethylsilane and Organothiocyanates Generated In Situ 下载免费PDF全文
Bilguun Bayarmagnai Christian Matheis Dr. Kévin Jouvin Prof. Dr. Lukas J. Goossen 《Angewandte Chemie (International ed. in English)》2015,54(19):5753-5756
A copper‐CF2H complex generated in situ from copper thiocyanate and TMS? CF2H smoothly converts organothiocyanates into valuable difluoromethyl thioethers. This reaction step can be combined with several thiocyanation methods to one‐pot protocols, allowing late‐stage difluoromethylthiolations of widely available alkyl halides and arenediazonium salts. This strategy enables the introduction of difluoromethylthio groups—a largely unexplored substituent with highly promising properties—into drug‐like molecules. 相似文献
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Patrizia Galzerano Dario Agostino Giorgio Bencivenni Dr. Letizia Sambri Dr. Giuseppe Bartoli Prof. Paolo Melchiorre Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(20):6069-6076
A simple and convenient method for the direct, aminocatalytic, and highly enantioselective Mannich reactions of aldehydes with in situ generated N‐carbamoyl imines has been developed. Both α‐imino esters and aromatic imines serve as suitable electrophilic components. Moreover, the judicious selection of commercially available secondary amine catalysts allows selective access to the desired stereoisomer of the N‐tert‐butoxycarbonyl (Boc) or N‐carbobenzyloxy (Cbz) Mannich adducts, with high control over the syn or anti relative configuration and almost perfect enantioselectivity. Besides the possibility to fully control the stereochemistry of the Mannich reaction, the main advantage of this method lies in the operational simplicity; the highly reactive N‐carbamate‐protected imines are generated in situ from stable and easily handled α‐amido sulfones. 相似文献
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Intramolecular C-H insertion using NHC-di-rhodium(II) complexes: the influence of axial coordination
In this work we show that the intramolecular C-H insertion of diazo-acetamides catalysed by di-rhodium(II) complexes can be highly influenced by the axial ligand on the di-rhodium(II) complex. Axially monocoordinated NHC-Rh2(OAc)4 complexes have a distinct reactivity from the parent Rh2(OAc)4 complex affording the cyclisation products in different rates and selectivities. Surprisingly, a new reaction mode emerged when using these complexes which led to a decarbonylation pathway. 相似文献
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YANG Lei TIAN Jin-Lei LIU Zhan-Quan YAN Shi-Ping② LIAO Dai-Zheng JIANG Zong-Hui CHENG Peng 《结构化学》2004,23(5)
1 INTRODUCTION As a versatile ligand, N3- has been attracted great interest for several decades. In addition to mono- dentate coordination through a single N-donor, the azide group is not only an efficient antiferromag- netic coupler in the 1,3-fashion… 相似文献
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Dr. Raphaël Nougué Dr. Shintaro Takahashi Dr. Antoine Baceiredo Dr. Nathalie Saffon-Merceron Prof. Vicenç Branchadell Dr. Tsuyoshi Kato 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215394
A phosphine-stabilized silacyclopropyl cation 2 has been synthesized and fully characterized. Of particular interest, 2 reversibly isomerizes into the corresponding seven-membered cyclic (alkyl)(amino)silylene 3 at room temperature via a formal migratory ethylene insertion into the Si−P bond. Although silylene 3 has not been spectroscopically detected, its transient formation has been evidenced by the isolation of the corresponding disilene dimer 5 as well as by trapping reactions. 相似文献
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Ali Ramazani Behnaz Abdian Fatemeh Zeinali Nasrabadi Morteza Rouhani 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):642-648
Abstract Reaction of N-isocyaniminotriphenylphosphorane with biacetyl in the presence of (E)-cinnamic acids proceeds smoothly at room temperature and under neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and straightforward under mild conditions and no side reactions are observed. 相似文献