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过渡金属催化的偶联反应是构筑C-C键的高效方法,在有机合成中得到了广泛的应用.然而,相对于Heck反应、Negishi偶联与Suzuki偶联等构筑C(sp2)-C(sp2)键的反应,过渡金属催化的构筑C(sp3)-C(sp3)键的偶联反应较难进行,发展较晚.近年来,烷基-烷基C-C键偶联反应受到广泛的重视,一些高效催化剂被开发出来,其中镍催化剂展示出独特的催化活性和选择性.本文将综述镍催化烷基-烷基C-C键偶联反应最新研究进展,主要包括烷基亲电试剂与金属有机试剂交叉偶联反应、导向基参与的C(sp3)-H键活化的偶联反应、镍-光反应催化剂协同催化偶联反应、烷基亲电试剂与亲电试剂的还原偶联反应和镍催化烯烃加成反应等. 相似文献
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过渡金属催化(类)卤化物和不同金属试剂的交叉偶联反应是构建不同类型碳碳键和碳杂原子键的重要方法之一。该类反应一般使用活性较高的氯、溴、碘或类卤化物作为亲电试剂,尽管C—F键的键能较强,利用过渡金属直接活化较为惰性的芳基C—F键并参与实现的交叉偶联反应已有较多报道。此外,近期的研究表明,也可以通过直接活化烯基C—F键并催化实现该类底物参与不同类型的交叉偶联反应,从而进一步拓展了交叉偶联反应的底物适用范围,并应用于具有高附加值精细化学品的选择性合成。本文围绕钯或镍催化活化单氟或者多氟烯烃等底物参与的Negishi、Suzuki-Miyaura、Kumada、Hiyama和Sonogashira等5类交叉偶联反应,通过探讨已有方法的反应机理及其适用范围,综述了该领域的研究进展并进行了展望。 相似文献
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氮杂环丙烷类化合物是重要的有机合成子,其广泛存在于各种有机合成反应当中.因其独特的三元环结构,致使其具有较大的环张力.通常氮杂环丙烷类化合物可以与各种亲核试剂反应,合成各种传统方法难以合成的β-位取代的胺类化合物,其中包括氨基醇、氨基醚以及二胺类化合物.通过亲核试剂开氮杂环丙烷的反应研究已经相当成熟,此处不再赘述.此外,过渡金属催化的C—N活化是一类重要的合成方法.作为C—N活化重要底物,过渡金属催化氮杂环丙烷的开环偶联反应取得长足的发展.尤其是近十年来,镍催化氮杂环丙烷的开环偶联反应不断涌现.基于此,综述了镍催化在氮杂环丙烷开环偶联反应中的研究进展和设计原则,重点介绍氮杂环丙烷的开环原理,对比不同取代的氮杂环丙烷区域选择性,总结不同催化模式下的共性.本综述将从以下三个方面介绍氮杂环丙烷的开环偶联反应:其一是单独的镍催化模式;其二是光/镍协同共催化模式;其三则是电化学促进的镍催化模式.对于氮杂环丙烷的开环模式则可以分为:镍催化的SN2型亲核开环模式、卤素离子亲核开环模式以及电化学还原模式. 相似文献
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光介导的钌/镍双过渡金属光氧化还原催化策略可以实现室温条件下温和地构建C—P键,但由于金属镍的催化循环历程和外加碱的详细机理仍不够明确,本文利用密度泛函理论计算研究了二苯基氧化膦和芳基碘化物C—P键交叉偶联反应的机理.计算结果表明,结合光催化剂还原淬灭(RuⅡ-*RuⅡ-RuI-RuⅡ)和镍催化循环(Ni0-NiI-NiⅢ-NiI-Ni0)的自由基机制是优势路径,其中无机碱Cs2CO3发挥重要作用,它辅助底物二苯基氧化膦参与光催化剂淬灭,并通过分步质子耦合电子转移过程产生重要中间体磷自由基.该研究结果有助于加深研究者对光介导的氧化还原构建C—P键偶联反应机理的认知,我们希望可以为实验化学家进一步设计过渡金属镍和光催化剂协同催化构建C—X键提供思路. 相似文献
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由于碳-氟键的化学惰性,其高效催化转化一直是有机化学中的难题之一.本文运用密度泛函理论(DFT)计算,研究了镍催化碳-氟/碳-氢键交叉偶联反应构建2-芳基噁唑衍生物的机理.计算结果表明,体系中氟负离子能够稳定零价镍金属催化剂,得到氟负离子配位的阴离子镍活性催化物种.在氟负离子协助下碳-氟键对阴离子镍氧化加成得到二价芳基镍物种,是催化循环的速控步骤.在碳氢键切断过程中,Br?nsted碱直接进攻去质子,得到二芳基镍中间体,最终通过还原消除得到交叉偶联产物.在这一过程中,阴离子镍活性催化物种的稳定性明显高于通常推测的中性镍催化物种,这一模型为理解惰性碳-氟键活化反应机理提供了新的思路. 相似文献
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Zhao Y Wang H Hou X Hu Y Lei A Zhang H Zhu L 《Journal of the American Chemical Society》2006,128(47):15048-15049
Two different organometallic reagents now can cross-couple together with the oxidative cross-coupling strategy. Palladium catalyzed oxidative cross-couplings of alkylzinc and alkynylstannane reagents using desyl chloride as the oxidant have been explored, which produce the desired Csp-Csp3 cross-coupling product in surprisingly high selectivity and yields. The current catalytic system tolerates the presence of beta-H, and the reactions using long chain alkyl zinc reagents gave the cross-coupling product in excellent yields and selectivities. 相似文献
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实现资源和能源利用高效化、操作简单化、条件温和化、环境友好化以及产物高效选择性是有机合成的重要研究方向,而探索绿色温和条件下构建化学键的有效方法是有机合成领域的基本挑战之一。伴随着金属有机化学的发展,过渡金属催化的偶联反应已经成为构建碳-碳和碳-杂键的有效手段,而传统的交叉偶联一般是基于亲核试剂与亲电试剂之间的反应,需要进行预官能团化和再官能团化的步骤。近年来,在此基础上发展起来的氧化偶联反应利用合适的氧化剂实现两个亲核试剂直接构建化学键也得到了国内外有机化学家的广泛关注。氧化偶联反应的发展极大地提高了构建碳-碳键及碳-杂键的效率,尤其是利用交叉脱氢偶联实现直接的碳-氢键或杂-氢键的活化直接构建化学键,避免了传统偶联过程中的预官能团化步骤,为直接利用简单的原料实现高效、复杂的有机合成开辟了一条新的道路。越来越多的第一过渡金属催化的氧化偶联反应涉及到单电子转移的过程,这种自由基氧化偶联模式在绿色化学的发展中具有光明的前景。可见光是一种可再生的资源,可见光催化符合绿色合成、环境友好和可持续发展的理念,在有机合成领域中引起了广泛的关注。建立在光诱导的单电子转移过程的基础上,可见光催化为实现温和条件下构建化学键提供了一种新的思路。虽然很多的有机分子不能有效吸收可见光,但是利用可见光催化剂(光敏剂)在电子和能量转移过程中的独特优势,能够有效实现在可见光作用下的一系列光化学反应。光催化是有机合成构建新物质的一种有效的手段,随着光催化在有机合成领域中的发展,一系列新型温和而有效的可见光催化的氧化偶联反应也逐渐被报道。虽然过渡金属催化的氧化偶联反应已经取得了重大的进展,但是利用可见光催化的策略以实现两个亲核试剂之间化学键的构建作为一个新的领域,近年来才刚刚发展起来。尤其是结合可见光催化条件温和、环境友好的特点和氧化偶联反应的原子经济性特点,将可见光诱导的单电子转移过程运用到交叉脱氢偶联反应,引起了广泛的关注。光催化氧化偶联反应不仅解决了传统偶联中的步骤经济性和原子经济性的问题,同时也具备了可见光反应温和环保的特点。近几年来已经发展了多种类型的光催化氧化偶联反应,包括光催化氧化含氮化合物的偶联反应、光催化氧化脱羧偶联反应、以及光催化交叉偶联放氢反应等。但是在光催化氧化偶联领域的相关报道大多局限于含氮化合物和易氧化的底物的活化氧化,因此任然存在着很多的挑战。本文总结了最近几年来的不同反应类型的可见光催化的氧化偶联的研究和进展。而对这些反应的理解和认识,可以为人们发展更多的高效率和高选择性的可见光催化氧化偶联反应提供帮助。 相似文献
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Cross-coupling reactions have become indispensable tools for creating carbon-carbon (or heteroatom) bonds in organic synthesis. Like in other important transition metal catalyzed reactions, such as metathesis, addition, and polymerization, unsaturated compounds are usually employed as substrates for cross-coupling reactions. However during the past decade, a great deal of effort has been devoted to the use of alkyl halides as saturated compounds in cross-coupling reactions, which has resulted in significant progress in this undeveloped area by introducing new effective ligands. Many useful catalytic systems are now available for synthetic transformations based on C(sp(3))-C(sp(3)), C(sp(3))-C(sp(2)) and C(sp(3))-C(sp) bond formation as complementary methods to conventional C(sp(2))-C(sp(2)), C(sp(2))-C(sp) and C(sp)-C(sp) coupling. This tutorial review summarizes recent advances in cross-coupling reactions of alkyl halides and pseudohalides catalyzed by a palladium complex. 相似文献
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Nickel-and palladium-catalyzed cross-coupling reactions have attracted wide attentions,while ligandcontrolled selectivity in these reactions are still elusive,and calculations can help obtain possible catalytic cycles to generate different products and provide insights into key factors of selectivity,which facilitates the development of new catalyst systems to control reaction selectivity.This review covers our efforts and some significant achievements from other groups on ligand-controlled reaction selectivity of coupling reactions,including introduction,computational methods,selectivity control by ligands in Niand Pd-catalyzed coupling reactions,as well as summary and future perspectives. 相似文献
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Srikrishna Bera Xile Hu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):13992-13997
Metal hydride catalyzed hydrocarbonation reactions of alkenes are an efficient approach to construct new carbon–carbon bonds from readily available alkenes. However, the regioselectivity of hydrocarbonation remains challenging to be controlled. In nickel hydride (NiH) catalyzed hydrocarbonation, linear selectivity is most often obtained because of the relative stability of the linear Ni–alkyl intermediate over its branched counterpart. Herein, we show that the boronic pinacol ester (Bpin) group directs a Ni‐catalyzed hydrocarbonation to occur at its adjacent carbon center, resulting in formal branch selectivity. Both alkyl and aryl halides can be used as electrophiles in this hydrocarbonation, providing access to a wide range of secondary alkyl Bpin derivatives, which are valuable building blocks in synthetic chemistry. The utility of the method is demonstrated by the late‐stage functionalization of natural products and drug molecules, the synthesis of an anticancer agent, and iterative syntheses. 相似文献
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A new catalytic system based on P, O chelate palladium complexes for cross-coupling reactions is described. These catalysts have all shown high activity and selectivity under mild reaction condition. 相似文献
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Caleb Karmel Camille Z. Rubel Elena V. Kharitonova John F. Hartwig 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6130-6137
The steric effects of substituents on five-membered rings are less pronounced than those on six-membered rings because of the difference in bond angles. Thus, the regioselectivities of reactions of five-membered heteroarenes that occur with selectivities dictated by steric effects, such as the borylation of C−H bonds, have been poor in many cases. We report that the silylation of five-membered-ring heteroarenes occurs with high sterically derived regioselectivity when catalyzed by the combination of [Ir(cod)(OMe)]2 (cod=1,5-cyclooctadiene) and a phenanthroline ligand or a new pyridyl-imidazoline ligand that further increases the regioselectivity. The silylation reactions with these catalysts produce high yields of heteroarylsilanes from functionalization at the most sterically accessible C−H bonds of these rings under conditions that the borylation of C−H bonds with previously reported catalysts formed mixtures of products or products that are unstable. The heteroarylsilane products undergo cross-coupling reactions and substitution reactions with ipso selectivity to generate heteroarenes that bear halogen, aryl, and perfluoroalkyl substituents. 相似文献
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An air-stable and easy-to-handle nickel precatalyst, (9-phenanthrenyl)Ni(II)(PPh3)2Cl, was examined for the cross-coupling reactions of aryl tosylates with arylboronic acids. Under the optimized reaction conditions, the catalytic system tolerates a wide range of activated, neutral and deactivated substrates. The selectivity of this cross-coupling reaction towards aryl tosylates and arylboronic acids has been investigated. It is proposed that ligand 1,1′-bis(diphenylphosphino)ferrocene (dppf) plays a key role in the coupling by enforcing a cis geometry in key intermediates and the active Ni(0) species. 相似文献