[EN] TRICYCLIC PYRIMIDINES AS CYCLIN-DEPENDENT KINASE 7 (CDK7) INHIBITORS [FR] PYRIMIDINES TRICYCLIQUES UTILISÉES EN TANT QU'INHIBITEURS DE LA KINASE 7 DÉPENDANTE DES CYCLINES (CDK7)
Ligand-Induced Reductive Elimination of Ethane from Azopyridine Palladium Dimethyl Complexes
作者:Andrey E. Rudenko、Naomi E. Clayman、Katherine L. Walker、Jana K. Maclaren、Paul M. Zimmerman、Robert M. Waymouth
DOI:10.1021/jacs.8b06398
日期:2018.9.12
ethanefrom (azpy)PdMe2 complexes and the unique role of the redox-active azopyridine (azpy) ligands in facilitating this reaction. The (azpy)PdMe2 complexes are air- and moisture-stable in the solid form, but they readily produce ethane upon dissolution in polar solvents at temperatures from 10 °C to room temperature without the need for an external oxidant or elevated temperatures. Experimental and
还原消除 (RE) 是许多催化过程中的关键步骤。从 Pd(II) 物种中还原消除不饱和基团(芳基、乙烯基和乙炔基)比饱和烷基的 RE 快得多。除非受到热或氧化还原刺激,否则通过螯合二亚胺配体连接的 Pd(II) 二甲基复合物对 RE 是稳定的。在此,我们报告了来自 (azpy)PdMe2 复合物的乙烷的自发 RE 以及具有氧化还原活性的偶氮吡啶 (azpy) 配体在促进该反应中的独特作用。(azpy)PdMe2 复合物在固体形式下对空气和湿气稳定,但它们在 10°C 至室温的温度下溶解在极性溶剂中后很容易产生乙烷,而无需外部氧化剂或升高的温度。
Isolated Organometallic Nickel(III) and Nickel(IV) Complexes Relevant to Carbon–Carbon Bond Formation Reactions
作者:Jason W. Schultz、Kei Fuchigami、Bo Zheng、Nigam P. Rath、Liviu M. Mirica
DOI:10.1021/jacs.6b06862
日期:2016.10.5
aryl and/or alkyl ligands are commonly proposed as the active intermediates in cross-coupling reactions. Herein, we report the first isolated NiIII-dialkyl complex and show that this species is involved in stoichiometric and catalytic C-C bond formationreactions. Interestingly, the rate of C-C bond formation from a NiIII center is enhanced in the presence of an oxidant, suggesting the involvement of
鉴于镍催化的交叉偶联反应能够使用更广泛的亲电子试剂以及促进立体有择或立体选择性转化,近年来它们正在经历戏剧性的复苏。与广泛研究的通常采用抗磁性中间体的 Pd 催化剂相比,Ni 系统可以更容易地获得各种氧化态,包括奇电子构型。例如,具有芳基和/或烷基配体的有机金属 NiIII 中间体通常被认为是交叉偶联反应中的活性中间体。在此,我们报告了第一个分离的 NiIII-二烷基复合物,并表明该物种参与化学计量和催化 CC 键形成反应。有趣的是,在氧化剂的存在下,NiIII 中心形成 CC 键的速率增加,表明瞬态 NiIV 物种的参与。事实上,对于镍环系统,这样的 NiIV 物种被观察到并通过光谱表征。总的来说,这些研究表明 NiIII 和 NiIV 物质都可以在一系列 Ni 催化的交叉偶联反应中发挥重要作用,尤其是那些涉及烷基底物的反应。
Axial Donor Effects on Oxidatively Induced Ethane Formation from Nickel–Dimethyl Complexes
作者:Sofia M. Smith、Nigam P. Rath、Liviu M. Mirica
DOI:10.1021/acs.organomet.9b00438
日期:2019.10.14
pyridinophane ligands have been shown to stabilize uncommon high-valent palladium and nickel organometallic complexes. Described herein are the synthesis and detailed characterization of a series of NiII– and NiIII–dimethyl complexes supported by modified tetradentate pyridinophane ligands in which one or both of the N-methyl substituents were replaced with electron-withdrawing p-toluenesulfonyl groups
四齿吡啶并吡啶配体已显示出稳定罕见的高价钯和镍有机金属配合物的能力。本文描述了一系列由修饰的四齿吡啶并菲配体支撑的Ni II-和Ni III-二甲基配合物的合成和详细表征,其中一个或两个N-甲基取代基被吸电子对甲苯磺酰基取代,因此降低胺N原子的活性,并有利于形成具有较低配位数的Ni络合物。相应的Ni II-二甲基配合物表现出可及的氧化电位,并且它们的氧化生成Ni III通过EPR和X射线晶体学表征的物种。此外,Ni II-二甲基配合物在使用各种氧化剂(包括O 2和H 2 O 2)进行氧化诱导的还原消除后,会显示出选择性的乙烷形成,而不会产生任何C-杂原子产物。总体而言,这些结果表明,轴向供体较弱的(R N4)Ni II Me 2络合物对乙烷的形成更具反应性,这可能是由于相应的高价Ni中间体的失稳以及5和4坐标的形成这些镍物种的构象。
Ion beam studies of the reactions of atomic cobalt ions with alkanes: determination of metal-hydrogen and metal-carbon bond energies and an examination of the mechanism by which transition metals cleave carbon-carbon bonds
Deceptive similarities in the reactions of iron(I) and cobalt(I) with linear nitriles in the gas phase
作者:Carlito B. Lebrilla、Thomas Drewello、Helmut Schwarz
DOI:10.1021/ja00253a013
日期:1987.9
transition-metal ions Fe/sup +/ and Co/sup +/ with linear C(4)-C(12) nitriles are reported. In spite of an overall similar reactivity pattern, a more detailed analysis, based on the study of labeled nitriles, reveals distinct differences with regard to the mechanisms of elimination of alkenes and alkanes. For both metal ions, hydrogen and alkenes are generated from linear C(4)-C(12) nitriles, and the intermediates