Mechanistic study in azide-alkyne cycloaddition (CuAAC) catalyzed by bifunctional trinuclear copper(I) pyrazolate complex: Shift in rate-determining step
作者:Vladimir A. Larionov、Anna R. Stashneva、Aleksei A. Titov、Alexey A. Lisov、Michael G. Medvedev、Alexander F. Smol'yakov、Andrey M. Tsedilin、Elena S. Shubina、Victor I. Maleev
DOI:10.1016/j.jcat.2020.07.010
日期:2020.10
Trinuclear copper(I) pyrazolate [Cu(3,5-(CF3)2Pz)]3 was employed in a mechanistic study of azide-alkyne cycloaddition (CuAAC). It was shown that the copper complex operates as a bifunctional catalytic system (copper source and Brønsted base) under mild conditions (RT and air atmosphere) at lowcatalystloading (1 mol%). The rate-determining step of the reaction is the first C-N bond formation between
三核吡唑酸铜(I)[Cu(3,5-(CF 3)2 Pz)] 3被用于叠氮化物-炔烃环加成(CuAAC)的机理研究中。结果表明,铜的络合物在温和的条件下(RT和空气气氛下)以较低的催化剂负载量(1摩尔%)作为双功能催化体系(铜源和布朗斯台德碱)运行。该反应的决定速率的步骤是叠氮化物和乙炔之间的第一个CN键形成(叠氮化物迁移插入),而不是通常认为的乙炔铜(I)形成。观测到的动力学同位素效应等于1.1并通过DFT计算得到了支持。该反应对催化剂浓度具有二级依赖性,这意味着两个铜(I)中心参与了“双蝴蝶”四核配合物Cu 4 L 4(RC≡CH)2形成金属环的步骤在速率确定步骤中。DFT计算证明吡唑酸酯配体充当布朗斯台德碱,使乙炔分子去质子化,提供了成功的催化作用。基于DFT计算已经构建了合理的反应催化循环。
Thermal, non-catalyzed Huisgen cycloaddition for the preparation of 4,5-bis(trimethylsilyl)-1H-1,2,3-triazoles
作者:Ronald G. Brisbois、Alexandra M. Bergan、Aubrey J. Ellison、Percy Y. Griffin、Kent C. Hackbarth、Steven R. Larson
DOI:10.1016/j.tetlet.2012.11.019
日期:2013.1
The 1,2,3-triazole scaffold is an important pharmacophore and a versatile, increasingly leveraged, sub-structure in biochemical, materials, polymer, and metal-coordinating applications. Continuing advances in 1,2,3-triazole construction, by either non-catalyzed or metal-catalyzed azide/alkyne cycloaddition, foster further creative use. The work reported here establishes a general protocol for the synthesis of 4,5-bis(trimethylsilyl)-1H-1,2,3-triazoles via thermal Huisgen cycloaddition between azides and bis(trimethylsilyl)acetylene. (C) 2012 Elsevier Ltd. All rights reserved.