Nazarova Antonina L, Zayat Billal, Fokin Valery V, Narayan Sri R
Department of Chemistry, Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, CA, United States.
Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, United States.
Front Chem. 2022 Feb 25;10:830237. doi: 10.3389/fchem.2022.830237. eCollection 2022.
Time-dependent monitoring of the reactive intermediates provides valuable information about the mechanism of a synthetic transformation. However, the process frequently involves intermediates with short lifetimes that significantly challenge the accessibility of the desired kinetic data. We report cyclic voltammetry (CV) and nuclear magnetic resonance (NMR) spectroscopy studies of the cycloaddition reaction of organobismuth(III) compounds with organic azides under the copper(I)-catalyzed conditions. A series of bismuth(III) acetylides carrying diphenyl sulfone scaffolds have been synthesized to study the underlying electronic and steric effects of the tethered moieties capable of transannular oxygen O···Bi interactions and -functionality of the parent phenylacetylene backbones. While belonging to the family of copper-catalyzed azide-alkyne cycloaddition reactions, the reaction yielding 5-bismuth(III)-triazolide is the sole example of a complex catalytic transformation that features activity of bismuth(III) acetylides towards organic azides under copper(I)-catalyzed conditions. Stepwise continuous monitoring of the copper(I)/copper(0) redox activity of the copper(I) catalyst by cyclic voltammetry provided novel insights into the complex catalytic cycle of the bismuth(III)-triazolide formation. From CV-derived kinetic data, reaction rate parameters of the bismuth(III) acetylides coordination to the copper(I) catalyst (K) and equilibrium concentration of the copper species [cat] are compared with the overall 5-bismuth(III)-triazolide formation rate constant k obtained by H-NMR kinetic analysis.
对反应中间体进行时间依赖性监测可提供有关合成转化机理的有价值信息。然而,该过程经常涉及寿命较短的中间体,这对获取所需的动力学数据构成了重大挑战。我们报道了在铜(I)催化条件下有机铋(III)化合物与有机叠氮化物环加成反应的循环伏安法(CV)和核磁共振(NMR)光谱研究。合成了一系列带有二苯砜支架的铋(III)乙炔化物,以研究能够进行跨环氧O···Bi相互作用的连接部分的潜在电子和空间效应以及母体苯乙炔主链的官能团。虽然属于铜催化的叠氮化物-炔烃环加成反应家族,但生成5-铋(III)-三唑化物的反应是复杂催化转化的唯一例子,其特点是在铜(I)催化条件下铋(III)乙炔化物对有机叠氮化物具有活性。通过循环伏安法对铜(I)催化剂的铜(I)/铜(0)氧化还原活性进行逐步连续监测,为铋(III)-三唑化物形成的复杂催化循环提供了新的见解。根据CV衍生的动力学数据,将铋(III)乙炔化物与铜(I)催化剂配位的反应速率参数(K)和铜物种的平衡浓度[cat]与通过1H-NMR动力学分析获得的整体5-铋(III)-三唑化物形成速率常数k进行比较。