DataSheet1_Electrochemical Studies of the Cycloaddition Activity of Bismuth(III) Acetylides Towards Organic Azides Under Copper(I)-Catalyzed Conditions.PDF

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 in situ 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 para-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 (KA) and equilibrium concentration of the copper species [cat]eq. are compared with the overall 5-bismuth(III)-triazolide formation rate constant kobs obtained by 1H-NMR kinetic analysis.

对反应中间体的时间依赖性监测可为合成转化的反应机制提供极具价值的信息。然而该过程往往涉及寿命极短的中间体，这极大阻碍了目标动力学数据的获取。我们报道了铜(I)催化条件下有机铋(III)化合物与有机叠氮化物发生环加成反应的原位循环伏安法（cyclic voltammetry, CV）及核磁共振（nuclear magnetic resonance, NMR）光谱研究。我们合成了一系列带有二苯砜骨架的铋(III)炔化物，以探究具备跨环氧-铋（O···Bi）相互作用能力的锚定取代基，以及母本苯乙炔骨架对位官能化修饰所带来的电子效应与空间位阻效应。尽管该反应属于铜催化叠氮-炔环加成反应家族，但生成5-铋(III)三唑化物的该反应是唯一一例复杂催化转化过程，其展现出铋(III)炔化物在铜(I)催化条件下对有机叠氮化物的反应活性。通过循环伏安法对铜(I)催化剂的铜(I)/铜(0)氧化还原活性进行分步连续监测，为5-铋(III)三唑化物形成的复杂催化循环提供了全新的认知。基于循环伏安法得到的动力学数据，我们将铋(III)炔化物与铜(I)催化剂配位的反应速率参数（KA）、铜物种的平衡浓度[cat]eq，与通过1H-NMR动力学分析得到的整体5-铋(III)三唑化物生成速率常数kobs进行了对比。