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Online High-Performance Liquid Chromatography Analysis of Buchwald–Hartwig Aminations from within an Inert Environment
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-11-01 , DOI: 10.1021/acscatal.0c03530
Thomas C. Malig 1 , Lars P. E. Yunker 1 , Sebastian Steiner 1 , Jason E. Hein 1
Affiliation  

Obtaining data-dense reaction profiles for reactions performed under an inert atmosphere remains a significant challenge obfuscating mechanistic analysis. To this end, we have developed a reaction monitoring platform capable of automated sampling and online HPLC analysis to generate temporal profiles for reactions performed from within a glovebox. The device allows for facile reaction progress analysis to aid in mechanistic studies of air-sensitive chemical transformations. The platform has demonstrated high reproducibility regarding sample mixing, dilution, delivery, and analysis. We employed the sampling platform to acquire temporal profiles for a series of Buchwald–Hartwig aminations. Parallel coupling reactions using iodobenzene and bromobenzene both exhibit complex kinetics. A competition reaction including both aryl halides demonstrated high selectivity for iodobenzene indicative of catalyst monopoly. The temporal profile for the difunctionalized substrate 1,4-iodobromobenzene was unexpected based on our parallel and competition studies and is indicative of a distinct underlying mechanism. We attribute this unanticipated reactivity to intramolecular catalyst transfer through the π system as seen in “living” polymerization transfer catalyst systems. The use of this automated sampling platform has greatly increased mechanistic understanding despite performing only a small number of experiments.

中文翻译:

惰性环境中布赫瓦尔德-哈特维格胺胺的在线高效液相色谱分析

对于在惰性气氛下进行的反应而言,获得数据密集的反应曲线仍然是使机理分析难以理解的重大挑战。为此,我们开发了一个反应监测平台,该平台能够自动采样和在线HPLC分析,以生成在手套箱内进行的反应的时间曲线。该设备允许轻松进行反应进度分析,以帮助进行空气敏感化学转化的机理研究。该平台在样品混合,稀释,递送和分析方面表现出很高的重现性。我们采用了采样平台来获取一系列布赫瓦尔德-哈特维奇胺化的时间分布。使用碘代苯和溴代苯的平行偶联反应均表现出复杂的动力学。包括两种芳基卤化物的竞争反应表明对碘苯的高选择性表明了催化剂的垄断。根据我们的平行研究和竞争研究,双官能化底物1,4-碘代溴苯的时间变化是出乎意料的,并且表明了不同的潜在机理。我们将这种意外的反应性归因于分子内催化剂通过π系统的转移,如“活性”聚合转移催化剂系统中所见。尽管仅执行少量实验,但使用此自动采样平台仍大大提高了对机械的理解。根据我们的平行研究和竞争研究,4-碘溴苯是出乎意料的,并且表明了其独特的潜在机理。我们将这种意外的反应性归因于分子内催化剂通过π系统的转移,如“活性”聚合转移催化剂系统中所见。尽管仅执行少量实验,但使用此自动采样平台仍大大提高了对机械的理解。根据我们的平行研究和竞争研究,4-碘溴苯是出乎意料的,并且表明了其独特的潜在机理。我们将这种意外的反应性归因于分子内催化剂通过π系统的转移,如“活性”聚合转移催化剂系统中所见。尽管仅执行少量实验,但使用此自动采样平台仍大大提高了对机械的理解。
更新日期:2020-11-21
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