Hanson Carly S, Devery James J
Department of Chemistry & Biochemistry, Loyola University Chicago.
Department of Chemistry & Biochemistry, Loyola University Chicago;
J Vis Exp. 2020 Feb 20(156). doi: 10.3791/60745.
Lewis acid-activation of carbonyl-containing substrates is a fundamental basis for facilitating transformations in organic chemistry. Historically, characterization of these interactions has been limited to models equivalent to stoichiometric reactions. Here, we report a method utilizing in situ infrared spectroscopy to probe the solution interactions between Lewis acids and carbonyls under synthetically relevant conditions. Using this method, we were able to identify 1:1 complexation between GaCl3 and acetone and a highly ligated complex for FeCl3 and acetone. The impact of this technique on mechanistic understanding is illustrated by application to the mechanism of Lewis acid-mediated carbonyl-olefin metathesis in which we were able to observe competitive binding interactions between substrate carbonyl and product carbonyl with the catalyst.
路易斯酸对含羰基底物的活化是促进有机化学转化的基本基础。从历史上看，这些相互作用的表征仅限于等同于化学计量反应的模型。在此，我们报告了一种利用原位红外光谱在合成相关条件下探测路易斯酸与羰基之间溶液相互作用的方法。使用这种方法，我们能够确定GaCl₃与丙酮之间的1:1络合以及FeCl₃与丙酮的高度配位络合物。通过将该技术应用于路易斯酸介导的羰基 - 烯烃复分解反应机理，说明了该技术对机理理解的影响，在该反应中我们能够观察到底物羰基和产物羰基与催化剂之间的竞争性结合相互作用。
