NMR Quantification of the Effects of Ligands and Counterions on Lewis Acid Catalysis.,The Journal of Organic Chemistry

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NMR Quantification of the Effects of Ligands and Counterions on Lewis Acid Catalysis.
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2019-12-11 , DOI: 10.1021/acs.joc.9b02107
Julia J Jennings ₁ , Benjamin W Wigman ₁ , Brittany M Armstrong ₁ , Annaliese K Franz ₁

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The relative Lewis acidity of a variety of metal-ligand catalyst complexes is quantified using 31P NMR spectroscopy. Three 31P NMR probes, including two new bidentate binding probes, are compared on the basis of different binding modes (i.e., monodentate vs bidentate) and the relative scale of their downfield shift upon binding to Lewis acid complexes. Bidentate coordination of catalyst complexes including metal catalysts, ligands, and counterions were assessed due to their importance to asymmetric catalysis. The effect of ligands, counterions, and additives on Lewis acidity is quantified and correlated to reaction yield at an early time point as an approximation for catalytic activity/efficiency and chelation mode in two organic transformations. Binding studies were performed under catalytically relevant conditions, giving further applicability to synthesis. Insight into activation modes are revealed through this analysis.

中文翻译：

配体和抗衡离子对Lewis酸催化作用的NMR定量。

使用31P NMR光谱定量分析各种金属-配体催化剂配合物的相对Lewis酸度。根据不同的结合方式（即单齿对双齿）和结合路易斯酸复合物时其低场位移的相对范围，对包括两种新的双齿结合探针在内的三种31P NMR探针进行了比较。由于它们对不对称催化的重要性，因此对包括金属催化剂，配体和抗衡离子在内的催化剂配合物的双配位进行了评估。量化配体，抗衡离子和添加剂对Lewis酸度的影响，并将其与早期反应点的反应产率相关联，作为两个有机转化中催化活性/效率和螯合模式的近似值。结合研究是在催化相关条件下进行的，进一步适用于合成。通过此分析可以洞悉激活模式。

更新日期：2019-12-11

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