Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08901, United States.
Department of Chemistry, Columbia University , New York, New York 10027, United States.
J Am Chem Soc. 2017 Oct 25;139(42):14917-14930. doi: 10.1021/jacs.7b05229. Epub 2017 Oct 17.
In recent years, triazolylidene carbenes have come to the forefront as important organocatalysts for a wide range of reactions. The fundamental properties of these species, however, remain largely unknown. Herein, the gas phase acidities have been measured and calculated for a series of triazolium cations (the conjugate acids of the triazolylidene carbenes) that have not been heretofore examined in vacuo. The results are discussed in the context of these species as catalysts. We find correlations between the gas phase acidity and selectivity in two Umpolung reactions catalyzed by these species; such correlations are the first of their kind. We are able to use these linear correlations to improve reaction enantioselectivity. These results establish the possibility of using these thermochemical properties to predict reactivity in related transformations.
近年来，三唑啉亚基卡宾作为广泛反应的重要有机催化剂引起了人们的关注。然而，这些物质的基本性质在很大程度上仍然未知。在此，我们测量并计算了一系列此前尚未在真空中进行研究的三唑翁阳离子（三唑啉亚基卡宾的共轭酸）的气相酸度。我们根据这些物质作为催化剂的情况讨论了这些结果。我们发现，气相酸度与这两种 Umpolung 反应中这些物质催化的选择性之间存在相关性；这种相关性尚属首次。我们能够使用这些线性相关性来提高反应对映选择性。这些结果为使用这些热化学性质来预测相关转化中的反应性奠定了可能性。
