Santiago Celine B, Milo Anat, Sigman Matthew S
Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
J Am Chem Soc. 2016 Oct 12;138(40):13424-13430. doi: 10.1021/jacs.6b08799. Epub 2016 Oct 3.
The effects of aryl ring ortho-, meta-, and para-substitution on site selectivity and enantioselectivity were investigated in the following reactions: (1) enantioselective Pd-catalyzed redox-relay Heck reaction of arylboronic acids, (2) Pd-catalyzed β-aryl elimination of triarylmethanols, and (3) benzoylformate decarboxylase-catalyzed enantioselective benzoin condensation of benzaldehydes. Through these studies, it is demonstrated that the electronic and steric effects of various substituents on selectivities obtained in these reactions can be described by NBO charges, the IR carbonyl stretching frequency, and Sterimol values of various substituted benzoic acids. An extended compilation of NBO charges and IR carbonyl stretching frequencies of various substituted benzoic acids was used as an alternative to Hammett values. These parameters provide a correlative tool that allows for the analysis of a much greater range of substituent effects because they can also account for proximal and remote steric effects.
在以下反应中研究了芳环邻位、间位和对位取代对位点选择性和对映选择性的影响：（1）钯催化的芳基硼酸对映选择性氧化还原接力Heck反应，（2）钯催化的三芳基甲醇的β-芳基消除反应，以及（3）苯甲酰甲酸脱羧酶催化的苯甲醛对映选择性安息香缩合反应。通过这些研究表明，各种取代基在这些反应中获得的选择性上的电子和空间效应可以用自然键轨道（NBO）电荷、红外羰基伸缩频率以及各种取代苯甲酸的Sterimol值来描述。各种取代苯甲酸的NBO电荷和红外羰基伸缩频率的扩展汇编被用作哈米特值的替代物。这些参数提供了一种相关工具，因为它们还可以考虑近端和远程空间效应，从而能够分析更大范围的取代基效应。
