Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, 119991, Russia.
Department of Organic Chemistry I, Faculty of Chemistry, University of Basque Country UPV/EHU, Paseo Manuel Lardizabal 3, 20018, San Sebastian, Spain.
Chemistry. 2020 Jun 2;26(31):7074-7082. doi: 10.1002/chem.201905708. Epub 2020 May 11.
The results of extended comparative investigation of nickel(II) Schiff base complexes (containing various auxiliary chiral moieties) commonly used as a methodological platform for the asymmetric synthesis of tailor-made α-amino acids are provided. The following issues are addressed: 1) redox activity (determining the possibility for electrochemically induced reactions); 2) quantitative estimation of the reactivity of deprotonated complexes towards electrophiles; and 3) quantum-chemical estimation of noncovalent interactions in the metal coordination environment (which shed light on the origin of the stereochemical outcome observed for different stereoinductors). Possible mechanisms that determine the relationship between the stereochemical configuration of a molecule and its electronic structure are discussed. The DFT-calculated HOMO-LUMO energies and localization, as well as relative energies for the (S)- and (R)-alanine derivatives, that determine the stereoinduction efficiency in thermodynamically controlled reactions in nickel(II) coordination are provided. The computational data are supported by experimental results on the monobenzylation of glycine derivatives.
提供了对镍（II）希夫碱配合物（含有各种辅助手性部分）的扩展比较研究的结果，这些配合物通常用作定制α-氨基酸不对称合成的方法学平台。解决了以下问题：1）氧化还原活性（确定电化学诱导反应的可能性）；2）对去质子化配合物与亲电试剂的反应性进行定量估计；3）对金属配位环境中非共价相互作用的量子化学估计（阐明了观察到的不同立体诱导剂的立体化学结果的起源）。讨论了决定分子的立体化学构型与其电子结构之间关系的可能机制。提供了决定镍（II）配位中热力学控制反应中立体诱导效率的（S）-和（R）-丙氨酸衍生物的 HOMO-LUMO 能量和定位以及相对能量的 DFT 计算数据。计算数据得到了甘氨酸衍生物的单苄基化实验结果的支持。
