Department of Organic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland.
Molecules. 2020 Jan 14;25(2):330. doi: 10.3390/molecules25020330.
An increasing interest in the synthesis and use of optically active pyridine -oxides as chiral controllers for asymmetric reactions has been observed in the last few years. Chiral heteroaromatic -oxides can work as powerful electron-pair donors, providing suitable electronic environments in the transition state formed within the reaction. The nucleophilicity of the oxygen atom in -oxides, coupled with a high affinity of silicon to oxygen, represent ideal properties for the development of synthetic methodology based on nucleophilic activation of organosilicon reagents. The application of chiral -oxides as efficient organocatalysts in allylation, propargylation, allenylation, and ring-opening of meso-epoxides, as well as chiral ligands for metal complexes catalyzing Michael addition or nitroaldol reaction, can also be found in the literature. This review deals with stereoselective applications of -oxides, and how the differentiating properties are correlated with their structure. It contains more recent results, covering approximately the last ten years. All the reported examples have been divided into five classes, according to the chirality elements present in their basic molecular frameworks.
近年来，人们对合成和使用光学活性吡啶 - 氧化物作为不对称反应的手性控制剂越来越感兴趣。手性杂环 - 氧化物可以作为强大的电子对供体，在反应形成的过渡态中提供合适的电子环境。- 氧化物中氧原子的亲核性，加上硅对氧的高亲和力，代表了基于有机硅试剂亲核活化的合成方法发展的理想特性。在文献中也可以找到手性 - 氧化物作为有效的有机催化剂在烯丙基化、炔丙基化、烯丙基化和内消旋 - 环氧开环反应中的应用，以及作为手性配体用于催化迈克尔加成或硝基醇醛反应的金属配合物。这篇综述讨论了 - 氧化物的立体选择性应用，以及这些特性如何与其结构相关。它包含了最近的结果，涵盖了大约过去十年的时间。根据其基本分子框架中存在的手性元素，所有报道的例子都被分为五类。
