Heteroaromatic N-Oxides in Asymmetric Catalysis: A Review
Heteroaromatic N-Oxides in Asymmetric Catalysis: A Review
复制标题
DOI：
10.3390/molecules25020330
复制
发表时间：
2020-01
期刊：
影响因子：
4.6
通讯作者：
Zuzanna Wrzeszcz;R. Siedlecka
中科院分区：
文献类型：
--
作者：
Zuzanna Wrzeszcz;R. Siedlecka
近年来，光学活性吡啶N-氧化物作为手性控制剂在不对称反应中的应用越来越受到人们的关注。手性杂芳族N-氧化物可以作为强有力的电子对供体，在反应中形成的过渡态提供合适的电子环境。N-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学发展的理想性质。手性N-氧化物作为有效的有机催化剂在烯丙基化、炔丙基化、丙二烯化和内消旋环氧化物的开环中的应用，以及用于催化迈克尔加成或硝基醛醇反应的金属络合物的手性配体，也可以在文献中找到。本文综述了N-氧化物的立体选择性应用，以及它们的结构与分化性质的关系。它包含了最近的结果，大约涵盖了过去十年。所有已报道的实例已被分为五类，根据其基本分子框架中存在的手性元素。
An increasing interest in the synthesis and use of optically active pyridine N-oxides as chiral controllers for asymmetric reactions has been observed in the last few years. Chiral heteroaromatic N-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 N-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 N-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 N-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.