Heteroaromatic N-Oxides in Asymmetric Catalysis: A Review

Autor: Zuzanna Wrzeszcz, Renata Siedlecka
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Molecules, Vol 25, Iss 2, p 330 (2020)
Druh dokumentu: article
ISSN: 1420-3049
DOI: 10.3390/molecules25020330
Popis: 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.
Databáze: Directory of Open Access Journals
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