Unsaturated chiral-only-at-metal rhodium(iii) complexes bearing SiN-type ligands
Enantiopure chiral-at-metal rhodium(III) unsaturated 16e complexes have been obtained from racemic [Rh(SiN)2Cl] (SiN= 8-(dimethylsilyl)quinoline) using a readily accessible chiral spiroborate as chiral resolution agent. This strategy allows an easy access to enantiopure neutral Δ/Λ-Rh(SiN)2Cl and ca...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad del País Vasco |
| Repositorio: | Addi. Archivo Digital para la Docencia y la Investigación |
| OAI Identifier: | oai:addi.ehu.eus:10810/70057 |
| Acceso en línea: | http://hdl.handle.net/10810/70057 |
| Access Level: | acceso abierto |
| Palabra clave: | rhodium(iii) complexes chiral-at-metal Diels Alder Danishefsky's diene |
| Sumario: | Enantiopure chiral-at-metal rhodium(III) unsaturated 16e complexes have been obtained from racemic [Rh(SiN)2Cl] (SiN= 8-(dimethylsilyl)quinoline) using a readily accessible chiral spiroborate as chiral resolution agent. This strategy allows an easy access to enantiopure neutral Δ/Λ-Rh(SiN)2Cl and cationic Δ/Λ-Rh(SiN)2[BAr4F] unsaturated complexes, wherein rhodium(III) is coordinated to two inert silylquinoline ligands in a propeller-like arrangement. Graphical abstract: Unsaturated chiral-only-at-metal rhodium(iii) complexes bearing SiN-type ligands In the field of asymmetric catalysis, transition metal catalysts are commonly used due to their remarkable efficiency.1 The predominant methodology in transition metal asymmetric catalysis involves the use of chiral ligands. However, there is a growing interest in a less studied method involving chiral-at-metal complexes formed by non-chiral ligands, mainly due to the seminal work of E. Meggers.2 This approach consists of a metal centre coordinated by two bidentate ligands in a propeller-type fashion. High configurational stability at the stereogenic metal centre is the main requirement for chiral metal catalysts. In addition, for the substrate to interact with the metal centre of the catalyst, the presence of labile auxiliary ligands, such as acetonitrile, is required. Two advantages of using chiral-at-metal complexes as asymmetric catalysts should be noted. First, the non-chiral ligands are easier to prepare than their chiral counterparts, thus offering a wider variety. Secondly, in chiral-at-metal catalysts, the metal centre, which is the reaction centre for catalysis, is also the stereogenic centre responsible for the overall enantioselectivity. Most of the chiral-at-metal complexes used as asymmetric catalysts reported to date are octahedral complexes with d6 transition metals.3–6 Cationic complexes of iridium(iii)3 and rhodium(iii)4 with two bidentate anionic ligands (CN ligands; Fig. 1a left) and two labile acetonitrile ligands have been widely used chiral-at-metal catalysts. More recently, ruthenium(ii)5 and iron(ii)6 di-cationic complexes bearing bidentate neutral ligands (CN ligands; Fig. 1a right) and also two labile acetonitrile ligands have also been studied. |
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