Iridium Complexes with Phosphine-Phosphite Ligands. Structural Aspects and Application in the Catalytic Asymmetric Hydrogenation of N-Aryl Imines
详细信息 查看全文
- 作者：Sergio Vargas ; Miguel Rubio ; André ; s Suá ; rez ; Diego del Rí ; o ; Eleuterio Á ; lvarez ; and Antonio Pizzano
- 刊名：Organometallics
- 出版年：2006
- 出版时间：February 13, 2006
- 年：2006
- 卷：25
- 期：4
- 页码：961 - 973
- 全文大小：449K
- 年卷期：v.25,no.4(February 13, 2006)
- ISSN：1520-6041
文摘
A family of modularly designed phosphine-phosphites (P-OP), possessing a C-C-O backbone, hasbeen synthesized and evaluated in the iridium-catalyzed asymmetric hydrogenation of N-aryl imines.The enantioselectivity of this reaction is highly dependent on the nature of the ligand, and catalystsbridged by an oxyethylene fragment have produced significantly higher enantiomeric excesses (
ee >20%) than their o-oxyphenylene counterparts. Structural studies by X-ray crystallography and NMRspectroscopy of complexes with the formulation [Ir(COD)(P-OP)]BF4 and Ir(Cl)(CO)(P-OP), complemented by DFT calculations of model compounds of the chlorocarbonyls, have shown important differencesbetween complexes bridged by an aliphatic or an aromatic bridge, regarding the iridacycle conformationand the location of phosphine substituents. Catalyst optimization has afforded enantioselectivities from72 to 85% ee in the hydrogenation of several N-aryl imines.
ee >20%) than their o-oxyphenylene counterparts. Structural studies by X-ray crystallography and NMRspectroscopy of complexes with the formulation [Ir(COD)(P-OP)]BF4 and Ir(Cl)(CO)(P-OP), complemented by DFT calculations of model compounds of the chlorocarbonyls, have shown important differencesbetween complexes bridged by an aliphatic or an aromatic bridge, regarding the iridacycle conformationand the location of phosphine substituents. Catalyst optimization has afforded enantioselectivities from72 to 85% ee in the hydrogenation of several N-aryl imines.