Efficient Ru(II)-catalyzed asymmetric hydrogenation of simple ketones with C₂-symmetric planar chiral metallocenyl phosphinooxazoline ligands

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• 作者：Hui Guo^a ; Delong Liu^a ; Nicholas A. Butt^b ; Yangang Liu^a ; Wanbin Zhang^a ; ^b ; ^{wanbin@sjtu.edu.cn}
• 关键词：Ketone ; Planar chirality ; Phosphinooxazoline ligands ; Ru-catalyzed asymmetric hydrogenation
• 刊名：Tetrahedron
• 出版年：2012
• 出版时间：22 April, 2012
• 年：2012
• 卷：68
• 期：16
• 页码：3295-3299
• 全文大小：422 K

文摘

C₂-symmetric metallocenyl planar phosphinooxazoline ligands (boldFont"">2 and boldFont"">3) have been applied in the Ru(II)-catalyzed asymmetric hydrogenation of simple ketones. This type of ligands enjoys the advantages of dual reaction sites as well as larger steric hindrance than their corresponding C₁-symmetric counterparts. As a result, almost quantitative conversions and excellent enantioselectivities were obtained for a series of simple ketones. Under the optimal reaction conditions, up to 99.7 % ee was obtained in many cases. It was also confirmed that hydrogen rather than reaction solvent i-PrOH is at work in the hydrogenation procedure.