Synthesis and Use in Asymmetric Hydrogenations of Solely Planar Chiral 1,2-Disubstituted and 1,2,3-Trisubstituted Ferrocenyl Diphosphines: A Comparative Study

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• 作者：Yaping Wang ; Walter Weissensteiner ; Felix Spindler ; Vladimir B. Arion ; Kurt Mereiter
• 刊名：Organometallics
• 出版年：2007
• 出版时间：July 2, 2007
• 年：2007
• 卷：26
• 期：14
• 页码：3530 - 3540
• 全文大小：212K
• 年卷期：v.26,no.14(July 2, 2007)
• ISSN：1520-6041

文摘

A total of 12 enantiopure 1,2-disubstituted and 1,2,3-trisubstituted ferrocenyl diphosphines [1-Ph₂P-2-R₂PCH₂-3-R'-Fc, R = Cy, t-Bu, 3,5-(CH₃)₂C₆H₃), R' = H, CH₃, Ph, 3,5-(CH₃)₂C₆H₃)] have beensynthesized, characterized, and tested in asymmetric rhodium- and ruthenium-catalyzed hydrogenationsof four alkenes and two ketones. The performance of these ferrocene derivatives in catalytic hydrogenationswas compared to those of catalysts based on Josiphos, PPF-t-Bu₂, and Xyliphos [1-Ph₂P-2-R₂P(CH₃)CH-Fc, R = Cy, t-Bu, 3,5-(CH₃)₂C₆H₃)]. Dichloro palladium(II) complexes of Xyliphos and its analogueslacking the stereogenic center were synthesized as model compounds, and their molecular structureswere studied in solution and, for four complexes, in the solid state. In hydrogenation reactions thereplacement of Xyliphos as the catalyst ligand with its analogues lacking the stereogenic center leads tochanges in product configurations or significant increases or decreases in ee values.