Biferrocene-Based Diphosphine Ligands: Synthesis and Application of Walphos Analogues in Asymmetric Hydrogenations

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• 作者：Afrooz Zirakzadeh ; Manuela A. Gro脽 ; Yaping Wang ; Kurt Mereiter ; Felix Spindler ; Walter Weissensteiner
• 刊名：Organometallics
• 出版年：2013
• 出版时间：February 25, 2013
• 年：2013
• 卷：32
• 期：4
• 页码：1075-1084
• 全文大小：489K
• 年卷期：v.32,no.4(February 25, 2013)
• ISSN：1520-6041

文摘

A total of four biferrocene-based Walphos-type ligands have been synthesized, structurally characterized, and tested in the rhodium-, ruthenium- and iridium-catalyzed hydrogenation of alkenes and ketones. Negishi coupling conditions allowed the biferrocene backbone of these diphosphine ligands to be built up diastereoselectively from the two nonidentical and nonracemic ferrocene fragments (R)-1-(N,N-dimethylamino)ethylferrocene and (S_Fc)-2-bromoiodoferrocene. The molecular structures of (S_Fc)-2-bromoiodoferrocene, the coupling product, two ligands, and the two complexes ([PdCl₂(L)] and [RuCl(p-cymene)(L)]PF₆) were determined by X-ray diffraction. The structural features of complexes and the catalysis results obtained with the newly synthesized biferrocene-based ligands were compared with those of the corresponding Walphos ligands.