Synthesis and Structure of Platinum Bis(phospholane) Complexes Pt(diphos*)(R)(X), Catalyst Precursors for Asymmetric Phosphine Alkylation

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• 作者：Marites A. Guino-o ; Andrew H. Zureick ; Natalia F. Blank ; Brian J. Anderson ; Timothy W. Chapp ; Youngmin Kim ; David S. Glueck ; Arnold L. Rheingold
• 刊名：Organometallics
• 出版年：2012
• 出版时间：October 8, 2012
• 年：2012
• 卷：31
• 期：19
• 页码：6900-6910
• 全文大小：516K
• 年卷期：v.31,no.19(October 8, 2012)
• ISSN：1520-6041

文摘

The complexes Pt((R,R)-Me-DuPhos)(Ph)(Cl) (1) and Pt((R,R)-i-Pr-DuPhos)(Ph)(Cl) (2) have been used as catalyst precursors in Pt-catalyzed asymmetric alkylation of secondary phosphines. To investigate structure鈥搑eactivity鈥搒electivity relationships in these reactions, analogous complexes with different bis(phospholane) ligands and/or Pt-hydrocarbyl groups were prepared. Treatment of Pt(COD)(R)(Cl) (R = Me, Ph) with BPE or DuPhos ligands gave Pt((R,R)-Me-BPE)(Me)(Cl) (3), Pt((R,R)-Ph-BPE)(Me)(Cl) (5), Pt((R,R)-Ph-BPE)(Ph)(Cl) (6), and Pt((R,R)-i-Pr-DuPhos)(Me)(Cl) (7). However, treatment of Pt(COD)(Me)(Cl) with (R,R)-Me-FerroLANE gave a mixture of products, which were converted upon heating to Pt((R,R)-Me-FerroLANE)(Me)(Cl) (8). A related mixture formed from Pt(COD)(Ph)(Cl) precipitated trans-[Pt((R,R)-Me-FerroLANE)(Ph)(Cl)]_n (9T), which on treatment with AgOTf followed by LiCl gave cis-Pt((R,R)-Me-FerroLANE)(Ph)(Cl) (9) as the major product. The reaction of Pt(COD)(Ph)(Cl) with (R,R)-Me-BPE gave the dinuclear dication [(Pt((R,R)-Me-BPE)(Ph))₂(渭-(R,R)-Me-BPE))][Cl]₂ (10) instead of the expected Pt((R,R)-Me-BPE)(Ph)(Cl) (4). The iodide Pt((R,R)-Me-BPE)(Ph)(I) (11) was formed from Pt(COD)(Ph)(I) and BPE but decomposed readily. Treatment of Pt(COD)X₂ with (R,R)-Me-BPE gave Pt((R,R)-Me-BPE)X₂ (X = Cl (12), I (13)). Reaction of Pt(COD)Ph₂ with (R,R)-Me-BPE gave Pt((R,R)-Me-BPE)Ph₂ (14), which was protonated with HCl to yield 4. Treatment of Pt((R,R)-Me-DuPhos)Cl₂ with excess (9-phenanthryl)magnesium bromide gave Pt((R,R)-Me-DuPhos)(9-phenanthryl)(Br) (15), while a similar reaction with excess (6-methoxy-2-naphthyl)magnesium bromide gave Pt((R,R)-Me-DuPhos)Ar₂ (16). Complexes 3, 4, 6鈥?b>10, and 12鈥?b>14 were structurally characterized by X-ray crystallography. Structure鈥搑eactivity鈥搒electivity relationships in this series of Pt catalyst precursors were investigated in the catalytic alkylation of the bis(secondary phosphine) PhHP(CH₂)₃PHPh with benzyl bromide.