Allylation of Ketones with a Ferrocene‐Based Planar Chiral Lewis Acid

Boshra, Ramez; Doshi, Ami; Jäkle, Frieder

doi:10.1002/ange.200704687

Cited by 9 publications

(2 citation statements)

References 26 publications

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“…Keywords: boron · chirality · ferrocenes · ferrocenylboranes · Lewis acids A C H T U N G T R E N N U N G (BClMe)A C H T U N G T R E N N U N G (SnMe 2 Cl) (A, Fc= ferrocene) can be resolved into its constituent planar chiral enantiomers and that these can be subsequently employed in the enantioselective allylation of ketones. [20] In this context, we would like to also note that Aldridge and co-workers recently obtained compound B in enantiomerically pure form by regioselective ortho-metalation and subsequent diastereomer separation by recrystallization (see Scheme 1). [21] Herein, we describe a high-yielding enantioselective synthesis route to the planar chiral napththyl ferrocenylborane 1,2-Fc(Np)A C H T U N G T R E N N U N G (BCl 2 ) (Np= naphthyl), which in turn serves as a versatile precursor to other chiral organoborane Lewis acids through subsequent transmetalation reactions.…”

Section: Introductionmentioning

confidence: 96%

“…19 Prior efforts by our group involved studies on the binding properties of heteronuclear bidentate 1‐stannyl‐2‐borylferrocene derivatives, which are obtained in their racemic form by a rearrangement reaction from 1,1′‐bis(trimethylstannyl) ferrocene and boron halides RBCl 2 (R=Cl, Ph, C 6 F 5 ) 13. 14 We have demonstrated that the bidentate Lewis acid 1,2‐Fc(BClMe)(SnMe 2 Cl) ( A , Fc=ferrocene) can be resolved into its constituent planar chiral enantiomers and that these can be subsequently employed in the enantioselective allylation of ketones 20. In this context, we would like to also note that Aldridge and co‐workers recently obtained compound B in enantiomerically pure form by regioselective ortho ‐metalation and subsequent diastereomer separation by recrystallization (see Scheme ) 21…”

Section: Introductionmentioning

confidence: 99%

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Planar Chiral Organoborane Lewis Acids Derived from Naphthylferrocene

Chen

Venkatasubbaiah

Thilagar

et al. 2010

Chemistry A European J

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Enantiomerically pure metalated 2-(1-naphthyl)ferrocene (NpFc) derivatives NpFcM (M=SnMe(3), HgCl) were prepared and characterized by multinuclear NMR and UV/Vis spectroscopy, cyclic voltammetry, and elemental analysis. Optical rotation measurements were performed and the absolute configuration of the new planar chiral ferrocene species was confirmed by single-crystal X-ray diffraction analysis. The mercuriated species NpFcHgCl proved suitable as a reagent for the preparation of the chiral organoborane Lewis acid NpFcBCl(2), which can in turn be converted to other ferrocenylboranes by replacement of Cl with nucleophiles. The highly Lewis acidic perfluoroarylborane derivatives NpFcB(C(6)F(5))Cl and NpFcB(C(6)F(5))(2) were successfully prepared by treatment with CuC(6)F(5). The structures were studied by single-crystal X-ray diffraction and variable-temperature (19)F NMR spectroscopy, which suggested that pi stacking of a C(6)F(5) group on boron with the adjacent naphthyl group is energetically favorable. UV/Vis absorption spectroscopy and cyclic voltammetry measurements were performed to examine the electronic properties of these novel redox-active chiral Lewis acids.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Planar Chiral Organoborane Lewis Acids Derived from Naphthylferrocene

Chen

Venkatasubbaiah

Thilagar

et al. 2010

Chemistry A European J

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Diferrocenophosphaborin: A Planar‐Chiral, Redox‐Active and Anion‐Responsive Ambiphilic Ligand

et al. 2015

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An ew class of Janus-like ambiphilic ligands is introduced. The rigid diferrocene backbone in heterocycles 4-SnP and 4-BP creates an unprecedented chiral environment as demonstrated by multinuclear NMR and single-crystal X-ray studies.I na ddition, the ligands are redox-responsive and the Lewis acidic borane moiety in 4-BP can be exploited to further tune the properties:aclear decrease in the CO stretching frequency of aV aska-type Rh I complex 5-BP is observed upon addition of fluoride ions.Thus,the Lewis acid and Lewis base sites influence each other and their strength can be modulated by redox chemistry and anion binding.

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A Family of Chiral Ferrocenyl Diols: Modular Synthesis, Solid‐State Characterization, and Application in Asymmetric Organocatalysis

2016

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Readily available chiral diol scaffolds are useful as sources of chirality for asymmetric synthesis,however,few such scaffolds are readily available in enantiopure form. Reported herein is ac heap and modular synthesis of an ovel family of chiral ferrocenyl diols in excellent yields with excellent enantioand diastereoselectivity (> 99 %e ea nd 99 %d e). These diols possess not only planar and central chirality,b ut also axial chirality around the central iron atom. Characterization of these diols by X-ray crystallography revealed intra-and intermolecular hydrogen-bond networks depending on substitution at the carbinol positions.The potential of these diols as catalysts was subsequently demonstrated in an asymmetric hetero-Diels-Alder reaction which provided cycloadducts in up to 84 %y ield with ee values ranging from À92 to + 72 %.With applications as chiral auxiliaries,ligands,and catalysts,

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Allylation of Ketones with a Ferrocene‐Based Planar Chiral Lewis Acid

Cited by 9 publications

References 26 publications

Planar Chiral Organoborane Lewis Acids Derived from Naphthylferrocene

Planar Chiral Organoborane Lewis Acids Derived from Naphthylferrocene

Diferrocenophosphaborin: A Planar‐Chiral, Redox‐Active and Anion‐Responsive Ambiphilic Ligand

A Family of Chiral Ferrocenyl Diols: Modular Synthesis, Solid‐State Characterization, and Application in Asymmetric Organocatalysis

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