Highly effective and recyclable dendritic BINAP ligands for asymmetric hydrogenation

Fan, Qing‐Hua; Chen, Yongming; Chen, Xiaomin; Jiang, Dazhi; Xi, Fu; Chan, Albert S. C.

doi:10.1039/b001503m

Cited by 145 publications

(58 citation statements)

References 26 publications

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“…8 Phosphine ligands of which the phosphorus center is part of the dendrimer backbone, were reported by the groups of Dubois and Kakkar, respectively. 9 Furthermore, dendronenlarged diphosphines derived from DPPF, 10 DPPE, 11 and BINAP 12 were studied. Surprisingly, dendron attachment to monodentate phosphines has attracted much less attention.…”

Section: Introductionmentioning

confidence: 99%

Design and synthesis of tris[bis(benzylammonium)aryl]phosphines with bulky meta-substituents

2003

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Abstract-A novel 3,5,3 0 ,5 0 ,3 00 ,5 00 -hexakis(dimethylamino)methyl substituted triphenylphosphine analogue has been prepared. The six amine functionalities of the corresponding phosphine oxide and sulfide were alkylated quantitatively with methyl iodide and benzyl bromide, as well as with G1 and G2 Fréchet dendrons to afford the respective hexa-ammonium triarylphosphine oxides and sulfides. The phosphine sulfide derivatives were deprotected with P(n-Bu) 3 to afford a series of hexa-ammonium triarylphosphines that range from small molecules to first and second generation dendrimers (MW up to 5451.44). Upon formation of the hexa-ammonium salt a clear shift in 31 P NMR is observed, indicative for opening of the C -P-C angle of the triaryl phosphine. Calculations on the hexacationic phosphines show an increased barrier of rotation around the P-C(aryl) bond with increasing size of the N-substituents. The calculated structure of the G2-dendron alkylated hexa-ammonium triarylphosphine shows that this dendritic phosphine has a disc-like rather than a cone-like structure, with an estimated cone angle of approximately 1808 q

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Section: Introductionmentioning

confidence: 99%

Design and synthesis of tris[bis(benzylammonium)aryl]phosphines with bulky meta-substituents

2003

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“…Final R values [I > 2s(I)]: R(F) = 0.0587, wR(F2) = 0.1335, GoF = 0.977, absolute structure parameter 0.02 (12). Crystallographic data (excluding structure factors) for the structure …”

Section: General Procedures For the Hydrosilylation Experimentsmentioning

confidence: 99%

“…[10,11] Fan et al have synthesised a variety of functionalised BINAP ligands bearing dendritic wedges. [12][13][14][15][16][17] In order to attach the polyaryl ether dendrons to the ligand they introduced amino groups in the 5-or 5,5'-positions. These dendritic ligands have been tested as catalysts in various hydrogenation reactions, showing similar selectivities as the BINAP ligand itself but improved recycling properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Peripherally Functionalised Dendritic Binaphthyl (BINAP)‐Systems and their Application as Ligands in the Copper‐Catalysed Hydrosilylation of Acetophenone

Kassube¹,

Wadepohl²,

Gade³

2008

Adv Synth Catal

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Two series of peripherally functionalised dendrimers were synthesised based on poly(ethyleneimine) and poly(amidoamine) (PAMAM) dendri-A C H T U N G T R E N N U N G mers by reaction of (R)-6-N- [(g-carboxyl)butanoyl]-aminomethyl-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl ("Glutaroyl-Aminap") with first to fifth generation PPI and zeroth to fourth generation PAMAM dendrimers using ethyl-N,N-dimethylcarbodiimide (EDC)/1-hydroxybenzotriazole as coupling reagents. All dendritic ligands were characterised by NMR spectroscopy, elemental analysis and, for generations G0-G3, MALDI-TOF mass spectrometry. The relationship between the size/generation of the dendritic ligands and their catalytic properties was established in the asymmetric hydrosilylation of acetophenone. It could be shown that (R)-6-aminomethyl-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl ("HAminap") can be attached to the dendrimers without any significant loss of catalytic selectivity compared to the monomeric ligand Benzoyl-Aminap. The selectivities observed in these reactions were higher than those obtained using unfunctionalised BINAP as ligand.

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“…[9] Fan et al synthesised a variety of functionalised BINAP-ligands bearing dendritic wedges. [10][11][12][13][14][15] To attach the polyaryl ether dendrons to the ligand they introduced amino groups in the 5-or 5,5'-positions. Those dendritic ligands have been tested as catalysts in various hydrogenation reactions, showing similar enantioselectivities as the BINAP ligand itself but with improved recycling properties.…”

Section: Introductionmentioning

confidence: 99%

Immobilisation of the BINAP Ligand on Dendrimers and Hyperbranched Polymers: Dependence of the Catalytic Properties on the Linker Unit

2009

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A series of immobilised Carbo-BINAP ligands has been synthesised using poly(propylene imine) (PPI) dendrimers as soluble supports. They contain up to 64 BINAP ligands at their periphery without an additional linking unit. Despite the high steric requirements of the ligand, all dendrimers could be completely functionalised, resulting in the immobilised systems in good yields. Furthermore, the immobilisation strategy that worked out for the fixation of AMINAP ligands with additional linking units as well as of Carbo-BINAP ligands without additional linking units on dendrimers has thus been extended to less regularly hyperbranched poly(ethylene imines) (PEI) as soluble supports. In that way it has been possible to attach on average 9, 26, and 138 Glutaroyl-AMINAP or Carbo-BINAP ligands to PEIs of different molecular weights. The catalytic properties of these systems in the copper-catalysed hydrosilylation of acetophenone were investigated. The dendritic PPI-bound Carbo-BINAP ligands displayed a strong dependence of enantioselectivity and activity on the generation of the dendrimer. For the Carbo-BINAP and Glutaroyl-AMINAP ligands immobilised on the hyperbranched polymers, however, activities and enantioselectivities comparable to those of the mononuclear catalysts were found. The macromolecular, immobilised BINAP ligands could be recycled several times without any observable loss of activity or enantioselectivity.

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Highly effective and recyclable dendritic BINAP ligands for asymmetric hydrogenation

Cited by 145 publications

References 26 publications

Design and synthesis of tris[bis(benzylammonium)aryl]phosphines with bulky meta-substituents

Design and synthesis of tris[bis(benzylammonium)aryl]phosphines with bulky meta-substituents

Synthesis of Peripherally Functionalised Dendritic Binaphthyl (BINAP)‐Systems and their Application as Ligands in the Copper‐Catalysed Hydrosilylation of Acetophenone

Immobilisation of the BINAP Ligand on Dendrimers and Hyperbranched Polymers: Dependence of the Catalytic Properties on the Linker Unit

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