New monodentate chiral phosphite ligands for asymmetric hydrogenation

Hannen, Peter; Militzer, Hans‐Christian; Vogl, Erasmus M.; Rampf, Florian A.

doi:10.1039/b306793a

Cited by 49 publications

(24 citation statements)

References 7 publications

(5 reference statements)

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“…The mixture was stirred for additional 3 h. The obtained solution was washed with water (200 mL), dried over Na 2 SO 4 , filtered, and concentrated. The residue was purified by flash chromatography (silica gel, CH 2 Cl 2 ) to give the desired product; yields: 40-67 %.…”

Section: General Procedures For Preparation Of Ligandsmentioning

confidence: 99%

“…A dry autoclave under argon atmosphere was charged with a mixture of the rhodium complex 1 (1.25 mg; 2 10 À3 mmol) and 316 mg (2 mmol) of substrate 9 in 2 mL of [BDMIM]BF 4 . Hydrogen was blown through, and hydrogen at 25 bar was introduced.…”

Section: Procedures For Hydrogenation In [Bdmim]bfmentioning

confidence: 99%

“…Since then this chemistry has been generalized to include other reaction types and other monodentate P ligands, [4] and the first detailed mechanistic study has appeared. [5] None of these chiral ligands has been prepared and used catalytically in ionic form.…”

Section: Introductionmentioning

confidence: 99%

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Chiral Ionic Phosphites and Diamidophosphites: A Novel Group of Efficient Ligands for Asymmetric Catalysis

et al. 2007

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Seven members of a new class of chiral P-monodentate cationic phosphites and diamidophosphites have been synthesized for the first time and tested as ligands in asymmetric transition metal catalysis. Up to 96 % ee was achieved in the rhodium-catalyzed asymmetric hydrogenation of functionalized olefins and up to 99 % ee in the palladium-catalyzed allylic allylation. Applications of the immobilized cationic rhodium complex to asymmetric catalytic synthesis have also been demonstrated.

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Section: General Procedures For Preparation Of Ligandsmentioning

confidence: 99%

Section: Procedures For Hydrogenation In [Bdmim]bfmentioning

confidence: 99%

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Chiral Ionic Phosphites and Diamidophosphites: A Novel Group of Efficient Ligands for Asymmetric Catalysis

et al. 2007

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“…The replacement of the chiral binaphthyl structure in the monophosphite 30 with an achiral biphenyl structure led to an extremely low enantioselectivity (49.7% ee) in rhodium-catalyzed asymmetric hydrogenation of arylenamides. In another example, the chiral monophosphite with a chiral biphenyl backbone developed by Rampf and coworker also gave a low enantioselectivity in asymmetric hydrogenation of enamides [39].…”

Section: Chiral Monodentate Phosphite Ligandsmentioning

confidence: 99%

Enantioselective Hydrogenation of Enamines with Monodentate Phosphorus Ligands

Zhou

Xie

2010

Chiral Amine Synthesis

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Chiral amines are widely used as chiral ligands, auxiliaries, resolving agents, and important intermediates in synthetic chemistry. Asymmetric hydrogenation of enamines such as enamides is an atom economic and straightforward protocol for the preparation of chiral amines. In 1972, Kagan reported the first example of asymmetric hydrogenation of enamides with chiral Rh-DIOP complex as a catalyst [1]. This opened a new window for the asymmetric synthesis of chiral N-acyl amines although the enantioselectivity of the reaction was not more than 78% ee (Scheme 8.1). When Noyori et al. introduced chiral Ru-BINAP, it significantly increased the level of enantioselectivity to 99.5% ee in the asymmetric hydrogenation of N-acyl-1-alkylidenetetrahydroisoquinolines [2]. However, this ruthenium-catalyzed asymmetric hydrogenation is very sensitive to the stereochemistry of the enamide, with only the (Z)-isomer of the enamide being hydrogenated while the (E)-isomer was recovered intact (Scheme 8.2). Another breakthrough in this field came in 1996 when Burk et al. showed that chiral rhodium complexes bearing a diphosphine ligand Me-DuPHOS or Me-BPE could hydrogenate a-arylenamides to yield a wide variety of valuable a-1-arylethylamine derivatives with high enantioselectivities (up to 98.5% ee) (Scheme 8.3) [3]. The merit of this hydrogenation is that both (E)-and (Z)-isomers of b-substituted enamides can be hydrogenated, thus enlarging the substrate scope of the reaction. Subsequently, many efficient diphosphines, such as BICP (bis(diphenylphosphino)dicyclopentane) [4], PennPhosP, NHAc NHAc 1 bar H 2 [RhCl(COD) 2 ] 2 /(S,S)-DIOP EtOH-C 6 H 6 (2 :1), rt 95% yield, 78% ee PPh 2 PPh 2 O O (S,S)-DIOP Scheme 8.1 Rh-DIOP catalyzed asymmetric hydrogenation of enamides.

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“…Since that, ligands of type (BINOL)P-OR have been successfully applied in the hydrogenation of model substrates [12][13][14]. Atropoisomeric ligands containing a biphenyl skeleton have been also developed for Rh-catalysed asymmetric hydrogenations [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Rhodium complexes containing chiral P-donor ligands as catalysts for asymmetric hydrogenation in non conventional media

et al. 2011

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Rhodium-catalysed asymmetric hydrogenation using P-donor ligands, such as new fluorinated (R)-BINOL and azadioxaphosphabicyclo[3.3.0]octane derivatives was carried out in different reaction media such as organic solvent (CH 2 Cl 2 ), ionic liquid ([BMI][PF 6 ]), supercritical carbon dioxide (scCO 2 ) and [BMI][PF 6 ]/scCO 2 mixture. The best enantioselectivities were obtained in neat [BMI][PF 6 ], allowing a recycling up to ten times without activity loss. However, the enantioselectivity was lost due to ligand leaching. The ionic liquid phase containing rhodium molecular species was supported on functionalized multi-walled carbon nanotubes in order to improve the recycling, but unfortunately the asymmetric induction was lost upon catalyst immobilization.

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New monodentate chiral phosphite ligands for asymmetric hydrogenation

Cited by 49 publications

References 7 publications

Chiral Ionic Phosphites and Diamidophosphites: A Novel Group of Efficient Ligands for Asymmetric Catalysis

Chiral Ionic Phosphites and Diamidophosphites: A Novel Group of Efficient Ligands for Asymmetric Catalysis

Enantioselective Hydrogenation of Enamines with Monodentate Phosphorus Ligands

Rhodium complexes containing chiral P-donor ligands as catalysts for asymmetric hydrogenation in non conventional media

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