A Stereochemically Well-Defined Rhodium(III) Catalyst for Asymmetric Transfer Hydrogenation of Ketones

Matharu, Daljit S.; Morris, David J.; Kawamoto, Aparecida M.; Clarkson, Guy J.; Wills, Martin

doi:10.1021/ol052559f

Cited by 169 publications

(64 citation statements)

References 31 publications

(18 reference statements)

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“…8,17 It is usually formed in-situ through the reaction of the it is not surprising that under the experimental conditions used both bases are fully protonated. Furthermore, the solvent system is not just acetonitrile; it is a mixture of acetonitrile, ca.…”

Section: Resultsmentioning

confidence: 99%

The kinetics and mechanism of the organo-iridium-catalysed enantioselective reduction of imines

et al. 2016

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The iridium complex of pentamethylcyclopentadiene and (S,S)-1,2-diphenyl-N ′ -tosylethane-1,2-diamine is an effective catalyst for the asymmetric transfer hydrogenation of imine substrates under acidic conditions. Using the Ir catalyst and a 5:2 ratio of formic acid: triethylamine as the hydride source for the asymmetric transfer hydrogenation of 1-methyl-3,4-dihydroisoquinoline and its 6,7-dimethoxy substituted derivative, in either acetonitrile or dichloromethane, shows unusual enantiomeric excess (ee) profiles for the product amines. The reactions initially give predominantly the (R) enantiomer of the chiral amine products with >90% ee but which then decreases significantly during the reaction. The decrease in ee is not due to racemisation of the product amine, but because the rate of formation of the (R)-enantiomer follows first-order kinetics whereas that for the (S)-enantiomer is zero-order. This difference in reaction order explains the change in selectivity as the reaction proceeds -the rate formation of the (R)-enantiomer decreases exponentially with time while that for the (S)-enantiomer remains constant. A reaction scheme is proposed which requires rate-limiting hydride transfer from the iridium hydride to the iminium ion for the first-order rate of formation of the (R)-enantiomer amine and rate-limiting dissociation of the product for the zero-order rate of formation of the (S)-enantiomer.

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Section: Resultsmentioning

confidence: 99%

The kinetics and mechanism of the organo-iridium-catalysed enantioselective reduction of imines

et al. 2016

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“…In order to support the tethered catalyst 1, developed by Wills and co-workers (Figure 1), [19] we decided to utilize a linker that could be connected to amine-functionalized soluble and solid supports via simple amide coupling procedures. In order to avoid unwanted interactions between catalyst and support, sufficient distance between the polymeric support and the catalytic center had to be assured.…”

Section: Resultsmentioning

confidence: 99%

“…[18] These catalysts showed high rates and excellent enantioselectivities in the triethylamine/formic acid system as well as in aqueous solutions of sodium formate. [19,20] With respect to operational and environmental aspects, a major drawback of homogeneously dissolved catalysts is the elaborate separation from reactants and products after the reaction has finished. In order to overcome this problem and to permit catalyst recycling, a multitude of methods for the immobilization of catalysts has been developed.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of a Modified Tethered Rhodium(III)‐p‐Toluenesulfonyl‐1,2‐diphenylethylenediamine Catalyst on Soluble and Solid Polymeric Supports and Successful Application to Asymmetric Transfer Hydrogenation of Ketones

et al. 2010

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Catalyst immobilization through covalent attachment onto a support is one strategy to provide recyclable systems. Here, soluble and surface-functionalized solid polymers were used as supports for a modified tethered rhodiumAThe supported catalysts were applied to the asymmetric transfer hydrogenation of phenyl ketones in aqueous solution of sodium formate. High ee values (up to 99%) and good activities were achieved. It was discovered that the solid polymersupported catalyst could be recycled at least four times without a significant decrease of the activity when a mixture of sodium formate and formic acid was used as the hydrogen source. This catalytic system provides a promising approach towards an ecologically and economically rational production of enantioenriched building blocks.

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“…[103] The importance of this transformation was recognized in 2001 when Noyori was awarded the Nobel Prize for Chemistry, shared with Knowles and Sharpless. [104] While ruthenium complexes have been undisputedly popular catalysts in ATH [105] and in AH [106] of ketones, iridiumbased systems have received more attention in the asymmetric hydrogenation of imines [1] (vide supra) as well as in asymmetric hydrogenations of (unfunctionalized) olefins. [4] Nonetheless, recent developments have demonstrated the great potential of chiral iridium complexes also as catalysts for ketone reductions.…”

Section: Iridium-catalyzed Asymmetric Hydrogenation and Transfer Hydrmentioning

confidence: 99%

Enantioselective Synthesis of Alcohols and Amines by Iridium‐Catalyzed Hydrogenation, Transfer Hydrogenation, and Related Processes

Bartoszewicz

Ahlsten

Martín‐Matute

2013

Chemistry A European J

160

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The preparation of chiral alcohols and amines by using iridium catalysis is reviewed. The methods presented include the reduction of ketones or imines by using hydrogen (hydrogenations), isopropanol, formic acid, or formate (transfer hydrogenations). Also dynamic and oxidative kinetic resolutions leading to chiral alcohols and amines are included. Selected literature reports from early contributions to December 2012 are discussed.

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A Stereochemically Well-Defined Rhodium(III) Catalyst for Asymmetric Transfer Hydrogenation of Ketones

Cited by 169 publications

References 31 publications

The kinetics and mechanism of the organo-iridium-catalysed enantioselective reduction of imines

The kinetics and mechanism of the organo-iridium-catalysed enantioselective reduction of imines

Immobilization of a Modified Tethered Rhodium(III)‐p‐Toluenesulfonyl‐1,2‐diphenylethylenediamine Catalyst on Soluble and Solid Polymeric Supports and Successful Application to Asymmetric Transfer Hydrogenation of Ketones

Enantioselective Synthesis of Alcohols and Amines by Iridium‐Catalyzed Hydrogenation, Transfer Hydrogenation, and Related Processes

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