Chiral imidazolidinone and proline-derived surface modifiers for the Pt-catalysed asymmetric hydrogenation of activated ketones

Holland, Mareike C.; Meemken, Fabian; Baiker, Alfons; Gilmour, Ryan

doi:10.1016/j.molcata.2014.10.016

Cited by 12 publications

(8 citation statements)

References 34 publications

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“…Most previously synthesized modifiers have been derived from NEA. 3 More recently, Holland et al 74 synthesized a series of imidazolidinone and proline derivatives and tested them concerning their potential as chiral modifiers for the Pt-catalyzed asymmetric hydrogenation of KPL, MBF, and TFAP performed at low H 2 pressures (1 and 10 bar) . No improved enantiodifferentiation could be achieved compared to the parent cinchona alkaloids.…”

Section: Chiral Modifiersmentioning

confidence: 99%

Recent Progress in Heterogeneous Asymmetric Hydrogenation of C═O and C═C Bonds on Supported Noble Metal Catalysts

2017

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The ease of separation, simple regeneration, and the usually high stability of solid catalysts facilitating continuous production processes have stimulated the development of heterogeneous asymmetric hydrogenation catalysis. The simplest and so far most promising strategy to induce enantioselectivity to solid metal catalysts is their modification by chiral organic compounds, as most prominently represented by the cinchona-modified Pt and Pd catalysts for the asymmetric hydrogenation of activated C═O and C═C bonds. In this Review, we provide a systematic account of the research accomplished in the past decade on noble metal-based heterogeneous asymmetric hydrogenation of prochiral C═O and C═C bonds, including all important facets of these catalytic systems. The advances made are critically analyzed, and future research challenges are identified.

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Section: Chiral Modifiersmentioning

confidence: 99%

Recent Progress in Heterogeneous Asymmetric Hydrogenation of C═O and C═C Bonds on Supported Noble Metal Catalysts

2017

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“…The knowledge about the structural requirements of the chiral modifier gained by the experiments with cinchona alkaloids and their derivatives has been used for a modular built-up of simpler modifiers based on enantiomerically pure 2-hydroxy-2-arylethylamines, 26 27,28 and 1-(1-naphtyl)ethylamine. 31 Finally it should be stressed that the optimal choice of the modifier is strongly dependent on the structure of the substrate and the solvent used. A common feature of all efficient synthetic modifiers is the aromatic moiety acting as anchoring unit.…”

Section: View Article Onlinementioning

confidence: 99%

“…Recently the potential of chiral imidazolidinone and proline-derived surface modifiers has been explored, however these synthetic modifiers showed inferior performance compared to cinchona alkaloids. 31 Finally it should be stressed that the optimal choice of the modifier is strongly dependent on the structure of the substrate and the solvent used. This specificity renders it difficult to provide a general rule for the choice of the most suitable modifier for a particular ketone.…”

Section: Chiral Modificationmentioning

confidence: 99%

Crucial aspects in the design of chirally modified noble metal catalysts for asymmetric hydrogenation of activated ketones

Baiker

2015

Chem. Soc. Rev.

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In view of the importance of optically pure chiral products there is ample reason to develop methods that facilitate their efficient production. Compared to the mostly applied homogeneous catalysts based on transition metals coordinated to suitable chiral ligands, heterogeneous chiral catalysts could offer several features that are beneficial for practical application such as stability, ease of catalyst separation and regeneration as well as straightforward access to continuous process operation. Various strategies have been developed for imparting chirality to catalytic active surfaces, among which the chiral modification of active metal surfaces by adsorption of suitable chiral organic compounds has so far been among the most successful. In this tutorial review lessons learned from research on asymmetric hydrogenation on chirally modified noble metals will be presented. Key aspects for the design of such catalysts will be elucidated using chirally modified platinum catalysts for the asymmetric hydrogenation of α-activated ketones as an example.

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“…In recognition of the initial report on cinchona alkaloid-modified Pt catalysts, the general method is referred to as the Orito reaction . In mechanistic studies of the Orito reaction, particular attention has been paid to the structural requirements of the chiral modifier and to the intermolecular interactions leading to stereodirection. − For example, there have been many investigations of the effects of introducing structural variations in chiral modifiers. − In a particularly comprehensive study, Baiker and co-workers compared the hydrogenation of ketopantolactone on Pt modified by 22 secondary amine derivatives of the synthetic modifier ( R )-1-(1-naphthyl)ethylamine, ( R )-NEA . They found that while ( R )-NEA induced an enantiomeric excess (ee) of 52%, 17 of the derivatives produced significantly lower values (ee ≤ 40%) and only two yielded values above 60%.…”

Section: Introductionmentioning

confidence: 99%

Relative Abundances of Surface Diastereomeric Complexes Formed by Two Chiral Modifiers That Differ by a Methyl Group

et al. 2020

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Enantioselectivity in heterogeneous catalysis can be induced through the adsorption of optically active compounds known as chiral modifiers. The modifiers typically stereodirect prochiral reactants on the metal surface through the formation of diastereomeric complexes. Surface science measurements on model systems show several examples where such complexes display multiple abundant binding configurations. Insights into the factors determining the relative populations of complexation states can be potentially gained from comparing slightly variant chiral modifiers. Here, we compare scanning tunneling microscopy (STM) data for chirality transfer complexes formed by (R)-1-(1-naphthyl)ethylamine and (R)-1-(8-methyl-1-naphthyl)ethylamine coadsorbed with the prochiral substrate 2,2,2-trifluoroacetophenone in order to probe for changes induced by the methyl substituent. The comparison shows changes in relative abundances beyond those predicted by only direct steric interaction. Density functional theory (DFT) methods are used to calculate complexation energies. A number of rationalizations are proposed for the experimentally determined differences in relative abundances and also for differences between DFT-predicted and STM-measured populations.

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Chiral imidazolidinone and proline-derived surface modifiers for the Pt-catalysed asymmetric hydrogenation of activated ketones

Cited by 12 publications

References 34 publications

Recent Progress in Heterogeneous Asymmetric Hydrogenation of C═O and C═C Bonds on Supported Noble Metal Catalysts

Recent Progress in Heterogeneous Asymmetric Hydrogenation of C═O and C═C Bonds on Supported Noble Metal Catalysts

Crucial aspects in the design of chirally modified noble metal catalysts for asymmetric hydrogenation of activated ketones

Relative Abundances of Surface Diastereomeric Complexes Formed by Two Chiral Modifiers That Differ by a Methyl Group

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