New organocatalysts for the asymmetric reduction of imines with trichlorosilane

Malkov, Andrei V.; Vranková, Kvetoslava; Sigerson, Ralph C.; Stončius, Sigitas; Kočovský, Pavel

doi:10.1016/j.tet.2009.08.048

Cited by 44 publications

(24 citation statements)

References 75 publications

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“…17 Despite it being more than a decade since the first asymmetric catalysts for this type of transformation were reported, mechanistic data and insights have been sporadic, and only tentative models have been put forward to explain the selectivity. 18 The most comprehensive study to date is that put forward by Malkov et al, 19 crucially noting the dependence of adventitious Brønsted acids to ensure the success of these reactions. Given the scarcity of mechanistic detail for these catalytic processes, a more in depth structural analysis of the imidazole catalyst system developed in these laboratories has now been conducted, providing new insights into the mechanism of this process, and has delivered a new catalyst with even higher activity.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic investigations of the asymmetric hydrosilylation of ketimines with trichlorosilane reveals a dual activation model and an organocatalyst with enhanced efficiency

Reeder

Torri

et al. 2017

Org. Biomol. Chem.

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Structural probes used to help elucidate mechanistic information of the organocatalyzed asymmetric ketimine hydrosilylation have revealed a new catalyst with unprecedented catalytic activity, maintaining adequate performance at 0.01 mol% loading. A new 'dual activation' model has been proposed that relies on the presence of both a Lewis basic and Brønsted acidic site within the catalyst architecture.

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Section: Introductionmentioning

confidence: 99%

Mechanistic investigations of the asymmetric hydrosilylation of ketimines with trichlorosilane reveals a dual activation model and an organocatalyst with enhanced efficiency

Reeder

Torri

et al. 2017

Org. Biomol. Chem.

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“…2). In the N- formyl valine derivative E [10–11] the proposed transition-state structure involves the formation of a hydrogen-bond between the amide group of the catalyst and the substrate as a necessary element for stereocontrol (for another example of relevant N -formyl proline derivative see [12]). Also in Sun catalysts F [13–14] and sulfinamide G [15] as well as in chiral picolinamides H , reported by Zhang [16–17] and intensely studied by our group [18–23], the presence of the acidic hydrogen of the amide group is essential for the stereochemical efficiency of the metal-free catalyst.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective reduction of ketoimines promoted by easily available (S)-proline derivatives

Bonsignore¹,

Benaglia²,

Raimondi³

et al. 2013

Beilstein J. Org. Chem.

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SummaryThe behavior of readily synthesized and even commercially available (S)-proline derivatives, was studied in the trichlorosilane-mediated reduction of ketoimines. A small library of structurally and electronically modified chiral Lewis bases was considered; such compounds were shown to promote the enantioselective reduction of different substrates in good chemical yields. In the HSiCl3 addition to the model substrate N-phenylacetophenone imine, the organocatalyst of choice led to the formation of the corresponding amine with good stereoselectivity, up to 75% ee. Theoretical studies were also performed in order to elucidate the origin of the stereoselection.

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“…Two new ( S )‐valine‐derived organocatalysts ( 3a , 3b , Scheme ), each bearing a bulky aromatic substituent at the amidic nitrogen, were recently synthesized 12. The efficiencies of the new compounds were tested in model reductions of ketoimines derived from aryl methyl ketones and were found to be slightly inferior to that of Sigamide ( 2c ).…”

Section: Discussionmentioning

confidence: 99%

Trichlorosilane‐Mediated Stereoselective Reduction of C=N Bonds

2010

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The reduction of C=N bonds represents a powerful and widely used transformation allowing new nitrogen‐containing stereocenters to be generated. Chiral amino groups are ubiquitous in a variety of bioactive molecules such as alkaloids, natural products, drugs, and medical agents, so the development of a catalytic stereoselective process for the preparation of enantiomerically enriched amines through ketoimine reduction is attracting increasing interest, especially in view of future industrial applications. Great efforts to develop efficient organocatalytic methods to perform enantioselective imine reductions and reductive amination processes have recently been made. In the last few years, trichlorosilane‐mediated reductions have received constantly increasing attention because the potential to generate chiral catalysts for imine reduction simply by coordination of HSiCl3 with a chiral Lewis base has allowed the development of several efficient organocatalytic systems. Here we offer a complete overview of different chiral promoters of stereoselective reductions with trichlorosilane, classified as N‐formyl derivatives, which may be considered historically the first class of compounds developed as chiral activators of trichlorosilane, picolinamide derivatives, and miscellaneous compounds presented in that order.

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New organocatalysts for the asymmetric reduction of imines with trichlorosilane

Cited by 44 publications

References 75 publications

Mechanistic investigations of the asymmetric hydrosilylation of ketimines with trichlorosilane reveals a dual activation model and an organocatalyst with enhanced efficiency

Mechanistic investigations of the asymmetric hydrosilylation of ketimines with trichlorosilane reveals a dual activation model and an organocatalyst with enhanced efficiency

Enantioselective reduction of ketoimines promoted by easily available (S)-proline derivatives

Trichlorosilane‐Mediated Stereoselective Reduction of C=N Bonds

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