The First Highly Enantioselective Lewis Base Organocatalyzed Hydrosilylation of α‐Imino Esters

Xue, Zhouyang; Jiang, Yan; Yuan, Wei‐Cheng; Zhang, Xiaomei

doi:10.1002/ejoc.200901312

Cited by 57 publications

(20 citation statements)

References 23 publications

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“…Zhang also very recently reported an efficient protocol for the organocatalytic synthesis of α‐amino esters 36. Novel chiral Lewis base organocatalysts derived from trans ‐4‐hydroxy‐ L ‐proline were developed (Scheme ); notably, the catalyst of choice, compound 22 , exhibited only moderate enantioselectivities in the hydrosilylation of N ‐aryl β‐enamino esters, but promoted the hydrosilylation of α‐imino esters with high enantioselectivities (up to 93 % ee values).…”

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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Section: Discussionmentioning

confidence: 99%

Trichlorosilane‐Mediated Stereoselective Reduction of C=N Bonds

2010

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“…11 Nearly all of the 17 catalysts screened displayed good to excellent activity, but varied in their selectivity. 11 Nearly all of the 17 catalysts screened displayed good to excellent activity, but varied in their selectivity.…”

Section: Methodsmentioning

confidence: 99%

Trichlorosilane mediated asymmetric reductions of the CN bond

2012

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Chiral amines are key components in numerous bioactive molecules. The development of efficient and economical ways to access molecules containing this functional group still remains a challenge at the forefront of synthetic chemistry. Of the methods that do exist, the trichlorosilane mediated organocatalytic reduction of ketimines offers significant potential as an alternative strategy. In this perspective, we wish to highlight the progress made in the past decade in this field and offer a direct quantitative comparison to transition-metal mediated process.

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“…Several picholinamide‐sulfonate catalysts ( 2 a – 2 f ) that performed well in catalyzing the hydrosilylation‐transacylation reaction of α‐acyloxy‐β‐enamino esters exhibited poor enantioselectivity in this reaction (Table ). Then other picholinamide catalysts were tested and 2 j was found to exhibit the best ee value (73% ee ) in the reaction. Therefore 2 j was determined as the optimal catalyst for the reaction and used through out the research.…”

Section: Evaluation Of the Chiral Lewis Base Catalysts 2 In Hydrosilymentioning

confidence: 99%

Synthesis of Chiral α‐Mercapto‐β‐acylamido Esters via One‐Pot Asymmetric Hydrosilylation−transacylation of α‐Acylthio‐β‐Enamino Esters

et al. 2019

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Chiral α-mercapto-β-amino acid derivatives are highly significant for the development of new synthetic methodology and pharmaceutics. Until now, only a few catalytic asymmetric transformations for the synthesis of optically active α-mercapto-β-amino acid derivatives have been developed. In continuation of our ongoing research on asymmetric hydrosilylation, herein we report a one-pot asymmetric hydrosilylation-transacylation of N-unprotected α-acylthio-β-enamino esters by employing a chiral picolinamide Lewis base as a catalyst. The reactions afforded a wide variety of α-mercapto-β-acylamido esters with good yields (up to 99%) in good diastereoselectivities (> 20 : 1 d.r.) and moderate to good enantioselectivities (up to 86% ee). Furthermore, the absolute configuration of one product was determined and the configurations of other products were assigned by analogy. Finally, based on the absolute configuration of the product, a mechanism was proposed.[a] Dr.A solution of trichlorosilane (31 μL, 0.3 mmol, 3.0 equiv.) in 120 μL of DCM was added to a stirred solution of the corresponding αacylthio-β-enamino ester 1 (0.1 mmol), BzOH (0.3 mmol) and catalyst 2 j (0.02 mmol) in DCM (1.0 mL) at 0°C. The mixture was stirred at the same temperature for 24 h. Then the reaction mixture was treated with water at room temperature for 1 hour. Afterwards the mixture was extracted with DCM. The combined extracts were washed with brine and dried over anhydrous Na 2 SO 4 . The solvent was removed in vacuo. The residue was subjected to flash column chromatography (silica gel, PE/EA = 20 : 1) to give the desired product. The dr and ee values were determined using established HPLC techniques with chiral stationary phases.

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The First Highly Enantioselective Lewis Base Organocatalyzed Hydrosilylation of α‐Imino Esters

Cited by 57 publications

References 23 publications

Trichlorosilane‐Mediated Stereoselective Reduction of C=N Bonds

Trichlorosilane‐Mediated Stereoselective Reduction of C=N Bonds

Trichlorosilane mediated asymmetric reductions of the CN bond

Synthesis of Chiral α‐Mercapto‐β‐acylamido Esters via One‐Pot Asymmetric Hydrosilylation−transacylation of α‐Acylthio‐β‐Enamino Esters

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