The asymmetric reduction of imidazolinones with trichlorosilane

Wagner, Christian; Kotthaus, Andreas; Kirsch, Stefan F.

doi:10.1039/c7cc01561e

Cited by 13 publications

(5 citation statements)

References 51 publications

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“…Our investigation started with a test of our hypothesis that iminium ion intermediate IM would be generated from imine 1 , enamine 2 , and trichlorosilane − and reduced intramolecularly by the hydrosilyl group in the presence of an appropriate Lewis base (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of Nitrogen-Containing Compounds from Enamines

et al. 2017

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The domino reaction of enamines, electrophiles (N-sulfonylimines, N-tosylisocyanate, or diethyl azodicarboxylate), and trichlorosilane provided trans-amines (trans/cis = > 99:1 to 96:4). Meanwhile, the sequential imino ene-type reaction of enamines and electrophiles/NaBHCN reduction afforded cis-amines (trans/cis = 1:>99 to 15:85). The reversal of selectivity is discussed on the basis of diastereofacial selection of the plausible iminium ion intermediates. For the domino reaction of cyclic enamines and cyclic imines, high enantioselectivity (er = 95.7:4.3 to 99.9:0.1) was achieved by utilizing chiral Lewis base catalysts.

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Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of Nitrogen-Containing Compounds from Enamines

et al. 2017

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“…[64] In 2017, Kirsch reported a novel Lewis base organocatalyst on the basis of 2,2'-bispyrrolidine core for the enantioselective reduction of imidazolinones with trichlorosilane. [65] In the presence of catalyst 37, the reduction reaction proceed smoothly under mild reaction condition, affording the chiral imidazolidinone adducts with high yields and excellent enantioselectivities (Scheme 11g). As for the aryl-substituted imidazolinone substrates, only 2 mol% catalyst loading was required.…”

Section: Chiral Picolinamide Derivatives As Catalystsmentioning

confidence: 99%

The Development of Organocatalytic Asymmetric Reduction of Carbonyls and Imines Using Silicon Hydrides

et al. 2021

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The asymmetric reduction of prochiral ketones and ketimines represents one of the most important and practical chemical transformations toward the synthesis of valuable chiral alcohols and amines. Among the existing strategies, organocatalyzed asymmetric reduction of carbonyls and imines using silicon hydrides is attractive due to low-cost, chemical stability, and easy handling in experiments. In this review, we wish to highlight the recent progress made in the past fifteen years in this field. Four catalytic systems of different activation modes are presented and discussed in detail. We aim to help shed light on common features that enable highly enantioselective silicon hydride reductions through organocatalysis and provide the design principles for the development of more effective catalytic systems.

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“…Thus, the catalyst role was mainly analyzed through the observed enantioselectivity. The low degree of induction achieved with Cbz-L-Val was surprising, since a variety of catalysts have been reported based on this amino acid [4][5][6][7][47][48][49]. Only appreciable asymmetric induction (62% ee) was observed for Cbz-L-Pro, probably due to its cyclic structure that can reduce the conformational freedom at the transition state, favoring an efficient chirality transfer [50].…”

Section: Catalyst Screeningmentioning

confidence: 99%

Rational Design of Simple Organocatalysts for the HSiCl3 Enantioselective Reduction of (E)-N-(1-Phenylethylidene)aniline

et al. 2021

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Prolinamides are well-known organocatalysts for the HSiCl3 reduction of imines; however, custom design of catalysts is based on trial-and-error experiments. In this work, we have used a combination of computational calculations and experimental work, including kinetic analyses, to properly understand this process and to design optimized catalysts for the benchmark (E)-N-(1-phenylethylidene)aniline. The best results have been obtained with the amide derived from 4-methoxyaniline and the N-pivaloyl protected proline, for which the catalyzed process is almost 600 times faster than the uncatalyzed one. Mechanistic studies reveal that the formation of the component supramolecular complex catalyst-HSiCl3-substrate, involving hydrogen bonding breaking and costly conformational changes in the prolinamide, is an important step in the overall process.

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The asymmetric reduction of imidazolinones with trichlorosilane

Cited by 13 publications

References 51 publications

Stereoselective Synthesis of Nitrogen-Containing Compounds from Enamines

Stereoselective Synthesis of Nitrogen-Containing Compounds from Enamines

The Development of Organocatalytic Asymmetric Reduction of Carbonyls and Imines Using Silicon Hydrides

Rational Design of Simple Organocatalysts for the HSiCl3 Enantioselective Reduction of (E)-N-(1-Phenylethylidene)aniline

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