Asymmetric Substitution at the Tetrasubstituted Chiral Carbon: Catalytic Ring-Opening Alkylation of Racemic 2,2-Disubstituted Aziridines with 3-Substituted Oxindoles

Ohmatsu, Kohsuke; Ando, Yumiko; Ooi, Takashi

doi:10.1021/ja411647x

Cited by 119 publications

(33 citation statements)

References 65 publications

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“…[9] Altogether,t hese results prove that our catalysts allow for the simultaneous facecontrol of 2 and ak inetic resolutiono fo xaziridines 7. [17][18][19][20] Further insights into this reaction were obtained by determiningt he (non)linear effects. [21] We first varied the enantiomeric composition of the catalyst using racemic 7b at different concentrations (Figure 2u pper diagram).…”

Section: Resultsmentioning

confidence: 99%

Bifunctional Ammonium Salt Catalyzed Asymmetric α‐Hydroxylation of β‐Ketoesters by Simultaneous Resolution of Oxaziridines

Novacek

Izzo

Vetticatt

et al. 2016

Chemistry A European J

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Chiral bifunctional urea-containing ammonium salts were found to be very efficient catalysts for asymmetric α-hydroxylation reactions of β-ketoesters with oxaziridines under base-free conditions. The reaction is accompanied by a simultaneous kinetic resolution of the oxaziridine and a plausible and so far unprecedented bifunctional transition-state model has been obtained by means of DFT calculations.

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Section: Resultsmentioning

confidence: 99%

Bifunctional Ammonium Salt Catalyzed Asymmetric α‐Hydroxylation of β‐Ketoesters by Simultaneous Resolution of Oxaziridines

Novacek

Izzo

Vetticatt

et al. 2016

Chemistry A European J

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“…Owing to the therapeutic significance of these compounds, several approaches have been reported for its asymmetric transformations. Some of the most common strategies include asymmetric conjugate addition, aldol and Mannich reaction, Morita‐Baylis‐Hillman reaction and ring opening . In contrast, only few reports have been documented in the direct alkylation approach.…”

Section: Methodsmentioning

confidence: 99%

Catalytic and Enantioselective Direct α‐Alkylation of 3‐Aryl and 3‐Alkyl Oxindole Using Quinine‐Derived Urea Catalyst

et al. 2018

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We report herein an enantioselective direct α‐alkylation of various substituted oxindole derivatives using simple alkyl bromide and a bifunctional quinine‐derived urea catalyst. The developed method catalyzes the α‐alkylation of both 3‐aryl and 3‐alkyl substituted oxindole. The alkylated oxindole products, which contain a chiral quaternary stereocenter were afforded in excellent yields (up to 99%) and moderate to good enantioselectivity (up to 83%).

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“…A related aziridine ring opening with oxindoles 131 enables an efficient kinetic resolution to afford protected amines 134 (Scheme ) . Ring opening of the 2,2‐ disubstituted aziridines 132 occurs with inversion at the more‐substituted quaternary carbon to install a quaternary center.…”

Section: Alkylations With Secondary Electrophilesmentioning

confidence: 99%

Diastereoselective Electrophile‐Directed Alkylations

2019

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Electrophile‐directed alkylations in which a chiral, sp3‐hybridized electrophile, dictates the facial attack on a prochiral nucleophile, provides a powerful method of asymmetric induction. The strategy is inherently efficient because the asymmetry of an sp3‐hybridized electrophile is propagated to install two contiguous chiral centers, the first through an SN2 displacement and the second through preferential facial recognition. The two primary modes of topological matching are through steric approach control and chelation between the electrophile and nucleophile. Electrophiles capable of chelation generally induce higher diastereoselectivity for secondary and primary electrophiles. Key parameters that influence the stereoselectivity are those expected for enolate/anion alkylations: solvent, cation, complexing agents. A generalized enolate‐electrophile alkylation model is used to provide an evaluative framework for collecting related alkylations with the aim of providing insight into the origin of the electrophile‐directed diastereoselectivity as a powerful synthetic strategy.

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Asymmetric Substitution at the Tetrasubstituted Chiral Carbon: Catalytic Ring-Opening Alkylation of Racemic 2,2-Disubstituted Aziridines with 3-Substituted Oxindoles

Cited by 119 publications

References 65 publications

Bifunctional Ammonium Salt Catalyzed Asymmetric α‐Hydroxylation of β‐Ketoesters by Simultaneous Resolution of Oxaziridines

Bifunctional Ammonium Salt Catalyzed Asymmetric α‐Hydroxylation of β‐Ketoesters by Simultaneous Resolution of Oxaziridines

Catalytic and Enantioselective Direct α‐Alkylation of 3‐Aryl and 3‐Alkyl Oxindole Using Quinine‐Derived Urea Catalyst

Diastereoselective Electrophile‐Directed Alkylations

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