Enantioselective Synthesis of Quaternary Carbon Stereocenters: Addition of 3‐Substituted Oxindoles to Vinyl Sulfone Catalyzed by Pentanidiums

Zong, Lili; Du, Shubo; Chin, Kek Foo; Wang, Chao; Tan, Choon‐Hong

doi:10.1002/ange.201503844

Cited by 20 publications

(3 citation statements)

References 116 publications

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“…To our surprise, we found that pentanidinium could catalyze the Michael addition of 3‐alkyloxindole and vinyl phenyl sulfone with high efficiency (Scheme 5). [45] …”

Section: Pentanidinium Catalyzed Enantioselective Phase‐transfer Reac...mentioning

confidence: 99%

Ion Pair Catalyst ‐ Pentanidinium

Qin

Zhang

et al. 2023

The Chemical Record

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In this account, we further describe our already developed N‐sp2 hybrid guanidinium as an efficient phase‐transfer catalyst and ion pair catalysis based on N‐sp2 hybrid pentanidinium and its application in some new reactions. The sp3 hybrid quaternary ammonium salt has a tetrahedral structure, which means that three sides of it can be effectively steric, allowing the remaining side to be close to the substrate. However, the sp2 hybrid ammonium salt allows the substrate to form ion pairs from both directions respectively, so it is a greater challenge to control the stereoselectivity of the reaction. Van der Waals forces, such as hydrogen bonds and π-π ${\pi -\pi }$ interactions, have been used to make electrophiles approach from a certain direction, leading to a higher enantioselectivity. Based on the above idea, we designed an N‐sp2 hybrid phase‐transfer catalyst, pentanidinium. Pentanidinium has five conjugated nitrogen atoms, one of which has a formal positive charge, which is necessary for it to become an ion pair catalyst. We have confirmed that pentanidinium can catalyze α‐hydroxylation of 3‐substituted‐2‐oxindoles, Michael addition of 3‐alkyloxindoles with vinyl sulfone, and alkylation reactions of sulfenate anions and dihydrocoumarins, desymmetrization of pro‐chiral sulfinate to afford enantioenriched sulfinate esters. Pentanidinium with side chain structure changes can also be catalyzed efficiently with enantioconvergent halogenophilic nucleophilic substitution, including azidation and thioesterification. In the reaction catalyzed by pentanidinium, it always attracts us with the advantages of low catalytic load and good enantioselectivity.

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“…To our surprise, we found that pentanidinium could catalyze the Michael addition of 3‐alkyloxindole and vinyl phenyl sulfone with high efficiency (Scheme 5). [45] …”

Section: Pentanidinium Catalyzed Enantioselective Phase‐transfer Reac...mentioning

confidence: 99%

Ion Pair Catalyst ‐ Pentanidinium

Qin

Zhang

et al. 2023

The Chemical Record

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“…Alternatively,hydrolysis of the cyano group using Rh(COD) 2 OTf and acetaldehyde oxime in refluxing toluene gave the amide 7aa,a nd subsequent reductive cyclization gave rise to the pyrroloindoline 8aa,which is the ubiquitous core structure of awide array of biologically relevant natural products. [17] Finally,the synthetic utility of this catalytic method was clearly demonstrated by its application to the concise asymmetric synthesis of chiral spirocyclohexane oxindole derivatives [Eq. (2) in Scheme 2].…”

Section: Angewandte Chemiementioning

confidence: 99%

Nickel‐Catalyzed Conjugate Addition of Silyl Ketene Imines to In Situ Generated Indol‐2‐ones: Highly Enantioselective Construction of Vicinal All‐Carbon Quaternary Stereocenters

et al. 2017

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The first enantioselective conjugate addition of silyl ketene imines to in situ generated indol-2-ones was performed in the presence of ac hiral N,N'-dioxide/Ni II catalyst. This method provides efficient access to chiral b-alkyl nitriles bearing congested vicinal all-carbon quaternary stereocenters in up to 90 %y ield with 23:1 d.r.a nd 98 %e e. The products enable facile transformations to chiral pyrroloindoline frameworks and spirocyclohexane oxindole derivatives.Apossible transition state was also proposed to explain the origin of the asymmetric induction.

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“…We have recently developed pentanidium27282930 and dicationic bisguanidinium ( BG ) as efficient phase-transfer3132 and ion pair catalysts3334353637. We have utilized bisguanidinium permanganate ion pair catalyst for the enantioselective oxidation of alkenes38.…”

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confidence: 99%

Bisguanidinium dinuclear oxodiperoxomolybdosulfate ion pair-catalyzed enantioselective sulfoxidation

et al. 2016

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Catalytic use of peroxomolybdate for asymmetric transformations has attracted increasing attention due to its catalytic properties and application in catalysis. Herein, we report chiral bisguanidinium dinuclear oxodiperoxomolybdosulfate [BG]2+[(μ-SO4)Mo2O2(μ-O2)2(O2)2]2− ion pair, as a catalyst for enantioselective sulfoxidation using aqueous H2O2 as the terminal oxidant. The ion pair catalyst is isolatable, stable and useful for the oxidation of a range of dialkyl sulfides. The practical utility was illustrated using a gram-scale synthesis of armodafinil, a commercial drug, with the catalyst generated in situ from 0.25 mol% of bisguanidinium and 2.5 mol% of Na2MoO4·2H2O. Structural characterization of this ion pair catalyst has been successfully achieved using single-crystal X-ray crystallography.

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Enantioselective Synthesis of Quaternary Carbon Stereocenters: Addition of 3‐Substituted Oxindoles to Vinyl Sulfone Catalyzed by Pentanidiums

Cited by 20 publications

References 116 publications

Ion Pair Catalyst ‐ Pentanidinium

Ion Pair Catalyst ‐ Pentanidinium

Nickel‐Catalyzed Conjugate Addition of Silyl Ketene Imines to In Situ Generated Indol‐2‐ones: Highly Enantioselective Construction of Vicinal All‐Carbon Quaternary Stereocenters

Bisguanidinium dinuclear oxodiperoxomolybdosulfate ion pair-catalyzed enantioselective sulfoxidation

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