Enantioselective Copper(I)‐Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

Dasgupta, Srimoyee; Rivas, Thomas; Watson, Mary P.

doi:10.1002/anie.201507373

Cited by 70 publications

(40 citation statements)

References 56 publications

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“…[12] Theconfigurations of other products were assigned by analogy.U nfortunately,1alkylisochroman acetals are poor substrates under these reaction conditions.N od esired product was observed in the reaction of 1-methoxy-1-methylisochromane with phenyl acetylene. [12] Theconfigurations of other products were assigned by analogy.U nfortunately,1alkylisochroman acetals are poor substrates under these reaction conditions.N od esired product was observed in the reaction of 1-methoxy-1-methylisochromane with phenyl acetylene.…”

Section: Methodsmentioning

confidence: 99%

Enantioselective Copper(I)‐Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

2015

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An enantioselective,copper(I)-catalyzed addition of terminal alkynes to isochroman ketals to set diaryl, tetrasubstituted stereocenters has been developed. The success of this reaction relies on identification of aCu/PyBoxcatalyst capable of distinguishing the faces of the diaryl-substituted oxocarbenium ion. This challenging transformation enables efficient conversion of readily available,racemic ketals into high-value enantioenriched isochroman products with fully substituted stereogenic centers.High yields and enantiomeric excesses are observed for various isochroman ketals and an arrayo f alkynes.Scheme 1. Enantioselective additions to oxocarbeniumions.

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Section: Methodsmentioning

confidence: 99%

Enantioselective Copper(I)‐Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

2015

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“…[1] Thec ombination of C À Hf unctionalization and annulation with various p-unsaturated reactants has been recognized as avaluable strategy for the efficient construction of carbocyclic and heterocyclicc ompounds. Owing to their equilibrium under metal catalysis, [7] allylic acetals might serve as highly activated acrolein oxonium precursors for cross-coupling reactions (Scheme 1A). [3] Azomethine imines have been widely employed in cycloaddition reactions with various coupling partners such as alkenes,a lkynes,a nd allenoates.…”

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confidence: 99%

Allylic Acetals as Acrolein Oxonium Precursors in Tandem C−H Allylation and [3+2] Dipolar Cycloaddition

et al. 2019

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The ruthenium(II)-catalyzed C À Hfunctionalization of (hetero)aryl azomethine imines with allylic acetals is described.The initial formation of allylidene-(methyl)oxoniums from allylic acetals could trigger C(sp 2 )À Ha llylation, and subsequent endo-type [3+ +2] dipolar cycloaddition of polar azomethine fragments to deliver valuable indenopyrazolopyrazolones.T he utility of this method is showcased by the late-stage functionalization of bioactive molecules such as estrone and celecoxib.C ombined experimental and computational investigations elucidate ap lausible mechanism of this new tandem reaction. Notably,the reductive transformation of synthesized compounds into biologically relevant diazocine frameworks highlights the importance of the developed methodology.Inrecent decades,g reat advances in transition-metal-catalyzed CÀHf unctionalization have been achieved due to its remarkable advantage in atom economy and environmental sustainability. [1] Thec ombination of C À Hf unctionalization and annulation with various p-unsaturated reactants has been recognized as avaluable strategy for the efficient construction of carbocyclic and heterocyclicc ompounds. [2] Significant progress in this direction has been realized by av ariety of transition-metal catalysts.I np articular, ruthenium catalysts have been employed due to their low cost, high efficiency, broad substrate scope,a nd good functional group tolerance under relatively mild conditions. [3] Azomethine imines have been widely employed in cycloaddition reactions with various coupling partners such as alkenes,a lkynes,a nd allenoates. [4] Recently,L ie tal. has reported the C(sp 2 ) À Hf unctionalization of azomethine imines under Rh III catalysis to provide 1,2-dihydrophthalazi-nes [5a] and bridged benzoxazepines. [5b] Alkenes have been intensively studied for the formation of heterocyclic compounds in CÀHf unctionalization event involving the nucleophilic addition of directing groups to olefinic moieties or the electrophilic addition of directing groups to M À Ci ntermediates.V ery recently,our group disclosed the Rh III -catalyzed C À Hf unctionalization and in situ annulation reaction using Morita-Baylis-Hillman adducts to afford 2-benzazepines, [6a] bridged benzoxazepines, [6b] and 2-naphthols. [6c] In these transformations,weobserved that the ester functionality on MBH adducts can lower the energy barrier of the migratory insertion step,h ence enhancing the catalytic cycle.O nt he other hand, allyl acetate was inactive under the identical reaction condition, which was supported by DFT calculations. [6a] These results indicate that the electron density on olefin moiety is crucial for the success of the reaction. In this regard, we envisioned that we might overcome this issue if ah igher inductive effect at the allylic position can be produced. Owing to their equilibrium under metal catalysis, [7] allylic acetals might serve as highly activated acrolein oxonium precursors for cross-coupling reactions (Scheme 1A). Interestingly,w ed iscovered in the...

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“…[13] Obwohl Oxocarbeniumionen umfangreich in Glykosylierungen und Naturstoffsynthesen ausgeschçpft wurden, sind ihre Anwendungen in asymmetrischen Synthesen rar. [13] Obwohl Oxocarbeniumionen umfangreich in Glykosylierungen und Naturstoffsynthesen ausgeschçpft wurden, sind ihre Anwendungen in asymmetrischen Synthesen rar.…”

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Kann ein Keton reaktiver als ein Aldehyd sein? Katalytische asymmetrische Synthese von substituierten Tetrahydrofuranen

2018

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O-Heterocyclen mit tetrasubstituiertem stereogenem Zentrum entstehen in einer katalytischen, chemo-und enantioselektiven nukleophilen Addition von Silylketenacetalen an Ketoaldehyde,bei der das Keton bevorzugt reagiert. 5-und 6-Ringe mit aromatischen oder aliphatischen Substituenten werden erhalten. Außerdem werden 2,2,5-trisubstituierte und 2,2,5,5-tetrasubstituierte Tetrahydrofurane mit exzellenten Stereoselektivitäten synthetisiert. Der synthetische Nutzen der beschriebenen Methode wird durch die dreistufige Synthese der Seitenkette von Anhydroharringtonin demonstriert.

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Enantioselective Copper(I)‐Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

Cited by 70 publications

References 56 publications

Enantioselective Copper(I)‐Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

Enantioselective Copper(I)‐Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

Allylic Acetals as Acrolein Oxonium Precursors in Tandem C−H Allylation and [3+2] Dipolar Cycloaddition

Kann ein Keton reaktiver als ein Aldehyd sein? Katalytische asymmetrische Synthese von substituierten Tetrahydrofuranen

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