Gold- or Indium-Catalyzed Cross-Coupling of Bromoalkynes with Allylsilanes through a Concealed Rearrangement

Orbe, M. Elena de; Zanini, Margherita; Quinonero, Ophélie; Echavarren, Antonio M.

doi:10.1021/acscatal.9b02314

Cited by 47 publications

(63 citation statements)

References 36 publications

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“…We were able to demonstrate for the first time that the chloroalkynylation of 1,1‐disubstituted alkenes 2 can be achieved through gold(I) catalysis leading to the homopropargyl chlorides 3 in good yields (Scheme a) . This reaction principle can also be extended to bromoacetylenes 4 and 1,2‐disubstituted alkenes ( 5 ; Scheme b) and represents one of the few examples for gold(I)‐catalyzed reactions where the triple bond remains after the reaction . In the case of the gold(I)‐catalyzed haloalkynylation of cyclic alkenes, a side reaction, namely the already known gold(I)‐catalyzed [2+2] cycloaddition, takes place (Scheme b) .…”

Section: Methodsmentioning

confidence: 89%

“…This reaction principle can also be extended to bromoacetylenes 4 and 1,2‐disubstituted alkenes ( 5 ; Scheme b) and represents one of the few examples for gold(I)‐catalyzed reactions where the triple bond remains after the reaction . In the case of the gold(I)‐catalyzed haloalkynylation of cyclic alkenes, a side reaction, namely the already known gold(I)‐catalyzed [2+2] cycloaddition, takes place (Scheme b) . The bromoalkynylation of cyclic alkenes proceeds via a trans addition and can also be accomplished enantioselectively by the use of chiral gold(I) catalysts …”

Section: Methodsmentioning

confidence: 99%

“…Subsequent shift of the aryl group leads to the gold complex 20 , in which the carbon atom that was initially attached to the chlorine atom is now directly bound to the aromatic unit. A mechanism involving a bromonium cyclic intermediate similar to 18 has been proposed for the bromoalkynylation of 1,2‐disubstituted alkenes . Route B starts with addition to the C1 carbon atom of gold complex 14 to form the vinyl cation 22 .…”

Section: Methodsmentioning

confidence: 99%

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Gold(I)‐Catalyzed Haloalkynylation of Aryl Alkynes: Two Pathways, One Goal

Kreuzahler

Haberhauer

2020

Angew Chem Int Ed

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Haloalkynylation reactions provide an efficient method for the simultaneous introduction of a halogen atom and an acetylenic unit. For the first time, we report a gold(I)‐catalyzed haloalkynylation of aryl alkynes that delivers exclusively the cis addition product. This method enables the simple synthesis of conjugated and halogenated enynes in yields of up to 90 %. Notably, quantum chemical calculations reveal an exceptional interplay between the place of the attack at the chloroacetylene: No matter which C−C bond is formed, the same enyne product is always formed. This is only possible through rearrangement of the corresponding skeleton. Hereby, one reaction pathway proceeds via a chloronium ion with a subsequent aryl shift; in the second case the corresponding vinyl cation is stabilized by a 1,3‐chlorine shift. 13C‐labeling experiments confirmed that the reaction proceeds through both reaction pathways.

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Section: Methodsmentioning

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Gold(I)‐Catalyzed Haloalkynylation of Aryl Alkynes: Two Pathways, One Goal

Kreuzahler

Haberhauer

2020

Angew Chem Int Ed

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“…[8] On this basis, we decided to explore the behavior of this type of ligand in the Au I -catalyzed cycloaddition of bromoalkynes with alkenes.T he reactiono f( bromoethynyl)benzene 1a with cyclopentene 2 was chosen asaplatform for preliminary studies. Considering the high synthetic value of the haloalkynylation products and the absence of precedents for this reaction, [9,10] further efforts were directed to find conditions to increase the yield of the insertion product 4a.S ubtle differences in the ligand structure and reaction conditions provedt oh ave am arked effect in the product distribution. To check whethert his minor product is also formed under Zhang's experimental conditions, the reaction was also performed with IPrAuCl precatalyst B.Inf act, as imilaramount(15 %) of 4a was obtained in this case, along with the reported [2+ +2] cycloaddition product 3,o btained in 41 %y ield (entry 2).…”

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confidence: 99%

Au^I‐Catalyzed Haloalkynylation of Alkenes

García-Fernández

Llorente

Iglesias‐Sigüenza

et al. 2019

Chemistry A European J

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The formal insertiono fa lkenes into aromatic chloro-a nd bromoalkynes takes place under cationic gold catalysis. This haloalkynylation reactionc an be performed with cyclic, gem-disubstituted and monosubstituted alkenes, using BINAP,t riazolo [4,3-b]isoquinolin-3-ylidenel igands or SPhos, respectively.T he products were isolated in moderatet oe xcellent yieldsa nd with complete diastereo-and regioselectivity;t he halogen atom bondingt he more substituted carbon of the alkene.P reliminary experiments showedt hat the enantioselective haloalkynylation of cyclopentene can be performedw ith (S)-BINAP to afford the insertion productsw ithmoderate to good enantioselectivities.Cationicg old complexes are the most active catalysts for the electrophilic activation of carbon-carbon multiple bonds, being particularlye fficient and selective for alkynes. [1] In 2010, Echavarren and co-workers discoveredt he intermolecular [2+ +2] cycloadditiono fa lkenes and alkynes, one of the most fundamental transformations in this field and av aluablet ool for the synthesiso fc yclobutenes [2] (Scheme 1A). Very recently, the group of Zhang showed that chloroalkynes are also suitable substrates in such [2+ +2] cycloadditions, leading in this case to valuable chlorocyclobutenes [3] (Scheme 1B). The reaction with bromoalkynes,h owever, led to ap oor yield of the cycloadduct in as ingle example.On the other hand, we have been interested in the design of NHCs featuring heterobi(tri)cyclic architectures,w hich offers opportunities for the modulation of their sterica nd electronic properties. [4] Within this group, triazolylidenes embedded in tricyclic architectures exhibit an extraordinary p-acceptor character,q uantitatively assessed by 77 Se NMR spectroscopy [5] in a model ligand L (Figure 1). [6] Combinedw ith ah igh level of steric protection, the electronic properties of this type of NHCs make them particularly attractive for Au I -catalyzed reactions, particularly fort hose in which the activation of the substrate is the rate-limitings tep. [7] Moreover,t he performance of such ligands hasa lready been shown in challenging asymmetric intermolecular cycloaddition reactions of allenamides. [8] On this basis, we decided to explore the behavior of this type of ligand in the Au I -catalyzed cycloaddition of bromoalkynes with alkenes.T he reactiono f( bromoethynyl)benzene 1a with cyclopentene 2 was chosen asaplatform for preliminary studies. The reaction performed with precatalyst A (L·AuCl) under Zhang's conditions {5 mol % B ((IPr·AuCl), IPr = 1,3bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene)/ 10 mol %N aBArF (sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) in DCE, [1a] = 0,1 m,4 0 8C} afforded the expected cyclobutene 3,i solated in 46 %y ield and,s urprisingly,t he bromoalkynylation (formal insertion) product 4a was isolated as a minor component in 16 %y ield (Table 1, entry 1). To check whethert his minor product is also formed under Zhang's experimental conditions, the reaction was also performed with IPrAuCl p...

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“…Wir konnten erstmalig zeigen, dass eine Chloralkinylierung der 1,1‐disubstituierten Alkene 2 mittels Gold(I)‐Katalyse möglich ist und in guten Ausbeuten zu den homopropargylischen Chloriden 3 führt (Schema a) . Dieses Reaktionsprinzip kann auch auf die Bromacetylene 4 und die 1,2‐disubstituierten Alkene 5 (Schema b) erweitert werden und stellt eines von wenigen Beispielen für Gold(I)‐katalysierte Reaktionen dar, bei dem die Dreifachbindung im Produkt erhalten bleibt . Im Fall der Gold(I)‐katalysierten Haloalkinylierung von cyclischen Alkenen findet eine Nebenreaktion statt, nämlich die bereits bekannte [2+2]‐Cycloaddition (Schema b) .…”

Section: Methodsunclassified

Gold(I)‐katalysierte Haloalkinylierung von Arylalkinen: Zwei Wege, ein Ziel

Kreuzahler

Haberhauer

2020

Angewandte Chemie

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Haloalkynylation reactions provide an efficient method for the simultaneous introduction of a halogen atom and an acetylenic unit. For the first time, we report a gold(I)catalyzed haloalkynylation of aryl alkynes that delivers exclusively the cis addition product. This method enables the simple synthesis of conjugated and halogenated enynes in yields of up to 90 %. Notably, quantum chemical calculations reveal an exceptional interplay between the place of the attack at the chloroacetylene: No matter which CÀC bond is formed, the same enyne product is always formed. This is only possible through rearrangement of the corresponding skeleton. Hereby, one reaction pathway proceeds via a chloronium ion with a subsequent aryl shift; in the second case the corresponding vinyl cation is stabilized by a 1,3-chlorine shift. 13 C-labeling experiments confirmed that the reaction proceeds through both reaction pathways.

show abstract

Gold- or Indium-Catalyzed Cross-Coupling of Bromoalkynes with Allylsilanes through a Concealed Rearrangement

Cited by 47 publications

References 36 publications

Gold(I)‐Catalyzed Haloalkynylation of Aryl Alkynes: Two Pathways, One Goal

Gold(I)‐Catalyzed Haloalkynylation of Aryl Alkynes: Two Pathways, One Goal

Au^I‐Catalyzed Haloalkynylation of Alkenes

Gold(I)‐katalysierte Haloalkinylierung von Arylalkinen: Zwei Wege, ein Ziel

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Gold- or Indium-Catalyzed Cross-Coupling of Bromoalkynes with Allylsilanes through a Concealed Rearrangement

Cited by 47 publications

References 36 publications

Gold(I)‐Catalyzed Haloalkynylation of Aryl Alkynes: Two Pathways, One Goal

Gold(I)‐Catalyzed Haloalkynylation of Aryl Alkynes: Two Pathways, One Goal

AuI‐Catalyzed Haloalkynylation of Alkenes

Gold(I)‐katalysierte Haloalkinylierung von Arylalkinen: Zwei Wege, ein Ziel

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Au^I‐Catalyzed Haloalkynylation of Alkenes