Synthesis of Fused Arylboronic Esters via Cobalt(0)-Mediated Cycloaddition of Alkynylboronates with α,ω-Diynes

Gandon, Vincent; Leca, Dominique; Aechtner, Tobias; Vollhardt, K. Peter C.; Malacria, and Max; Aubert, Corinne

doi:10.1021/ol0485823

Cited by 93 publications

(51 citation statements)

References 25 publications

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“…However, examples featuring enol ethers were restricted to cocyclization with the monoalkyne (phenylethynyl)pinacolborate. The synthetic value of the products [14] prompted the current study.…”

Section: Introductionmentioning

confidence: 99%

Cobalt‐Mediated Linear 2:1 Co‐oligomerization of Alkynes with Enol Ethers to Give 1‐Alkoxy‐1,3,5‐Trienes: A Missing Mode of Reactivity

Lebœuf

Iannazzo

Geny

et al. 2010

Chemistry A European J

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A variety of 1,6-heptadiynes and certain borylalkynes co-oligomerize with enol ethers in the presence of [CpCo(C(2)H(4))(2)] (Cp=cyclopentadienyl) to furnish the hitherto elusive acyclic 2:1 products, 1,3,5-trien-1-ol ethers, in preference to or in competition with the alternative pathway that leads to the standard [2+2+2] cycloadducts, 5-alkoxy-1,3-cyclohexadienes. Minor variations, such as lengthening the diyne tether, cause reversion to the standard mechanism. The trienes, including synthetically potent borylated derivatives, are generated with excellent levels of chemo-, regio-, and diastereoselectivity, and are obtained directly by decomplexation of the crude mixtures during chromatography. The cyclohexadienes are isolated as the corresponding dehydroalkoxylated arenes. In one example, even ethene functions as a linear cotrimerization partner. The alkoxytrienes are thermally labile with respect to 6pi-electrocyclization-elimination to give the same arenes that are the products of cycloaddition. The latter, regardless of the mechanism of their formation, can be viewed as the result of a formal [2+2+2] cyclization of the starting alkynes with acetylene. One-pot conditions for the exclusive formation of arenes are developed. DFT computations indicate that cyclohexadiene and triene formation share a common intermediate, a cobaltacycloheptadiene, from which reductive elimination and beta-hydride elimination compete.

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Section: Introductionmentioning

confidence: 99%

Cobalt‐Mediated Linear 2:1 Co‐oligomerization of Alkynes with Enol Ethers to Give 1‐Alkoxy‐1,3,5‐Trienes: A Missing Mode of Reactivity

Lebœuf

Iannazzo

Geny

et al. 2010

Chemistry A European J

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“…So kçnnen z. B. Alkinylboronate [9] oder Diborylacetylene [10] als Reagentien und Metallaborane als Katalysatoren eingesetzt werden. [11] Deshalb zogen wir Cyclisierungen als eine Mçglichkeit zur Azaborinsynthese in Betracht.…”

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Metall‐vermittelte Synthese von 1,4‐Di‐tert‐butyl‐1,4‐azaborin

et al. 2012

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Klavierstück im 1,4‐Takt: Während 1,2‐Azaborine schon lange bekannt sind, weiß man noch wenig über ihre 1,3‐ und 1,4‐Gegenstücke. Jetzt gelang die einfache, kontrollierte Synthese von 1,4‐Di‐tert‐butyl‐1,4‐azaborin ausgehend von Acetylen und Di‐tert‐butyliminoboran über eine Metall‐vermittelte formale [2+2+2]‐Cycloaddition. Ein η4‐1,2‐Azaboret‐Klavierhockerkomplex wurde als Reaktionsintermediat identifiziert.

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“…Polyfunctionalized boron compounds were obtained with excellent meta-selectivities (>95:<5) and in good yields under mild conditions. For instance, starting from diene (13) and enyne (14), 1,4-cyclohexadiene (15) was obtained in 91% yield (Fig. (7)).…”

Section: Iii-2 [4+2] Cycloadditionsmentioning

confidence: 99%

Cycloadditions, Cycloisomerizations and Related Reactions of Alkynes Bearing Group 13 or 14 Heteroelements

Gandon¹,

Aubert²,

Malacrìa

2005

COC

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Cycloaddition and cycloisomerization reactions involving alkynes grant a rapid access to arenes, cyclic dienes, and cyclopentenone derivatives. The use of alkynes substituted by group 13 or 14 heteroelements as partners for such reactions is an emerging strategy. Indeed, the specific electronic properties of these heteroelements can play a crucial role for controlling the chemo-and regioselective outcome of a given reaction. Moreover, the heteroatoms can be considered as latent functional groups and would allow for further transformations including Suzuki-Miyaura or Stille crosscouplings. Both aspects will be presented in this review.

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Synthesis of Fused Arylboronic Esters via Cobalt(0)-Mediated Cycloaddition of Alkynylboronates with α,ω-Diynes

Abstract: [reaction: see text] Co(2)(CO)(6)-complexed alkynyl pinacolborane derivatives are readily transformed with functional group tolerance into fused arylboronates via the [2 + 2 + 2]cycloaddition to alpha,omega-diynes.

Cited by 93 publications

References 25 publications

Cobalt‐Mediated Linear 2:1 Co‐oligomerization of Alkynes with Enol Ethers to Give 1‐Alkoxy‐1,3,5‐Trienes: A Missing Mode of Reactivity

Cobalt‐Mediated Linear 2:1 Co‐oligomerization of Alkynes with Enol Ethers to Give 1‐Alkoxy‐1,3,5‐Trienes: A Missing Mode of Reactivity

Metall‐vermittelte Synthese von 1,4‐Di‐tert‐butyl‐1,4‐azaborin

Cycloadditions, Cycloisomerizations and Related Reactions of Alkynes Bearing Group 13 or 14 Heteroelements

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