1,1-Dibromoalkenes as versatile reagents to a transition metal-free and stereoselective synthesis of ( E )-1-bromo-1-selenoalkenes and ketene selenoacetals

Webber, Rodrigo; Peglow, Thiago J.; Nobre, Patrick C.; Barcellos, Angelita M.; Roehrs, Juliano A.; Schumacher, Ricardo F.; Perin, Gelson

doi:10.1016/j.tetlet.2016.07.018

Cited by 11 publications

(12 citation statements)

References 40 publications

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“…For this purpose, it was necessary to prepare the key selenanyl alkynes 6 a ‐ c from 1‐(2,2‐dibromovinyl)‐2‐butylselenanylbenzene 2 a . It was possible using a reaction that was recently developed by us to prepare ( E )‐1‐bromo‐1‐selenanylalkenes …”

Section: Resultsmentioning

confidence: 99%

“…The vinyl selenides 7 were prepared starting from 2 a and diaryl diselenides 8 a ‐ c in the presence of NaBH 4 /PEG‐400 as a reducing system (to generate in situ the nucleophilic selenium species) . The crude product was subject to a dehydrobromination using 1.0 equiv.…”

Section: Resultsmentioning

confidence: 99%

“…Considering the previously described works, a plausible mechanism for the synthesis of 2‐arylsulfanylbenzo[ b ]selenophenes 5 starting from 1‐(2,2‐dibromovinyl)‐2‐butylselenanylbenzene 2 a is depicted on Scheme . The first step is the addition of the nucleophilic sulfur species to the double bond of 2 a , affording the intermediate A .…”

Section: Resultsmentioning

confidence: 99%

“…Recently, Ni and co‐workers described the reaction of 1,1‐dibromoalkenes with several thiols in a basic media to afford selectively sulfanyl alkynes in good yields. More recently, we described the synthesis of ( E )‐1‐bromo‐1‐selenanylalkenes and ketene selenanylacetals, and ( E )‐bromostyrenes starting from 1,1‐dibromoalkenes. Considering the versatility of the electrophilic cyclization approach to access 3‐functionalized benzo[ b ]selenophenes, we envisioned that 1‐(2‐organylchalcogenylethynyl)‐2‐butylselenanylbenzenes 3 could be a suitable starting material to this reaction.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of 2‐Organylchalcogenyl–benzo[b]selenophenes: 1‐(2,2‐Dibromovinyl)‐2‐butylselenanylbenzenes as Precursors to Access Alkynes Susceptible to Cyclization

et al. 2017

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A convenient synthesis of 1‐(2‐organylchalcogenylethynyl)‐2‐butylselenanylbenzenes was established taking advantage of the selective reaction of 1‐(2,2‐dibromovinyl)‐2‐butylselenanylbenzenes with thiols or diorganyl diselenides. The new 1‐(2‐chalcogenylethynyl)‐2‐butylselenanylbenzenes were prepared in good yields and used as precursors of 2‐organylchalcogenylbenzo[b]selenophenes via electrophilic cyclization using I2, Br2 or PhSeBr as electrophiles. Different classes of new 3‐substituted‐ (3‐iodo, 3‐bromo, 3‐phenylselenanyl) benzo[b]selenophenes were prepared in good yields. The synthetic application of the obtained products was demonstrated employing the benzo[b]selenophenes in Suzuki and Sonogashira cross‐coupling reactions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis of 2‐Organylchalcogenyl–benzo[b]selenophenes: 1‐(2,2‐Dibromovinyl)‐2‐butylselenanylbenzenes as Precursors to Access Alkynes Susceptible to Cyclization

et al. 2017

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“…[13] Boronate complex formation was carried out with lithiated carbamate 2,followed by promotion of the 1,2-metallate rearrangement by addition of magnesium bromide in methanol and warming to 40 8 8C[ Eq. (1)].…”

Section: Allenesareversatilefunctionalgroupsthatcanbeemployedmentioning

confidence: 99%

Enantiodivergent Synthesis of Allenes by Point‐to‐Axial Chirality Transfer

et al. 2018

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Abstract: An enantiodivergent method for the synthesis of multiply substituted allenes is described. Highly enantioenriched,p oint-chiral boronic esters were synthesized by homologation of a-seleno alkenyl boronic esters with lithiated carbamates and eliminated to form axially chiral allene products.B ye mploying either oxidative or alkylative conditions,b oth syn and anti elimination could be achieved with complete stereospecificity.The process enables the synthesis of either Mo rPallenes from as ingle isomer of ap oint-chiral precursor and can be employed for the enantioselective assembly of di-, tri-, and tetrasubstituted allenes.

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Enantiodivergent Synthesis of Allenes by Point‐to‐Axial Chirality Transfer

et al. 2018

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An enantiodivergent method for the synthesis of multiply substituted allenes is described. Highly enantioenriched, point‐chiral boronic esters were synthesized by homologation of α‐seleno alkenyl boronic esters with lithiated carbamates and eliminated to form axially chiral allene products. By employing either oxidative or alkylative conditions, both syn and anti elimination could be achieved with complete stereospecificity. The process enables the synthesis of either M or P allenes from a single isomer of a point‐chiral precursor and can be employed for the enantioselective assembly of di‐, tri‐, and tetrasubstituted allenes.

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1,1-Dibromoalkenes as versatile reagents to a transition metal-free and stereoselective synthesis of ( E )-1-bromo-1-selenoalkenes and ketene selenoacetals

Cited by 11 publications

References 40 publications

Synthesis of 2‐Organylchalcogenyl–benzo[b]selenophenes: 1‐(2,2‐Dibromovinyl)‐2‐butylselenanylbenzenes as Precursors to Access Alkynes Susceptible to Cyclization

Synthesis of 2‐Organylchalcogenyl–benzo[b]selenophenes: 1‐(2,2‐Dibromovinyl)‐2‐butylselenanylbenzenes as Precursors to Access Alkynes Susceptible to Cyclization

Enantiodivergent Synthesis of Allenes by Point‐to‐Axial Chirality Transfer

Enantiodivergent Synthesis of Allenes by Point‐to‐Axial Chirality Transfer

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