An unusual Michael addition–dealkylation or elimination via the reaction of tertiary or secondary amines with a (Z)-iodoacrylate

Maw, Graham N.; Thirsk, Carl; Whiting, Andrew

doi:10.1016/s0040-4039(01)01806-8

Cited by 19 publications

(11 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Each method has significant drawbacks; use of organolithium and Grignard reagents may be precluded by other functionality within the molecule, Ullmann couplings typically require high temperatures as well as stoichiometric copper and although the nickel-and palladium-promoted process can be made catalytic through the use of a stoichiometric reductant, the stereoselectivity seen for alkenyl halides is typically poor. [8] As part of our endeavours [9] to construct viridenomycin, [10] palladium-catalysed crosscoupling reactions have been examined involving methyl Z-iodoacrylate 1 and a vinylboronate ester [11] 2 which resulted in complications, rather than HeckMizoroki coupling of the vinylboronate. [12] These chemoselectivity problems were circumvented by use of kinetic and optimisation studies [13] such that methyl Z-iodoacrylate 1 could be selectively coupled to give solely the Heck-Mizoroki product 3.…”

mentioning

confidence: 99%

A Stereoselective Palladium‐Mediated Reductive Coupling of Electron‐Deficient Terminal Iodoalkenes

et al. 2008

Self Cite

View full text Add to dashboard Cite

Iodoacrylate esters undergo palladiumcatalysed reductive homocoupling to derive dienyl diester derivatives. This reductive coupling can be extended to ester-substituted terminal iododienes to derive tetraene diesters. In all cases, the reactions show relatively high levels of stereocontrol, which shows an inversion of stereochemistry about one iodoalkene unit. This process, and the suggestion that the reaction releases diiodine, is consistent with a syn-1,2-addition of an iodopalladium(II)-alkene species across another iodoalkene unit (carbometallation step), followed by reductive syn-elimination of iodopalladium iodide to derive palladium(II) iodide. It appears that under the reaction conditions employed, palladium(II) iodide may equilibrate to palladium(0) and diiodine, which can be observed or trapped out from the reaction mixture.

show abstract

mentioning

confidence: 99%

A Stereoselective Palladium‐Mediated Reductive Coupling of Electron‐Deficient Terminal Iodoalkenes

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…Two possible pathways for tributylamine‐mediated E /Z‐isomerization of 5 involve reversible Michael or isocyanate addition‐elimination pathways, which would yield zwitterionic intermediates 8 and 9 , respectively. Rotation of the requisite carbon–carbon bond in these intermediates, followed by elimination of tributylamine, would effect interconverion of E ‐ 5 and Z ‐ 5 .…”

Section: Resultsmentioning

confidence: 99%

Thermal Synthesis of 3‐Bromothieno[3,2‐c]pyridin‐4‐(5H)‐one: A Telescoped Procedure with Tributylamine

Boros

Káldor

2014

Journal of Heterocyclic Chem

View full text Add to dashboard Cite

3‐Bromothieno[3,2‐c]pyridine‐4‐(5H)‐one (1) was prepared from (2E)‐3‐(4‐bromo‐2‐thienyl)‐2‐propenoic acid (3) by the Eloy–Deryckere thermal benzo/heteropyridinone synthesis. A telescoped procedure was developed, which reduces some of the risk associated with the classic procedure. Use of tributylamine as an additive in this process was shown to facilitate E/Z‐isomerization of the intermediate vinyl isocyanate and lower the temperature necessary for the overall thermal process.

show abstract

“…Iodo-acrilatos podem gerar enaminonas por reação com aminas primárias e secundárias, em ótimos rendimentos 69 . Enonas sulfonil 70 (Esquema 7) ou triclorometil 71 (Esquema 8) substituídas surgem como substratos inusitados na preparação de enaminonas.…”

Section: Esquema 2 Esquemaunclassified

Síntese de enaminonas

Ferraz¹,

Pereira²

2004

Quím. Nova

View full text Add to dashboard Cite

Recebido em 18/9/02; aceito em 13/6/03 SYNTHESIS OF ENAMINONES. The general term "enaminone" is applied to any compound bearing the conjugated system N-C=C-C=O. Enaminones are typical capto-dative ethylenes, showing particular properties due to π-electron delocalization. Their reactivity can be predicted by structural patterns of substitution, conformation and configuration, making them versatile synthetic building blocks. In this review, a variety of methods for the synthesis of enaminones is described. The methods were divided into condensation of amines to β-dicarbonyl compounds, addition of amines to α,β-unsaturated carbonyl compounds, condensation between carbonyl compounds and N-unsaturated functions and other methods, covering the period from 1993 to 2001.Keywords: β-enamino ketones; β-enamino esters; methods of preparation. INTRODUÇÃOO termo geral "enaminona" refere-se a qualquer composto que apresente o sistema conjugado N-C=C-C=O. Enaminonas são compostos β-enamino carbonílicos, derivados de β-dicetonas, β-ceto ésteres e outros compostos β-dicarbonílicos. Os representantes mais comuns desta classe são β-enamino cetonas e β-enamino ésteres, também chamados de amidas vinílogas e carbamatos ou uretanas vinílogas, respectivamente; denominações como "β-aminoenona", "acilvinilamina" e "acilenamina" também são encontradas na literatura.Compostos deste tipo são considerados etilenos capto-dativos típicos, devido ao efeito mesomérico dos substituintes acil e amino sobre a ligação dupla (o que também é denominado efeito "pushpull" de elétrons) 1 . A deslocalização de elétrons π, decorrente deste efeito, tem como conseqüência uma notável polarização destes carbonos olefínicos (como se pode constatar pelos seus deslocamentos químicos de 13 C não usuais) 2 , conferindo a estes compostos uma natureza reativa distinta de seus correlatos estruturais enamina e enona (pela estabilização de seus estados de transição polares) 3 . O efeito mesomérico em enaminonas também é responsável pela coexistência de isômeros conformacionais e configuracionais, devido à restrição rotacional de ligações σ (aumento do caráter π das ligações N-C e C-CO) e à atenuação da barreira de isomerização da dupla ligação olefínica (caráter π diminuído) 4 , esta última podendo ocorrer até mesmo à temperatura ambiente 5 . Quatro formas isoméricas (Esquema 1) são possíveis, e a predominância e a interconversão entre elas dependem de diversos fatores estruturais. O tipo e o volume de substituintes em enaminonas acíclicas podem favorecer uma determinada forma isomérica, em razão de uma menor tensão estrutural ou de uma maior planaridade para conjugação de elétrons π 6,7 . O tautomerismo imino-enamina também pode favorecer o equilíbrio conformacional 8 , e o isômero cis-s-cis pode ser estabilizado por ponte de hidrogênio intramolecular (R 1 = H) [9][10][11] . A isomeria conformacional também é observada para o grupo amino (R 1 ≠ R 2 ), cuja restrição rotacional se intensifica proporcionalmente ao grau de conjugação no sistema enaminona 12 (neste caso a ...

show abstract

An unusual Michael addition–dealkylation or elimination via the reaction of tertiary or secondary amines with a (Z)-iodoacrylate

Cited by 19 publications

References 18 publications

A Stereoselective Palladium‐Mediated Reductive Coupling of Electron‐Deficient Terminal Iodoalkenes

A Stereoselective Palladium‐Mediated Reductive Coupling of Electron‐Deficient Terminal Iodoalkenes

Thermal Synthesis of 3‐Bromothieno[3,2‐c]pyridin‐4‐(5H)‐one: A Telescoped Procedure with Tributylamine

Síntese de enaminonas

Contact Info

Product

Resources

About