N-Heterocyclic carbene (NHC) catalyzed annulation of enals and vinyl ketones: a novel synthesis of [2H]-pyranones

Nair, Vijay; Paul, Rony Rajan; Lakshmi, K. C. Seetha; Menon, Rajeev S.; Jose, Anu; Sinu, C. R.

doi:10.1016/j.tetlet.2011.08.157

Cited by 51 publications

(15 citation statements)

References 32 publications

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“…3f As shown in Scheme , their reactions with ketenes,6 aldehydes,5, 7 and esters8 give rise to the formation of azolium enolates 2 ,3h, 5–8 equivalents of ester enolates, which have recently gained great attention. Enolates 2 are usually generated in situ and serve as reactive and synthetically useful nucleophiles in [2+2],6a–e [2+3],6f and [2+4]6g,h, 7, 8b cycloadditions,5–8 Michael additions,7e–h and Mannich reactions8a as well as in enantioselective protonations6i,j, 7a and halogenations (Scheme ) 6k…”

Section: Methodsmentioning

confidence: 99%

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO₂: Intermediates and Pathways

Chang

Wang

et al. 2014

Chemistry A European J

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Titanium dioxide with surface-loaded palladium (Pd-TiO2) was able to easily remove all ten bromine atoms from decabromodiphenyl ether (BDE209) within 1 h under the irradiation of sunlight or an artificial light source. By contrast, fewer than three bromine atoms were eliminated on the pristine TiO2 even with prolonged irradiation (5 h). During the photocatalytic debromination, moreover, the formed BDE intermediates exhibited a significant difference between the Pd-TiO2 and pristine TiO2 systems, and much less position selectivity for the debromination on Pd-TiO2 was observed than that on the pristine TiO2 surface. For another polybrominated diphenyl ether (BDE15), pristine TiO2 was incapable of its photocatalytic reduction, whereas the loading of Pd enabled its debromination to diphenyl ether within 20 min. In addition, an evident induction period appeared in the photocatalytic debromination of BDE15 on Pd-TiO2. The experiments imply that the Pd-cocatalyzed effect changes significantly the photocatalytic reductive debromination pathways.

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Section: Methodsmentioning

confidence: 99%

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO₂: Intermediates and Pathways

Chang

Wang

et al. 2014

Chemistry A European J

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“…3f Ihre Reaktion mit Ketenen,6 Aldehyden5, 7 oder Estern8 führt zur Bildung von Azolium‐Enolaten ( 2 ; Schema ),3h, 5–8 die als Äquivalente von Ester‐Enolaten5 in jüngerer Zeit große Beachtung fanden. Die Enolate 2 werden üblicherweise in situ erzeugt und dienen als reaktive und synthetisch wertvolle Nucleophile bei [2+2]‐,6a–e [2+3]‐6f und [2+4]‐6g,h, 7, 8b Cycloadditionen,5–8 bei Michael‐Additionen7e–h und Mannich‐Reaktionen8a sowie bei enantioselektiven Protonierungen6i,j, 7a und Halogenierungen (Schema ) 6k…”

Section: Methodsunclassified

Struktur und ambidente Reaktivität von Azolium‐Enolaten

Maji

Mayr

2013

Angewandte Chemie

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“…It was found that this synthesis is more efficient upon the addition of ionic liquid 1,3-bis(methanesulfonyl)-imidazolium chloride (20) (15 mol%) and application of DMAP (4-dimethylaminopyridine) or DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) as the base (20 mol%). 21 The result was somewhat surprising as the homoenolate annulation of α,β-unsaturated ketones (chalcones) in other cases provided substituted cyclopentenes. pathways, one has to distinguish between two general versions of the cycloadditions taking place on 24 (or their fused derivatives): with alkynes 25 or with alkenes 28 as dienophiles.…”

Section: Methodsmentioning

confidence: 99%

Regio- and stereoselective syntheses and cycloadditions of substituted 2H-pyran-2-ones and their fused derivatives

Kranjc¹,

Kočevar²

2013

Arkivoc

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Microwave-assisted conditions have been shown to be very efficient for the synthesis of a variety of compounds containing 2H-pyran-2-one skeleton that plays important roles in nature and in synthetic chemistry. Furthermore, such compounds (especially those incorporating a 3-acylamino group) were shown to be efficient partners for the Diels-Alder reactions with a variety of dienophiles including acetylene derivatives, maleic anhydride, substituted maleimides, vinyl-moiety-containing dienophiles, as well as (Z)-1-methoxybut-1-en-3-yne. Reactions were carried out under conventional thermal conditions, microwave irradiation and under high pressure (13-15 kbar) and resulted in a plethora of different product types: anilines, bi-and terphenyls, indoles, isoindoles, 2-oxabicyclo[2.2.2]oct-5-enes and bicyclo[2.2.2]octenes. Many of the transformations showed remarkable regio-and stereoselectivity, depending primarily on the substitution patterns of the reactants and reaction conditions applied.

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N-Heterocyclic carbene (NHC) catalyzed annulation of enals and vinyl ketones: a novel synthesis of [2H]-pyranones

Cited by 51 publications

References 32 publications

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO₂: Intermediates and Pathways

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO₂: Intermediates and Pathways

Struktur und ambidente Reaktivität von Azolium‐Enolaten

Regio- and stereoselective syntheses and cycloadditions of substituted 2H-pyran-2-ones and their fused derivatives

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N-Heterocyclic carbene (NHC) catalyzed annulation of enals and vinyl ketones: a novel synthesis of [2H]-pyranones

Cited by 51 publications

References 32 publications

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO2: Intermediates and Pathways

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO2: Intermediates and Pathways

Struktur und ambidente Reaktivität von Azolium‐Enolaten

Regio- and stereoselective syntheses and cycloadditions of substituted 2H-pyran-2-ones and their fused derivatives

Contact Info

Product

Resources

About

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO₂: Intermediates and Pathways

Rapid, Photocatalytic, and Deep Debromination of Polybrominated Diphenyl Ethers on Pd–TiO₂: Intermediates and Pathways