Bromination of 2-acetylthiophene and its derivatives

Смирнов, В. А.; Lipkin, A. E.

doi:10.1007/bf00569154

Cited by 11 publications

(5 citation statements)

References 3 publications

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“…The inclusion of a cationic alkyl ammonium substituent into asymmetrical DTEs 1-3 begins with amino acids as starting materials. 28 Initially, we had used NBS and 10 mol% perchloric acid as a phase-transfer catalyst. There are several reported methods for the conversion of primary amines to tertiary amines.…”

Section: Synthesis Of Asymmetrical Amphiphilic Dtesmentioning

confidence: 99%

“…The electrophilic bromination of the coupled products was achieved in good yield to produce 10 and 11 using N-bromosuccinimide (NBS) as the brominating reagent in an acetic anhydride-acetic acid solution. 28 Initially, we had used NBS and 10 mol% perchloric acid as a phase-transfer catalyst. 29 However, reaction times were significantly longer (i.e., greater than three fold) under these reaction conditions.…”

Section: Synthesis Of Asymmetrical Amphiphilic Dtesmentioning

confidence: 99%

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Photocontrol of ion permeation in lipid vesicles with amphiphilic dithienylethenes

et al. 2015

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The integration of photochromic dithienylethenes (DTEs) with lipid vesicles as photoresponsive membrane disruptors for ion transport applications has been examined. We have synthesized three amphiphilic DTEs 1-3 that incorporate a terminally charged alkyl chain, and contain methyl or phenylethynyl substituents at the reactive carbons. Our photochromic reactivity studies suggest that the inclusion of a single alkyl chain favors the photoactive antiparallel conformation of DTEs, given the significant improvement in the cyclization quantum yield over previous phenylethynyl derivatives. Our ion permeation studies show that the open-ring isomers of these DTEs are more disruptive than the closed-ring isomers in the four lipid vesicle systems studied, regardless of their lamellar phase at room temperature. In addition, a steric effect was clearly observed as DTEs incorporating the comparatively smaller methyl group exhibited lower rates of ion permeation than the bulkier phenylethynyl group. In all cases, UV irradiation led to a reduction in ion permeability. In fact, the methyl analog exhibited a significant reduction in ion permeability in gel-phase lipid vesicles upon UV exposure. Also, the hexyl chain derivatives had a greater effect on membrane permeability than the dodecyl derivative owing to their relative position in the bilayer membrane of lipid vesicles.

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Section: Synthesis Of Asymmetrical Amphiphilic Dtesmentioning

confidence: 99%

Section: Synthesis Of Asymmetrical Amphiphilic Dtesmentioning

confidence: 99%

Photocontrol of ion permeation in lipid vesicles with amphiphilic dithienylethenes

et al. 2015

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“…2-Acetyl-5-bromothiophene (1n) was prepared by bromination of 2-acetylthiophene with NBS. 19 a-Bromo ketones 2a, f-g were synthesized by bromination of the corresponding ketones with dioxane dibromide. 20 5-Cyano-2-acetylthiophene was synthesized by reaction of 5-iodo-2-acetylthiophene with copper (I) cyanide.…”

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confidence: 99%

One Step Preparation of 1,4-Diketones from Methyl Ketones and α-Bromomethyl Ketones in the Presence of ZnCl2 · t-BuOH · Et2NR as a Condensation Agent

2000

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1,4-Diketones have been prepared in one step from methyl ketones and a-bromomethyl ketones under the action of ZnCl 2 ·t-BuOH·Et 2 NR as a condensation agent with moderate to high yields. The mechanistic pathway of the reaction is proposed to go through aldol condensation of ketones followed by 1,3-dehydrobromination of aldol products and cleavage of activated cyclopropyl intermediates.1,4-Diketones are useful synthetic intermediates for the preparation of five-membered carbocyclic and heterocyclic compounds. 1 Among the most convenient methods for the synthesis of asymmetrical 1,4-diketones, 2-15 the Michael-Stetter addition of aldehydes to a,b-unsaturated ketones, 6-10 as well as alkylation of stabilized alkaline metal enolates, 10-13 enamines, 13,14 and tin enolates 15 by a-halocarbonyl compounds should be mentioned. However, to our knowledge, the Michael-Stetter method does not give satisfactory results with electron-poor aromatic substrates, 10 and the last three methods are restricted mainly by aromatic or symmetrical aliphatic starting nucleophiles, which should be prepared from the corresponding carbonyl compounds.Recently, we have reported a new simple and regioselective method for the preparation of 1,4-diketones directly from methyl ketones and a-bromo ketones. 16,17 This method is based on the thermodynamically controlled cross aldol condensation of methyl ketones with a-bromo ketones followed by 1,3-dehydrobromination of the aldol products and cleavage of the corresponding intermediate activated cyclopropyl derivatives to 1,4-diketones. Using this approach, we have developed two main preparative procedures. The first is based on the application of two separate stages: aldol condensation of methyl ketones with a-bromo ketones in the presence of magnesium bases, and subsequent conversion of the aldol products into 1,4-diketones by treatment with tertiary amine. 16 In the second procedure, we have succeeded in combining these both stages into one using titanium isopropoxide as the condensation agent. 17In this paper, we propose another simple one step procedure for the preparation of 1,4-diketones 5a-r from methyl ketones 1a-n and a-bromo ketones 2a-g, which gives better results for the synthesis of products with strong a Compounds 3−5: R 1 , R 2 , see Table 1.

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“…40,41 Suzuki cross-coupling reactions of 2-acetyl-5-bromothiophene (2) with activated and deactivated aryl(heteroaryl)boronic acids 3a-e were carried out under thermal heating as well as microwave irradiation conditions using Pd(II)-precatalyst 1 as shown in Table 1. The cross-coupling reactions yielded of the corresponding 5-aryl(heteroaryl)-2-acetylthiophenes 4-8 in almost full conversions with excellent isolated yields regardless of the heating mode.…”

Section: Resultsmentioning

confidence: 99%

Microwave-assisted synthesis of 2-acetyl-5-arylthiophenes and 4-(5-arylthiophen-2-yl)thiazoles via Suzuki coupling in water

Dawood¹,

Elamin²,

Farag³

2015

Arkivoc

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2-Acetyl-5-bromothiophene and 4-(5-bromothiophen-2-yl)-2-methyl-1,3-thiazole, as deactivated bromide candidates, were prepared and used for Suzuki cross-coupling reactions with a number of aryl(hetaryl)boronic acids in water or DMF as solvents. The cross-coupling reactions were carried out under thermal heating as well as microwave irradiating conditions using a benzothiazole-based Pd(II)-precatalyst. Optimization of the catalytic reaction condition was also studied.

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Bromination of 2-acetylthiophene and its derivatives

Cited by 11 publications

References 3 publications

Photocontrol of ion permeation in lipid vesicles with amphiphilic dithienylethenes

Photocontrol of ion permeation in lipid vesicles with amphiphilic dithienylethenes

One Step Preparation of 1,4-Diketones from Methyl Ketones and α-Bromomethyl Ketones in the Presence of ZnCl2 · t-BuOH · Et2NR as a Condensation Agent

Microwave-assisted synthesis of 2-acetyl-5-arylthiophenes and 4-(5-arylthiophen-2-yl)thiazoles via Suzuki coupling in water

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