- Exploring Green Solvents Associated to Pd/C as Heterogeneous Catalyst for Direct Arylation of Heteroaromatics with Aryl Bromides
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Metal residues are certainly one of the major sources of contamination of products in metal-catalyzed direct arylation reactions. We found that the use of only 1 mol% of the heterogeneous catalyst Pd/C promotes very efficiently the direct arylations of most heteroaromatics. In the presence of this catalyst and potassium acetate as the base, the direct arylation of thiophenes, furans, pyrroles, thiazoles, imidazoles or isoxazoles, using aryl bromides as coupling partners, proceeds highly regioselectively and in moderate to very high yields. With several heteroarenes both electron-deficient and electron-rich aryl bromides were tolerated; moreover, with the most reactive heteroarenes, the Pd/C catalyst tolerated green solvents such as diethyl carbonate, 3-methylbutan-1-ol and pentan-1-ol, affording a synthetic scheme with low environmental impact. (Figure presented.).
- Mao, Shuxin,Shi, Xinzhe,Soulé, Jean-Fran?ois,Doucet, Henri
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p. 3306 - 3317
(2018/08/03)
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- Synthesis, mesomorphic behaviour and optical anisotropy of some novel materials for nematic mixtures of high birefringence
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Structural moieties including core units (such as phenyl, naphthyl and thiophenyl), linking groups (such as ethynyl), terminal substituents (such as cyano, isothiocyanato and fluoro), and lateral fluoro substituents have been incorporated into novel mater
- Hird, Michael,Toyne, Kenneth J.,Goodby, John W.,Gray, George W.,Minter, Victoria,Tuffin, Rachel P.,McDonnell, Damien G.
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p. 1731 - 1743
(2007/10/03)
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- New Liquid Crystalline Compounds Based on Thiophene
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A homologous series of 2-alkyl-5-(4'-cyanophenyl)thiophenes has been prepared and shown to have improved properties for use in liquid crystal displays.The thiophene ring is prepared from a 1-(4'-bromophenyl)-1,4-dioxoalkane, constructed using the Stetter procedure, by the action of Lawessons reagent, and the cyano-group is finally introduced using a copper(I)-mediated exchange reaction.
- Brettle, Roger,Dunmur, David A.,Marson, Charles M.,Pinol, Milagros,Toriyama, Kazuhisa
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p. 613 - 616
(2007/10/02)
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