17351-95-0Relevant academic research and scientific papers
Ligand-free Ullmann-type C-heteroatom couplings under practical conditions
Gueell, Imma,Ribas, Xavi
supporting information, p. 3188 - 3195 (2014/06/09)
A new practical ligand-free protocol for copper-catalyzed C-heteroatom cross-coupling reactions (Ullmann-type) is described. The use of dimethyl sulfoxide (DMSO) as the solvent overcomes the need to use organic auxiliary ligands; thus, DMSO is revealed as a nontoxic and superior solvent for Ullmann-type coupling reactions. This method allows the arylation of a wide range of amides, alcohols, and amines under practical conditions with bromobenzene and iodobenzene derivatives and will likely find direct application in current organic synthesis. The competitive reactivity among different functional groups is reported and rationalized, and the possibility to achieve selective arylation reactions is demonstrated. Copyright
Substituent exchange reactions of trimeric and tetrameric aryloxycyclophosphazenes with sodium 2,2,2-trifluoroethoxide
Liu, Xiao,Breon, Jonathan P.,Chen, Chen,Allcock, Harry R.
experimental part, p. 2100 - 2109 (2012/03/22)
Substituent exchange reactions of sodium 2,2,2-trifluoroethoxide with trimeric and tetrameric aryloxycyclophosphazenes with phenoxy, 4-formylphenoxy, 4-cyanophenoxy and 4-nitrophenoxy side groups were conducted at 66°C in THF and monitored by 31P NMR and mass spectrometry. These are model reactions for their counterparts with high polymeric linear organophosphazenes. The ease of displacement of OAr in cyclic trimeric and tetrameric molecules by CF3CH2O increased significantly with the presence of electron-withdrawing substituents in the polyphosphazene in the order, phenoxy ? 4-formylphenoxy 4-cyanophenoxy ≈ 4-nitrophenoxy. Fully substituted 2,2,2-trifluoroethoxyphosphazene trimer and tetramer were formed by side group exchange, but these reactions were followed by an attack by the nucleophile on the α-carbon of the 2,2,2-trifluoroethoxy groups linked to phosphorus to give a species in which one trifluoroethoxy group had been replaced by an ONa unit, and bis(trifluoroethyl) ether was formed as a side product. On the other hand, only partly exchanged species were formed when sodium phenoxide reacted with the trifluoroethoxy phosphazene trimer and tetramer, but again a product with an ONa side group was formed eventually together with phenyltrifluoroethyl ether generated via alpha-carbon attack. The relative sensitivity of 2,2,2-trifluoroethoxy and phenoxyphosphazene cyclic trimers and tetramers to the presence of trifluoroethoxide was established.
Fluoride-promoted ligand exchange in diaryliodonium salts
Wang, Bijia,Cerny, Ronald L.,Uppaluri, Shriharsha,Kempinger, Jayson J.,Dimagno, Stephen G.
body text, p. 1113 - 1121 (2011/02/25)
Diaryliodonium salts are shown to undergo rapid, fluoride-promoted aryl exchange reactions at room temperature in acetonitrile. Aryl exchange is shown to be exquisitely sensitive to the concentration of fluoride ion in solution; fast exchange is observed as the fluoride concentration approaches a stoichiometric amount at 50 mM substrate concentration. The reaction is slowed, but not halted if benzene is the solvent, indicating that free fluoride ion or a four-coordinate anionic I(III) species may be responsible for the exchange. The fluoride-promoted aryl exchange reaction is general and allows direct measurement of the relative stabilities of diaryliodonium salts featuring different aryl substituents. The aryl exchange reaction may be of practical use for the preparation of hitherto inaccessible diaryliodonium salts, thus it also has implications for labeling radiotracers for molecular imaging with 18F-fluoride (t1/2 = 109.7 min).
Participation of a heterolytic path in the photochemistry of chlorobenzene
Lazzaroni, Simone,Protti, Stefano,Fagnoni, Maurizio,Albini, Angelo
experimental part, p. 140 - 144 (2010/10/20)
The photochemistry of chlorobenzene in different media has been studied in the presence of oxygen as well as of allyltrimethylsilane and benzene. These are selective traps of the phenyl radical and of the phenyl cation, respectively. Photo-homolysis is a primary process, under most conditions the main processes. However, in an acidic alcohol such as 2,2,2-trifluoroethanol (TFE), this is substituted by photoheterolysis, though with a lower efficiency.
Facile access to fluorinated aryl and vinyl ethers through copper-catalysed reaction of fluoro alcohols
Vukga, Daniela,Legros, Juelien,Crousse, Benoit,Bonnet-Delpon, Daniele
experimental part, p. 3513 - 3518 (2009/12/01)
Fluorinated alcohols react with aryl and vinyl halides by copper-catalysed cross-coupling reactions to afford the corresponding ethers. With trifluoroethanol (TFE) the reaction proceeds with both iodides and bromides and a wide range of aromatic substituents are tolerated. When higher fluorinated homologues such as C7P15CH2OH were used, the corresponding products were obtained in good yields, thus of-fering an interesting entry to fluorous tagging.
Solvolysis of methoxy-substituted diaryliodonium tetrafluoroborates: Attempted generation of a stabilized aryl cation
Fujita, Morifumi,Mishima, Eri,Okuyama, Tadashi
, p. 241 - 244 (2008/03/13)
Solvolyses of monomethoxy- and dimethoxyphenyl(phenyl)iodonium (ArI +Ph) tetrafluoroborates were carried out in methanol and 2,2,2-trifluoroethanol (TFE) at 130°C. The solvolysis products include alkoxide substitution products (ArOR and PhOR) as well as iodoarenes (PhI and ArI). The ratios of ArOR/PhOR range from 8/2 to 4/6. The results are argued against formation of aryl cation. Copyright
A method of hydroxylation org. compd. sulfonylated
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Page 21, (2010/02/14)
The invention concerns a method for sulphonylating a hydroxylated organic compound. The invention concerns in particular aliphatic hydroxylated compounds and more particularly those which comprise on their aliphatic chain, an electroattractive group. The
Method for sulphonylating a hydroxylated organic compound
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Page 8, (2010/11/30)
The invention concerns a method for sulphonylating a hydroxylated organic compound. The invention concerns in particular aliphatic hydroxylated compounds and more particularly those which comprise on their aliphatic chain, an electroattractive group. The
Copper(II)-catalyzed ether synthesis from aliphatic alcohols and potassium organotrifluoroborate salts
Quach, Tan D.,Batey, Robert A.
, p. 1381 - 1384 (2007/10/03)
(Matrix presented) A protocol for the copper(II)-catalyzed etherification of aliphatic alcohols under mild and essentially neutral conditions is described. Air- and moisture-stable potassium alkenyl- and aryltrifluoroborate salts undergo cross-coupling with a variety of aliphatic primary and secondary alcohols and phenols, and are tolerant of a range of functional groups. The optimized conditions utilize catalytic copper(II) acetate with 4-(dimethylamino)pyridine as ligand in the presence of 4 A molecular sieves under an atmosphere of oxygen.
A product analytical study of the thermal and photolytic decomposition of some arenediazonium salts in solution
Canning, Peter S. J.,Maskill, Howard,McCrudden, Katharine,Sexton, Brian
, p. 789 - 800 (2007/10/03)
Products of thermal and photochemical reactions of eleven arenediazonium tetrafluoroborates in various solvents have been analyzed. All compounds in most solvents undergo unimolecular heterolysis to give singlet aryl cations which are captured by solvent. This mechanism is dominant for arenediazonium ions without electron-withdrawing substituents in all solvents, and the only reaction observed in water. Additionally, appreciable yields of fluoroarenes are obtained by fluoride abstraction by the aryl cation from fluorinated solvents and from tetrafluoroborate in fluorinated solvents. Yields from photochemical processes are very similar to those from thermal reactions indicating that the main reactions proceed through common or very similar intermediates. Aryl cations formed from ion-paired diazonium ions may react with the counterion, but fragmentation of dissociated diazonium ions leads only to solvent-derived product. Some arenediazonium ions in some solvents undergo an alternative radical reaction leading principally to hydrodediazoniation. It is proposed that this reaction involves initial rate-limiting electron transfer from ethanol to the arenediazonium ion followed rapidly by homolysis of the resultant aryldiazenyl radical. Within the same solvent cage, the aryl radical then either abstracts an α-hydrogen from the ethanol radical cation generated in the first step to give the reduction product and protonated acetaldehyde, or combines with it at the oxygen to give a protonated aryl ethyl ether.
