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Transfer Reagent (transfer + reagent)
Selected AbstractsChemInform Abstract: Synthesis of Thioesters by Simultaneous Activation of Carboxylic Acids and Alcohols Using PPh3/NBS with Benzyltriethylammonium Tetrathiomolybdate as the Sulfur Transfer Reagent.CHEMINFORM, Issue 12 2010Purushothaman Gopinath Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: 2-Azido-1,3-dimethylimidazolinium Chloride: An Efficient Diazo Transfer Reagent for 1,3-Dicarbonyl Compounds.CHEMINFORM, Issue 11 2010Mitsuru Kitamura Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Regio- and Stereospecific Synthesis of ,-Sulfonamidodisulfides and ,-Sulfonamidosulfides from Aziridines Using Tetrathiomolybdate as a Sulfur Transfer Reagent.CHEMINFORM, Issue 30 2007Devarajulu Sureshkumar Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] ChemInform Abstract: N-Alkylation of 2,4,5-Triphenyl Imidazole Derivatives Using a New Phase Transfer Reagent under PTC Conditions.CHEMINFORM, Issue 1 2002Joseph Paul Jayachandran Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis and Characterization of Pyrazolyl-Functionalized Imidazolium-Based Ionic Liquids and Hemilabile (Carbene)palladium(II) Complex Catalyzed Heck ReactionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2007Ruihu Wang Abstract Neat reactions of 1-(pyrazolylmethyl)imidazole with an excess of alkyl or polyfluoroalkyl halides at 100 °C followed by subsequent metathetical reactions with LiN(SO2CF3)2 or KPF6 at 25 °C gave rise to a series of monoquaternary salts 3a,3k. These salts can be also prepared through treatment of 1-alkylimidazole with 1-(chloromethyl)pyrazole hydrochloride in the presence of base, followed by anion exchange with LiN(SO2CF3)2 or KPF6. Their phase-transition temperature, thermal stability, density and solubility in common solvents have been investigated. Most of the bis(trifluoromethanesulfon)amide salts are room-temperature ionic liquids. The effect of anions and of alkyl substituents bonded to the imidazolium cation on the physicochemical properties was examined. Using 3-butyl-1-(pyrazolylmethyl)imidazolium chloride (2d), the precursor of 3-butyl-1-(pyrazolylmethyl)imidazolium bis(trifluoromethanesulfon)amide (3d), as a reactant, a hemilabile (N-heterocyclic carbene)palladium(II) complex 4 was synthesized through a (carbene)silver(I) transfer reagent. It was characterized by single-crystal X-ray diffraction analysis. The catalytic activity and recyclability of 4 in 3d were preliminarily evaluated by consecutive Heck reactions using different substrates. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Novel Approach to 2-Chloro-2-fluorostyrenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2003Valentine G. Nenajdenko Abstract A new general catalytic olefination reaction (COR) of aromatic and heteroaromatic aldehydes and ketones was applied to synthesise 2-chloro-2-fluorostyrenes. The two-stage procedure includes the transformation of carbonyl compounds into hydrazones followed by treatment with CFCl3 mediated by copper catalysis. Trichlorofluoromethane was used as a chlorofluoromethylene transfer reagent. The reaction proceeds stereoselectively and the target alkenes were obtained in high yield. A proposed mechanism for the reaction is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Copper-catalyzed phosphinidene transfer to ethylene, acetylene, and carbon monoxide: A computational studyINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2010Matthew J. Amme Abstract A DFT study of phosphinidene transfer by copper model catalysts is reported. PR-transfer pathways are highly exergonic with respect to catalyst and phosphinidene transfer reagent. Calculated free energy barriers by which (dhpe)Cu(PMe) active species yields functionalized products are reasonable for modeled substrates,ethylene, acetylene, and carbon monoxide. Calculations suggest a (dhpe)CuI(-PMe·,) formulation as more appropriate than (dhpe)CuII(=PMe2,). The preferred pathway for production of phosphirane (phosphirene) is via direct [1 + 2] addition of ethylene (acetylene) to the PMe group of (dhpe)Cu(PMe), which contrasts the [2 + 2] mechanism for the reaction of ethylene with Ni0 -phosphinidenes. In light of simulations for neutral and cationic models, it is concluded that the extra electron in copper destabilizes [2 + 2] pathways. Calculated energetics for (dhpe)Cu(PMe) versus (en)Cu(PMe), dhpe = 1,2- bis(dihydrophosphino)ethane, en = ethylenediamine, indicate that the former is a more potent for PR-transfer. Thus, it is inferred that modifications that result in a more electron deficient metal center will yield better group transfer catalysts. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Polymer having a trithiocarbonate moiety in the main chain: Application to reversible addition,fragmentation chain transfer controlled thermal and photoinduced monomer insertion polymerizationsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2006Suguru Motokucho Abstract A polymer having a trithiocarbonate moiety in its main chain was synthesized with a cyclic, five-membered dithiocarbonate as a building block. The trithiocarbonate in the polymer acted as a reversible addition,fragmentation chain transfer reagent to mediate a controlled insertion polymerization of styrene into the polymer main chain, giving the corresponding sequence-ordered polymer having a well-defined polystyrene segment in the main chain. During the polymerization, the polystyrene segment in the main chain gained its molecular weight, which maintained a linear relationship with the conversion of styrene. The insertion polymerization of styrene was induced not only thermally but also by ultraviolet irradiation. This photoinduced polymerization was well controlled by the trithiocarbonate moiety to give the corresponding polymer, whose structure was virtually the same as that obtained by the thermal polymerization. © 2006 Wiley Periodicals, Inc. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6324,6331, 2006 [source] Differentiation of isobaric compounds using chemical ionization reaction mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2005Kevin P. Wyche The technique of proton transfer reaction mass spectrometry (PTR-MS) couples a proton transfer reagent, usually H3O+, with a drift tube and mass spectrometer to determine concentrations of volatile organic compounds. Here we describe a first attempt to use chemical ionization (CI) reagents other than proton transfer species inside a PTR-MS instrument. The ability to switch to other types of CI reagents provides an extra dimension to the technique. This capability is demonstrated by focusing on the ability to distinguish several isobaric aldehydes and ketones, including the atmospherically important molecules methacrolein and methyl vinyl ketone. Two CI reagents were selected, H3O+ and NO+, both being cleanly generated in a low intensity radioactive source prior to injection into the drift tube. By recording spectra with both of these reagents, the contributions from different isobaric molecules can be separated by virtue of their unique spectrometric ,fingerprints'. The work demonstrates that this form of instrumentation is not restricted to proton transfer reagents and is the basis of a more general technique, chemical ionization reaction mass spectrometry (CIRMS). Copyright © 2005 John Wiley & Sons, Ltd. [source] Stable N-Heterocyclic Carbene Adducts of Arylchlorosilylenes and Their Germanium HomologuesCHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2010Alexander Abstract The first N-heterocyclic carbene adducts of arylchlorosilylenes are reported and compared with the homologous germanium compounds. The arylsilicon(II) chlorides SiArCl(Im-Me4) [Ar=C6H3 -2,6-Mes2 (Mes=C6H2 -2,4,6-Me3), C6H3 -2,6-Trip2 (Trip=C6H2 -2,4,6- iPr3)] were obtained selectively on dehydrochlorination of the arylchlorosilanes SiArHCl2 with 1,3,4,5-tetramethylimidazol-2-ylidene (Im-Me4). The analogous arylgermanium(II) chlorides GeArCl(Im-Me4) were prepared by metathetical exchange of GeCl2(Im-Me4) with LiC6H3 -2,6-Mes2 or addition of Im-Me4 to GeCl(C6H3 -2,6-Trip2). All compounds were fully characterized. Density functional calculations on ECl(C6H3 -2,6-Trip2)(Im-Me4), where E=Si, Ge, at different levels of theory show very good agreement between calculated and experimental bonding parameters, and NBO analyses reveal similar electronic structures of the two aryltetrel(II) chlorides. The low gas-phase Gibbs free energy of bond dissociation of SiCl(C6H3 -2,6-Trip2)(Im-Me4) (,=28.1,kJ,mol,1) suggests that the carbene adducts SiArCl(Im-Me4) may be valuable transfer reagents of the arylsilicon(II) chlorides SiArCl. [source] | ||||||||||