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Phase-Transfer Catalysts (phase-transfer + catalyst)
Kinds of Phase-Transfer Catalysts Selected AbstractsChemInform Abstract: Nucleophilic Ring Opening of Epoxides Promoted by Multi-Site Phase-Transfer Catalyst: An Efficient and Eco-Friendly Route to Synthesis of ,-Hydroxy-thiocyanate.CHEMINFORM, Issue 52 2009Ali Reza Kiasat 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Polymer Imidazole Salt as Phase-Transfer Catalyst in Halex Fluorination Irradiated by Microwave.CHEMINFORM, Issue 40 2007Zheng Yong Liang 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] Catalytic Asymmetric Alkylation of ,-Cyanocarboxylates Using a Phase-Transfer Catalyst.CHEMINFORM, Issue 27 2007Kazuhiro Nagata 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] Enantio- and Diastereoselective Catalytic Mannich-Type Reaction of a Glycine Schiff Base Using a Chiral Two-Center Phase-Transfer Catalyst.CHEMINFORM, Issue 45 2005Akihiro Okada Abstract For Abstract see ChemInform Abstract in Full Text. [source] C2 -Symmetric Chiral Pentacyclic Guanidine: A Phase-Transfer Catalyst for the Asymmetric Alkylation of tert-Butyl Glycinate Schiff Base.CHEMINFORM, Issue 48 2002Tetsuya Kita Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Synthesis of Azidohydrins from Epoxides Using Quaternized Amino Functionalized Cross-Linked Polyacrylamide as a New Polymeric Phase-Transfer Catalyst.CHEMINFORM, Issue 7 2002B. Tamami 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] Recoverable Phase-Transfer Catalysts with Fluorinated Anions: Generation and Reactions of Dichlorocarbene and CCl3 Anion in the Heterogeneous System KOH(s)/CHCl3/nBu4NPF6EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2008Galina V. Kryshtal Abstract Tetraalkylammonium salts bearing PF6, and BF4, anions have been recognized as recoverable phase-transfer catalysts for the synthesis of 1,1-dichlorocyclopropane and ,-(trichloromethyl)carbinol derivatives from alkenes or aldehydes in the heterogeneous system KOH(s)/CHCl3. The catalysts retained their catalytic activity over several reactioncycles.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Reversal of Enantioselectivity by Tuning the Conformational Flexibility of Phase-Transfer Catalysts,ANGEWANDTE CHEMIE, Issue 15 2010Ming-Qing Hua Eine Umkehrung der Enantioselektivität wurde bei der konjugierten Addition von Nitroalkanen an Chalkone beobachtet, wenn spirocyclische quartäre Ammoniumsalze auf Binol-Basis als Phasentransferkatalysatoren eingesetzt wurden. Neuartige chirale Katalysatoren wurden entworfen und synthetisiert (siehe Struktur). [source] ChemInform Abstract: Electronically Modified Polymer-Supported Cinchona Phase-Transfer Catalysts for Asymmetric Synthesis of ,-Alkyl-,-amino Acid Derivatives.CHEMINFORM, Issue 34 2008Qinghua Shi 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 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: Recoverable Phase-Transfer Catalysts with Fluorinated Anions: Generation and Reactions of Dichlorocarbene and CCl3 Anion in the Heterogeneous System KOH(s)/CHCl3/nBu4NPF6.CHEMINFORM, Issue 29 2008Galina V. Kryshtal 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 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: Recoverable Phase-Transfer Catalysts with Fluorinated Anions: Generation and Reactions of Dichlorocarbene and CCl3 Anion in the Heterogeneous System KOH(s)/CHCl3/nBu4NPF6.CHEMINFORM, Issue 29 2008Galina V. Kryshtal 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 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: A New Class of Acetophenone-Based Cinchona Alkaloids as Phase-Transfer Catalysts: Application to the Enantioselective Synthesis of ,-Amino Acids.CHEMINFORM, Issue 14 2008Jian Lv 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Convenient Preparation of Chiral Phase-Transfer Catalysts with Conformationally Fixed Biphenyl Core for Catalytic Asymmetric Synthesis of ,-Alkyl- and ,,,-Dialkyl-,-amino Acids: Application to the Short Asymmetric Synthesis of BIRT-377.CHEMINFORM, Issue 41 2007Yong-Gang Wang 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] Magnetically Separable Phase-Transfer Catalysts.CHEMINFORM, Issue 12 2007Masato Kawamura 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] Asymmetric Phase-Transfer Catalysis of Homo- and Heterochiral Quaternary Ammonium Salts: Development and Application of Conformationally Flexible Chiral Phase-Transfer Catalysts.CHEMINFORM, Issue 10 2007Takashi Ooi 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] Asymmetric Glycolate Aldol Reactions Using Cinchonium Phase-Transfer Catalysts.CHEMINFORM, Issue 1 2006Merritt B. Andrus Abstract For Abstract see ChemInform Abstract in Full Text. [source] Tetraalkylammonium and 1,3-Dialkylimidazolium Salts with Fluorinated Anions as Recoverable Phase-Transfer Catalysts in Solid Base Promoted Cross-Aldol Condensations.CHEMINFORM, Issue 44 2005Galina V. Kryshtal Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Pyridyl Sulfobetaines as Phase-Transfer Catalysts for Reactions Involving Dichlorocarbene.CHEMINFORM, Issue 15 2002G.-K. Kupyatis 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: Water-Soluble Calixarenes as New Inverse Phase-Transfer Catalysts.CHEMINFORM, Issue 43 2001Michael Addition Reactions in Water., Their Application to Aldol-Type Condensation 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: New Polymer-Supported Chiral Phase-Transfer Catalysts in the Asymmetric Synthesis of ,-Amino Acids: The Role of a Spacer.CHEMINFORM, Issue 36 2001Baptiste Thierry 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] Monomeric Cu(II) Complex Containing Chiral Phase-transfer Catalyst as Ligand and Its Asymmetrically Catalytic ReactionCHINESE JOURNAL OF CHEMISTRY, Issue 2 2008Zhi-Rong QU Abstract The thermal treatment of CuCl2 with N -(4,-vinylbenzyl)cinchonidinium chloride (L1) afforded a monomeric discrete homochiral copper(II) complex N -4,-(vinylbenzyl)cinchonidinium trichlorocoprate(II) (1). Their applications to the enantioselectively catalytic alkylation reaction of N -(diphenylmethylidene)glycine tert -butyl ester (3) show that the higher ee value observed in catalyst 1 than that in the corresponding free ligand L1 is probably due to the rigidity enhancement after the coordination of N atom of quinoline ring to the copper ion. [source] Highly Selective Preparation of a Chiral Quaternary Allyl Aryl Piperidinedione by Palladium-Catalyzed Asymmetric Allylation Under Solid,Liquid Phase-Transfer CatalysisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2007Audrey Nowicki Abstract The combination of a chiral palladium catalyst and a solid,liquid phase-transfer catalyst provides an effective method for the chemo- and enantioselective preparation of the chiral quaternary center of an allyl aryl piperidinedione. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Highly Enantioselective Synthesis of No-Carrier-Added 6-[18F]Fluoro- L -dopa by Chiral Phase-Transfer AlkylationEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2004Christian Lemaire Abstract [18F]Fluoro- L -dopa, an important radiopharmaceutical for positron emission tomography (PET), has been synthesized using a phase-transfer alkylation reaction. A chiral quaternary ammonium salt derived from a Cinchona alkaloid served as phase-transfer catalyst for the enantioselective alkylation of a glycine derivative. The active methylene group of this Schiff-base substrate was deprotonated with cesium hydroxide and rapidly alkylated by the 2-[18F]fluoro-4,5-dimethoxybenzyl halide (X = Br, I). The reaction proceeded with high yield (> 90%) at 0 °C or room temperature in various solvents such as toluene or dichloromethane. Preparation of the [18F]alkylating agent on a solid support was developed. After labelling, the labeled [18F]fluoroveratraldehyde was trapped on a tC18 cartridge and then converted on the cartridge into the corresponding benzyl halide derivatives by addition of aqueous sodium borohydride and gaseous hydrobromic or -iodic acid. Hydrolysis and purification by preparative HPLC made 6-[18F]fluoro- L -dopa ready for human injection in a 25,30% decay-corrected radiochemical yield in a synthesis time of 100 min. The product was found to be chemically, radiochemically and enantiomerically pure (ee > 95%). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Kinetics of synthesis of bis-(benzoxazolyl-2-methyl) sulfide under phase-transfer catalysis conditionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2009Zuo-Xiang Zeng Kinetics of synthesis of bis-(benzoxazolyl-2-methyl) sulfide (BBMS) is investigated under phase-transfer catalysis conditions. Thus, the reaction of 2-chloromethylbenzoxazole and sodium sulfide is carried out in a two-phase (organic/water) medium, and quaternary ammonium salt and quaternary phosphonium salt are used as phase-transfer catalyst (PTC) in the reaction. The conversion of 2-chloromethylbenzoxazole is dramatically enhanced by adding a small quantity of PTC and is also greatly affected by the reaction conditions. The effects of various reaction variables on the kinetics are investigated, including the amount of catalyst, the temperature, the kinds of catalysts, the kinds of solvents, and the agitation speed. An interfacial reaction mechanism is proposed to explain the characteristics of the reaction. A pseudo-first-order rate model is established to describe the relationship between the fractional conversion and the reaction time. The kinetics data demonstrate that the model is suitable to the reaction of synthesis of BBMS. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 296,302, 2009 [source] Phase-Transfer-Catalyzed Olefin Isomerization/,-Alkylation of ,-Alkynylcrotonates as a Route for 1,4-EnynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Takuya Hashimoto Abstract The phase-transfer-catalyzed alkylation of ,-alkynylcrotonates was developed as a means to provide 1,4-enynes deconjugated by an all-carbon quaternary center. Extension to the asymmetric version using the chiral phase-transfer catalyst (S)- 3 provided the alkylated compounds with up to 87% ee. [source] 3,5-Bis(n -perfluorooctyl)benzyltriethylammonium Bromide (F-TEBA): An Efficient, Easily Recoverable Fluorous Catalyst for Solid-Liquid PTC ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Gianluca Pozzi Abstract A readily available 3,5-bis(perfluorooctyl)benzyl bromide and triethylamine were reacted under mild conditions to give 3,5-bis(n -perfluorooctyl)benzyltriethylammonium bromide (F-TEBA), an analogue of the versatile phase-transfer catalyst, benzyltriethylammonium chloride (TEBA), containing two fluorous ponytails. This perfluoroalkylated quaternary ammonium salt was successfully employed as a catalyst in a variety of reactions run under solid-liquid phase-transfer catalysis (SL-PTC) conditions. Thus, being both hydrophobic and lipophobic, F-TEBA could be quickly recovered in quantitative yields, and reused without loss of activity over several reaction cycles. [source] Phenol recovery from simulated wastewater using a vertical membrane reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Manoj Jhanwar Abstract Phenol was recovered from the simulated wastewater in the form of a useful product, allyl phenyl ether, using A-172 membrane as phase-transfer catalyst in a batch and a continuous membrane reactor. The effects of temperature, agitation rates and flow rates of aqueous and organic phases, and concentrations of phenol and allyl bromide on the yield of allyl phenyl ether in the organic phase and phenol removal in the aqueous phase after the reaction were studied. Activation energy and turnover number of the reaction were calculated as well. In the batch mode, the phenol concentration in the treated aqueous phase was found to be < 2 ppm, reduced from 5000 ppm, and more than 99% of the phenol was recovered in the form of allyl phenyl ether after reacting for 180 min. In a continuous mode, the phenol concentration can be reduced from 5000 to 100 ppm in the steady state operation of the reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Organocatalytic Asymmetric Mannich Reactions with N -Boc and N -Cbz Protected ,-Amido Sulfones (Boc: tert -Butoxycarbonyl, Cbz: Benzyloxycarbonyl)CHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2007Olindo Marianacci Abstract Different malonates and ,-ketoesters can react with N - tert -butoxycarbonyl- (N -Boc) and N -benzyloxycarbonyl- (N -Cbz) protected ,-amido sulfones in an organocatalytic asymmetric Mannich-type reaction. The reaction makes use of a simple and easily obtained phase-transfer catalyst and proceeds under very mild and user-friendly conditions. The optimised protocol avoids the preparation and the isolation of the relatively unstable N -Boc and N- Cbz imines that are generated in situ from the bench-stable ,-amido sulfones. The corresponding Mannich bases are generally obtained in good yields and enantioselectivities, and can be readily transformed into key compounds, such as optically active ,3 -amino acids in one easy step. Enantioenriched N -Boc and N -Cbz protected ,-amino acids that are suitable for peptide synthesis are also available from the Mannich adducts through simple manipulations. Control experiments showed the dual role of the enolate,catalyst ion pair in this reaction, as well as the crucial role of the presence of water to achieve high enantioselectivities. [source] Asymmetric inducing synthesis of optically active tetrahedral cluster containing SMCOW coreCHINESE JOURNAL OF CHEMISTRY, Issue 7 2004Quan-Yi Zhao Abstract The chiral clusters (,3 -S)MCoW(CO)8[n5 -C5H4C(O)OCH3] =Ru (2), Fe (3)] were synthesized by asymmetric induction of N-benzylcinchonium chloride as phase-transfer catalyst (PTC). The most suitable amount of PTC is 70 mol%. Cluster 3 was determined by single crystal X-ray diffraction analysis. The best ee of the chiral cluster is over 20%. [source] Amphiphilic Iron(II) and Nickel(II) Complexes Based on Alkylated Diazaoxa- and TriazacyclononaneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2008David Domínguez-Gutiérrez Abstract It is known that including a metal into a micellar solution enhances both the colour and catalytic potential of such systems. This fact is well exemplified by the broad use of surfactant species as phase-transfer catalysts. In the present work, we report our studies concerning the aggregation properties of a series of iron and nickel-based triazacyclononane metalloamphiphiles. Upon multiple alkylation of the triazamacrocycle, we were able to obtain amphiphilic complexes that aggregate in toluene. We characterised the sizes and shapes of the aggregates by dynamic light scattering while their nature was assessed by atomic force microscopy.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] | |||||||||||||||||||||||||