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Oxazoline
Terms modified by Oxazoline Selected AbstractsChemInform Abstract: Oxazoline,Thiourea as a Bifunctional Organocatalyst: Enantioselective aza-Henry Reactions.CHEMINFORM, Issue 3 2008Yu-wei Chang 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: Polymer-Bound Bis(Oxazoline) as a Chiral Catalyst.CHEMINFORM, Issue 46 2001Kristina Hallman 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] New Dihydroxy Bis(Oxazoline) Ligands for the Palladium-Catalyzed Asymmetric Allylic Alkylation: Experimental Investigations of the Origin of the Reversal of the EnantioselectivityCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2004Hassan Aït-Haddou Dr. Abstract The origin of the reversal of the enantioselectivity in the palladium-catalyzed allylic alkylation of rac -1,3-diphenyl-2-propenyl acetate with dimethyl malonate anion using chiral dihydroxy bis(oxazoline) "BO" ligands derived from (1S,2S)-(+)-2-amino-1-phenyl-1,3-propanediol was investigated. To determine the structural effects of the dihydroxy BO ligand on this unique phenomenon, new homochiral dihydroxy BO ligands were prepared from L -threonine and L -serine and were assessed in the transformation. The results obtained with these novel BO ligands, compared with the one obtained by using the dihydroxy BO ligands derived from (1S,2S)-(+)-2-amino-1-phenyl-1,3-propanediol, reveal that the reversal in the enantioselectivity observed with the dihydroxy BO ligand depends on the structure of the ligand. The effect of different bases used to generate the dimethyl malonate anion was also examined. The results are discussed in terms of the interaction of one hydroxy group in the intermediate ,-allyl palladium complex with the dimethyl malonate anion. [source] Discovery of a New Class of Non-imidazole Oxazoline-Based Histamine H3 Receptor (H3R) Inverse AgonistsCHEMMEDCHEM, Issue 7 2009Sylvain Célanire Dr. Abstract H3R inverse agonists based on an aminopropoxy-phenyloxazoline framework constitute highly valuable druglike lead compounds that display efficacy in a mouse model of recognition memory. [source] Ruthenium Complexes Containing Chiral N-Donor Ligands as Catalysts in Acetophenone Hydrogen Transfer , New Amino Effect on EnantioselectivityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005Montserrat Gómez Abstract New p -cymene ruthenium species containing chiral amino alcohols (1,3), primary (4,7) and secondary (8, 9) amino-oxazolines, were tested as catalysts in the hydrogen transfer of acetophenone, using 2-propanol as the hydrogen source. A remarkable effect on the enantioselectivity, but also on the activity, was observed depending on the amino-type oxazoline, Ru/8 and Ru/9 being low active and nonselective catalytic systems, in contrast to their primary counterpart Ru/5. Complexes containing amino-oxazolines (10,12) were prepared and fully characterized, both in solution and in solid state. The X-ray structure was determined for (SRu,RC)- 10. The diastereomeric ratios observed for complexes 10 and 11 were determined by 1H NMR and confirmed by means of structural modeling (semi-empirical PM3(tm) level). DFT theoretical calculations for the transition states involved in the hydrogen transfer process proved the important differences in their relative populations, which could justify the enantioselectivity divergences observed between primary and secondary amino-oxazoline ruthenium systems. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] New [Ru3(CO)12]-Based Catalysts with Imidazolinium Salt, Diimine, or Bis(oxazoline) Ligands and Ruthenium Bis(oxazoline) Complex for Tandem Isomerisation/Claisen Rearrangement of Dienyl Ethers , X-ray Structure of [RuCl{(R,R)-bis(isopropyloxazoline)}(p -cymene)]BF4EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2003Hamed Ben Ammar Abstract The reaction of various 1,7-dienes in the presence of the three-component catalyst A: [Ru3(CO)12]/imidazolinium salt/Cs2CO3 (1:1:2) leads to the tandem alkene isomerisation/Claisen rearrangement affording ,,,-unsaturated aldehydes. Other three component catalysts: [Ru3(CO)12]/diimine/Cs2CO3 and [Ru3(CO)12]/benzoxazoline or chiral bis(oxazoline)/Cs2CO3 offer new active catalytic systems for these tandem reactions. Two ruthenium complexes containing optically active bis(oxazoline), [RuCl{(R,R)-bis(oxazoline)}(p -cymene)]BF4, were prepared and the X-ray structure of one of them (18) was established. The combination of chiral 18/imidazolinium salt/Cs2CO3 (1:1:2) catalysed the above reaction of 1,6-dienes and the results suggest initial catalytic isomerisation followed by a thermal Claisen rearrangement. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Chiral 6,6,-Bis(oxazolyl)-1,1,-biphenyls as Ligands for Copper(I)-Catalyzed Asymmetric CyclopropanationEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2007Karamali Khanbabaee Abstract A series of chiral bis(oxazoline)s with biphenyl backbones were synthesized from enantiomerically pure (S)- and (R)-hexabenzyloxydiphenic acid (1) and their utility in copper(I)-catalyzed asymmetric cyclopropanation was investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Sequential Stereoselective Catalysis: Two Single-Flask Reactions of a Substrate in the Presence of a Bifunctional Chiral Ligand and Different Transition MetalsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2003Rita Annunziata Abstract A new bifunctional ligand capable of promoting different stereoselective catalytic transformations in combination with different transition metals has been prepared by connecting with a spacer a bis(oxazoline) to dihydroquinidine; this ligand was employed in a one-flask procedure in which methyl (E)-3-(4-vinylphenyl)propenoate underwent first cyclopropanation at the electron-rich double bond and then dihydroxylation at the electron-poor alkene to afford a product containing four stereocenters with complete regiocontrol and high stereoselectivity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Proton Transport from Dendritic Helical-Pore-Incorporated PolymersomesADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Anthony J. Kim Abstract The ability to add synthetic channels to polymersome (polymer vesicle) membranes could lead to novel membrane composites with unique selectivity and permeability. Proton transport through two different synthetic pores, self-assembled from either a dendritic dipeptide, (6Nf-3,4-3,5)12G2-CH2 -Boc-L-Tyr-L-Ala-OMe, or a dendritic ester, (R)-4Bp-3,4-dm8G1-COOMe, incorporated into polymersome membranes are studied. Polymersomes provide an excellent platform for studying such transport processes due to their robustness and mechanical and chemical stability compared to liposomes. It is found that the incorporated dendritic dipeptide and dendritic ester assemble into stable helical pores in the poly(ethylene oxide)-polybutadiene (PEO-PBD) polymersomes but not in the poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyl oxazoline) (PMOX-PDMS-PMOX) polymersomes. The incorporation is confirmed by circular dichroism (CD), changes in purely synthetic mechanical strength (e.g., areal expansion modulus) as assessed by micropipette aspiration, and cryo-TEM. In addition to the structural analyses, a transport measurement shows the incorporated dendritic helical pores allow facile transport of protons across the polymersome membranes after up to one month of storage. This integration of synthetic porous channels with polymersome substrates could provide a valuable tool for studying active transport processes in a composite membrane. These composites will ultimately expand the family of biologically inspired porous-membrane mimics. [source] Cu(II)-Azabis(oxazoline)-Complexes Immobilized on Superparamagnetic Magnetite@Silica-Nanoparticles: A Highly Selective and Recyclable Catalyst for the Kinetic Resolution of 1,2-DiolsADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Alexander Schätz Abstract Two different types of azide functionalized magnetite@silica nanoparticles are synthesized, which are ideally suited as inexpensive supports for catalysts and reagents as demonstrated with the grafting of copper(II)-azabis(oxazoline) complexes via a copper(I) catalyzed azide/alkyne cycloaddition (CuAAC) reaction. The potential of the immobilized complexes as catalysts is tested in the desymmetrization of racemic 1,2-diols through asymmetric benzoylation. Compared to azabis(oxazolines) "clicked" to common polymeric supports such as MeOPEG or Merrifield resin, Fe3O4@SiO2 proves to be superior with respect to activity and selectivity, as exemplified by employing the catalysts in up to five runs with consistent high activity and selectivity. Recycling of the catalysts is achieved quantitatively by magnetic decantation. [source] Development of Diphenylamine-Linked Bis(imidazoline) Ligands and Their Application in Asymmetric Friedel,Crafts Alkylation of Indole Derivatives with NitroalkenesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Han Liu Abstract The new diphenylamine-linked bis(imidazoline) ligands were prepared through Kelly-You's imidazoline formation procedure mediated by Hendrickson's reagent in good yields. The novel ligands were tested in the asymmetric Friedel,Crafts alkylation of indole derivatives with nitroalkenes. In most cases, good yields (up to 97%) and excellent enantioselectivities (up to 98%) can be achieved. The optimized bis(imidazoline) ligand with trans -diphenyl substitution on the imidazoline ring gave better enantioselectivity than the corresponding bis(oxazoline) ligand. [source] Highly Enantioselective Friedel,Crafts Reaction of Indole with Alkylidenemalonates Catalyzed by Heteroarylidene Malonate-Derived Bis(oxazoline) Copper(II) ComplexesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Yan-Jin Sun Abstract A series of cheap and easily accessible heteroarylidenemalonate-derived bis(oxazoline) ligands 1 and 2 were synthesized and their copper(II) complexes were applied to the catalytic Friedel,Crafts reaction between indoles and diethyl alkylidenemalonates, Excellent asymmetric enantioselectivities were afforded for the S -enantiomer (up to >99% ee) in isobutyl alcohol, and the R -enantiomer (up to 96.5% ee) in dichloromethane. [source] Combining Fluorous and Triazole Moieties for the Tagging of Chiral Azabis(oxazoline) LigandsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Ramesh Rasappan Abstract New fluorous-tagged azabis(oxazoline) ligands were prepared using the copper-catalyzed azide-alkyne cycloaddition as ligation method. The resulting ligands were tested in copper-catalyzed asymmetric benzoylations (up to 99% ee), nitroaldol (up to 90% ee), and Michael reactions (up to 82% ee). The combination of unpolar fluorinated alkyl chains and polar triazole moieties imposes properties that are beneficial for the catalysts with respect to recyclability and selectivity. The scope and limitation of this strategy in comparison to analogous catalysts immobilized on methoxypolyethylene glycol (MeOPEG) or polystyrene is discussed. Moreover, this study shows that the choice of solvent for a given reaction is crucial to arrive at highly recyclable bis(oxazoline) catalysts. [source] Efficient Heterogeneous Asymmetric Catalysis of the Mukaiyama Aldol Reaction by Silica- and Ionic Liquid-Supported Lewis Acid Copper(II) Complexes of Bis(oxazolines)ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2 2008S. Doherty Abstract Lewis acid complexes based on copper(II) and an imidazolium-tagged bis(oxazoline) have been used to catalyse the asymmetric Mukaiyama aldol reaction between methyl pyruvate and 1-methoxy-1-trimethylsilyloxypropene under homogeneous and heterogeneous conditions. Although the ees obtained in ionic liquid were similar to those found in dichloromethane, there was a significant rate enhancement in the ionic liquid with reactions typically reaching completion within 2,min compared with only 55,% conversion after 60,min in dichloromethane. However, this rate enhancement was offset by lower chemoselectivity in ionic liquids due to the formation of 3-hydroxy-1,3-diphenylbutan-1-one as a by-product. Supporting the catalyst on silica or an imidazolium-modified silica using the ionic liquid or in an ionic liquid-diethyl ether system completely suppressed the formation of this by-product without reducing the enantioselectivity. Although the heterogeneous systems were characterised by a drop in catalytic activity the system could be recycled up to five times without any loss in conversion or ee. [source] Multipurpose box- and azabox-Based Immobilized Chiral CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Abstract Azabis(oxazolines) can be used as chiral ligands in the copper-catalyzed enantioselective Mukaiyama aldol reaction. When supported on solids, azabis(oxazoline)-copper complexes are more easily deactivated than their analogous bis(oxazoline)-copper complexes, and are not compatible with the use of coordinating solvents in the method of preparation. The performance of the immobilized catalysts (up to 86,% ee) depends on the support and the reaction solvent, with some positive effect on enantioselectivity due to surface effects. The deactivation is not irreversible and the deactivated catalysts show excellent performance in the cyclopropanation reaction, providing added value to the supported multipurpose catalysts. [source] New type of phenolic resin,The curing reaction of bisphenol A based benzoxazine with bisoxazoline and the properties of the cured resin.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Abstract The curing reaction of a bisphenol A based benzoxazine [2,2-bis(3,4-dihydro-3-phenyl-1,3-benzoxazine) propane (Ba)] and bisoxazoline with a latent curing agent and the properties of the cured resins were investigated. With a latent curing agent, the ring-opening reaction of the benzoxazine ring occurred more rapidly, and then the phenolic hydroxyl group generated by the ring-opening reaction of the benzoxazine ring also reacted with the oxazoline ring more rapidly. The cure time of molten resins from Ba and bisoxazoline with a latent curing agent was reduced, and the cure temperature was lowered, in comparison with those of resins from Ba and bisoxazoline without a latent curing agent. The melt viscosity of molten resins from Ba and bisoxazoline with a latent curing agent was kept around 50 Pa s at 80°C even after 30 min, and molten resins from Ba and bisoxazoline with a latent curing agent showed good thermal stability below 80°C. However, above 170°C, the curing reaction of Ba with bisoxazoline with a latent curing agent proceeded rapidly. Cured resins from Ba and bisoxazoline with a latent curing agent showed good heat resistance, flame resistance, mechanical properties, and electrical insulation in comparison with cured resins from Ba and bisoxazoline without a latent curing agent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Characterization of different poly(2-ethyl-2-oxazoline)s via matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2009Anja Baumgaertel Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) coupled with CID (collision-induced dissociation) has been used for the detailed characterization of two poly(2-ethyl-2-oxazoline)s as part of a continuing study of synthetic polymers by MALDI-TOF MS/MS. These experiments provided information about the variety of fragmentation pathways for poly(oxazoline)s. It was possible to show that, in addition to the eliminations of small molecules, like ethene and hydrogen, the McLafferty rearrangement is also a possible fragmentation route. A library of fragmentation pathways for synthetic polymers was also constructed and such a library should enable the fast and automated data analysis of polymers in the future. Copyright © 2009 John Wiley & Sons, Ltd. [source] Asymmetric Nazarov Reaction Catalyzed by Chiral Tris(oxazoline)/Copper(II),ANGEWANDTE CHEMIE, Issue 26 2010Peng Cao Dr. In Gegenwart eines dreizähnigen Liganden führte die Titelreaktion hoch effizient zu chiralen O-Heterohexahydroindenonen. Die Produkte wurden mit ausgezeichneten Ausbeuten, Enantio- und Diastereoselektivitäten erhalten. HFIP=Hexafluor-2-propanol, BArF= Tetrakis[3,5-bis(trifluormethyl)phenyl]borat. [source] ChemInform Abstract: Study of the Recycling Possibilities for Azabis(oxazoline),Cobalt Complexes as Catalysts for Enantioselective Conjugate Reduction.CHEMINFORM, Issue 31 2010Luis Aldea 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: Asymmetric [2,3]-Wittig Rearrangement of Oxygenated Allyl Benzyl Ethers in the Presence of a Chiral Di-tBu-bis(oxazoline) Ligand: A Novel Synthetic Approach to THF Lignans.CHEMINFORM, Issue 5 2010Maria 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] ChemInform Abstract: Asymmetric Friedel,Crafts Alkylation of Electron-Rich N-Heterocycles with Nitroalkenes Catalyzed by Diphenylamine-Tethered Bis(oxazoline) and Bis(thiazoline) Zn(II) Complexes.CHEMINFORM, Issue 46 2008Han Liu 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: Asymmetric Friedel,Crafts Alkylation of Methoxyfuran with Nitroalkenes Catalyzed by Diphenylamine-Tethered Bis(oxazoline),Zn(II) Complexes.CHEMINFORM, Issue 12 2008Han Liu 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] The Application of Bis(oxazoline) Ligands in the Catalytic Enantioselective Methallylation of Aldehydes.CHEMINFORM, Issue 29 2007Grainne C. Hargaden 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] A Flexible and Versatile Strategy for the Covalent Immobilization of Chiral Catalysts Based on Pyridinebis(oxazoline) Ligands.CHEMINFORM, Issue 49 2005Alfonso Cornejo Abstract For Abstract see ChemInform Abstract in Full Text. [source] Copper(II) Triflate-bis(oxazoline)-Catalyzed Enantioselective Electrophilic Fluorination of ,-Ketoesters.CHEMINFORM, Issue 28 2004Jun-An Ma No abstract is available for this article. [source] New Dihydroxy Bis(oxazoline) Ligands for the Palladium-Catalyzed Asymmetric Allylic Alkylation: Experimental Investigations of the Origin of the Reversal of the Enantioselectivity.CHEMINFORM, Issue 25 2004Hassan Ait-Haddou Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of Novel C2 -Symmetric Chiral Bis(oxazoline) Ligands and their Application in the Enantioselective Addition of Diethylzinc to Aldehydes.CHEMINFORM, Issue 22 2004Bin Fu Abstract For Abstract see ChemInform Abstract in Full Text. [source] New [Ru3(CO)12]-Based Catalysts with Imidazolinium Salt, Diimine, or Bis(oxazoline) Ligands and Ruthenium Bis(oxazoline) Complex for Tandem Isomerization/Claisen Rearrangement of Dienyl Ethers , X-Ray Structure of [RuCl{(R,R)-bis(isopropyloxazoline)}(p-cymene)]BF4.CHEMINFORM, Issue 12 2004Hamed Ben Ammar Abstract For Abstract see ChemInform Abstract in Full Text. [source] Bis(oxazoline)titanium Complexes as Chiral Catalysts for Enantioselective Hydrosilylation of Ketones , A Combined Experimental and Theoretical Investigation.CHEMINFORM, Issue 47 2003Marco Bandini Abstract For Abstract see ChemInform Abstract in Full Text. [source] Catalytic and Highly Enantioselective Reactions of ,-Sulfonyl Carbanions with Chiral Bis(oxazoline)sCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2008Shuichi Nakamura Prof. Abstract The enantioselective reactions of lithiated benzyl trifluoromethyl sulfones with a substoichiometric amount of a bis(oxazoline) and various aldehydes is disclosed. The products were formed with excellent diastereo- and enantioselectivities. Fluorination of the sulfone with N -fluorobenzenesulfonimide and a stoichiometric amount of a bis(oxazoline) gave products with extremely high enantioselectivities (up to 99,%,ee; ee=enantiomeric excess). The enantioselective reaction was confirmed to proceed through a dynamic thermodynamic resolution pathway. [source] | ||||||||||||||||||||||||||||