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Efficient Access (efficient + access)
Selected AbstractsEfficient Access to Nonhydrolyzable Initiator tRNA Based on the Synthesis of 3,-Azido-3,-Deoxyadenosine RNA,ANGEWANDTE CHEMIE, Issue 41 2010Jessica Steger Hydrolyse-resistente 3,-Aminoacyl-tRNA-Konjugate mit einer stabilen Amidverknüpfung statt der natürlichen Esterfunktion sind nützliche Substrate für biochemische Untersuchungen ribosomaler Prozesse. Entscheidend bei einem neuartigen Verfahren zur Herstellung des stabilen E.-coli -Initiator-tRNA-Derivats 3,-(N -Formylmethionyl)amino-tRNAfMet ist die Synthese von 3,-Azidooligoribonucleotiden unter Verwendung eines neuen funktionalisierten Festphasenträgers. [source] Efficient Access to Extended Yagupolskii,Umemoto-Type Reagents: Triflic Acid Catalyzed Intramolecular Cyclization of ortho -Ethynylaryltrifluoromethylsulfanes,ANGEWANDTE CHEMIE, Issue 3 2010Andrej Matsnev Chef im Ring: Die S -(Trifluormethyl)benzo[b]thiophenium-Salze 1, Analoga für Yagupolskii-Umemoto-Reagentien, wurden durch eine neuartige Trifluormethansulfonsäure-katalysierte intramolekulare Cyclisierung aus ortho -Ethinylaryltrifluormethylsulfanen 2 synthetisiert. 1,j erwies sich als besonders nützlich in der elektrophilen Trifluormethylierung von ,-Ketoestern und Dicyanalkylidenen. [source] Rhodium-Catalyzed Enantioselective and Diastereoselective Hydrogenation of ,-Ketoenamides: Efficient Access to anti 1,3-Amino Alcohols,ANGEWANDTE CHEMIE, Issue 33 2009Huiling Geng Nützliche chirale Bausteine werden mit ausgezeichneter Enantio- und Diastereoselektivität bei einer Tandemhydrierung von (Z)-,-Ketoenamiden gebildet, die wiederum durch direkte Kondensation von 1,3-Diketonen mit Acetamid erhalten werden (siehe Schema). Die chiralen Aminoalkoholprodukte können durch Hydrogenolyse mit Pd/C in nützliche ,-Arylisobutylamine überführt werden. R1=Aryl, Heteroaryl, Methyl; R2=Alkyl. [source] ChemInform Abstract: Domino Heck,Aza-Michael Reactions: Efficient Access to 1-Substituted Tetrahydro-,-carbolines.CHEMINFORM, Issue 25 2010Daniel L. Priebbenow 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: Efficient Access to Polysubstituted Amidines, Benzimidazoles and Pyrimidines from Amides.CHEMINFORM, Issue 23 2010Jing Wang 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: Rhodium-Catalyzed Enantioselective and Diastereoselective Hydrogenation of ,-Ketoenamides: Efficient Access to anti 1,3-Amino AlcoholsCHEMINFORM, Issue 51 2009Huiling Geng 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: Heterogeneous Gold Catalysts for Efficient Access to Functionalized Lactones.CHEMINFORM, Issue 7 2009Florentina Neatu 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: Palladium-Catalyzed Direct (Hetero)arylation of Ethyl Oxazole-4-carboxylate: An Efficient Access to (Hetero)aryloxazoles.CHEMINFORM, Issue 5 2009Cecile Verrier 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: Multicomponent Domino Reaction Promoted by Mg(ClO4)2: Highly Efficient Access to Functionalized 1,4-Dihydropyridines.CHEMINFORM, Issue 50 2008Giuseppe Bartoli 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] Asymmetric Michael Reaction: Novel Efficient Access to Chiral ,-Ketophosphonates (III).CHEMINFORM, Issue 34 2007Sandrine Delarue-Cochin 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] Lawesson,s Reagent and Microwaves: A New Efficient Access to Benzoxazoles and Benzothiazoles from Carboxylic Acids under Solvent-Free Conditions.CHEMINFORM, Issue 24 2007Julio A. Seijas 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] Efficient Access to Cyclic Ureas via Pd-Catalyzed Cyclization.CHEMINFORM, Issue 49 2006Mark McLaughlin 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] Efficient Access to Novel Mono- and Disubstituted Pyrido[3,2-d]pyrimidines.CHEMINFORM, Issue 49 2006Abdellatif Tikad 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] Enantioselective Organocatalytic Aminomethylation of Aldehydes: A Role for Ionic Interactions and Efficient Access to ,2 -Amino Acids.CHEMINFORM, Issue 38 2006Yonggui Chi 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] Palladium(0)-Catalyzed Cross-Coupling of Fluorous Bis(pinacolato)diboron: An Efficient Access to Fluorous Boronates.CHEMINFORM, Issue 48 2005Yangen Huang Abstract For Abstract see ChemInform Abstract in Full Text. [source] Novel Conditions for the Julia,Colonna Epoxidation Reaction Providing Efficient Access to Chiral, Nonracemic Epoxides.CHEMINFORM, Issue 40 2004Thomas Geller Abstract For Abstract see ChemInform Abstract in Full Text. [source] Efficient Access to Chiral ,-Arylamides via Asymmetric 1,4-Additions of Potassium Trifluoro(organo)borates.CHEMINFORM, Issue 38 2004Mathieu Pucheault Abstract For Abstract see ChemInform Abstract in Full Text. [source] Efficient Access to Fused Ring Compounds via Dearomatization/Ring-Closing Metathesis.CHEMINFORM, Issue 15 2004E. Peter Kuendig Abstract For Abstract see ChemInform Abstract in Full Text. [source] Aminolysis of Cyclic Thioxocarbonate of (R,R)-Di-tert-butyl Tartrate: Efficient Access to Thio- and Thiolcarbamates.CHEMINFORM, Issue 40 2002Ludovic Faissat Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Efficient Access to Perfluoroalkylated Aryl Compounds by Heck Reaction.CHEMINFORM, Issue 14 2002Sylvain Darses 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] Rhodium/Phosphine/Amine,HBr Catalyst System for Highly Selective Cross-Cyclodimerization of Aryl- and Alkylalkynes: Efficient Access to Multisubstituted Naphthalene DerivativesCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2010Koichi Sakabe Trinity: The combination of rhodium/phosphine/amine,HBr enables the highly selective catalytic cross-cyclodimerization of diarylacetylenes with aliphatic alkynes to afford the corresponding multiply substituted naphthalenes in good-to-high yields. The catalyst system also allows the use of some alkenes as the coupling partners, which provides a facile route to highly functionalized dihydronaphthalenes (see scheme). [source] Highly Efficient Access to Bi- and Tricyclic Ketals through Gold-Catalyzed Tandem Reactions of 4-Acyl-1,6-diynesCHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2009Jia Meng Dr. Abstract Single step: Fused bicyclic and bridged tricyclic ketals were synthesized in a single step from the reactions of easily available 4-acyl-1,6-diynes with H2O and alkanols (see scheme). The highly efficient AuCl3 -catalyzed multicomponent domino reactions, involving five CO bond formations, can proceed in a highly regio- and diastereoselective manner at room temperature under air and lead to structures of high molecular complexity from simple starting materials in an atom economic way. [source] Heterogeneous Gold Catalysts for Efficient Access to Functionalized LactonesCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2008Florentina Nea Abstract A novel class of heterogeneous gold catalysts supported on zeolite beta-NH4+ was prepared by the deposition,precipitation method. This new class of catalyst showed interesting catalytic activities for the intramolecular cycloisomerization of ,-acetylenic carboxylic acids leading to functionalized ,-alkylidene ,-butyrolactones. Analysis of the supported gold species with in situ X-ray photoelectron spectroscopy (in situ XPS) suggests that cationic Au (possibly AuIII) can play an important role in such reactions. The high discrepancy in catalyst stability in favor of the Au supported on the zeolite system over bulk Au2O3 is explained by 1),the size of the particles and 2),the reversibility of the redox deactivating process (AuIII,AuI) in the presence of oxygen for the supported system. The efficiency of this system allowed reaction under mild heterogeneous conditions. The potential for catalyst recycling was also highlighted. [source] Optimal Control of Rigid-Link Manipulators by Indirect MethodsGAMM - MITTEILUNGEN, Issue 1 2008Rainer Callies Abstract The present paper is a survey and research paper on the treatment of optimal control problems of rigid-link manipulators by indirect methods. Maximum Principle based approaches provide an excellent tool to calculate optimal reference trajectories for multi-link manipulators with high accuracy. Their major drawback was the need to explicitly formulate the complicated system of adjoint differential equations and to apply the full apparatus of optimal control theory. This is necessary in order to convert the optimal control problem into a piecewise defined, nonlinear multi-point boundary value problem. An accurate and efficient access to first- and higher-order derivatives is crucial. The approach described in this paper allows it to generate all the derivative information recursively and simultaneously with the recursive formulation of the equations of motion. Nonlinear state and control constraints are treated without any simplifications by transforming them into sequences of systems of linear equations. By these means, the modeling of the complete optimal control problem and the accompanying boundary value problem is automated to a great extent. The fast numerical solution is by the advanced multiple shooting method JANUS. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Spirocyclic Chiral Borate for Catalytic Enantioselective Nozaki-Hiyama Allylation of KetonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Xin-Ren Huang Abstract A new class of chiral spirocyclic borate ligands 5a,d with a rigid borocycle has been developed. The catalyst formed from chromium(II)- 5a promotes the highly efficient enantioselective Nozaki,Hiyama allylation of alkyl and aryl ketones using allyl bromide. The scope of the present method is shown to be wide, and it affords an efficient access to chiral tertiary homoallylic alcohols. [source] Chiral Phosphoric Acid-Catalyzed Enantioselective Aza-Friedel,Crafts Reaction of IndolesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2007Masahiro Terada Abstract A highly enantioselective 1,2-aza-Friedel,Crafts reaction of N - tert -butyldimethylsilylindole with N - tert -butoxycarbonyl aromatic imines is demonstrated using a BINOL-derived monophosphoric acid catalyst. The present approach provides efficient access to 3-indolylmethaneamines with aryl substituents in excellent enantioselectivities (up to 98,% ee). An inversion in the sense of enantioselection was found between monophosphoric acid catalysts bearing different substituents introduced at the 3,3,-position of binaphthyl backbone. We also calculated the three-dimensional structure of the monophosphoric acid catalysts to speculate on the inversion of the stereochemical outcome. [source] Merging Organic and Polymer Chemistries to Create Glycomaterials for Glycomics ApplicationsMACROMOLECULAR BIOSCIENCE, Issue 8 2006Géraldine Coullerez Abstract Summary: Oligosaccharides at cell surfaces are known to play a critical role in many biological processes such as biorecognition, interactions between cells and with artificial surfaces, immune response, infection and inflammation. In order to facilitate studies of the role of sugars, an increasing number of novel tools are becoming available. New synthetic strategies now provide much more efficient access to complex carbohydrates or glycoconjugates. Branched carbohydrates and hybrids of carbohydrates conjugated to polymers have been prepared using solution and/or solid-phase synthesis and advanced methods of polymerization. These materials are essential for the development of methodologies to study and map the molecular structure-function relationship at interfaces. This article highlights recent advances in the synthesis of carbohydrates and polymer hybrids mimicking the properties and functionalities of the natural oligosaccharides, as well as selected applications in biology, biotechnology and diagnostics. [source] ChemInform Abstract: Pt(IV)-Catalyzed Hydroamination Triggered Cyclization: A Strategy to Fused Pyrrole[1,2-a]quinoxalines, Indolo[1,2-a]quinoxalines, and Indolo[3,2-c]quinolines.CHEMINFORM, Issue 40 2010Nitin T. Patil Abstract The Pt-catalyzed coupling of alkynols with pyrrole- and indole-substituted anilines allows an efficient access to fused title compounds. [source] | |||||||||||||||||||||||||