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Sequential Reactions (sequential + reaction)
Selected AbstractsPalladium-Catalyzed Sequential Reactions via Allene Intermediates for the Rapid Synthesis of Fused Polycyclic Pyrrole DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Xian Huang Abstract In this paper, we report a novel sequential reaction sequence consisting of a series of processes including Sonogashira coupling, propargyl-allenyl isomerization, [3+2],cycloaddition, denitrogenation, and highly selective biradical coupling reaction, providing an efficient synthesis of fused polycyclic pyrrole derivatives. The reaction features one CC bond and two CN bonds formed to construct the pyrrole unit, together with two rings efficiently assembled in one stroke. [source] Copper-Catalyzed Diastereo- and Enantioselective Sequential Reactions of Propargylic Acetates with (E)-2,4-PentadienylamineCHEMCATCHEM, Issue 2 2010Gaku Hattori Natural selection: The copper-catalyzed diastereo- and enantioselective sequential reactions of propargylic acetates with (E)-2,4-pentadienylamine give the corresponding 1,2-disubstituted tetrahydroisoindoles in high yields with high diastereo- and enantioselectivities, in which only a single copper works as a catalyst to promote both steps: the propargylic amination and intramolecular [4+2] cycloaddition. [source] A Single Catalyst for Sequential Reactions: Dual Homogeneous and Heterogeneous Behavior of Palladium Nanoparticles in SolutionCHEMCATCHEM, Issue 2 2009Susanna Jansat Dr. One becomes two: Palladium nanoparticles stabilized by ionic liquids are used as the sole catalytic precursors for sequential Heck and hydrogenation processes. The dual role of these systems, which act as both a heterogeneous catalyst and also as a reservoir of catalytically active molecular species, is investigated. [source] ChemInform Abstract: One-Pot Silver-Catalyzed and PIDA-Mediated Sequential Reactions: Synthesis of Polysubstituted Pyrroles Directly from Alkynoates and Amines.CHEMINFORM, Issue 23 2010Weibing Liu 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: Synthesis of Funtionalized H-Pyrazolo[5,1-a]isoquinolines via Sequential Reactions of N,-(Alkynylbenzylidene)hydrazides.CHEMINFORM, Issue 12 2010Zhiyuan Chen 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: Platinum- and Palladium-Catalyzed Sequential Reactions: Regioselective Synthesis of 9-Fluorenylidenes from 9-Ethynylfluoren-9-yl Carboxylates and Furans.CHEMINFORM, Issue 50 2009Koji Miki 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] An Acidic Layered Clay Is Combined with a Basic Layered Clay for One-Pot Sequential Reactions.CHEMINFORM, Issue 47 2005Ken Motokura Abstract For Abstract see ChemInform Abstract in Full Text. [source] Ruthenium- and Platinum-Catalyzed Sequential Reactions: Selective Synthesis of Fused Polycyclic Compounds from Propargylic Alcohols and Alkenes.CHEMINFORM, Issue 16 2005Yoshiaki Nishibayashi No abstract is available for this article. [source] Efficient Synthesis of Benzopyrano[2,3-b]pyridines by Sequential Reactions of 1,3-Bis-silyl Enol Ethers with 3-Cyanobenzopyrylium Triflates.CHEMINFORM, Issue 40 2003Peter Langer Abstract For Abstract see ChemInform Abstract in Full Text. [source] Efficient and General Synthesis of 3-Aminoindolines and 3-Aminoindoles via Copper-Catalyzed Three-Component Coupling ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Dmitri Chernyak Abstract An efficient three-component coupling (TCC) reaction toward a variety of 3-aminoindoline and 3-aminoindole derivatives has been developed. This cascade transformation proceeds via the copper-catalyzed coupling reaction between 2-aminobenzaldehyde, a secondary amine, and an alkyne leading to a propargylamine intermediate which, under the reaction conditions, undergoes cyclization into the indoline core. The latter, upon treatment with a base, smoothly isomerizes into the indole. Alternatively, the indole can directly be synthesized in a one-pot sequential reaction. [source] Polymerization compounding composites of nylon-6,6/short glass fiberPOLYMER COMPOSITES, Issue 4 2003Wei Feng Nylon-6,6 was grafted onto the surface of short glass fibers through the sequential reaction of adipoyl chloride and hexamethylenediamine onto the fiber surface. Grafted and unsized short glass fibers (USGF) were used to prepare composites with nylon-6,6 via melt blending. The glass fibers were found to act as nucleating agents for the nylon-6,6 matrix. Grafted glass fiber composites have higher crystallization temperatures than USGF composites, indicating that grafted nylon-6,6 molecules further increase crystallization rate of composites. Grafted glass fiber composites were also found to have higher tensile strength, tensile modulus, dynamic storage modulus, and melt viscosity than USGF composites. Property enhancement is attributed to improved wetting and interactions between the nylon-6,6 matrix and the modified surface of glass fibers, which is supported by scanning electron microscopy (SEM) analysis. The glass transition (tan ,) temperatures extracted from dynamic mechanical analysis (DMA) are found to be unchanged for USGF, while in the case of grafted glass fiber, tan , increases with increasing glass fiber contents. Moreover, the peak values (i.e., intensity) of tan , are slightly lower for grafted glass fiber composites than for USGF composites, further indicating improved interactions between the grafted glass fibers and nylon-6,6 matrix. The Halpin-Tsai and modified Kelly-Tyson models were used to predict the tensile modulus and tensile strength, respectively. [source] Silver-Catalyzed Aldehyde Olefination Using SiloxyalkynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010Jianwei Sun Abstract We describe the development of a silver-catalyzed carbonyl olefination employing electron-rich siloxyalkynes. This process constitutes an efficient synthesis of trisubstituted unsaturated esters, and represents an alternative to the widely utilized Horner,Wadsworth,Emmons reaction. Excellent diastereoselectivities are observed for a range of aldehydes using either 1-siloxy-1-propyne or 1-siloxy-1-hexyne. This mild catalytic process also enables chemoselective olefination of aldehydes in the presence of either ester or ketone functionality. Furthermore, since no by-products are generated, this catalytic process is perfectly suited for development of sequential reactions that can be carried out in a single flask. [source] The chemiionization reactions Ce + O and Ce + O2: Assignment of the observed chemielectron bandsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2009Tanya K. Todorova Abstract Multiconfigurational quantum chemical methods (CASSCF/CASPT2) have been used to study the chemiionization reactions Ce + O , CeO+ + e, and Ce + O2 , CeO + e,. Selected spectroscopic constants for CeOn and CeO (n = 1, 2), as well as reaction enthalpies of the chemiionization reactions of interest, have been computed and compared with experimental values. In contrast to the lanthanum case, for both Ce + O2(X3,) and Ce + O2( a1,g), the Ce + O2 , CeO + e, reaction is shown to be exothermic, and thus, contributes to the experimental chemielectron spectra. The apparent discrepancy between the computed reaction enthalpies and the high kinetic energy offset values measured in the chemielectron spectra is rationalized by arguing that chemielectrons are produced mainly via two sequential reactions (Ce + O2 , CeO + O, followed by Ce + O , CeO+ + e,) as in the case of lanthanum. For Ce + O2 (a1,g), a chemielectron band with higher kinetic energy than that recorded for Ce + O2( X3,) is obtained. This is attributed to production of O( 1D) from the reaction Ce + O2( a1,g) , CeO + O( 1D), followed by chemiionization via the reaction Ce + O( 1D) , CeO+ + e,. Accurate potential energy curves for the ground and a number of excited states of CeO and CeO+ have been computed, and a mechanism for the chemiionization reactions investigated experimentally was proposed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Synthesis and properties of silica/polystyrene/polyaniline conductive composite particlesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2005Chia-Fen Lee Abstract In this study, silica/polystyrene/polyaniline (SiO2/PS/PANI) conductive composite particles were synthesized by four sequential reactions. The nanosized SiO2 particles were synthesized from tetraethoxysilane (TEOS) by a sol,gel process with water as the solvent medium, followed by a surface modification with triethoxyvinylsilane; then the surface modified SiO2 particles were used as seeds to synthesize SiO2/PS composite particles with soapless seeded emulsion polymerization. Finally, the SiO2/PS particles were used as seeds to synthesize the SiO2/PS/PANI conductive composite particles. The sol,gel process of SiO2, the effect of surface modification, and several other factors that influenced polymerization of styrene in the soapless seeded emulsion polymerization will be discussed. Either potassium persulfate (KPS) or 2,2,-azobis(isobutyramidine) dihydrochloride (AIBA) was used as the initiator to synthesize the uniform SiO2/PS particles successfully, and the cross-section morphology of the SiO2/PS particles was found to be of a core,shell structure, with SiO2 as the core, and PS as the shell. The SiO2/PS particles were well dispersed in many organic solvents. In the following step to synthesize SiO2/PS/PANI conductive composite particles, sodium dodecyl sulfate (SDS) played an important role, specifically, to absorb aniline onto the surfaces of the SiO2/PS particles to carry out the polymerization of aniline over the entire surface of the particles. The conductivity of the SiO2/PS/PANI composite particles approached that of semiconductive materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 342,354, 2005 [source] Copper-Catalyzed Diastereo- and Enantioselective Sequential Reactions of Propargylic Acetates with (E)-2,4-PentadienylamineCHEMCATCHEM, Issue 2 2010Gaku Hattori Natural selection: The copper-catalyzed diastereo- and enantioselective sequential reactions of propargylic acetates with (E)-2,4-pentadienylamine give the corresponding 1,2-disubstituted tetrahydroisoindoles in high yields with high diastereo- and enantioselectivities, in which only a single copper works as a catalyst to promote both steps: the propargylic amination and intramolecular [4+2] cycloaddition. [source] Fluorous "racemic" mixture synthesis: Polysaccharide-based chiral columns for simultaneous demix and enantioseparation of racemic fluorous tagged compoundsCHIRALITY, Issue 3-4 2008Takayuki Tonoi Abstract The proof of concept experiments of fluorous "racemic" mixture synthesis (FRMS) is shown using polysaccharide-based chiral stationary phases. The mixture of racemic O -benzoylmandelate derivatives bearing different lengths of fluorous cleavable tags undergoes sequential reactions to provide individual derivatives as well as their enantiomers resolved on polysaccharide-based chiral HPLC columns (DAICEL CHIRALCEL® and CHIRALPAK® series). Chirality, 2008. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||