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Microwave Conditions (microwave + condition)
Selected AbstractsChemInform Abstract: A Convenient Synthesis of tert-Butyl Ethers under Microwave Condition.CHEMINFORM, Issue 33 2008K. A. Mahammed 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] Titanium(IV) Chloride Promoted Syntheses of New Imidazo[1,2-a]pyridine Derivatives under Microwave Conditions.CHEMINFORM, Issue 20 2006Lisheng Cai 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] Combining Enabling Techniques in Organic Synthesis: Solid Phase Assisted Catalysis under Microwave Conditions Using a Stable Pd(II)-Precatalyst.CHEMINFORM, Issue 13 2006Kamal M. Dawood 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] Comparative Study of Heck Reaction under Thermal and Microwave Conditions.CHEMINFORM, Issue 5 2005S. B. Solabannavar Abstract For Abstract see ChemInform Abstract in Full Text. [source] One-Pot Homolytic Aromatic Substitutions/HWE Olefinations under Microwave Conditions for the Formation of a Small Oxindole Library.CHEMINFORM, Issue 4 2005Antje Teichert Abstract For Abstract see ChemInform Abstract in Full Text. [source] An efficient one-pot synthesis of 6-aryl-5-cyano-2-thiopyrimidinone derivatives and their piperidinium ionic forms, x-ray crystal structuresJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2006Saeed Balalaie Three-component condensation of benzaldehyde derivatives, alkyl cyanoacetates and thiourea in the presence of piperidine in reflux condition provides a direct route to piperidinium 6-aryl-5-cyano 2-thiopyrimidonate salts in good yields. These reactions were also carried out under microwave irradiation. The yields of products under the microwave condition were better as compared to the reflux media. The acidification of these ionic forms resulted in the formation of 6-aryl-5-cyano-2-thiopyrimidone derivatives. The X-ray structures of the ionic forms (4, 5, and 7) show that there are anionic thiopyrimidinone skeletons hydrogen bridged with piperidinium cations. [source] One-pot three-component synthesis of 2-substituted 4-aminoquinazolinesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2006Kurosh Rad-Moghadam A facile and rapid synthesis of the title compounds via one-pot reaction of 2-aminobenzonitrile, orthoesters and ammonium acetate under solvent-free and microwave condition is described. [source] Synthesis and alkylation of 5-(3-chlorobenzo[b]thien-2-yl)-4H -1,2,4-triazole-3-thiol under classical and microwave conditions.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2006AM1 semiemperical calculations for investigating the regioselectivity of alkylation Under microwave irradiation (MWI), 5-(3-chlorobenzo[b]thien-2-yl)-4H -1,2,4-triazole-3-thiol (3) was synthesized in a good yield by intramolecular cyclization of the carbonyl thiosemicarbazide 2. A regioselective S-alkylation of 3 with benzyl chloride or allyl bromide has been achieved by using triethylamine as a base, while other different basic conditions led to a mixture of bis(alkylated) derivatives N4, S- and S, N2 -, under both of classical and MWI conditions. The relative stabilities, charge densities, dipole moments and electronic energies of reactants, transition states and intermediates were calculated by the AM1 method and used for investigating the regioselectivity. [source] An efficient synthesis of 1- H -pyrazole-4-carboxylic acid esters with vilsmeier reagent under neat conditionsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2004R. Sridhar A convenient, solvent-free Vilsmeier reagent is experimented under neat condition (both thermal and microwave conditions). An efficient method for the synthesis of various substituted 1H -pyrazole-4-carboxylic acid esters is reported. [source] Microwave-Assisted One-Pot Synthesis of Hyperbranched Epoxide-Amine AdductsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2009Julia Theis Abstract Hyperbranched epoxide-amine adducts were synthesized by a one-pot microwave (MW) assisted reaction. 4-(2,3-epoxypropyl-1-oxy)benzonitrile was hydrogenated using Pd/C under microwave conditions, forming the AB2 monomer 1-aminomethyl-4-(2,3-epoxypropyl-1-oxy)benzene. Depending on the reaction temperature this monomer immediately reacts to give hyperbranched epoxide-amine adducts. Mass spectrometric investigations proved the formation of a homologous series of oligomers containing up to six repeating units. Due to the complexing properties of the poly(amino alcohol) moieties in the presence of Cu2+ ions, large aggregates were formed. [source] Microwave and Ionic Liquids: Inverse Temperature Dependence of Viscosity in Aqueous Medium of Grafted CopolymersMACROMOLECULAR REACTION ENGINEERING, Issue 9 2009Ella Bezdushna Abstract We elaborated a route to the thermosensitive polyelectrolyte system composed of 1-methyl-3-vinylimidazolium salt with , -cyclodextrin complexed counterions and mono-(meth)acrylic functionalized poly(N -isopropylacrylamide) as grafted side chains via a three-step synthetic procedure. The aqueous solution of the polyelectrolyte displays partially inverse thermoresponsive behavior; it exhibits enhancement of shear viscosity up to body temperature. Furthermore, based on classically prepared poly(NIPAAm) bearing terminal amino groups, corresponding (meth-) acrylamide-type of macromonomers were easily obtained under microwave conditions. [source] ChemInform Abstract: Synthesis of 9-Alkyl-6-amino[1,2,4]triazolo[3,4-c]-5-azaquinoxalines.CHEMINFORM, Issue 33 2010Effective SNAr Amination of Highly Electron-Poor Heterocycles. Abstract The previously reported substrates (I) readily undergo an SNAr reaction with ammonia in acetonitrile solution under thermal or microwave conditions. [source] Heterogeneous Versus Homogeneous Palladium Catalysts for Ligandless Mizoroki,Heck Reactions: A Comparison of Batch/Microwave and Continuous-Flow ProcessingCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2009Abstract Mizoroki,Heck couplings of aryl iodides and bromides with butyl acrylate were investigated as model systems to perform transition-metal-catalyzed transformations in continuous-flow mode. As a suitable ligandless catalyst system for the Mizoroki,Heck couplings both heterogeneous and homogeneous Pd catalysts (Pd/C and Pd acetate) were considered. In batch mode, full conversion with excellent selectivity for coupling was achieved applying high-temperature microwave conditions with Pd levels as low as 10,3,mol,%. In continuous-flow mode with Pd/C as a catalyst, significant Pd leaching from the heterogeneous catalyst was observed as these Mizoroki,Heck couplings proceed by a homogeneous mechanism involving soluble Pd colloids/nanoparticles. By applying low levels of Pd acetate as homogeneous Pd precatalyst, successful continuous-flow Mizoroki,Heck transformations were performed in a high-temperature/pressure flow reactor. For both aryl iodides and bromides, high isolated product yields of the cinnamic esters were obtained. Mechanistic issues involving the Pd-catalyzed Mizoroki,Heck reactions are discussed. [source] 9,10-Diarylanthracenes as Molecular Switches: Syntheses, Properties, Isomerisations and Their Reactions with Singlet OxygenCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2008Daniel Zehm Abstract A series of 9,10-diarylanthracenes with various substituents at the ortho positions have been synthesised by palladium-catalysed cross-coupling reactions. Such compounds exhibit interesting physical properties and can be applied as molecular switches. Despite the high steric demand of the substituents, products were formed in moderate-to-good yields. In some cases, microwave conditions further improved yields. Bis-coupling afforded two isomers (syn and anti) that do not interconvert at room temperature. These products were easily separated and their relative stereochemistries were unequivocally assigned by NMR spectroscopy and X-ray analysis. The syn and anti isomers exhibit different physical properties (e.g., melting points and solubilities) and interconversion by rotation around the aryl,aryl axis commences at <100,°C for fluoro-substituted diarylanthracenes and at >300,°C for alkyl- or alkoxy-substituted diarylanthracenes. The reactions with singlet oxygen were studied separately and revealed different reactivities and reaction pathways. The yields and reactivities depend on the size and electronic nature of the substituents. The anti isomers form the same 9,10-endoperoxides as the syn species, occasionally accompanied by unexpected 1,4-endoperoxides as byproducts. Thermolysis of the endoperoxides exclusively yielded the syn isomers. The interesting rotation around the aryl,aryl axis allows the application of 9,10-diarylanthracenes as molecular switches, which are triggered by light and air under mild conditions. Finally, the oxygenation and thermolysis sequence provides a simple, synthetic access to a single stereoisomer (syn) from an unselective coupling step. [source] Microwave-Assisted Heterogeneous Cross-Coupling Reactions Catalyzed by Nickel-in-Charcoal (Ni/C)CHEMISTRY - AN ASIAN JOURNAL, Issue 3 2006Bruce Abstract A study involving the relatively rare combination of heterogeneous catalysis conducted under microwave conditions is presented. Carbon,carbon bond formation, including Negishi and Suzuki couplings, can be quickly effected with aryl chloride partners by using a base metal (nickel) adsorbed in the pores of activated charcoal. Aminations were also studied, along with cross-couplings of vinyl alanes with benzylic chlorides as a means to stereodefined allylated aromatics. Reaction times for all these processes are typically reduced from several hours to minutes in a microwave reactor. [source] | |||||||||||||||||||||||||