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Large-Scale Preparation (large-scale + preparation)
Selected AbstractsAn Efficient Method for the Large-Scale Preparation of 3- O -Acetyl-11-oxo-,-boswellic Acid and Other Boswellic AcidsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2003Johann Jauch Abstract 3- O -Acetyl-11-oxo-,-boswellic acid (AKBA), found in incense, is a potent inhibitor of 5-lipoxygenase, p38 and p42 MAP kinase and topoisomerases. Starting from crude extracts from incense, procedures are presented for the efficient large-scale synthesis of AKBA and other boswellic acids (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] ChemInform Abstract: Development of a New Synthetic Route of a Non-Peptide CCR5 Antagonist, TAK-779, for Large-Scale Preparation.CHEMINFORM, Issue 15 2001Tomomi Ikemoto 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] Large-scale preparation of the homogeneous LolA,lipoprotein complex and efficient in vitro transfer of lipoproteins to the outer membrane in a LolB-dependent mannerPROTEIN SCIENCE, Issue 12 2007Shoji Watanabe Abstract An ATP-binding cassette transporter LolCDE complex of Escherichia coli releases lipoproteins destined to the outer membrane from the inner membrane as a complex with a periplasmic chaperone, LolA. Interaction of the LolA,lipoprotein complex with an outer membrane receptor, LolB, then causes localization of lipoproteins to the outer membrane. As far as examined, formation of the LolA,lipoprotein complex strictly depends on ATP hydrolysis by the LolCDE complex in the presence of LolA. It has been speculated, based on crystallographic and biochemical observations, that LolA undergoes an ATP-dependent conformational change upon lipoprotein binding. Thus, preparation of a large amount of the LolA,lipoprotein complex is difficult. Moreover, lipoproteins bound to LolA are heterogeneous. We report here that the coexpression of LolA and outer membrane-specific lipoprotein Pal from a very efficient plasmid causes the unusual accumulation of the LolA,Pal complex in the periplasm. The complex was purified to homogeneity and shown to be a functional intermediate of the lipoprotein localization pathway. In vitro incorporation of Pal into outer membranes revealed that a single molecule of LolB catalyzes the incorporation of more than 100 molecules of Pal into outer membranes. Moreover, the LolB-dependent incorporation of Pal was not affected by excess-free LolA, indicating that LolB specifically interacts with liganded LolA. Finally, the LolB depletion caused the accumulation of a significant amount of Pal in the periplasm, thereby establishing the conditions for preparation of the homogeneous LolA,lipoprotein complex. [source] The Oriented Self-Assembly of Magnetic Fe3O4 Nanoparticles into Monodisperse Microspheres and Their Use as Substrates in the Formation of Fe3O4 NanorodsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2008Guangcheng Xi Abstract We describe a facile solvothermal route for the large-scale preparation of ferromagnetic Fe3O4 sub-micrometer spheres and nanorods by using FeCl3 as the iron source, oleic acid as the surfactant, and ethylene glycol as the reducing agent and solvent. The as-synthesized Fe3O4 microspheres are composed of a mess of Fe3O4 nanoparticles with a size of 10 nm and have nearly monodisperse diameters that can be controlled in the range 100,410 nm. HRTEM images and SAED patterns show that these microspheres present a "single-crystalline" nature, which can be attributed to the highly oriented assembly of the small Fe3O4 nanoparticles. Interestingly, by using the pre-synthesized Fe3O4 microspheres as the growth substrate, single-crystalline Fe3O4 nanorods can be formed on the surfaces of the microspheres. These nanorods are about 7,20 nm in diameter and 120,400 nm in length, and have smooth surfaces. The formation mechanisms of the Fe3O4 microspheres and nanorods have been investigated and discussed. Furthermore, the magnetic properties of the as-synthesized microspheres and nanorods have also been investigated and the magnetization saturation values are 74.6 and 92.3 emu/g, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] OPTIMIZATION OF ENZYMATIC SYNTHESIS OF ISOMALTO-OLIGOSACCHARIDES PRODUCTIONJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2009M.C. RABELO ABSTRACT Glucosyltransferases can be applied in the synthesis of prebiotic oligosaccharides. Enzymatic synthesis using acceptors can be used to obtain these carbohydrates. When maltose is the acceptor, oligosaccharides containing one maltose moiety and up to eight glucose units linked by ,-1,6-glycosidic bonds are obtained as the product of dextransucrase acceptor reaction. In this work, the enzymatic synthesis of isomalto-oligosaccharides using dextransucrase from Leuconostoc mesenteroides NRRL B-512F was optimized by response surface methodology. The effect of maltose and sucrose concentrations on the acceptor reaction was evaluated in a batch reactor system. Partially purified enzyme was used to reduce the enzyme purification cost. The results showed that high sucrose concentrations in conjunction with high maltose levels enhanced the isomalto-oligosaccharide synthesis. A productivity of 42.95 mmol/L.h of isomalto-oligosaccharides was obtained at the optimal operating condition (100 mmol/L of sucrose and 200 mmol/L of maltose). PRATICAL APPLICATIONS Oligosaccharides as prebiotic have a large application in food formulations, and their beneficial role in human health have been extensively studied. Although the acceptor mechanism of dextransucrase has already been extensively studied, an industrial process has not been developed yet for enzyme synthesis of isomalto-oligosaccharide. The process studied in this work allows the large-scale preparation of isomalto-oligosaccharide using partially purified enzyme. [source] Phase-Transfer-Catalyzed Intramolecular Cyclization of ortho -Alkynyl Phenyl Ether Derivatives for Synthesis of 2,3-Disubstituted Benzo[b]furansADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Jie Hu Abstract A variety of substituted benzo[b]furans are readily prepared in good to excellent yields under the mild reaction conditions from o -(1-alkynylphenoxy)-1-phenylethanone under phase-transfer catalysis (PTC). This methodology accommodates simple experimental operations, inexpensive and environmentally benign catalysts, metal catalyst-free conditions, facile reagents and the possibility to conduct large-scale preparations. The development of carbon-carbon bond formation processes via an overall structural isomerization represents the most atom-economical approach. [source] Cyclopropyl Building Blocks for Organic Synthesis, 131.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 15 2006Palladium-Catalyzed Bicyclization with Carbonyl Insertion of Alkenyl-Tethered Propargyl Carbonates Towards a Scalable Synthesis of Various 2-(Bicyclo[3.1.0]hex-1-yl)acrylates Abstract The Pd-catalyzed 5- exo-trig- 3 -exo-trig cascade cyclization of 1,6-enynes with a propargyl carbonate terminus offers the shortest synthetic route to variously substituted 2-(bicyclo[3.1.0]hex-1-yl)acrylates, a novel class of prospective monomers for low-shrinkage polymers. To apply this reaction to large-scale preparations of the said bicyclic acrylates, a flexible Pd catalyst system with tunable reactivity has been developed. The dependence of the product and diastereomer distribution on both the reaction conditions, including the type of palladium catalyst used, and on the nature of the substrate has been investigated. A variety of methyl 2-(bicyclo[3.1.0]hex-1-yl)acrylates and parent carboxylic acids as well as some of their derivatives of potential interest towards a technical application were prepared on a multigram scale. A general large-scale synthesis of the cyclization precursors bearing one or two carbonyl groups in the tether is also disclosed. [source] | ||||||||||