Search results for " Synthesis"
showing 10 items of 1625 documents
Hydrothermal synthesis of zeolites from rhyolitic pumice of different geological origins
1983
Abstract Twelve samples of rhyolitic pumice from widely different origins were subjected to zeolitization in standard hydrothermal conditions (solid/liquid ratio, 1 5 ; T , 95°C; reaction time, 5 h; alkaline solution 5 N NaOH). The Si Al ratio of the starting material was of special importance in that zeolites formed with Si Al ratios similar to or smaller than that of the parent material. Pumice with low SiO 2 Al 2 O 3 , and high Fe content, preferentially gave rise to zeolites with lower SiO 2 Al 2 O 3 ratio than in the case of lower Fe and higher SiO 2 Al 2 O 3 ratio.
Enantioselective α-alkylation of unsaturated carboxylic acids using a chiral lithium amide
2001
Abstract The regio- and stereochemistry of the alkylation of dienediolates from unsaturated carboxylic acids with benzylic halides, which often results in mixtures of isomers, can be controlled by means of changes in the lithium amide, allowing the α-regioisomer to be obtained as the major diastereoisomer. In addition, when chiral amines are used, moderate enantiomeric excesses can be attained.
ChemInform Abstract: Enantioselective α-Alkylation of Unsaturated Carboxylic Acids Using a Chiral Lithium Amide.
2010
Abstract The regio- and stereochemistry of the alkylation of dienediolates from unsaturated carboxylic acids with benzylic halides, which often results in mixtures of isomers, can be controlled by means of changes in the lithium amide, allowing the α-regioisomer to be obtained as the major diastereoisomer. In addition, when chiral amines are used, moderate enantiomeric excesses can be attained.
Gallium Concentration Optimisation of Gallium Doped Zinc Oxide for Improvement of Optical Properties
2021
The research has been supported by project ERA.NET RUS_ST2017-05 (Latvia) and No. 18-52-76002 (Russia). The Institute of Solid State Physics, University of Latvia as the Centre of Excellence has received funding from the European Union’s Hori-zon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming-Phase2 under grant agreement No. 739508, project CAMART².
Metabolic fluxes and l-lysine synthesis by Corynebacterium glutamicum in relation to cellular total reducing activity
2001
Abstract The total reducing activity (TRA) of cells was used to estimate the physiological activity of Corynebacterium glutamicum under conditions of l -lysine synthesis. This was estimated as the rate of reduction of 2,3,5- triphenyltetrazolium chloride by intact cells. TRA of cells was linearly correlated with the intracellular concentrations of RNA and the bacterial growth rate. It was concluded that this activity reflected the rate of energy generation in cells. A decrease in TRA of growing cells was related to an increase in bacterial lysine synthesis activity. Alteration in metabolic pathway functioning and an increase in the intracellular concentrations of lysine precursors favoured …
Coordination networks incorporating halogen-bond donor sites and azobenzene groups
2016
Two Zn coordination networks, {[Zn(1)(Py)2]2(2-propanol)}n (3) and {[Zn(1)2(Bipy)2](DMF)2}n (4), incorporating halogen-bond (XB) donor sites and azobenzene groups have been synthesized and fully characterized. Obtaining 3 and 4 confirms that it is possible to use a ligand wherein its coordination bond acceptor sites and XB donor sites are on the same molecular scaffold (i.e., an aromatic ring) without interfering with each other. We demonstrate that XBs play a fundamental role in the architectures and properties of the obtained coordination networks. In 3, XBs promote the formation of 2D supramolecular layers, which, by overlapping each other, allow the incorporation of 2-propanol as a gues…
Total synthesis of two potent anti-inflammatory macrolactones of the oxacyclododecindione type
2015
An esterification/Friedel-Crafts-cyclization approach permitted the first successful synthetic entry into the oxacyclododecindione subclass of the dihydroxyphenylacetic acid lactone-type natural products. This route allowed the preparation of two highly active anti-inflammatory fungal secondary metabolites 14-deoxyoxacyclododecindione and 14-deoxy-4-dechlorooxacyclododecindione as well as their 14-desmethyl analogues.
Total synthesis and biological evaluation of seven new anti-inflammatory oxacyclododecindione-type macrolactones
2020
Through variation of our previously published total synthesis of two highly active anti-inflammatory macrolactones from the oxacyclododecindione family (J. Tauber, M. Rohr, T. Walter, G. Erkel and T. Opatz, Org. Biomol. Chem., 2015, 13, 7813-7821), seven new representatives of this compound class were prepared. Substitution of the 14-hydroxy group in oxacyclododecindione with a methyl substituent provided a readily accessible non-natural analogue which has similar pharmacological properties to the scarcely available natural product. Since the producible amount of substance is therefore no longer restricted by low fermentation yields, extensive in vivo studies become possible for the first t…
Synthesis of Lamellarin U and Lamellarin G Trimethyl Ether by Alkylation of a Deprotonated α-Aminonitrile
2008
1,2,3,4-Tetrahydroisoquinoline-1-carbonitriles can serve as starting materials for the one-pot synthesis of 5,6-dihydropyrrolo[2,1 a]isoquinolines and 1-benzyl-3,4-dihydroisoquinolines. The latter compounds were transformed to lamellarin G trimethyl ether and lamellarin U in short reaction sequences. This method allows the introduction of acid-sensitive protecting groups for the phenolic hydroxy functions which would be cleaved under the harsh conditions of the classical Bischler-Napieralski reaction.