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Efficient Preparation (efficient + preparation)
Selected AbstractsIlicic Acid as a Natural Quiron for the Efficient Preparation of Bioactive ,- and ,-EudesmolEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2009Alejandro F. Barrero Abstract An efficient procedure for the isolation of the sesquiterpene ilicic acid (3) on a multigram scale of extracts obtained from aerial parts of Inula viscosa (Asteraceae) was developed. Acid 3 is an appropriate starting material for short, enantiospecific syntheses of ,-eudesmol (1) and ,-eudesmol (2), natural products featuring significant antiangiogenic and anti-Alzheimer properties. Synthesis of 1 was achieved in six steps and the synthesis of 2 in seven, producing overall yields of 52 and 41,%, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] ChemInform Abstract: An Efficient Preparation of N-Alkyl-2-benzazepine Derivatives and Investigation of Their Biological Activity.CHEMINFORM, Issue 45 2009Akio Kamimura 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: An Efficient Preparation of New Homoallylamines and ,-Aminonitriles Bearing Furyl and Thienyl Rings.CHEMINFORM, Issue 40 2008Leonor Y. Vargas Mendez 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: An Efficient Preparation of New Sulfonyl Fluorides and Lithium Sulfonates.CHEMINFORM, Issue 15 2008Fabien Toulgoat 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: Bismesitylmagnesium: A Thermally Stable and Non-Nucleophilic Carbon-Centered Base Reagent for the Efficient Preparation of Silyl Enol Ethers.CHEMINFORM, Issue 14 2008William J. Kerr 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: An Efficient Preparation of Bis(indole)methanes Catalyzed by Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate Salts in Aqueous Medium.CHEMINFORM, Issue 8 2008Bei-Sih Liao 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] Reactions Between Weinreb Amides and 2-Magnesiated Oxazoles: A Simple and Efficient Preparation of 2-Acyl Oxazoles.CHEMINFORM, Issue 48 2007Daniel J. Pippel 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 Preparation of Medium Ring Oxygen Heterocycles.CHEMINFORM, Issue 29 2007Atsuko Nishiguchi 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] Fast and Efficient Preparation of Baylis,Hillman-Derived (E)-Allylic Azides and Related Compounds in Aqueous Medium.CHEMINFORM, Issue 11 2007Marcus M. Sa 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] Heteropolyacid Encapsulated into Mesoporous Silica Framework for an Efficient Preparation of 1,1-Diacetates from Aldehydes under a Solvent-Free Condition.CHEMINFORM, Issue 9 2007Jianmin Wang 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] An Efficient Preparation and Some Reactions of 2-Dimethylaminomethylene-1,3-bis(dimethylimonio)propane Diperchlorate.CHEMINFORM, Issue 31 2006Khiari Jameleddine 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 Preparation of ((3-Chloro-2-fluorophenyl)- [7-methoxy-8- (3-morpholin-4-yl-propoxy)-10,11-dihydro-5-oxa-2,4,11-triazadibenzo (a,d)cyclohepten-1-yl]amine) for in vivo Study.CHEMINFORM, Issue 23 2006Hu Liu 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 Preparation of 2-Pyridylpyridines Using ,-N,N-Dialkylated Aminoacroleins or Their Equivalent as Vinadinium Tetrafluoroborate.CHEMINFORM, Issue 45 2005Hirokazu Kuwabara Abstract For Abstract see ChemInform Abstract in Full Text. [source] Efficient Preparation of Nitrosoarenes for the Synthesis of Azobenzenes.CHEMINFORM, Issue 32 2005Beate Priewisch No abstract is available for this article. [source] Efficient Preparation of Functionalized Hybrid Organic/Inorganic Wells,Dawson-Type Polyoxotungstates.CHEMINFORM, Issue 32 2005Sebastian Bareyt No abstract is available for this article. [source] A Short and Efficient Preparation of Methyl-[1,2,4]oxadiazolium Derivatives with Plant-Inducing Activity.CHEMINFORM, Issue 36 2004Markus R. Dobler Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Convenient and Efficient Preparation of ,-Substituted ,-Haloenones from Diazodicarbonyl Compounds.CHEMINFORM, Issue 11 2004Yong Rok Lee Abstract For Abstract see ChemInform Abstract in Full Text. [source] Efficient Preparation of 1,4,8-Trimethylcyclam and Its Conversion into a Thioalkyl-Pendant Pentadentate Chelate.CHEMINFORM, Issue 10 2004Jason A. Halfen No abstract is available for this article. [source] Efficient Preparation of ,-Trifluoromethyl Acrylates and Derivatives via Palladium Cross-Coupling Reactions.CHEMINFORM, Issue 26 2003Gildas Prie Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: An Efficient Preparation of 6-Alkoxy-Substituted BenzocyclobutenonesCHEMINFORM, Issue 33 2001Christopher J. Bungard 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: An Efficient Preparation of 2H-Cyclohepta[b]furan-2-ones.CHEMINFORM, Issue 26 2001Noboru Morita 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] Efficient Preparation of Photoswitchable Dithienylethene-Linker-Conjugates by Palladium-Catalyzed Coupling Reactions of Terminal Alkynes with Thienyl Chlorides and Other Aryl HalidesCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2010Marc Zastrow Abstract Three photochromic dithienylethene-linker-conjugates with an adamantane core containing different spacer lengths and footprint areas with carboxylic anchoring groups are synthesized. The synthetic routes start either from the ethynylene-linker 5 or the iodo-substituted linker 8. Reaction conditions for the final Sonogashira coupling step between ethynylene-linker 5 with the chloro-substituted dithienylethene 4 in the presence of [PdCl2(CH3CN)2]/X-Phos and Cs2CO3 or K3PO4 are optimized using 2-chloro-5-methylthiophene (9) and triethylsilylacetylene or triisopropylsilylacetylene (10,a,b) as model compounds. Experimental conditions are found to suppress the activation of the C(sp)Si bond in TIPS-acetylene 10,b, a reaction leading to a subsequent cross-coupling reaction to form by-product 12. Furthermore, activation of the C(sp)Si bond in the presence of the fluorinated backbone of the chloro-substituted dithienylethene 4 can also be prevented. The photochromic properties of the conjugate 3 and its precursor dithienylethene 7,b are also investigated. Beschrieben wird die Synthese von drei photochromen Dithienylethen-Linker-Konjugaten, bestehend aus einer zentralen Adamantaneinheit, Carbonsäure-Ankergruppen, sowie variierenden "Spacerlängen" und unterschiedlichen Fußabdrücken. Die synthetischen Routen zu diesen Verbindungen beginnen entweder ausgehend von dem Ethinylen-Linker 5 oder von dem Iod-substituierten Linker 8. Für die finale Sonogashira-Kupplung wurden dabei Reaktionsbedingungen zwischen dem Ethinylen-Linker 5 und dem Chlor-substituierten Dithienylethen 4 in Gegenwart von [PdCl2(CH3CN)2]/X-Phos und Cs2CO3 oder K3PO4 verwendet, die anhand von Modellstudien mit 2-Chlor-5-methylthiophen (9) und Triethylsilylacetylen oder Triisopropylsilylacetylen (10,a,b) optimiert wurden. Dabei wurden experimentelle Bedingungen gefunden, um die Aktivierung der C(sp)-Si-Bindung von TIPS-Acetylen 10,b zu unterdrücken, welche ansonsten zu dem Nebenprodukt 12 führte. Darüber hinaus konnte die Aktivierung der C(sp)-Si-Bindung in Anwesenheit des fluorierten Rückgrats des chlor-substituierten Dithienylethen 4 verhindert werden. Schließlich wurden die photochromen Eigenschaften des Konjugates 3 und der Vorläuferverbindung 7,b untersucht. [source] Synthesis and Electrochemical Study of an Original Copper(II)-Capped Salen,Cyclodextrin ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2010Elise Deunf Abstract A new metallocapped cyclodextrin (CD) was synthesized by the regioselective debenzylation, induced by diisobutylaluminium hydride (DIBAL-H), of perbenzylated cyclodextrins. This reaction allowed for the efficient preparation of an unprecedented CD,salen type copper(II) complex. The electrochemical behavior of both the bound and unbound CD,salen compounds was investigated by cyclic voltammetry. Notably, it was shown that the presence of tert -butyl groups at the ortho - and para -positions of the salen aromatic rings stabilized the copper(II) phenoxyl radical species that was generated upon the one-electron oxidation of the starting compound. Importantly, this stabilization remained effective when the salen-type ligand was covalently attached to the CD. This allowed for investigations of the reactivity of the copper(II) phenoxyl radical complex towards a primary alcohol to be performed by cyclic voltammetry. This reaction can be considered as mimicking the behavior of galactose oxidase. However, under these conditions, no reactivity was observed in the presence of benzyl alcohol. This may be due to distortion, either of the initially square planar salen ligand after its grafting to the CD primary face, and/or of the CD itself. On the other hand, the electrochemical reduction of the un-grafted copper(II) salen-type ligand led to a transient anionic species that exhibited significant stability on the time-scale of the slow cyclic voltammetry measurement in the absence of the CD, but was unstable in the presence of the CD. In the latter case, it was demonstrated that the anionic species was protonated by the CD. Importantly, this protonation was not fast enough to prevent catalytic activation of iodomethane by the electro-generated copper(I)-capped salen CD complex. [source] Synthesis and Biological Evaluation of Non-Hydrolyzable 1,2,3-Triazole-Linked Sialic Acid Derivatives as Neuraminidase InhibitorsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2009Michel Weïwer Abstract ,-Sialic acid azide 1 has been used as a substrate for the efficient preparation of 1,2,3-triazole derivatives of sialic acid using the copper-catalyzed azide,alkyne Huisgen cycloaddition ("click chemistry"). Our approach is to generate non-natural N-glycosides of sialic acid that are resistant to neuraminidase-catalyzed hydrolysis as opposed to the natural O-glycosides. These N-glycosides would act as neuraminidase inhibitors to prevent the release of new virions. As a preliminary study, a small library of 1,2,3-triazole-linked sialic acid derivatives has been synthesized in 71,89,% yield. A disaccharide mimic of sialic acid has also been prepared using the ,-sialic acid azide 1 and a C-8 propargyl sialic acid acceptor in 68,% yield. A model sialic acid coated dendrimer was also synthesized from a perpropargylated pentaerythritol acceptor. These novel sialic acid derivatives were then evaluated as potential neuraminidase inhibitors using a 96-well plate fluorescence assay; micromolar IC50 values wereobserved, comparable to the known sialidase inhibitorNeu5Ac2en.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Diradical-Promoted Two-Carbon Ring-Expansion Reactions by Thermal Isomerization: Synthesis of Functionalized Macrocyclic KetonesHELVETICA CHIMICA ACTA, Issue 7 2004Georg Rüedi A new method for the smooth and highly efficient preparation of functionalized macrocyclic ketones has been developed. Pyrolysis of medium- and large-ring 3-vinylcycloalkanones by dynamic gas-phase thermo-isomerization (DGPTI) at 600,630° yielded, under insertion of a previously attached vinyl side chain by means of a 1,3-C shift, the corresponding ,,, -unsaturated cycloalkanones. The yield of the two-carbon ring-expanded ketones greatly depended on the relative ring strains of substrate and product (5,87%, cf. Table,5). The formation of minor amounts of one-carbon ring-expanded cycloalkenes (<10%) can be ascribed to a subsequent decarbonylation step. A reaction mechanism involving initial cleavage of the weakest single bond in the molecule has been established (cf. Scheme,6). Recombination within the generated diradical intermediate in terminal vinylogous position led to the observed products, while reclosure gave recovered starting material. Substituents on the vinyl moiety were transferred locospecifically into the ring-expanded products. An isopropenyl group did not significantly affect the isomerization process, whereas substrates bearing a prop-1-enyl group in , -position enabled competing intramolecular H-abstraction reactions, leading to acyclic dienones (cf. Schemes,9,11). DGPTI of the 13-membered analogue directly yielded 4-muscenone, which, upon hydrogenation, led to the valuable musk odorant (±)-muscone. Increasing the steric hindrance on the vinyl moiety gave rise to diminishing amounts of the desired ,,, -unsaturated cycloalkanones. This novel two-carbon ring-expansion protocol was also successfully applied to 3-ethynylcycloalkanones, giving rise to the corresponding ring-expanded cyclic allenes (cf. Scheme,13). [source] A Selective and Benign Synthesis of Functionalized Benzalacetones via Mizoroki,Heck Reaction Using Aryldiazonium SaltsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Therese Stern Abstract Palladium-catalyzed Mizoroki,Heck reactions were carried out in the presence of calcium carbonate in alcoholic solvents. Under these conditions an efficient preparation of functionalized benzalacetones was developed. The reactions were carried out at room temperature and aerobic conditions, giving the products within several minutes in up to 95% isolated yields. Furthermore, some kinetic investigations, mechanistic insights and considerations are presented. [source] Synthesis of poly(cyclohexene oxide)- block -polystyrene by combination of radical-promoted cationic polymerization, atom transfer radical polymerization and click chemistryPOLYMER INTERNATIONAL, Issue 6 2010Mustafa Degirmenci Abstract The combination of radical-promoted cationic polymerization, atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of poly(cyclohexene oxide)- block -polystyrene (PCHO- b -PSt). Alkyne end-functionalized poly(cyclohexene oxide) (PCHO-alkyne) was prepared by radical-promoted cationic polymerization of cyclohexene oxide monomer in the presence of 1,2-diphenyl-2-(2-propynyloxy)-1-ethanone (B-alkyne) and an onium salt, namely 1-ethoxy-2-methylpyridinium hexafluorophosphate, as the initiating system. The B-alkyne compound was synthesized using benzoin photoinitiator and propargyl bromide. Well-defined bromine-terminated polystyrene (PSt-Br) was prepared by ATRP using 2-oxo-1,2-diphenylethyl-2-bromopropanoate as initiator. Subsequently, the bromine chain end of PSt-Br was converted to an azide group to obtain PSt-N3 by a simple nucleophilic substitution reaction. Then the coupling reaction between the azide end group in PSt-N3 and PCHO-alkyne was performed with Cu(I) catalysis in order to obtain the PCHO- b -PSt block copolymer. The structures of all polymers were determined. Copyright © 2010 Society of Chemical Industry [source] | ||||||||||||||||||||||