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Very Mild Conditions (very + mild_condition)
Selected AbstractsEfficient Addition Reaction of Bromonitromethane to Aldehydes Catalyzed by NaI: A New Route to 1-Bromo-1-nitroalkan-2-ols under Very Mild Conditions.CHEMINFORM, Issue 15 2007Jose M. Concellon 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] ChemInform Abstract: Cu/SiO2 -Catalyzed Hydrogenation of Cyclohexanones under Very Mild Conditions.CHEMINFORM, Issue 36 2002Nicoletta Ravasio 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] Cycloaddition of nitrile oxides to substituted vinylphosphonatesHETEROATOM CHEMISTRY, Issue 4 2003Yong Ye Cycloaddition of nitrile oxides to substituted vinylphosphonates was performed. A series of 4,5-dihydroisoxazoles containing phosphonyl group were synthesized under very mild condition in excellent regiospecificity. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:309,311, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10149 [source] Mild Synthesis of ,-Amino-,,,-difluoro Ketones from Acylsilanes and Trifluoromethyltrimethylsilane in a One-Pot Imino Aldol Reaction,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2005Sylvain Jonet Abstract ,-Amino-,,,-difluoro ketones have been very conveniently prepared in a one-pot procedure from acylsilanes, trifluoromethyltrimethylsilane and imines. The key intermediate in this reaction is a difluoroenoxysilane. The Lewis acid promoted imino aldol reaction was performed with BF3·OEt2 or under very mild conditions using a catalytic amount of Yb(OTf)3. The reaction with chiral benzylimines occurred in good yield with 52,78,% de. Palladium-catalyzed hydrogenolysis furnished an unprotected ,-amino-,,,-difluoro ketone or a ,-amino-,,,-difluoro alcohol. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Highly Enantioselective Michael Addition of Cyclic 1,3-Dicarbonyl Compounds to ,,,-Unsaturated ,-Keto EstersADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Xing-Kuan Chen Abstract A highly enantioselective Michael addition of cyclic 1,3-dicarbonyl compounds to ,,,-unsaturated ,-keto esters catalyzed by amino acid-derived thiourea-tertiary-amine catalysts is presented. Using 5,mol% of a novel tyrosine-derived thiourea catalyst, a series of chiral coumarin derivatives were obtained in excellent yields (up to 99%) and with up to 96% ee under very mild conditions within a short reaction time. [source] Base- and Copper-Catalyzed Intramolecular Cyclization for the Direct Synthesis of DihydrofuransADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Yong-Fei Chen Abstract A simple and convenient synthetic approach to dihydrofurans has been developed from the cyclization of 2-propynyl-1,3-dicarbonyl compounds catalyzed by potassium tert -butoxide, copper(II) trifluoromethanesulfonate and triphenylphosphine using methanol/dichloromethane as the solvent under very mild conditions. Moreover, dihydrofurans could be easily transformed into the corresponding furans in the presence of trifluoroacetic acid. [source] Regioselective and Enantioselective Hydroformylation of DialkylacrylamidesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Abstract Dimethylacrylamide can be hydroformylated with very high chemo- and regioselectivity. Asymmetric hydroformylation of this substrate is possible, provided steps are taken to minimise racemisation of the aldehyde products, and this work demonstrates the effect of various conditions and variables on racemisation. Using the Landis diazaphospholane ligands up to 68% ee can be realised under very mild conditions. Other dialkylacrylamides were also hydroformylated under mild conditions giving similar or better enantioselectivities, including the Weinreb amide of acrylic acid (71% ee), and the asymmetric hydroformylation of diethylacrylamide producing the chiral aldehyde with up to 82% ee. [source] Copper-Catalyzed Preparation of ,-Alkylidenebutenolides and Isocoumarins under Mild Palladium-Free ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009Samuel Inack-Ngi Abstract A general and efficient copper(I)-catalyzed cross-coupling and heterocyclization reaction of terminal alkynes and ,-iodo-,,,-unsaturated acid derivatives has been developed under very mild conditions. This method provides easy access from good to excellent yields of a variety of 5-ylidenebutenolides and 3-substituted isocoumarins with excellent regio- and stereoselectivity. This procedure does not require the use of any expensive supplementary additives, and is palladium-free. [source] Proton-Promoted Hydroamination of 3-Dialkylthiomethylene-1,4-pentadiynes with o -Phenylenediamines: A Facile Route to Benzo[b][1,4]diazepinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2008Yu-Long Zhao Abstract The first proton-promoted intermolecular hydroamination reaction of the enynes, ,,,-dialkynylketene S,S -acetals 2, is described. A series of benzo[b][1,4]diazepines, with the structures of 3 and 5, were prepared chemo- and regioselectively in good to high yields by reacting the readily available 1,4-diynes 2 with both terminal and internal alkyne functions with o -phenylenediamines under very mild conditions. [source] Creation of a Monomeric Ruthenium Species on the Surface of Micro-Size Copper Hydrogen Phosphate: An Active Heterogeneous Catalyst for Selective Aerobic Oxidation of AlcoholsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2007Junhua Liu Abstract A new micro-size copper hydrogen phosphate (CHP) synthesized by the emulsion method combined with a monomeric ruthenium species was found to be a very effective catalyst for the selective oxidation of alcohols. Several kinds of alcohols were transformed into the corresponding aldehydes or ketones over the RuCHP catalyst by oxygen under very mild conditions. The results showed that the CHP material was perfect as a catalyst support due to its high ion-exchange ability and adsorption capacity. [source] Controlled synthesis of amphiphilic biodegradable polylactide-grafted dextran copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2004Cécile Nouvel Abstract The whole controlled synthesis of novel amphiphilic polylactide (PLA)-grafted dextran copolymers was achieved. The control of the architecture of such biodegradable and potentially biocompatible copolymers has required a three-step synthesis based on the "grafting from" concept. The first step consisted of the partial silylation of the dextran hydroxyl groups. This protection step was followed by the ring-opening polymerization of D,L -lactide initiated from the remaining OH functions of the partially silylated polysaccharide. The third step involved the silylether group deprotection under very mild conditions. Based on previous studies, in which the control of the first step was achieved, this study is focused on the last two steps. Experimental conditions were investigated to ensure a controlled polymerization of D,L -lactide, in terms of grafting efficiency, graft length, and transesterification limitation. After polymerization, the final step was studied in order to avoid degradation of both polysaccharide backbone and polyester grafts. The chemical stability of dextran backbone was checked throughout each step of the synthesis. PLA-grafted dextrans and PLA-grafted (silylated dextrans) were proved to adopt a core-shell conformation in various solvents. Furthermore, preliminary experiments on the potential use of these amphiphilic grafted copolymers as liquid/liquid interface stabilizers were performed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2577,2588, 2004 [source] Synthesis and applications of novel fluoroalkyl end-capped cooligomers containing diphenylacetylene segments: a new approach to the surface arrangement of diphenylacetylene segments on the traditional organic polymerPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2010Masaki Mugisawa Abstract Fluoroalkyl end-capped cooligomers containing diphenylacetylene segments [RF -(DPMA)x -(Co-M)y - RF] were prepared by reaction of fluoroalkanoyl peroxide with 4-(phenylethynyl)phenyl methacrylate (DPMA) and radical polymerizable comonomers such as N,N -dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO) under very mild conditions. Fluorinated cooligomers containing diphenylacetylene segments thus obtained exhibited a good solubility in a variety of organic solvents. These fluorinated cooligomers were also applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate) (PMMA) to exhibit not only a good surface active property imparted by fluorine but also a fluorescent characteristic related to diphenylacetylene segments on their surface. In addition, these fluorinated cooligomers could form the nanometer size-controlled fluorinated molecular aggregates in chloroform. Interestingly, some benzenes and biphenyl (BP) derivatives could interact with these fluorinated oligomeric aggregates as guest molecules, and in particular 2-chloro-5-nitrobenzotrifluoride (CNB) was most effective for enhancing the fluorescent intensity of these guest molecules. Copyright © 2009 John Wiley & Sons, Ltd. [source] An affine-invariant multivariate sign test for cluster correlated dataTHE CANADIAN JOURNAL OF STATISTICS, Issue 4 2003Denis Larocque Abstract The author presents a multivariate location model for cluster correlated observations. He proposes an affine-invariant multivariate sign statistic for testing the value of the location parameter. His statistic is an adaptation of that proposed by Randles (2000). The author shows, under very mild conditions, that his test statistic is asymptotically distributed as a chi-squared random variable under the null hypothesis. In particular, the test can be used for skewed populations. In the context of a general multivariate normal model, the author obtains values of his test's Pitman asymptotic efficiency relative to another test based on the overall average. He shows that there is an improvement in the relative performance of the new test as soon as intra-cluster correlation is present Even in the univariate case, the new test can be very competitive for Gaussian data. Furthermore, the statistic is easy to compute, even for large dimensional data. The author shows through simulations that his test performs well compared to the average-based test. He illustrates its use with real data. L'auteur présente un modèle de position multivarié pour données corrélées en grappes. Il propose une statistique du signe multivarié affine-invariant permettant de tester la valeur du vecteur de position. Sa statistique est une adaptation de celle proposée par Randles (2000). L'auteur montre que sous des conditions peu restrictives, la loi asymptotique de sa statistique sous l'hypothèse nulle est celle du khi-deux. En particulier, le test peut ,tre utilisé avec des populations asymétriques. Dans le cadre d'un modèle multinormal général, l'auteur calcule les valeurs de l'efficacité asymptotique de Pitman de son test par rapport à un autre test basé sur la moyenne globale. Ses résultats montrent que la performance du nouveau test s'améliore en présence de corrélation intra-grappe. M,me dans le cas univarié, le nouveau test s'avère très performant pour des données gaussiennes. De plus, la statistique se calcule facilement, m,me en haute dimension. L'auteur montre par simulation que son test se comporte bien par rapport à celui fondé sur la moyenne globale. Il en illustre l'emploi au moyen de données réelles. [source] Fullerene-Mediated Activation of Dihydrogen: A New Method of Metal-Free Catalytic HydrogenationCHEMCATCHEM, Issue 5 2010Jochen Niemeyer Dr. A new type of metal-free catalytic hydrogenation has been developed, which allows for the reduction of various nitroarenes to the corresponding anilines with excellent yields and chemoselectivities. The hydrogenation takes place under very mild conditions using dihydrogen in combination with fullerene catalysts. [source] Preparation of 2-Quinolones by Sequential Heck Reduction,Cyclization (HRC) Reactions by Using a Multitask Palladium CatalystCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2009François-Xavier Felpin Dr. Abstract One-pot sequential Heck reduction,cyclization (HRC) reactions leading to the synthesis of substituted 2-quinolones have been developed by using a heterogeneous or mixed homogeneous/heterogeneous multitask palladium catalyst with charcoal as a support. The whole sequence occurs under very mild conditions without the need for additives (ligand or base) by taking advantage of the high reactivity of aryldiazonium salts as "super electrophiles". Recycling experiments showed that the reused heterogeneous Pd0/C catalyst was not able to promote another HRC sequence but was, however, still highly active for hydrogenation, hydrodehalogenation, as well as hydrogenolysis reactions. [source] Porphyrin-Functionalized Dendrimers: Synthesis and Application as Recyclable Photocatalysts in a Nanofiltration Membrane ReactorCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2005Suhas A. Chavan Dr. Abstract The convergent synthesis of a series of porphyrin-functionalized pyrimidine dendrimers has been accomplished by a procedure involving the nucleophilic aromatic substitution (NAS) as a key reaction step. The resulting dendritic porphyrin catalysts show high activity in the light-induced generation of singlet oxygen (1O2) from ground-state oxygen. These materials are synthetically useful photosensitizers for the oxidation of various olefinic compounds to the corresponding allylic hydroperoxides. Catalytic activities and regio- and stereoselectivities of the dendritic photosensitizers are comparable to those observed for mononuclear porphyrin catalysts. Recycling of the dendrimer-enlarged homogeneous photocatalysts was possible by solvent-resistant nanofiltration (SRNF) by using an oxidatively stable membrane consisting of a polysiloxane polymer and ultrastable Y zeolite as inorganic filler. Moreover, this membrane technology provides a safe way to isolate the hydroperoxide products under very mild conditions. The membrane showed high retention for the macromolecular catalysts, even in chlorinated solvents, but some oxidative degradation of the porphyrin units of the dendrimer was observed over multiple catalytic runs. [source] | |||||||||||||