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Improved Protocol (improved + protocol)
Selected AbstractsAn Improved Protocol for the Synthesis of Quinoline-2,3-dicarboxylates under Neutral Conditions via Biomimetic ApproachHELVETICA CHIMICA ACTA, Issue 2 2010Bandaru Madhav Abstract A mild and efficient protocol for synthesis of quinoline derivatives in aqueous medium under neutral conditions is described. The reaction proceeded smoothly in H2O catalyzed by supramolecular catalyst , -CD. By this protocol, various quinoline derivatives were synthesized in excellent yields. [source] An Improved Protocol for Palladium-Catalyzed Alkoxycarbonylations of Aryl Chlorides with Alkyl FormatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Thomas Schareina Abstract The palladium-catalyzed alkoxycarbonylation of aryl and heteroaryl halides using butyl formate has been investigated. In the presence of palladium(II) acetate/n -butylbis(1-adamantyl)phosphine (L1), and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as base for the first time non-activated chloroarenes can be conveniently carbonylated in good yields. [source] An Improved Protocol for the Direct Asymmetric Aldol Reaction in Ionic Liquids, Catalysed by Onium Ion-Tagged ProlinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2007Marco Lombardo Abstract Two onium ion-tagged prolines, imidazolium bis(trifluoromethylsulfonyl)imide-substituted proline 6 and butyldimethylammonium bis(trifluoromethylsulfonyl)imide-substituted proline 7, were synthesised and their catalytic activity in the direct asymmetric aldol condensation was studied in ionic liquids. For the reaction of acetone with various aldehydes, using 5,% of the catalyst, the yields of the aldols varied between 50,85,% while the ee values were in the 80,85,% range. Other ketones were studied too, the yields obtained in those cases being in the 35,78,% range while the enantioselectivities varied between 75,94,%. [source] ChemInform Abstract: Improved Protocol for Thorpe Reaction: Synthesis of 4-Amino-1-arylpyrazole Using Solid,Liquid Phase-Transfer Conditions.CHEMINFORM, Issue 27 2008Nirmal D. Desai 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] An Improved Protocol for Ligandless Suzuki,Miyaura Coupling in Water.CHEMINFORM, Issue 39 2006Dmitrii N. Korolev 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] Improved Protocol for the Diastereoselective Cyclopropanation of Alkenes Using Geminal Dizinc Carbenoids: A Study on the Effect of Zinc Iodide.CHEMINFORM, Issue 31 2004Jean-Francois Fournier Abstract For Abstract see ChemInform Abstract in Full Text. [source] An Improved Protocol for the Ruthenium(pybox)-Catalyzed Asymmetric Alkene Epoxidation.CHEMINFORM, Issue 52 2003Man Kin Tse Abstract For Abstract see ChemInform Abstract in Full Text. [source] An Improved Protocol for the RuO4 -Catalyzed Dihydroxylation of Olefins.CHEMINFORM, Issue 51 2003Bernd Plietker Abstract For Abstract see ChemInform Abstract in Full Text. [source] Bismuth Triflate Catalyzed One-Pot Synthesis of 3,4-Dihydropyrimidin-2-(1H)-ones: An Improved Protocol for the Biginelli Reaction.CHEMINFORM, Issue 15 2003Ravi Varala Abstract For Abstract see ChemInform Abstract in Full Text. [source] Improved Protocols for Molybdenum- und Tungsten-Catalyzed HydrostannationsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Alexander Abstract A series of (isonitrile)tungsten carbonyl complexes of type W(CO)m(CNR)n has been synthesized and evaluated as hydrostannation catalysts. The results are compared with those obtained by the previously reported tri(tert -butylisonitrile)molybdenum tricarbonyl catalyst, Mo(CO)3(CN- t- Bu)3 (=MoBI3). The yields and selectivities strongly depend on the isonitriles used, and with certain substrates better results are obtained compared to the molybdenum catalyst. No side products are observed in hydrostannations under microwave irradiation or when the reactions are carried out under an atmosphere of carbon monoxide. Based on these findings, a mechanistic rational is given, explaining the different pathways responsible for the formation of hydrostannation or distannation products. [source] Online CIEF-ESI-MS in glycerol,water media with a view to hydrophobic protein applicationsELECTROPHORESIS, Issue 23 2009Meriem Mokaddem Abstract A new online coupling of CIEF with ESI-MS has been developed in glycerol,water media. This improved protocol provides: (i) the electric continuity during the whole analysis by a discontinuous filling of the capillary with 60:40 (cm/cm) catholyte/proteins,ampholyte mixture; (ii) the use of an anticonvective medium, i.e. 30:70 glycerol/water, v/v, compatible with MS detection and as an aid to hydrophobic protein solubilization and (iii) the use of unmodified bare fused-silica capillaries, as the glycerol/water medium strongly reduces EOF. Focusing was performed in positive polarity and cathodic mobilization was achieved by both voltage and pressure application. The setup was optimized with respect to analysis time, sensitivity and precision on pI determination. The optimized anolyte and catholyte were composed of 50,mM formic acid/1,mM glutamic acid (pH 2.35) and 100,mM NH3/1,mM lysine (pH 10.6), respectively. The effects of ampholyte concentration, focusing time and ESI parameters were presented for model proteins and discussed. This new integrated protocol should be an easy and effective additional tool in the field of proteome analysis, providing a means for the characterization of a large number of hydrophilic and hydrophobic proteins. [source] Increasing the Scope of Palladium-Catalyzed Cyanations of Aryl ChloridesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Thomas Schareina Abstract An improved protocol for the palladium-catalyzed cyanation of electron-rich aryl chlorides with potassium ferrocyanide {K4[Fe(CN)6]} is presented. Compared to previous procedures the substrate scope is significantly broadened. [source] Efficient cloning of plant genomes into bacterial artificial chromosome (BAC) libraries with larger and more uniform insert sizePLANT BIOTECHNOLOGY JOURNAL, Issue 3 2004Boulos Chalhoub Summary The construction of bacterial artificial chromosome (BAC) libraries remains relatively complex and laborious, such that any technological improvement is considered to be highly advantageous. In this study, we addressed several aspects that improved the quality and efficiency of cloning of plant genomes into BACs. We set the ,single tube vector' preparation method with no precipitation or gel electrophoresis steps, which resulted in less vector DNA damage and a remarkable two- to threefold higher transformation efficiency compared with other known vector preparation methods. We used a reduced amount of DNA for partial digestion (up to 5 µg), which resulted in less BAC clones with small inserts. We performed electrophoresis in 0.25 × TBE (Tris, boric acid, ethylenediaminetetraacetic acid) buffer instead of 0.5 × TBE, which resulted in larger and more uniformly sized BAC inserts and, surprisingly, a two- to threefold higher transformation efficiency, probably due to less contamination with borate ions. We adopted a triple size selection that resulted in an increased mean insert size of up to 70 kb and a transformation efficiency comparable with that of double size selection. Overall, the improved protocol presented in this study resulted in a five- to sixfold higher cloning efficiency and larger and more uniformly sized BAC inserts. BAC libraries with the desired mean insert size (up to 200 kb) were constructed from several plant species, including hexaploid wheat. The improved protocol will render the construction of BAC libraries more available in plants and will greatly enhance genome analysis, gene mapping and cloning. [source] Detergent addition to tryptic digests and ion mobility separation prior to MS/MS improves peptide yield and protein identification for in situ proteomic investigation of frozen and formalin-fixed paraffin-embedded adenocarcinoma tissue sectionsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 10 2009Marie-Claude Djidja Abstract The identification of proteins involved in tumour progression or which permit enhanced or novel therapeutic targeting is essential for cancer research. Direct MALDI analysis of tissue sections is rapidly demonstrating its potential for protein imaging and profiling in the investigation of a range of disease states including cancer. MALDI-mass spectrometry imaging (MALDI-MSI) has been used here for direct visualisation and in situ characterisation of proteins in breast tumour tissue section samples. Frozen MCF7 breast tumour xenograft and human formalin-fixed paraffin-embedded breast cancer tissue sections were used. An improved protocol for on-tissue trypsin digestion is described incorporating the use of a detergent, which increases the yield of tryptic peptides for both fresh frozen and formalin-fixed paraffin-embedded tumour tissue sections. A novel approach combining MALDI-MSI and ion mobility separation MALDI-tandem mass spectrometry imaging for improving the detection of low-abundance proteins that are difficult to detect by direct MALDI-MSI analysis is described. In situ protein identification was carried out directly from the tissue section by MALDI-MSI. Numerous protein signals were detected and some proteins including histone H3, H4 and Grp75 that were abundant in the tumour region were identified. [source] An improved protocol for rapid freezing of protein samples for long-term storageACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2004Rapid freezing of protein samples Freezing of purified protein drops directly in liquid nitrogen is a convenient technique for the long-term storage of protein samples. Although this enhances reproducibility in follow-up crystallization experiments, some protein samples are not amenable to this technique. It has been discovered that plunging PCR tubes containing protein samples into liquid nitrogen results in more rapid freezing of the samples and can safely preserve some proteins that are damaged by drop-freezing. The PCR-tube method can also be adapted to a PCR-plate freezing method with applications for high-throughput and structural genomics projects. [source] | |||||||||||||