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New Synthetic Method (new + synthetic_method)
Selected AbstractsA New Synthetic Method for the Preparation of Star-Shaped Polyisobutylene with Hyperbranched Polystyrene CoreMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13 2007Gergely Kali Abstract Friedel,Crafts self-grafting of polystyrene (PSt) under quasiliving carbocationic polymerization was utilized to develop a new rapid one-pot method for the preparation of star-shaped polyisobutylene (PIB). First, the polymerization of isobutylene led to PIB with predetermined molecular weight (,=,2,000) and narrow molecular weight distribution (,=,1.03). Then addition of relatively small amount of styrene after isobutylene consumption yielded PIB-PSt diblocks. Multiple alkylation of the resulting PSt segments by the polystyryl cations led to hyperbranched PSt cores coupling PIB chains to form a star polymer in short reaction time (within an hour) compared to reported methods. The formation of star polymers by this self-grafting mechanism was proved by gel permeation chromatography equipped with online viscosimeter and 1H NMR spectroscopy. [source] ChemInform Abstract: A Hetero Pauson,Khand Reaction of Ketenimines: A New Synthetic Method for ,-Exomethylene-,,,-unsaturated ,-Lactams.CHEMINFORM, Issue 21 2010Takao Saito 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] NaBH4/Charcoal: A New Synthetic Method for Mild and Convenient Reduction of Nitroarenes.CHEMINFORM, Issue 7 2007Behzad Zeynizadeh 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] A New Synthetic Method for Dipeptides Containing ,,,-Didehydroamino Acids Utilizing an ,-Tosylglycine Residue.CHEMINFORM, Issue 15 2005Yohsuke Shiraishi No abstract is available for this article. [source] ChemInform Abstract: A New Synthetic Method for the Reduction of Imines by Samarium-Induced Reaction.CHEMINFORM, Issue 8 2002Bimal K. Banik 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 Synthesis of Benzofurans Utilizing [3,3]-Sigmatropic Rearrangement Triggered by N -Trifluoroacetylation of Oxime Ethers: Short Synthesis of Natural 2-ArylbenzofuransEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2007Norihiko Takeda Abstract A new synthetic method for the preparation of benzofurans has been developed. The key step of this method is the [3,3]-sigmatropic rearrangement of N -trifluoroacetyl-ene-hydroxylamines, which was triggered by acylation of oxime ethers. TFAA has been proved to be the best reagent to induce [3,3]-sigmatropic rearrangement for the synthesis of cyclic oracyclic dihydrobenzofurans. On the other hand, the TFAT-DMAP system is found to be the most effective for constructing various benzofurans. Synthetic utility of this reaction is demonstrated by the short synthesis of natural benzofurans without protection of the hydroxy group. The synthesis of Stemofuran A was accomplished via condensation of ketones with aryloxyamine and subsequent reaction with TFAT-DMAP in a four-step synthesis with 72,% overall yield. Similarly, Eupomatenoid 6 and Coumestan were synthesized through the reaction of oxime ether with TFAT-DMAP. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Study of the Reaction of 3-Formylrifamycin SV with Gaseous Ammonia and Acetone,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2006Krzysztof Bujnowski Abstract In the second stage of our study concerning the search for new antibacterial rifamycin antibiotics, reaction of the aldehydes 3-formylrifamycin SV (1) and 25- O -deacetyl-3-formylrifamycin SV with ammonia and acetone has been investigated. A new synthetic method for the preparation of a new group of rifamycin derivatives with a cyclic substituent at C-3 having a 4-piperidone structure, represented by compounds 6a, 6b, and 7a, has been developed. The structures of the compounds and a reaction mechanism have been proposed on the basis of mass spectrometry results as well as 1D and 2D 1H and 13C NMR analysis. The results of the in vitro tests confirm the antituberculous activity of the synthesized compounds. Furthermore, 6a, which is isolated in good yield, is a promising substrate for a new class of rifamycin derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] A New and Efficient Synthesis of the HMG-CoA Reductase Inhibitor PitavastatinHELVETICA CHIMICA ACTA, Issue 6 2007Murat Acemoglu Abstract A new synthetic method for the preparation of pitavastatin is described. The approach circumvents various synthetic problems associated with the buildup of the 3,5-dihydroxy-C7 acid side chain of HMG-CoA reductase inhibitors (statins). The use of the C6 -amide derivative 5 instead of ester derivatives in the coupling reaction with carboxaldehyde 8 (Scheme,3) prevents undesired side reactions, such as eliminations and retro -aldol reactions. The method provides synthetic statins, such as pitavastatin, in >99% ee and exceptionally high overall yield. The enantiomerically pure starting material, (3S)-3-{[(tert -butyl)dimethylsilyl]oxy}-5-oxo-5-{[(1S)-1-phenylethyl]amino}pentanoic acid (3c), is prepared by an improved procedure from 3-{[(tert -butyl)dimethylsilyl]oxy}glutaric anhydride (1) and (1S)-1-phenylethylamine (2c; Scheme,1). [source] GaN Nanofibers based on Electrospinning: Facile Synthesis, Controlled Assembly, Precise Doping, and Application as High Performance UV Photodetector,ADVANCED MATERIALS, Issue 2 2009Hui Wu Nitride nanofibers have been synthesized based on a simple electrospinning technique for the first time. No catalysts or templates are needed in this new synthetic method. Highly oriented GaN nanofiber arrays, as well as a high-performance UV photodetector based on single GaN nanofiber assembled FET devices, can be facilely fabricated using this technique. Precise doping of other elements into the GaN nanofibers is easy by this solution-based synthetic method. [source] Synthesis and biological evaluation of destruxin A and related analogsCHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2001T. Ast Abstract: This report describes the development of an efficient solid-phase synthesis protocol and adaptation of reported solution phase procedures for the synthesis of the cyclic depsihexapeptide destruxin A and related analogs. The solid-phase method described is based on standard Fmoc peptide chemistry, including a new synthetic method for the assembly of the depsi bond-containing unit. In order to select analogs of destruxin A for synthesis and evaluation of insecticidal activity, the work of Hellberg et al., describing a set of Z -descriptors for amino acid side-chains comparing their physicochemical properties, was utilized. Destruxin A and 27 different analogs with structural variations in four residues were synthesized and insecticidal activity was evaluated via injections into tobacco budworm (Heliothis virescens) larvae. Several destruxin A analogs were found to be at least as potent as the native compound. [source] Synthesis of N -Alkylhexahydroazepine by One-step Catalytic Alkylation and Hydrogenation of CaprolactamCHINESE JOURNAL OF CHEMISTRY, Issue 1 2006Jun-Ming Du Abstract A new synthetic method for the preparation of N -alkylhexahydroazepine by one-step catalytic alkylation and hydrogenation of caprolactam has been developed. Alkylated caprolactam was firstly synthesized by catalytic alkylation of caprolactam with alcohol and then directly hydrogenated into N -alkylhexahydroazepine over Cu-ZnO/, -Al2O3 catalyst. [source] | |||||||||||||||||||||||||