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Palladium-catalyzed Cross-coupling Reaction (palladium-catalyzed + cross-coupling_reaction)
Selected AbstractsDihydroazulene Photoswitches: The First Synthetic Protocol for Functionalizing the Seven-Membered RingEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2009Michael Åxman Petersen Abstract The first synthetic protocol for functionalizing the dihydroazulene (DHA) photoswitch in its seven-membered ring has been developed. This protocol is based on regioselective bromination, followed by regioselective elimination of HBr, and finally a palladium-catalyzed cross-coupling reaction with a terminal alkyne. The position of functionalization (C-7) was confirmed by X-ray crystal structure analysis. Light-induced ring opening of this compound to its vinylheptafulvene (VHF) isomer followed by thermal ring closure provides a mixture of two DHA regioisomers in a ratio that depends on the wavelength of irradiation and solvent polarity.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Syntheses of new unsymmetrically dodecakis(trifluoroethoxy)-substituted metallophthalocyanines by a palladium-catalyzed cross-coupling reactionJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2000Minquan Tian Novel unsymmetrical vanadyl and zinc dodecakis(2,2,2-trifluoroethoxy)phthalocyaninates with an iodo group were synthesized by a statistical condensation route. The palladium-catalyzed coupling reaction between such monoiodinated metallophthalocyanines and terminal acetylenic derivatives gave various new unsymmetrically dodecakis(2,2,2-trifluoroethoxy)-substituted metallophthalocyanines with extended exocyclic ,-conjugation. Unsymmetrical zinc dodecakis(2,2,2-trifluoroethoxy)phthalocyaninate with a nitro group was also prepared for comparison. All the target phthalocyanines were separated by common col umn chromatography and characterized by elemental analysis, ir and 1H-nmr, uv-visible and fast-atombombardment mass spectroscopy. [source] Preparation of 4-[11C]methylmetaraminol, a potential PET tracer for assessment of myocardial sympathetic innervationJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2003Oliver Langer Abstract The false adrenergic neurotransmitter [11C]meta -hydroxyephedrine ([11C]HED) is currently the PET tracer of choice for assessment of myocardial sympathetic innervation. The molecule is metabolised in the 4-position of the aromatic ring. The resulting radiolabelled metabolites need to be measured in order to obtain an arterial input function. Our aim was the development of a PET tracer with an increased metabolic stability relative to [11C]HED. We selected 4-methylmetaraminol as a candidate molecule for radiolabelling with 11C (t1/2 20.4 min). Our radiosynthetic approach towards 4-[11C]methylmetaraminol involved a palladium-catalyzed cross-coupling reaction of a protected 4-trimethylstannyl derivative of metaraminol with [11C]methyl iodide followed by removal of the protective groups. 4-[11C]methylmetaraminol was obtained in a final decay-corrected radiochemical yield of 20,25% within a synthesis time of 60,80 min. The specific radioactivity at the end of the synthesis ranged from 18,37 to GBq/,mol. The unlabelled reference molecule, 4-methylmetaraminol, was prepared in a 5-step synthesis starting from metaraminol. A biological evaluation of 4-[11C]methylmetaraminol is in progress and the results will be reported elsewhere. Copyright © 2002 John Wiley & Sons, Ltd. [source] Synthesis of silicon-bridged polythiophene derivatives and their applications to EL device materialsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2007Joji Ohshita Abstract Palladium-catalyzed oxidative homo-coupling of 2,6-bis(tributylstannyl)dithienosiloles with CuCl2 afforded poly(dithienosilole-2,6-diyl)s as novel polythiophene derivatives with intra-chain silicon bridges, which exhibited red-shifted UV absorption maxima by about 100 nm from those of the corresponding silole-free polythiophenes. Alternate copolymers also were prepared by palladium-catalyzed cross-coupling reactions of 2,6-dibromodithienosiloles with distannylthiophene or bithophene. These polymer films were applied to single and double-layered organic electroluminescence devices. It was found that some of the resulting polymers exhibited electroluminescence properties and emitted red light in EL devices with the structure of ITO/polymer/Mg-Ag. Introducing an electron-transporting Alq3 layer between the polymer film and the Mg-Ag cathode led to a remarkable improvement in the devices performance. An application of the copolymer to a field effect transistor was also studied. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4588,4596, 2007 [source] Deprotonative Metalation of Substituted Benzenes and Heteroaromatics Using Amino/Alkyl Mixed Lithium,Zinc CombinationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2010Katia Snégaroff Dr. Abstract Different homoleptic and heteroleptic lithium,zinc combinations were prepared, and structural elements obtained on the basis of NMR spectroscopic experiments and DFT calculations. In light of their ability to metalate anisole, pathways were proposed to justify the synergy observed for some mixtures. The best basic mixtures were obtained either by combining ZnCl2,TMEDA (TMEDA=N,N,N,,N, -tetramethylethylenediamine) with [Li(tmp)] (tmp=2,2,6,6-tetramethylpiperidino; 3,equiv) or by replacing one of the tmp in the precedent mixture with an alkyl group. The reactivity of the aromatic lithium zincates supposedly formed was next studied, and proved to be substrate-, base-, and electrophile-dependent. The aromatic lithium zincates were finally involved in palladium-catalyzed cross-coupling reactions with aromatic chlorides and bromides. [source] | ||||||||||