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Electrophilic Substitution Reaction (electrophilic + substitution_reaction)
Selected AbstractsReactions of Pendant Boryl Groups in Cp,Metal Complexes: Heterocyclic Ring Annelation in a CpIr SystemEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2008Christoph Herrmann Abstract Treatment of (cod)IrCl dimer with Li(allyl)cyclopentadienide gave (C5H4,CH2,CH=CH2)Ir(cod) (11). At 100 °C, 11 isomerizes cleanly into its ring-conjugated (trans -CH3,CH=CH,C5H4)Ir(cod) isomer (13). Subsequent addition of HB(C6F5)2 results in the formation of a product (16) that contains an annelated five-membered borata heterocycle at the Cp ring. This is probably formed by means of a reaction sequence involving regioselective hydroboration, followed by an electrophilic substitution reaction at the Cp ring by the strongly Lewis acidic ,B(C6F5)2 group, in which the iridium metal base acts as the proton abstractor. Products 13 and 16 were characterized by X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Silica Supported Sodium Hydrogen Sulfate and Amberlyst-15: Two Efficient Heterogeneous Catalysts for Facile Synthesis of Bis- and Tris(1H -indol-3-yl)methanes from Indoles and Carbonyl Compounds[1]ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2003Chimmani Ramesh Abstract Bis- and tris(1H -indol-3-yl)methanes are synthesized in high yields by an electrophilic substitution reaction of indoles with carbonyl compounds under mild reaction conditions using two efficient heterogeneous catalysts, silica supported sodium hydrogen sulfate (NaHSO4,SiO2) and amberlyst-15. The second catalyst can be reused. [source] Copper nitrate trihydrate catalyzed efficient synthesis of bis(indolyl)methanes in acetonitrile at room temperatureJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2007Aayesha Nasreen A catalytic amount of easily available and inexpensive Cu(NO3)3.3H2O (10 mol%) enables electrophilic substitution reaction of indole with structurally divergent aldehydes in acetonitrile to afford the corresponding bis(indolyl)methanes in moderate to excellent yields (65-98%) at ambient temperature. The reaction is highly chemoselective and applicable only to aldehydes and not to ketones. [source] An investigation of the 125I-radioiodination of colchicine for medical purposesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2009K. M. El-Azony Abstract A procedure for radioiodination of colchicine with iodine-125 is carried out via an electrophilic substitution reaction. The reaction parameters studied were colchicine concentration, pH of the reaction mixture, reaction time, temperature, different oxidizing agents and different organic media to optimize the conditions for the labeling of colchicine and to obtain a high radiochemical yield of the 125I-colchicine (125I-Col). Using 3.7,MBq of Na125I, 1.25,mM of colchicine as substrate, 1.1,mM of chloramine-T (CAT) as oxidizing agent in ethanol at 60°C for 5,min, a maximum radiochemical yield of 125I-Col (60%) was obtained. The specific activity of 125I-Col obtained was 44.4,MBq/0.5,mmol, and the labeled compound was not completely separated and purified from Col by means of high-pressure liquid chromatography (HPLC), so the uncertainty in the purity may affect the distribution and clearance routes due to the expected competition between 125I-Col and Col. The biological distribution in normal mice indicates the suitability of radioiodinated colchicine for imaging of muscles. Copyright © 2008 John Wiley & Sons, Ltd. [source] Temperature and solvent dependent NMR studies on mangiferin and complete NMR spectral assignments of its acyl and methyl derivativesMAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2006Shaheen Faizi Abstract By employing concerted 1 and 2D NMR techniques, exact NMR spectral assignments have been made of the acyl (2,7) and methyl (8 and 9) derivatives of mangiferin (1) isolated from the leaves of Bombax ceiba. Derivatives 2, 8 and 9 have been reported in literature, while 3,7 represent new compounds. The acetates 2 and 3 were found to be unstable and were converted into the same penta-acetate 4 at room temperature. Extensive NMR studies on mangiferin (1) and its derivatives showed that H-4 exchanges with deuterium of the solvent molecule more easily. This exchange under acidic conditions occurred at that position (C-4) where electrophilic substitution reactions can easily take place. This is the first report describing the exchange of C-4 proton of mangiferin (1), or any other xanthone, with deuterium of solvent molecules. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||