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C Bond Formation (c + bond_formation)
Selected AbstractsUtilization of the Versatility of Sulfur in C,C Bond Formation and Cleavage: Synthesis of ABC Taxoid SkeletonsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2007Subhash P. Chavan Abstract A practical and convenient five-step protocol is described to access the ABC ring system of Taxol by utilizing the versatility of the sulfur atom in its various oxidation states viz., condensation/Pummerer cyclization/coupling/annulation/fragmentation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] ChemInform Abstract: Stereoselective Synthesis of ,-Alkyl-,-keto Imides via Asymmetric Redox C,C Bond Formation Between ,-Alkyl-,-diazocarbonyl Compounds and Aldehydes.CHEMINFORM, Issue 2 2010Takuya Hashimoto 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] ChemInform Abstract: Mono-, Bis- and Tris-piperidine Fused Imidazolinium Salts: Their in situ Catalytic Applications for C,C Bond Formation in Aqueous SolutionsCHEMINFORM, Issue 2 2010Hayati Tuerkmen 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] ChemInform Abstract: Oxidative C,C Bond Formation (Scholl Reaction) with DDQ as an Efficient and Easily Recyclable Oxidant.CHEMINFORM, Issue 48 2009Linyi Zhai 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] ChemInform Abstract: Air-Tolerant C,C Bond Formation via Organometallic Ruthenium Catalysis: Diverse Catalytic Pathways Involving (C5Me5)Ru or (C5H5)Ru Are Robust to Molecular Oxygen.CHEMINFORM, Issue 45 2009Lukas Severa 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] ChemInform Abstract: Air-Tolerant C,C Bond Formation via Organometallic Ruthenium Catalysis: Diverse Catalytic Pathways Involving (C5Me5)Ru or (C5H5)Ru Are Robust to Molecular Oxygen.CHEMINFORM, Issue 45 2009Lukas Severa 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] ChemInform Abstract: Lipase-Catalyzed Direct Mannich Reaction in Water: Utilization of Biocatalytic Promiscuity for C,C Bond Formation in a "One-Pot" Synthesis.CHEMINFORM, Issue 45 2009Kun Li 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] ChemInform Abstract: Electron-Rich, Bicyclic Biaryl-Like KITPHOS Monophosphines via [4 + 2] Cycloaddition Between 1-Alkynylphosphine Oxides and Anthracene: Highly Efficient Ligands for Palladium-Catalyzed C,N and C,C Bond Formation.CHEMINFORM, Issue 52 2008Simon Doherty 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] ChemInform Abstract: Functionalizing Glycine Derivatives by Direct C,C Bond Formation.CHEMINFORM, Issue 51 2008Liang Zhao 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] ChemInform Abstract: Palladium-Catalyzed Domino Intramolecular N-Arylation/Intermolecular C,C Bond Formation for the Synthesis of Functionalized Benzodiazepinediones.CHEMINFORM, Issue 31 2008Angela Salcedo 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] ChemInform Abstract: Auto-Tandem Catalysis: Synthesis of Substituted 11H-Indolo[3,2-c]quinolines via Palladium-Catalyzed Intermolecular C,N and Intramolecular C,C Bond Formation.CHEMINFORM, Issue 27 2008Caroline Meyers 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] Synthesis of 3,4-Disubstituted 2H-Benzopyrans Through C,C Bond Formation via Electrophilic Cyclization.CHEMINFORM, Issue 27 2007Shilpa A. Worlikar 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] P,C Bond Formation via Direct and Three-Component Conjugate Addition Catalyzed by 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD).CHEMINFORM, Issue 15 2007Zhiyong Jiang 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 Reaction for sp3,sp3 C,C Bond Formation via Cooperation of Lewis Acid-Promoted/Rh-Catalyzed C,H Bond Activation.CHEMINFORM, Issue 51 2005Lei Shi Abstract For Abstract see ChemInform Abstract in Full Text. [source] Mn(III)-Based C,C Bond Formation: Regioselective ,,-Allylation of Various ,,,-Unsaturated, ,- and ,-Alkoxy ,,,-Unsaturated Ketones.CHEMINFORM, Issue 49 2005Cihangir Tanyeli Abstract For Abstract see ChemInform Abstract in Full Text. [source] Enantioselective Reductive Cyclization of 1,6-Enynes via Rhodium-Catalyzed Asymmetric Hydrogenation: C,C Bond Formation Precedes Hydrogen Activation.CHEMINFORM, Issue 38 2005Hye-Young Jang Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis and Application in Asymmetric C,C Bond Formation of Solution Phase Ligand Libraries of Monodentate Phosphoramidites.CHEMINFORM, Issue 41 2004Ate Duursma Abstract For Abstract see ChemInform Abstract in Full Text. [source] Nonaqueous and Halide-Free Route to Crystalline BaTiO3, SrTiO3, and (Ba,Sr)TiO3 Nanoparticles via a Mechanism Involving C,C Bond Formation.CHEMINFORM, Issue 40 2004Markus Niederberger Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Direct Access to 3-(2-Oxoalkyl)indoles via Aluminum Chloride Induced C,C Bond Formation.CHEMINFORM, Issue 33 2004Manojit Pal Abstract For Abstract see ChemInform Abstract in Full Text. [source] Hydrogen-Mediated C,C Bond Formation: Catalytic Regio- and Stereoselective Reductive Condensation of ,-Keto Aldehydes and 1,3-Enynes.CHEMINFORM, Issue 32 2004Hye-Young Jang Abstract For Abstract see ChemInform Abstract in Full Text. [source] Water-Accelerated Cationic ,-(7- endo) Cyclisation: Application to Indole-Based Peri-Annulated Polyheterocycles,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2010Mohammad Saifuddin Abstract An efficient and versatile method for the synthesis of indole-based polycyclic indolo-benzazepine and its derivatives through water-accelerated cationic ,-cyclisation is described. The strategy involves condensation of arylamine moieties linked to C-4 in indole/azaindole systems with arylaldehydes in water containing catalytic amount of Brønsted acids. The C,C bond formation in water is complete within 10,30 min, furnishing the title compounds in excellent yields and purities, whereas in organic solvents 10,12 h are required. Furthermore, aldehydes both with electron-donating and-withdrawing substituents facilitate the ,-cyclisation equally. [source] How Many Elementary Processes Are Involved in Base- and Acid-Promoted Aldol Condensations?EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2007Shinichi Yamabe Abstract The title reactions were investigated by density functional theory calculations. MeRC=O + OH, + (H2O)8 (R = H and Me) and MeCH=O + H3O+ + (H2O)8 systems were adopted to trace the elementary processes. Eight water molecules were included to assure proton shifts through hydrogen bonds. The OH, -containing reactions were confirmed to have three elementary processes. Whereas the rate-determining step of the reaction of acetaldehyde is C,H bond scission, that of acetone is C,C bond formation. The H3O+ -containing reactions have two elementary processes. The reactivity difference between OH, - and H3O+ -promoted reactions was discussed in terms of their mobility and hydration strength. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Enantio- and Diastereomerically Pure Decalins by Deslongchamps-Type Annulation of Dienolates Containing a Chiral Lactone SubstituentEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2007Thomas Tricotet Abstract A conceptionally novel 1,3-asymmetric induction has been established. It controls the relative and absolute configuration of up to 5 stereocenters. They emerge from the anionic Diels,Alder reactions ("Deslongchamps annulations") between oxocyclohexenecarboxylates 25, 29 and dienolates 26, 30. The latter contain a ,-lactone. A Ph3Si,CH2 substituent therein controls the asymmetry of C,C bond formation with ds , 10:1. Strangely, the preferred sense of attack of the dienophile is contrasteric. Cycloadduct 31 was processed by an unprecedented fluoride-induced ambient-temperature tandem fragmentation. It turned the lactone moiety into an allyl group and the ,-oxo (trimethylsilyl)ethyl ester into a ketone. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Borrowing Hydrogen: Indirect "Wittig" Olefination for the Formation of C,C Bonds from AlcoholsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2006Phillip J. Black Abstract The successful development of an indirect three-step domino sequence for the formation of C,C bonds from alcohol substrates is described. An iridium-catalysed dehydrogenation of alcohol 1 affords the intermediate aldehyde 2. The desired C,C bond can then be formed by a facile Wittig olefination, yielding the intermediate alkene 3. In the final step the alkene is hydrogenated to afford the indirect Wittig product, the alkane 4. The key to this process is the concept of borrowing hydrogen; hydrogen removed in the initial dehydrogenation step is simply borrowed by the iridium catalyst. Functioning as a hydrogen reservoir, the catalyst facilitates C,C bond formation before subsequently returning the borrowed hydrogen in the final step. Herein we present full details of our examination into both the substrate and reaction scope and the limitations of the catalytic cycle. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] 11C,C bond formation by palladium-mediated cross-coupling of alkenylzirconocenes with [11C]methyl iodideJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2006Frank R. Wuest Abstract A novel 11C,C bond formation based on the palladium-mediated cross-coupling reaction of alkenylzirconocenes with [11C]methyl iodide is described. The conversion of internal alkynes into the corresponding alkenylzirconocenes followed by transmetalation with Pd(PPh3)4 and subsequent cross-coupling with [11C]methyl iodide gave several 11C-labelled ,,,,-dimethyl-substituted alkenes. The palladium complex Pd(PPh3)4 proved to be superior to Pt(PPh3)4 or Ni(PPh3)4 as transition metal complex. The scope and limitations of the novel palladium-mediated cross-coupling reaction of alkenylzirconocenes with [11C]methyl iodide were tested with various internal alkynes. After heating at 60°C for 6 min radiochemical yields of up to 75% (based upon [11C]methyl iodide) could be achieved. Copyright © 2006 John Wiley & Sons, Ltd. [source] The active site of hydroxynitrile lyase from Prunus amygdalus: Modeling studies provide new insights into the mechanism of cyanogenesisPROTEIN SCIENCE, Issue 2 2002Ingrid Dreveny Abstract The FAD-dependent hydroxynitrile lyase from almond (Prunus amygdalus, PaHNL) catalyzes the cleavage of R -mandelonitrile into benzaldehyde and hydrocyanic acid. Catalysis of the reverse reaction,the enantiospecific formation of ,-hydroxynitriles,is now widely utilized in organic syntheses as one of the few industrially relevant examples of enzyme-mediated C,C bond formation. Starting from the recently determined X-ray crystal structure, systematic docking calculations with the natural substrate were used to locate the active site of the enzyme and to identify amino acid residues involved in substrate binding and catalysis. Analysis of the modeled substrate complexes supports an enzymatic mechanism that includes the flavin cofactor as a mere "spectator" of the reaction and relies on general acid/base catalysis by the conserved His-497. Stabilization of the negative charge of the cyanide ion is accomplished by a pronounced positive electrostatic potential at the binding site. PaHNL activity requires the FAD cofactor to be bound in its oxidized form, and calculations of the pKa of enzyme-bound HCN showed that the observed inactivation upon cofactor reduction is largely caused by the reversal of the electrostatic potential within the active site. The suggested mechanism closely resembles the one proposed for the FAD-independent, and structurally unrelated HNL from Hevea brasiliensis. Although the actual amino acid residues involved in the catalytic cycle are completely different in the two enzymes, a common motif for the mechanism of cyanogenesis (general acid/base catalysis plus electrostatic stabilization of the cyanide ion) becomes evident. [source] | ||||||||||