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Carbon Bond (carbon + bond)
Terms modified by Carbon Bond Selected AbstractsChemInform Abstract: NO Cations as Highly Efficient Catalysts for Carbon,Carbon Bond Forming Reactions.CHEMINFORM, Issue 48 2009Yasuhiro Yamashita 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] Structure,Reactivity Relationships in Oxidative Carbon,Carbon Bond Forming Reactions: A Mild and Efficient Approach to Stereoselective Syntheses of 2,6-Disubstituted Tetrahydropyrones.CHEMINFORM, Issue 6 2005Lijun Wang Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: A Radical Carbon,Carbon Bond Forming Reaction: Indium-Mediated Radical Addition to ,-Substituted Conjugated Alkenes in Aqueous Media.CHEMINFORM, Issue 33 2002Doo Ok Jang 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: Mechanistic Investigation of a Novel Vitamin B12 -Catalyzed Carbon,Carbon Bond Forming Reaction, the Reductive Dimerization of Arylalkenes.CHEMINFORM, Issue 30 2002Justin Shey 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: Mild Two-Step Process for the Transition-Metal-Free Synthesis of Carbon,Carbon Bonds from Allylic Alcohols/Ethers and Grignard Reagents.CHEMINFORM, Issue 33 2010Xinping Han Abstract The method involves the photochemically promoted allylic substitution reaction of allylic alcohols or ethers with phosphorothioic acid ester (II) followed by sp3,sp3 or sp2,sp3 bond formation of the resulting allylic phosphorothioate esters with various Grignard reagents. [source] A One-Pot, Metathesis,Hydrogenation Sequence for the Selective Formation of Carbon,Carbon Bonds.CHEMINFORM, Issue 11 2006Andrea J. Robinson 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] Highly Substituted Enynes via a Palladium-Catalyzed Tandem Three Carbon,Carbon Bonds Forming Reaction Procedure from Benzyl Halides and Alkynyl Tributyltin Reagents.CHEMINFORM, Issue 35 2004Laurent Romain Pottier Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Biphasic Manganese Carbonyl Reactions: A New Approach to Making Carbon,Carbon Bonds.CHEMINFORM, Issue 28 2002Nathalie Huther 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] Ultralong Carbon,Carbon Bonds in Dispirobis(10-methylacridan) Derivatives with an Acenaphthene, Pyracene, or Dihydropyracylene SkeletonCHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2008Hidetoshi Kawai Dr. Abstract Acenapthalene, pyracene, and dihydropyracylene attached to two units of spiroacridan are a novel class of hexaphenylethane (HPE) derivatives that have an ultralong CC bond (1.77,1.70,Å). These sterically challenged molecules were cleanly prepared by CC bond formation through two-electron reduction from the less-hindered dications. These ultralong bonds were realized based on several molecular-design concepts including enhanced "front strain" through "multiclamping" by means of fusing or bridging aryl groups in the HPE molecule. The lengths of these ultralong bonds and their relation to the conformation (torsional angle) were also validated by means of theoretical calculations. Bond-fission experiments revealed that the bonds are more easily cleaved than standard covalent bonds to produce the corresponding dication upon oxidation with an increase in the length of the CC bond. [source] Reaction of Thiolesters with Nitrogen YlidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2008Svatava Voltrova Abstract The pairing of unstabilized nitrogen ylides generated in situ with functionalized thiolesters under ambient conditions resulted in a new intramolecular carbon,carbon bond forming reaction. The scope of the reaction was illustrated with a series of substituted thiolester substrates. This reaction represents a new method for the synthesis of 2-substituted tetrahydrothienyl compounds through a unique 1,2-thiolate shift. Whereas nitrogen ylides have been used in synthesis previously, very few examples exist in which unstabilized nitrogen ylides have been utilized in synthetically meaningful transformations.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Oxidative behavior and relative reactivities of some unsaturated compounds towards hexachloroiridate(IV) in perchloric acid mediumINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 7 2002Kalyan K. Sen Gupta The kinetics of the oxidation of styrene, cinnamic acid, and some of their substituted derivatives by hexachloroiridate(IV) in dimethyl formamide,water mixtures and in the presence of perchloric acid have been investigated. The reactions appear to proceed via the formation of an unstable intermediate 1:1 complex between iridium(IV) and the substrate, followed by the decomposition of the complex in the rate-determining step. Correlation with , yielded , values of ,4.0 and ,3.5 which suggests the formation of a cationic intermediate in the rate-determining step of the reaction. Subsequent cleavage of the carbon,carbon bond yielded the product aldehydes. Thermodynamic and activation parameters associated with the equilibrium and the rate-determining steps were also evaluated. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 411,417, 2002 [source] New insights on the bridge carbon,carbon bond in propellanes: A theoretical study based on the analysis of the electron localization functionJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 5 2007Victor Polo Abstract The nature of the bonding between bridgehead carbon atoms (Ca, Ca,) as well as the ring strain in a family of 10 propellanes formed by three-, four-, or five-member rings: [1.1.1] (I), [2.1.1] (II), [3.1.1] (III), [2.2.1] (IV), [3.2.1] (V), [2.2.2] (VI), [3.3.1] (VII), [3.2.2] (VIII), [3.3.2] (IX), and [3.3.3] (X) are studied by means of the electron localization function (ELF) at the DFT level (B3LYP/cc-pVTZ). The ELF analysis of smaller propellanes (I, II, and III) reveals the coexistence of two resonance forms: one with a nonbonding electron pair partially delocalized between Ca and Ca, atoms outside the cage (ionic) and the other with a bridge bond between the same atoms (covalent). The weights of each form are calculated according to the ELF-basin populations, yielding 94, 88, and 53% for the ionic structure of I, II, and III, respectively, while larger propellanes (IV,X) present only the covalent form. The question of the s-character of the bridge bond is addressed by dissecting the bridge-bond ELF basin into the molecular orbital contributions. Finally, ,-aromaticity associated to surface electron delocalization has been analyzed by means of nucleus-independent chemical shift (NICS) calculations. The results point out that the stability of the fused ring structure of propellanes I, II, and III, can be assigned to the remarkable ,-aromaticity of the involved three-member rings. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source] Microsynthesis and mass spectral study of Chemical Weapons Convention related 2-alkyl-1,3,6,2-dioxathiaphosphocane-2-oxidesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2008Meehir Palit Chemical Weapons Convention (CWC)-related compounds where the phosphorus atom is part of a ring have very limited representation in mass spectral libraries and the open literature. Here we report electron ionization (EI), chemical ionization (CI) and electrospray ionization tandem mass spectrometry (ESI-MSn) spectra and retention indices for 2-alkyl-1,3,6,2-dioxathiaphosphocane-2-oxides (alkyl C1 to C3) which are new cyclic chemicals covered under the CWC. The EI mass spectra show a pattern of ion fragmentation that is similar to that of other cyclic phosphonates in that loss of the alkylphosphonic acid as a neutral loss is more important than the presence of the protonated alkylphosphonic acid. In contrast to other cyclic phosphonates, the 2-alkyl-1,3,6,2-dioxathiaphosphocane-2-oxides show almost no protonated alkylphosphonic acid and as a result the spectra do not carry the same distinctive signature of the phosphorus,carbon bond that is required for the chemical to be covered under the CWC. Copyright © 2008 John Wiley & Sons, Ltd. [source] The magic triangle goes MAD: experimental phasing with a bromine derivativeACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2010Tobias Beck Experimental phasing is an essential technique for the solution of macromolecular structures. Since many heavy-atom ion soaks suffer from nonspecific binding, a novel class of compounds has been developed that combines heavy atoms with functional groups for binding to proteins. The phasing tool 5-amino-2,4,6-tribromoisophthalic acid (B3C) contains three functional groups (two carboxylate groups and one amino group) that interact with proteins via hydrogen bonds. Three Br atoms suitable for anomalous dispersion phasing are arranged in an equilateral triangle and are thus readily identified in the heavy-atom substructure. B3C was incorporated into proteinase K and a multiwavelength anomalous dispersion (MAD) experiment at the Br,K edge was successfully carried out. Radiation damage to the bromine,carbon bond was investigated. A comparison with the phasing tool I3C that contains three I atoms for single-wavelength anomalous dispersion (SAD) phasing was also carried out. [source] Preliminary X-ray crystallographic analysis of the d -xylulose 5-phosphate phosphoketolase from Lactococcus lactisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2010Georgiana Petrareanu Phosphoketolases are thiamine diphosphate-dependent enzymes which play a central role in the pentose-phosphate pathway of heterofermentative lactic acid bacteria. They belong to the family of aldehyde-lyases and in the presence of phosphate ion cleave the carbon,carbon bond of the specific substrate d -xylulose 5-phosphate (or d -fructose 6-phosphate) to give acetyl phosphate and d -glyceraldehyde 3-phosphate (or d -erythrose 4-phosphate). Structural information about phosphoketolases is particularly important in order to fully understand their mechanism as well as the steric course of phosphoketolase-catalyzed reactions. Here, the purification, preliminary crystallization and crystallographic characterization of d -xylulose 5-phosphate phosphoketolase from Lactococcus lactis are reported. The presence of thiamine diphosphate during purification was essential for the enzymatic activity of the purified protein. The crystals belonged to the monoclinic space group P21. Diffraction data were obtained to a resolution of 2.2,Å. [source] Structure of HsaD, a steroid-degrading hydrolase, from Mycobacterium tuberculosisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2008Nathan Lack Tuberculosis is a major cause of death worldwide. Understanding of the pathogenicity of Mycobacterium tuberculosis has been advanced by gene analysis and has led to the identification of genes that are important for intracellular survival in macrophages. One of these genes encodes HsaD, a meta -cleavage product (MCP) hydrolase that catalyzes the hydrolytic cleavage of a carbon,carbon bond in cholesterol metabolism. This paper describes the production of HsaD as a recombinant protein and, following crystallization, the determination of its three-dimensional structure to 2.35,Å resolution by X-ray crystallography at the Diamond Light Source in Oxfordshire, England. To the authors' knowledge, this study constitutes the first report of a structure determined at the new synchrotron facility. The volume of the active-site cleft of the HsaD enzyme is more than double the corresponding active-site volumes of related MCP hydrolases involved in the catabolism of aromatic compounds, consistent with the specificity of HsaD for steroids such as cholesterol. Knowledge of the structure of the enzyme facilitates the design of inhibitors. [source] Site-Specific Functionalization of Proteins by Organopalladium Reactions,CHEMBIOCHEM, Issue 2 2007Koichiro Kodama Abstract A new carbon,carbon bond has been regioselectively introduced into a target position (position 32 or 174) of the Ras protein by two types of organopalladium reactions (Mizoroki,Heck and Sonogashira reactions). Reaction conditions were screened by using a model peptide, and the stability of the Ras protein under the reaction conditions was examined by using the wild-type Ras protein. Finally, the iF,Ras proteins containing a 4-iodo- L -phenylalanine residue were subjected to organopalladium reactions with vinylated or propargylated biotin. Site-specific biotinylations of the Ras protein were confirmed by Western blot and LC-MS/MS. [source] Synthesis, Structural Characterisation and Reactions of Some Vinylgold(I) Phosphane ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2006Fabian Mohr Abstract A series of vinylgold(I) complexes [Au(CR=CHR)L] (R = H, Me; L = PPh3, PPh2Me, PPhMe2) were prepared from the reaction of the Grignard reagents [MgBr(CR=CHR)] (R = H, Me) with the gold(I) phosphane complexes [AuCl(L)] (L = PPh3, PPh2Me, PPhMe2) at low temperature. The complexes were characterised by various spectroscopic techniques and, in the case of [Au(CMe=CHMe)(PPh3)], by a single-crystal X-ray structure determination. The gold,carbon bonds of these vinylgold(I) complexes are easily cleaved by acids and, in the presence of potassium permanganate, by species containing acidic protons. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Non-empirical calculations of NMR indirect carbon,carbon coupling constants.MAGNETIC RESONANCE IN CHEMISTRY, Issue 6 2005Aliphatic, Part 1, alicyclic oximes Abstract One-bond carbon,carbon coupling constants were calculated in a series of nine aliphatic and alicyclic oximes at the SOPPA (second-order polarization propagator approach) level in good agreement with the available experimental data, and several unknown couplings were predicted with high reliability. The experimental difference between J(C,C) of the corresponding carbon,carbon bonds in cis and trans orientations to the nitrogen lone pair is very well reproduced at the SOPPA level, and this provides an additional tool in the configurational assignment at the CN bond in oximes and related systems. Copyright © 2005 John Wiley & Sons, Ltd. [source] Bis(trimethylsilyl)methyl Derivatives of Calcium, Strontium and Barium: Potentially Useful Dialkyls of the Heavy Alkaline Earth ElementsCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2008Getting a complex! Dialkyls of the heavier Group,2 elements Ca, Sr and Ba (see figure) are simple to synthesise with careful selection of the correct alkyl ligand and reaction conditions. The crystal structures of three bis(trimethylsilyl)methyl complexes are reported, and contain the first unsupported Sr- and Ba-to-alkyl carbon bonds. [source] | |||||||||||||||||||||||||