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Carbon Bond Formation (carbon + bond_formation)
Selected AbstractsN -Acyliminium Ion Chemistry: Highly Efficient and Versatile Carbon,Carbon Bond Formation by Nucleophilic Substitution of Hydroxy Groups Catalyzed by Sn(NTf2)4ANGEWANDTE CHEMIE, Issue 4 2010Othman Dr., Raja Ben Atomökonomisch: Nichtmodifizierte N,O-Halbacetale wurden in einer katalytischen, hocheffizienten ,-Amidoalkylierung kohlenstoffzentrierter Nucleophile eingesetzt, darunter Siliciumverbindungen, aktive Methylenderivate, elektronenreiche Arene und selbst einfache Ketone (siehe Schema). In der Regel genügt 1,Mol-% des supersauren Lewis-Reagens Sn(NTf2)4 als Katalysator. [source] Regioselective Carbon,Carbon Bond Formation in Proteins with Palladium Catalysis; New Protein Chemistry by Organometallic ChemistryCHEMBIOCHEM, Issue 1 2006Koichiro Kodama Abstract Palladium-catalyzed reactions have contributed to the advancement of many areas of organic chemistry, in particular, the synthesis of organic compounds such as natural products and polymeric materials. In this study, we have used a Mizoroki,Heck reaction for site-specific carbon,carbon bond formation in the Ras protein. This was performed by the following two steps: 1) the His6 -fused Ras protein containing 4-iodo- L -phenylalanine at position 32 (iF32-Ras-His) was prepared by genetic engineering and 2) the aryl iodide group on the iF32-Ras-His was coupled with vinylated biotin in the presence of a palladium catalyst. The biotinylation was confirmed by Western blotting and liquid chromatography,mass spectrometry (LC-MS). The regioselectivity of the Mizoroki,Heck reaction was furthermore confirmed by LC-MS/MS analysis. However, in addition to the biotinylated product (bF32-Ras-His), a dehalogenated product (F32-Ras-His) was detected by LC-MS/MS. This dehalogenation resulted from the undesired termination of the Mizoroki,Heck reaction due to steric and electrostatic hindrance around residue 32. The biotinylated Ras showed binding activity for the Ras-binding domain as its downstream target, Raf-1, with no sign of decomposition. This study is the first report of an application of organometallic chemistry in protein chemistry. [source] ChemInform Abstract: N-Acyliminium Ion Chemistry: Highly Efficient and Versatile Carbon,Carbon Bond Formation by Nucleophilic Substitution of Hydroxy Groups Catalyzed by Sn(NTf2)4.CHEMINFORM, Issue 21 2010Raja Ben Othman 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: Ruthenium-Catalyzed Oxidative Cyanation of Tertiary Amines with Molecular Oxygen or Hydrogen Peroxide and Sodium Cyanide: sp3 C,H Bond Activation and Carbon,Carbon Bond Formation.CHEMINFORM, Issue 51 2008Shun-Ichi Murahashi 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: Direct Carbon,Carbon Bond Formation via Soft Enolization: A Facile and Efficient Synthesis of 1,3-Diketones.CHEMINFORM, Issue 12 2008Daniel Lim 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] Ruthenium-Catalyzed Carbon,Carbon Bond Formation via the Cleavage of an Unreactive Aryl Carbon,Nitrogen Bond in Aniline Derivatives with Organoboronates.CHEMINFORM, Issue 38 2007Satoshi Ueno 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] One-Pot Carbon,Carbon Bond Formation at the ,-Position of Cyclic Ketones: Oxidative Michael Addition with Alkyl Malonates.CHEMINFORM, Issue 33 2007Jun-ichi Matsuo 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] Oxidative Palladium(II) Catalysis: A Highly Efficient and Chemoselective Cross-Coupling Method for Carbon,Carbon Bond Formation under Base-Free and Nitrogenous-Ligand Conditions.CHEMINFORM, Issue 18 2007Kyung Soo Yoo 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] Palladium-Catalyzed Phosphorus,Carbon Bond Formation: Cross-Coupling Reactions of Alkyl Phosphinates with Aryl, Heteroaryl, Alkenyl, Benzylic, and Allylic Halides and Triflates.CHEMINFORM, Issue 42 2005Karla Bravo-Altamirano Abstract For Abstract see ChemInform Abstract in Full Text. [source] Active Metallic Indium Mediated Carbon,Carbon Bond Formation in Aqueous Media: Barbier-Type Allylation of Aldehydes.CHEMINFORM, Issue 1 2005Hua-Yue Wu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Sn-, Zeolite as Diastereoselective Water-Resistant Heterogeneous Lewis Acid Catalyst for Carbon,Carbon Bond Formation in the Intramolecular Carbonyl,Ene Reaction.CHEMINFORM, Issue 29 2004Avelino Corma Abstract For Abstract see ChemInform Abstract in Full Text. [source] Carbon,Carbon Bond Formation Using Bismuth in a Water Medium.CHEMINFORM, Issue 49 2003Hisakazu Miyamoto Abstract For Abstract see ChemInform Abstract in Full Text. [source] Generation of Reactive Species by One-Electron Reduction of Fischer-Type Carbene Complexes of Group 6 Metals and Their Use for Carbon,Carbon Bond Formation.CHEMINFORM, Issue 21 2003Kohei Fuchibe Abstract For Abstract see ChemInform Abstract in Full Text. [source] Successive Carbon,Carbon Bond Formation by Sequential Generation of Radical and Anionic Species with Manganese and Catalytic Amounts of PbCl2 and Me3SiCl.CHEMINFORM, Issue 20 2003Kazuhiko Takai Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Synthesis of Diketones from Carbonyl Compounds and ,,,-Dichloro-,,,-disulfinylalkanes with two Carbon,Carbon Bond Formation via Bis-sulfinyloxiranes.CHEMINFORM, Issue 41 2002Tsuyoshi Satoh Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Carbon,Carbon Bond Formation in Neutral Aqueous Medium by Modification of the Nozaki,Hiyama Reaction.CHEMINFORM, Issue 3 2002Karoly Micskei 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: An Asymmetric Catalytic Carbon,Carbon Bond Formation in a Fluorous Biphasic System Based on Perfluoroalkyl-BINOL.CHEMINFORM, Issue 9 2001Yuan Tian 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] Desymmetrisation of a Centrosymmetric Molecule by Carbon,Carbon Bond Formation: Asymmetric Aldol Reactions of a Centrosymmetric DialdehydeCHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2007Karen Dodd Abstract The desymmetrisation of centrosymmetric molecules by enantioselective carbon,carbon bond formation has been reported for the first time. A bimetallic zinc catalyst developed by Trost was exploited in the desymmetrisation of a centrosymmetric dialdehyde. The approach was successful with a range of ketone nucleophiles and was uniformly highly diastereoselective (>98:<2). The yield and the enantioselectivity of the reaction varied as a function of the ketone used, and the desymmetrised products were obtained in up to 74,% yield and 97,%,ee (ee=enantiomeric excess). The desymmetrisation of centrosymmetric molecules by enantioselective carbon,carbon bond formation is an efficient and convergent synthetic approach which is likely to find wide application in synthesis, particularly in the total synthesis of natural products with embedded centrosymmetric fragments. [source] ChemInform Abstract: Carbon,Carbon Bond Formations at the Benzylic Positions of N-Benzylxanthone Imines and N-Benzyldi-1-naphthyl Ketone Imine.CHEMINFORM, Issue 44 2009Takashi Niwa 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] Asymmetric Carbon,Carbon Bond Formations in Conjugate Additions of Lithiated N-Boc Allylic and Benzylic Amines to Nitroalkenes: Enantioselective Synthesis of Substituted Piperidines, Pyrrolidines, and Pyrimidinones.CHEMINFORM, Issue 6 2003Timothy A. Johnson Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of Benzomorphan Analogues by Intramolecular Buchwald,Hartwig CyclizationEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2007Anton S. Khartulyari Abstract A new strategy toward the important class of benzomorphans is described. The key bond formation is based on an intramolecular Buchwald,Hartwig enolate arylation reaction. Thus, alkylation of piperidones with ortho -bromobenzyl bromides provides the necessary substrates. In the presence of a palladium catalyst, a sterically hindered phosphane ligand, and a base, carbon,carbon bond formation to tricyclic benzomorphan derivatives takes place. After removal of the N -protecting group, derivatization reactions are possible. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis and NMR characterization of 6-Phenyl-6-deoxy-2,3-di- O -methylcellulose,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2002Dr Navzer (Nozar) D. Sachinvala Abstract Cellulose (1) was converted for the first time to 6-phenyl-6-deoxy-2,3-di- O -methylcellulose (6) in 33% overall yield. Intermediates in the five-step conversion of 1 to6 were: 6- O -tritylcellulose (2), 6- O -trityl-2,3-di- O -methylcellulose (3), 2,3-di- O -methylcellulose (4); and 6-bromo-6-deoxy-2,3-di- O -methylcellulose (5). Elemental and quantitative carbon-13 analyses were concurrently used to verify and confirm the degrees of substitution in each new polymer. Gel permeation chromotography (GPC) data were generated to monitor the changes in molecular weight (DPw) as the synthesis progressed, and the compound average decrease in cellulose DPw was , 27%. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the decomposition of all polymers. The degradation temperatures (,°C) and percent char at 500,°C of cellulose derivatives 2 to 6 were 308.6 and 6.3%, 227.6,°C and 9.7%, 273.9,°C and 30.2%, 200.4,°C and 25.6%, and 207.2,°C and 27.0%, respectively. The glass transition temperature (Tg) of6- O -tritylcellulose by dynamic mechanical analysis (DMA) occurred at 126.7,°C and the modulus (E,, Pa) dropped 8.9 fold in the transition from ,150,°C to,+,180,°C (6.6,×,109 to 7.4,×,108 Pa). Modulus at 20,°C was 3.26,×,109 Pa. Complete proton and carbon-13 chemical shift assignments of the repeating unit of the title polymer were made by a combination of the HMQC and COSY NMR methods. Ultimate non-destructive proof of carbon,carbon bond formation at C6 of the anhydroglucose moiety was established by generating correlations between resonances of CH26 (anhydroglucose) and C1,, H2,, and H6, of the attached aryl ring using the heteronuclear multiple-bond correlation (HMBC) method. In this study, we achieved three major objectives: (a) new methodologies for the chemical modification of cellulose were developed; (b) new cellulose derivatives were designed, prepared and characterized; (c) unequivocal structural proof for carbon,carbon bond formation with cellulose was derived non-destructively by use of one- and two-dimensional NMR methods. Copyright © 2002 John Wiley & Sons, Ltd. [source] Selective organic synthesis through generation and reactivity control of hyper-coordinate metal speciesTHE CHEMICAL RECORD, Issue 6 2008Tamejiro Hiyama Abstract This paper is a review of my 40 years of research at Kyoto, Sagamihara, and Yokohama, all based on the generation of hyper-coordinate metal species such as ate complexes and pentacoordinate silicates. The topics are: (i) carbenoid reagents for carbon,carbon bond-forming reactions, (ii) nucleophilic substitution at acetal carbons using aluminate reagents, (iii) preparation of magnesium enolates and its reaction with nitriles, (iv) Cr(II) reagents for reduction of organic halides and highly selective carbon,carbon bond formation, (v) organic synthesis with organosilion reagents/fluoride ions, (vi) cross-coupling reaction of organosilicon compounds, and (vii) silicon-based conjugate addition to ,,,-unsaturated carbonyl acceptors. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 337,350; 2008: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20162 [source] Regioselective Carbon,Carbon Bond Formation in Proteins with Palladium Catalysis; New Protein Chemistry by Organometallic ChemistryCHEMBIOCHEM, Issue 1 2006Koichiro Kodama Abstract Palladium-catalyzed reactions have contributed to the advancement of many areas of organic chemistry, in particular, the synthesis of organic compounds such as natural products and polymeric materials. In this study, we have used a Mizoroki,Heck reaction for site-specific carbon,carbon bond formation in the Ras protein. This was performed by the following two steps: 1) the His6 -fused Ras protein containing 4-iodo- L -phenylalanine at position 32 (iF32-Ras-His) was prepared by genetic engineering and 2) the aryl iodide group on the iF32-Ras-His was coupled with vinylated biotin in the presence of a palladium catalyst. The biotinylation was confirmed by Western blotting and liquid chromatography,mass spectrometry (LC-MS). The regioselectivity of the Mizoroki,Heck reaction was furthermore confirmed by LC-MS/MS analysis. However, in addition to the biotinylated product (bF32-Ras-His), a dehalogenated product (F32-Ras-His) was detected by LC-MS/MS. This dehalogenation resulted from the undesired termination of the Mizoroki,Heck reaction due to steric and electrostatic hindrance around residue 32. The biotinylated Ras showed binding activity for the Ras-binding domain as its downstream target, Raf-1, with no sign of decomposition. This study is the first report of an application of organometallic chemistry in protein chemistry. [source] Desymmetrisation of a Centrosymmetric Molecule by Carbon,Carbon Bond Formation: Asymmetric Aldol Reactions of a Centrosymmetric DialdehydeCHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2007Karen Dodd Abstract The desymmetrisation of centrosymmetric molecules by enantioselective carbon,carbon bond formation has been reported for the first time. A bimetallic zinc catalyst developed by Trost was exploited in the desymmetrisation of a centrosymmetric dialdehyde. The approach was successful with a range of ketone nucleophiles and was uniformly highly diastereoselective (>98:<2). The yield and the enantioselectivity of the reaction varied as a function of the ketone used, and the desymmetrised products were obtained in up to 74,% yield and 97,%,ee (ee=enantiomeric excess). The desymmetrisation of centrosymmetric molecules by enantioselective carbon,carbon bond formation is an efficient and convergent synthetic approach which is likely to find wide application in synthesis, particularly in the total synthesis of natural products with embedded centrosymmetric fragments. [source] Microwave-Assisted Heterogeneous Cross-Coupling Reactions Catalyzed by Nickel-in-Charcoal (Ni/C)CHEMISTRY - AN ASIAN JOURNAL, Issue 3 2006Bruce Abstract A study involving the relatively rare combination of heterogeneous catalysis conducted under microwave conditions is presented. Carbon,carbon bond formation, including Negishi and Suzuki couplings, can be quickly effected with aryl chloride partners by using a base metal (nickel) adsorbed in the pores of activated charcoal. Aminations were also studied, along with cross-couplings of vinyl alanes with benzylic chlorides as a means to stereodefined allylated aromatics. Reaction times for all these processes are typically reduced from several hours to minutes in a microwave reactor. [source] Synthesis of the Salicylihalamide Core Structure from Epichlorohydrin, Laying the Foundation to Macrolactone CollectionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2005Christian Herb Abstract Starting from (R)-epichlorohydrin, two successive carbon,carbon bond formations, one with acetylide and the other with cyanide, led to the 3-hydroxynitrile 20. This compound was further elaborated to the enynol 29 via an Evans aldol reaction of the derived aldehyde 22 with the pentenoyloxazolidinone 23 and conversion of the carboxyl to a methyl group after the aldol reaction. Mitsunobu esterification of the enynol 29 with the benzoic acid 5 gave rise to the ester 30 with two double bonds and one triple bond. After protection of the terminal triple bond with a TIPS group, the ring closing metathesis proceeded in good yield. The macrolactone E -33 was converted into the vinyl iodide 34 and the pyridin containing salicylihalamide analog 36. The described sequence, the two-sided elongation of epichlorohydrin appears as a general route to secondary alcohols that can be further elaborated to functionalized macrolactones. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Structure of macrophomate synthaseACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2004Toyoyuki Ose Macrophomate synthase (MPS) is an enzyme that catalyzes an extraordinarily complex conversion reaction, including two decarboxylations, two carbon,carbon bond formations and a dehydration, to form the benzoate analogue macrophomate from a 2-pyrone derivative and oxalacetate. Of these reactions, the two carbon,carbon bond formations are especially noteworthy because previous experiments have indicated that they proceed via a Diels,Alder reaction, one of the most widely used reactions in organic synthesis. The structural evidence that MPS catalyzes an intermolecular Diels,Alder reaction has been reported recently [Ose et al. (2003), Nature (London), 422, 185,189]. Interestingly, the tertiary structure as well as the quaternary structure of MPS are similar to those of 2-dehydro-3-deoxygalactarate (DDG) aldolase, a carbon,carbon bond-forming enzyme that catalyzes the reversible reaction of aldol condensation/cleavage. Here, the structure of MPS is described in detail and compared with that of DDG aldolase. Both enzymes have a (,/,)8 -barrel fold and are classified as belonging to the enolase superfamily based on their reaction strategy. The basic principles for carbon,carbon bond formation used by both MPS and DDG aldolase are the same with regard to trapping the enolate substrate and inducing subsequent reaction. The major differences in the active sites between these two enzymes are the recognition mechanisms of the second substrates, 2-pyrone and DDG, respectively. 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