Home About us Contact
|
Home About us Contact | ||
|
|
||
Unsaturated Compounds (unsaturated + compound)
Selected AbstractsTitanocene(II)-Promoted Cross-Coupling of Unsaturated CompoundsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2006Akitoshi Ogata Abstract Vinyl pivalate in the presence of the titanocene(II) reagent Cp2Ti[P(OEt)3]2 reacts both with nonpolar C,C triple bonds and with polar C=O double bonds, to produce conjugated dienes and allylic alcohols, respectively. Similar alkenylation also takes place when (Z)-alkenyl sulfones are treated with alkynes and carbonyl compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Metal-Free Catalytic Boration at the ,-Position of ,,,-Unsaturated Compounds: A Challenging Asymmetric Induction,ANGEWANDTE CHEMIE, Issue 30 2010Amadeu Bonet Ohne Zusatz von Übergangsmetallen wurden enantiomerenangereicherte sekundäre Boronsäureester mit einer Carbonylgruppe in ,-Stellung erhalten. Das neuartige organokatalytische System mit chiralen tertiären Phosphorverbindungen ergab Enantioselektivitäten bis 95,% ee. [source] ChemInform Abstract: Supported Cobalt Complex-Catalyzed Conjugate Addition of Indoles, Amines and Thiols to ,,,-Unsaturated Compounds.CHEMINFORM, Issue 42 2010Fatemeh Rajabi Abstract A supported cobalt complex is successfully used as a reusable catalyst for the Michael addition of thiols (I), amines (VI), and indoles (VIII) to alkenes (II) and (IV) under solvent-free conditions. [source] ChemInform Abstract: One-Pot Cross-Coupling of N-Acyl N,O-Acetals with ,,,-Unsaturated Compounds.CHEMINFORM, Issue 13 2010Yong-Gang Xiang 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: Synthesis of Heterocycles Based on Arylation Products of Unsaturated Compounds.CHEMINFORM, Issue 21 2009Part 17. 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: Synthesis of Aza-Henry Products and Enamines in Water by Michael Addition of Amines or Thiols to Activated Unsaturated Compounds.CHEMINFORM, Issue 24 2008Azim Ziyaei-Halimehjani 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] Homogeneous Electro-Mediated Reduction of Unsaturated Compounds Using Ni and Fe as Mediators in DMF.CHEMINFORM, Issue 39 2006Aderivaldo P. da Silva 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] Heterocycles Synthesis Based on Arylation Products of Unsaturated Compounds.CHEMINFORM, Issue 51 2005Part 7. Abstract For Abstract see ChemInform Abstract in Full Text. [source] Highly Efficient Phosphine-Catalyzed Aza-Michael Reactions of ,,,-Unsaturated Compounds with Carbamates in the Presence of TMSCl.CHEMINFORM, Issue 37 2004Li-Wen Xu Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Synthesis of Heterocycles Based on Products of Anion Arylation of Unsaturated Compounds.CHEMINFORM, Issue 17 2002Part 5. 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] Synthesis, Characterization, and Mechanism of Polymerization of Poly(but-2-ene sulfide),MACROMOLECULAR RAPID COMMUNICATIONS, Issue 15 2004Subramanian Sundarrajan Abstract Summary: The effect of structural factors on polymer formation versus cyclization is reported. The reaction of sodium sulfide with either 1,4-dibromobut-2-ene 1 or 1,4-dibromobutane 2 has been carried out in presence of a phase transfer catalyst and it was observed that the former yields polymer, whereas the latter gives cyclic and linear products. Interestingly, trans/cis isomerization takes place during the polymer formation from 1 and a plausible mechanism has also been discussed. The reaction mechanism for unsaturated compound 1 and saturated compound 2 is discussed here. [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] Synthesis of Functionalized Indoles with an ,-Stereogenic Ketone Moiety Through an Enantioselective Friedel,Crafts Alkylation with (E)-1,4-Diaryl-2-butene-1,4-dionesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Gonzalo Blay Abstract Chiral complexes of BINOL-based ligands with hafnium tert -butoxide catalyze the enantioselective Friedel,Crafts alkylation of indoles with (E)-1,4-diaryl-2-butene-1,4-diones at room temperature, with good yields and ee up to 94%. Hafnium(IV) was found to be a more effective Lewis acid than other frequently used metal ions such as titanium(IV) or zirconium(IV). Unlike the enantioselective Friedel,Crafts alkylation of indoles with ,,,-unsaturated compounds where the stereogenic center is generated in the ,-position to a carbonyl group, the Friedel,Crafts alkylation with 2-butene-1,4-diones described here generates an ,-stereogenic center with respect to one of the carbonyl groups. This can be regarded as an inversion of the normal reactivity pattern or umpolung. The enantioselective Friedel,Crafts alkylation of indoles with (E)-4-oxo-4-phenylbutenoates using a zirconium(IV)-BINOL catalyst is also reported. This reaction takes place regioselectively at the carbon in the ,-position to the ketone carbonyl group, generating an ,-ester stereogenic center. [source] Stereocontrolled alkylation of unsaturated compounds with alkoxytitanacyclopropane reagentsTHE CHEMICAL RECORD, Issue 5 2008Oleg Kulinkovich Abstract Interaction of titanium(IV) isopropoxide with ethylmagnesium bromide and its higher homologs leads to the generation of alkoxytitanacyclopropane species, which are able to act in the reactions with unsaturated compounds as 1,2-dicarbanionic alkylating agents. The present review is focused on the processes of intermolecular regio- and stereoselective alkylation of carboxylic esters and allylic alcohol derivatives with alkoxytitanacyclopropane reagents. The oxophilicity of the titanium atom and its tendency to form sterically crowded ate complexes are probably the main factors providing a high level of selectivity of these transformations. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 269,278; 2008: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20155 [source] Bonding in Tropolone, 2-Aminotropone, and Aminotroponimine: No Evidence of Resonance-Assisted Hydrogen-Bond EffectsCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2008Pablo Sanz Dr. Abstract The properties of the intramolecular hydrogen bond (IMHB) in tropolone, aminotropone, and aminotroponimine have been compared with those in the corresponding saturated analogues at the B3LYP/6-311+G(3df,2p)//B3LYP/6-311+G(d,p) level of theory. In general, all those compounds in which the seven-membered ring is unsaturated exhibit a stronger IMHB than their saturated counterparts. Nevertheless, this enhanced strength is not primarily due to resonance-assisted hydrogen-bond effects, but to the much higher intrinsic basicity and acidity of the hydrogen-bond acceptor and donor groups, respectively, in the unsaturated compounds. These acidity and basicity enhancements have a double origin: 1),the unsaturated nature of the moiety to which the hydrogen-bond donor and acceptor are attached and 2),the cyclic nature of the compounds under scrutiny. As has been found for hydroxymethylene and aminomethylene cyclobutanones, and cyclobutenones and their nitrogen-containing analogues, the IMHB strength follows the [donor, acceptor] trend: [OH, CNH]>[OH, CO]>[NH2, CNH]>[NH2, CO] and fulfills a Steiner,Limbach correlation similar to that followed by intermolecular hydrogen bonds. [source] Behaviour of [PdH(dppe)2]X (X=CF3SO3,, SbF6,, BF4,) as Proton or Hydride Donor: Relevance to CatalysisCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2004Michele Aresta Prof. Abstract The synthesis, characterization and properties of [PdH(dppe)2]+CF3SO3,,0.125,THF (1; dppe=1,2-bis(diphenylphosphanyl)ethane) and its SbF6, (1,) and BF4, (1,,) analogues, the missing members of the [MH(dppe)2]+X, (M=Ni, Pd, Pt) family, are described. The Pd hydrides are not stable in solution and can react as proton or hydride donors with formation of dihydrogen, [Pd(dppe)2]2+ and [Pd(dppe)2]. Complexes 1,1,, react with carbocations and carbanions by transferring a hydride and a proton, respectively. Such H, or H+ transfer occurs also towards unsaturated compounds, for example, hydrogenation of a CC double bond. Accordingly, 1 can hydrogenate methyl acrylate to methyl propionate. Complex 1,, is an effective (hourly turnover frequency=16) and very selective (100,%) catalyst for the hydrogenation of cyclohexen-2-one to cyclohexanone with dihydrogen under mild conditions. Density functional calculations coupled with a dielectric continuum model were carried out to compute the energetics of the hydride/proton transfer reactions, which were used to rationalize some of the experimental findings. Theory provides strong support for the thermodynamic and kinetic viability of a tetracoordinate Pd complex as an intermediate in the reactions. [source] Ceria-Based Solid Catalysts for Organic ChemistryCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 6 2010Laurence Vivier Dr. Abstract Ceria has been the subject of thorough investigations, mainly because of its use as an active component of catalytic converters for the treatment of exhaust gases. However, ceria-based catalysts have also been developed for different applications in organic chemistry. The redox and acid,base properties of ceria, either alone or in the presence of transition metals, are important parameters that allow to activate complex organic molecules and to selectively orient their transformation. Pure ceria is used in several organic reactions, such as the dehydration of alcohols, the alkylation of aromatic compounds, ketone formation, and aldolization, and in redox reactions. Ceria-supported metal catalysts allow the hydrogenation of many unsaturated compounds. They can also be used for coupling or ring-opening reactions. Cerium atoms can be added as dopants to catalytic system or impregnated onto zeolites and mesoporous catalyst materials to improve their performances. This Review demonstrates that the exceptional surface (and sometimes bulk) properties of ceria make cerium-based catalysts very effective for a broad range of organic reactions. [source] Synthesis of , -Amino Acids via Catalyst- and Solvent-Free Aza-Michael ReactionCHINESE JOURNAL OF CHEMISTRY, Issue 7 2008Bo ZOU Abstract A safe, environmentally friendly and cost-effective method for the synthesis of , -amino acid derivatives has been developed. Treatment of ,,, -unsaturated compounds with aliphatic amines furnishes , -amino acid derivatives in good to excellent yields via a catalyst- and solvent-free aza-Michael addition. [source] | ||||||||||||||||||||||