Search results for "Diene"

showing 10 items of 623 documents

[(1R,4S)-(+)-3-Benzoyl-1,7,7-trimethyl­bicyclo­[2.2.1]heptan-2-olato-κ2 O 2,O 3](η4-norbornadiene)rhodium(I)

2010

In the title complex mol-ecule, [Rh(C(17)H(19)O(2))(C(7)H(8))], the rhodium(I) metal centre is coordinated by the O atoms of a benzoyl-camphorate anion and the C=C bonds of the norbornadiene mol-ecule into a slightly distorted square-planar coordination geometry. The six-membered chelate ring is essentially planar (r.m.s. deviation = 0.0378 Å) and forms a dihedral angle of 31.67 (11)° with the phenyl ring.

Metal-Organic PapersBicyclic moleculeChemistryNorbornadienechemistry.chemical_elementGeneral ChemistryDihedral angleCondensed Matter PhysicsRing (chemistry)BioinformaticsMedicinal chemistryRhodiumMetalchemistry.chemical_compoundvisual_artvisual_art.visual_art_mediumGeneral Materials ScienceChelationCoordination geometryActa Crystallographica Section E: Structure Reports Online
researchProduct

A Molecular Electron Density Theory Study of the Competitiveness of Polar Diels–Alder and Polar Alder-ene Reactions

2018

Indexación: Scopus. Funding: Ministry of Economy and Competitiveness (MINECO) of the Spanish Government, project CTQ2016-78669-P (AEI/FEDER, UE) and Fondecyt (Chile) grant 1180348. Acknowledgments: This research was supported by the Ministry of Economy and Competitiveness (MINECO) of the Spanish Government, project CTQ2016-78669-P (AEI/FEDER, UE) and Fondecyt (Chile) grant 1180348. L.R.D. thanks Fondecyt for continuous support through Cooperación Internacional. M.R.-G. also thanks MINECO for a post-doctoral contract cofinanced by the European Social Fund (BES-2014-068258). The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions …

Models MolecularDienePharmaceutical Science01 natural sciencesAnalytical ChemistryDioxanesAlder-ene reactionschemistry.chemical_compoundComputational chemistryDrug DiscoverySingle bondLewis acids and basesBoranesLewis AcidsCycloaddition ReactionChemistryStereoisomerismPrins reactionMolecular Electron Density Theory Diels-Alder reactionsChemistry (miscellaneous)ElectrophileThermodynamicsMolecular Medicinecompetitive reactionscompetitive reactions polar reactionsAllylic rearrangementElectrons010402 general chemistryArticleCatalysislcsh:QD241-441lcsh:Organic chemistryPseudocyclic selectivityFormaldehydeButadienespolar reactionsPhysical and Theoretical ChemistryEne reactionDiels-Alder reactionsPrins reaction pseudocyclic selectivity010405 organic chemistryOrganic ChemistryMolecular Electron Density TheoryPolar reactionsPhenanthrenespseudocyclic selectivity0104 chemical sciencesPrins reactionQuantum TheoryCompetitive reactionsMolecules
researchProduct

EPR, ENDOR and TRIPLE Resonance and MO Studies on Ubiquinones (Q-n): Comparison of Radical Anions and Cations of Coenzymes Q-10 and Q-6 with the Mode…

1997

Radical anions and cations of the biologically important coenzymes Q-6 and Q-10, which have 6 and 10 unsaturated isoprene units in their side chains, respectively, have been generated in various solvents, and the results compared with those obtained for Q-0, a ubiquinone with no isoprene units, and for decylubiquinone Q-2 which has a saturated side chain. Hyperfine splitting constants (hfsc) of methyl and methoxy protons of the substituents in the quinone ring, and beta and gamma protons of the side chain were measured by EPR and ENDOR spectroscopy for both the radical anions and cations of Q-0, Q-6 and Q-10, and for the radical anion of Q-2. The relative signs of the hfsc were determined b…

Models MolecularFree RadicalsMolecular StructureUbiquinoneChemistryGeneral Chemical EngineeringRadicalElectron Spin Resonance SpectroscopyMolecular ConformationPhotochemistryResonance (chemistry)law.inventionQuinoneCrystallographyHemiterpeneslawPentanesButadienesSide chainMoleculeMolecular orbitalElectron paramagnetic resonanceHyperfine structureActa Chemica Scandinavica
researchProduct

Unveiling the Lewis Acid Catalyzed Diels–Alder Reactions Through the Molecular Electron Density Theory

2020

The effects of metal-based Lewis acid (LA) catalysts on the reaction rate and regioselectivity in polar Diels&ndash

Models MolecularReaction mechanismDieneChemistry OrganicMolecular ConformationNormal DistributionPharmaceutical ScienceElectrons010402 general chemistry01 natural sciencesArticleAnalytical ChemistryCatalysisReaction ratelcsh:QD241-441chemistry.chemical_compoundNucleophilelcsh:Organic chemistryComputational chemistryDrug DiscoveryButadienesLewis acids and basesPhysical and Theoretical ChemistryLewis Acidsrelation mechanismCycloaddition Reactioncatalysis010405 organic chemistryOrganic Chemistrymolecular electron density theoryRegioselectivityLewis acid0104 chemical sciences3. Good healthchemistryChemistry (miscellaneous)ElectrophileDiels–AlderSolventsMolecular MedicineQuantum TheoryThermodynamicsMolecules
researchProduct

Synthesis and application of β-substituted Pauson-Khand adducts: trifluoromethyl as a removable steering group.

2013

The reaction between alkynes (I) and norbornadiene (II) affords the β-substituted Pauson—Khand adducts (III) as single regioisomers and the trifluoromethyl steering group can be easily removed in the presence of DBU and water.

Models MolecularTrifluoromethylMolecular StructureChemistryNorbornadienePauson–Khand reactionRegioselectivityStereoisomerismGeneral MedicineGeneral ChemistryChemistry Techniques SyntheticCatalysisAdductchemistry.chemical_compoundAlkynesStructural isomerOrganic chemistryPolycyclic CompoundsSteering groupMicrowavesSesquiterpenesChlorofluorocarbons MethaneAngewandte Chemie (International ed. in English)
researchProduct

Artificial multiple criticality and phase equilibria: an investigation of the PC-SAFT approach

2005

The perturbed-chain statistical associating fluid theory (PC-SAFT) is studied for a wide range of temperature, T, pressure, p, and (effective) chain length, m, to establish the generic phase diagram of polymers according to this theory. In addition to the expected gas-liquid coexistence, two additional phase separations are found, termed "gas-gas" equilibrium (at very low densities) and "liquid-liquid" equilibrium (at densities where the system is expected to be solid already). These phase separations imply that in one-component polymer systems three critical points occur, as well as equilibria of three fluid phases at triple points. However, Monte Carlo simulations of the corresponding sys…

Models Molecularchemistry.chemical_classificationModels StatisticalPolymersMicrofluidicsMonte Carlo methodGeneral Physics and AstronomyThermodynamicsPolymerPhase TransitionCondensed Matter::Soft Condensed MatterPolybutadieneModels ChemicalCriticalitychemistryPhase (matter)High pressureComputer SimulationPhysical and Theoretical ChemistryAlgorithmsMacromoleculePhase diagramPhysical Chemistry Chemical Physics
researchProduct

ALTMET Polymerization of Amino Acid-Based Monomers Targeting Controlled Drug Release

2016

Giving the imminent necessity of a new generation of biodegradable and biocompatible polymers prepared from feedstock, the synthesis of a potentially biodegradable amino acid-based copolymer by the alternating diene metathesis (ALTMET) strategy is herein presented. The reaction was tailored to minimize isomerization and deactivation of ruthenium catalysts by intramolecular coordination with the amide carbonyl group of the amino-acid-based monomer. Alternated l-lysine–phosphoester copolymers with molar masses higher than 18 000 g/mol were obtained using Hoveyda–Grubbs second-generation and Umicore M2 catalysts. The copolymer was further used to prepare nanoparticles loaded with rifampicin (u…

Molar massPolymers and PlasticsDieneOrganic Chemistrychemistry.chemical_element02 engineering and technology010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical sciencesRutheniumInorganic ChemistryMiniemulsionchemistry.chemical_compoundMonomerchemistryPolymerizationAmidePolymer chemistryMaterials ChemistryCopolymer0210 nano-technologyMacromolecules
researchProduct

Enantioselective synthesis of fluorinated alpha-amino acids and derivatives in combination with ring-closing metathesis: intramolecular pi-stacking i…

2001

[reaction: see text]. Hydride reduction of C=N bonds stereocontrolled by intramolecular pi-stacking interactions of 1-naphthylsulfinyl and N-aryl groups, nonoxidative Pummerer rearrangement, and ring-closing metathesis are efficiently combined in a highly stereoselective entry to enantiomerically pure cyclic and acyclic fluorinated beta-amino alcohols and alpha-amino acid derivatives, respectively.

Molecular StructureChemistryHydrideStereochemistryPummerer rearrangementOrganic ChemistryStackingEnantioselective synthesisStereoisomerismFluorineMetathesisBiochemistryRing-closing metathesisIntramolecular forcePhysical and Theoretical ChemistryAmino AcidsAcyclic diene metathesisOrganic letters
researchProduct

Toward an Understanding of the Catalytic Role of Hydrogen-Bond Donor Solvents in the Hetero-Diels−Alder Reaction between Acetone and Butadiene Deriva…

2006

A detailed theoretical investigation of the catalytic role of hydrogen-bond- (HB-) donor molecules (water, methanol, chloroform, dichloromethane, and chloromethane) in the hetero-Diels-Alder reaction between acetone and N,N-dimethyl-1-amino-3-methoxy-1,3-butadiene is presented. This work extends a previous study (Domingo, L. R.; Andres, J. J. Org. Chem. 2003, 68, 8662) in which the importance of weak HB-donor solvents to catalyze more effectively than solvents with a higher dielectric constant but no HB-donor capability was analyzed. Now, based on density functional theory (DFT) at B3LYP/6-31+G(d) level calculations, different techniques for analyzing the nature of HB interaction, namely, n…

Molecular StructureHydrogen bondChloromethaneAtoms in moleculesHydrogen BondingInteraction energyCatalysisElectron localization functionAcetonechemistry.chemical_compoundModels ChemicalchemistryComputational chemistryButadienesSolventsQuantum TheoryMoleculeDensity functional theoryPhysical and Theoretical ChemistryEthersNatural bond orbitalThe Journal of Physical Chemistry A
researchProduct

A Bis(diazadiene) Adduct of MoCl 2 : Mononuclear, Octahedral, Undistorted and Diamagnetic

2004

The complex [MoCl2(iPr2dad)2] (iPr2dad = iPrN=CH−CH=N−iPr) is obtained in one step by reduction of [MoCl3(THF)3] in the presence of iPr2dad. The X-ray structure reveals a relatively undistorted octahedral coordination geometry with a relative cis configuration and points to a more appropriate description of the ligands as enediamides. The NMR investigation is in agreement with the same cis structure in solution and underlines the diamagnetism of the compound, at odds with previously reported very similar complexes. A bulk magnetic susceptibility measurement further confirms the compound’s diamagnetism. No equilibrium with a dinuclear, metal-metal bonded species is apparent from the solution…

MolybdenumDiazadiene ligands010405 organic chemistryChemistryLigandStereochemistry010402 general chemistry01 natural sciencesMagnetic susceptibilityX-ray diffraction0104 chemical sciencesAdductInorganic ChemistryCrystallographyOctahedronSpin stateDiamagnetismMolecule[CHIM.COOR]Chemical Sciences/Coordination chemistryCis–trans isomerismCoordination geometryEuropean Journal of Inorganic Chemistry
researchProduct