52,173 research outputs found
Recent Advances in the Synthetic and Mechanistic Aspects of the Ruthenium-catalyzed Carbon-heteroatom Bond Forming Reactions of Alkenes and Alkynes
The group’s recent advances in catalytic carbon-to-heteroatom bond forming reactions of alkenes and alkynes are described. For the C–O bond formation reaction, a well-defined bifunctional ruthenium-amido catalyst has been successfully employed for the conjugate addition of alcohols to acrylic compounds. The ruthenium-hydride complex (PCy3)2(CO)RuHCl was found to be a highly effective catalyst for the regioselective alkyne-to-carboxylic acid coupling reaction in yielding synthetically useful enol ester products. Cationic ruthenium-hydride catalyst generated in-situ from (PCy3)2(CO)RuHCl/HBF4·OEt2 was successfully utilized for both the hydroamination and related C–N bond forming reactions of alkenes. For the C–Si bond formation reaction, regio- and stereoselective dehydrosilylation of alkenes and hydrosilylation of alkynes have been developed by using a well-defined ruthenium-hydride catalyst. Scope and mechanistic aspects of these carbon-to-heteroatom bond forming reactions are discussed
Collective oscillations of dipolar Bose-Einstein condensates and accurate comparison between contact and dipolar interaction
We propose a scheme for the measurement of the s-wave scattering length
of an atom or molecule with significant dipole-dipole interaction with an
accuracy at the percent level. The frequencies of the collective oscillations
of a Bose-Einstein condensate are shifted by the magnetic dipole interaction.
The shift is polarization dependent and proportional to the ratio
of dipolar and s-wave coupling constants. Measuring the
differences in the frequencies for different polarization we can extract the
value of and thus measure . We calculate the frequency
shifts for a large variety of non-axisymmetric harmonic traps in the
Thomas-Fermi limit and find optimal trapping geometries to maximize the shifts.Comment: 4 pages, brief repor
Formation of Bicyclic Pyrroles from the Catalytic Coupling Reaction of 2,5-disubstituted Pyrroles with Terminal Alkynes, Involving the Activation of Multiple C-H bonds
Substituted bicyclic pyrroles are produced directly from the coupling reaction of 2,5-disubstituted pyrroles with terminal alkynes, involving the activation of multiple C–H bonds and regioselective cyclisation
Regioselective Formation of α-Vinylpyrroles from the Ruthenium-Catalyzed Coupling Reaction of Pyrroles and Terminal Alkynes Involving C–H Bond Activation
The cationic ruthenium catalyst Ru3(CO)12/NH4PF6 was found to be highly effective for the intermolecular coupling reaction of pyrroles and terminal alkynes to give gem-selective α-vinylpyrroles. The carbon isotope effect on the α-pyrrole carbon and the Hammett correlation from a series of para-substituted N-arylpyrroles (ρ = −0.90) indicate a rate-limiting C−C bond formation step of the coupling reaction
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