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Tomotaka Hirabayashi 《Tetrahedron》2006,62(10):2231-2234
The addition of water and alcohols to non-activated terminal alkynes was found to be promoted by an iridium complex combined with Lewis acid and phosphite. Thus, terminal alkynes reacted with water or alcohols to give ketones or ketals, respectively, in good to excellent yields. α,ω-Diyne like 1,7-octadiyne was converted into 1-(2-methyl-cyclopent-1-enyl)ethanone through the intramoleculer aldol condensation of the resulting 2,7-octanedione induced by Lewis acid. 相似文献
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Okino T Hoashi Y Furukawa T Xu X Takemoto Y 《Journal of the American Chemical Society》2005,127(1):119-125
We synthesized a new class of bifunctional catalysts bearing a thiourea moiety and an amino group on a chiral scaffold. Among them, thiourea 1e bearing 3,5-bis(trifluoromethyl)benzene and dimethylamino groups was revealed to be highly efficient for the asymmetric Michael reaction of 1,3-dicarbonyl compounds to nitroolefins. Furthermore, we have developed a new synthetic route for (R)-(-)-baclofen and a chiral quaternary carbon center with high enantioselectivity by Michael reaction. In these reactions, we assumed that a thiourea moiety and an amino group of the catalyst activates a nitroolefin and a 1,3-dicarbonyl compound, respectively, to afford the Michael adduct with high enantio- and diastereoselectivity. 相似文献
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The first Ritter-type reaction of alkylbenzenes with nitriles has been successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. Thus, treatment of ethylbenzene with ammonium hexanitratocerate(IV) (CAN) in the presence of a catalytic amount of NHPI in EtCN under argon produced the corresponding amide in good selectivity. 相似文献
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Enantioselective Michael reaction of malonates to nitroolefins catalyzed by bifunctional organocatalysts 总被引:1,自引:0,他引:1
Michael reaction of malonates to nitroolefins with chiral bifunctional organocatalysts, bearing both a thiourea and tertiary amino group, afforded Michael adducts with high yields and enantioselectivities (up to 95%, up to 93% ee). 相似文献
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The temporal profile and phase of the fifth harmonic of a Ti:sapphire laser were fully characterized by two-photon ionization frequency-resolved optical gating technique for the first time. The fifth harmonic was found to have negative chirp and the pulse compression was demonstrated. The negative chirp is well explained by using a zero-range potential model. This technique is scalable to extreme ultraviolet (XUV) and soft x-ray regions by using currently available light sources, making it possible to measure the pulse duration and phase of vacuum ultraviolet, XUV, and soft x-ray pulses. 相似文献
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Cover Picture: Theoretical and Experimental Study on Boron β‐Diketonate Complexes with Intense Two‐Photon‐Induced Fluorescence in Solution and in the Solid State (ChemPhysChem 14/2016)
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An analytical energy gradient formula for the density-matrix-based linear-scaling divide-and-conquer (DC) self-consistent field (SCF) method was proposed in a previous paper by Yang and Lee (YL) [J. Chem. Phys. 103, 5674 (1995)]. Since the formula by YL does not correspond to the exact gradient of the DC-SCF energy, we derive the exact formula by direct differentiation, which requires solving the coupled-perturbed equations while including the inter-subsystem coupling terms. Next, we present an alternative formula for approximately evaluating the DC-SCF energy gradient, assuming the variational condition for the subsystem density matrices. Numerical assessments confirmed that the DC-SCF energy gradient values obtained by the present formula are in reasonable agreement with the conventional SCF values when adopting a reliable buffer region. Furthermore, the performance of the present method was found to be better than that of the YL method. 相似文献