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51.
Ming Z. Gao 《Tetrahedron letters》2004,45(29):5649-5652
The novel structures of sulfur-containing chiral bis(oxazoline) compounds which have been synthesized have been determined by X-ray crystal diffraction analyses. A high enantioselectivity (ee >99%) in the asymmetric cyclopropanation of diphenylethene with diazoester using the bis(oxazoline)-Ru(II) catalyst was obtained. 相似文献
52.
53.
R. I. Kureshy N. H. Khan S. H. R. Abdi P. Iyer A. K. Bhatt 《Journal of molecular catalysis. A, Chemical》1997,120(1-3):101-108
A series of new dissymmetric chiral Schiff base complexes has been obtained by a systematic condensation of (1S,2S)(+)-diaminocyclohexane and 3-acetyl-4-hydroxy-6-methyl-2-pyrone with salicylaldehyde, 5-chloro-, 5-methoxy-and 5-nitrosalicylaldehyde and by subsequent metallation with manganese and ruthenium. The characterization of the complexes 1–8 was accomplished by physico chemical studies viz. microanalysis, IR-, UV/VIS-, and CD spectral studies, optical rotation, molar conductance measurements and cyclic voltammetry. Enantioselective epoxidation of non functionalised olefins, viz. cis-stilbene, trans-3-nonene and trans-4-octene with iodosyl benzene as oxidant was demonstrated in the presence of catalytic amounts of chiral Mn(III) and Ru(III) dissymmetric Schiff base complexes. Good optical yields of epoxides were obtained for the catalyst 4 with the substrates trans-3-nonene and cis-stilbene. 相似文献
54.
Hans‐Peter Kormann Günter Schmid Katrin Pelzer K. Philippot Bruno Chaudret 《无机化学与普通化学杂志》2004,630(12):1913-1918
Nanoporous alumina membranes, loaded with palladium and ruthenium nanoparticles of various size, were used for gas phase hydrogenation of 1, 3‐butadiene and for oxidation of carbon monoxide, respectively. Those membranes contain 109 ‐ 1011 pores per cm2, all running perpendicular to the surface. Membrane discs of 20 mm in diameter and only 60 μm thick, incorporated in a reactor in which the reactants can be pumped in a closed circuit through the pores, turned out to very actively catalyze hydrogenation of butadiene (Pd) and oxidation of CO (Ru). The activity of the Pd catalysts depends characteristically on the particles size, the gas flow, and of the educts ratio. As could be expected, larger particles are less active than smaller ones, whereas increasing gas flows in case of hydrogenation accelerates the reactions. Excessive hydrogen reduces selectivity with respect to the various butenes, but favours formation of butane. 相似文献
55.
56.
Ryan R. Burton 《Tetrahedron letters》2006,47(40):7185-7189
Ruthenium-catalyzed [2+2] cycloadditions between C1-substituted 7-oxanorbornadienes and alkynes were investigated. Most of the cycloadditions occurred smoothly at 65 °C, giving the cyclobutene cycloadducts in moderate to good yields. The C1 substituent showed strong effect on the regioselectivity (up to 110:1) of the cycloadditions. 相似文献
57.
The biomimetic catalytic enantioselective addition of aldehydes to amines is reported. This was accomplished by combining biomimetic coupled catalytic aerobic oxidation of amines involving ruthenium-induced dehydrogenation and organocatalytic asymmetric Mannich reactions. The novel one-pot reactions furnished β-amino aldehyde and α-amino acid derivatives in high yields with excellent chemoselectivity and up to >99% ee. 相似文献
58.
Reactions of 1,2,3,4-tetraphenyl-1,2,3,4-tetraphospholane (I) with triruthenium dodecacarbonyl at different temperatures result in the cleavage of P-P bonds and even P-C bond(s) in I to afford a series of new ruthenium cluster derivatives containing phosphido and phosphinidene ligands: a penta-ruthenium wing-tip bridged butterfly cluster [Ru5(CO)11(μ4-PPh)(μ3-PPh){(μ4-η2-(PPh)2CH2}] (1), a hepta-ruthenium polyhedral (consisting of two fused square pyramids with a co-apex) cluster [Ru7(CO)15(μ4-PPh)2{(μ2-PPh)2CH2}](2), a linked penta-ruthenium cluster [Ru4(CO)10(μ4-PPh)(μ3-PPh)2(μ3-η2-PPhCH2)Ru(CO)3] (3), and a hepta-nuclear polyhedral (consisting of two fused square pyramids with different apexes) cluster [Ru7(CO)15(μ4-PPh)2{(μ2-PPh)2CH2}](4). Clusters 2 and 4 are isomeric and differ only in the connection of the two square pyramids in the Ru7 polyhedron. All the newly obtained clusters have been fully characterized by spectroscopic (IR, FABMS, 1H- and 31P-NMR spectroscopy) and analytical techniques, and their molecular structures are established by single crystal X-ray diffraction analysis. 相似文献
59.
Giuliana Gervasio Domenica Marabello Andrea Secco 《Journal of organometallic chemistry》2004,689(1):35-42
The reaction of Ru3(CO)12 with but-2-yn-1,4-diol (HOCH2CCCH2OH, BUD) in CH3OH/KOH followed by acidification with HCl leads to four products, one of which has been identified as the title complex (μ-Cl)Ru3(CO)9[μ3-η4-H2CCC(H)CH2]. This is an open cluster containing a bridging Cl atom on the open side and a C4H5 moiety bound to all the metals. The structure of the complex has been determined by X-ray analysis.The thermal reaction of Ru3(CO)12 with BUD has been revisited for a comparison with the results in alkaline solution. The main product is the allylic derivative HRu3(CO)9[HCCHCCHO]. 相似文献
60.
Chandra S Kumar R 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):1050-1057
Reaction of divalent cobalt(II) and trivalent ruthenium(III) salts (NO3, SCN and SO4) with macrocyclic ligands L1, L2 and L3 having N2S2, N4 and N5 core, have been designed and carry out. All these three macrocyclic ligands and their complexes were obtained in pure form. Their structures were investigated by using microanalytical analyses, IR, mass, magnetic moments, electronic and EPR spectral studies. The redox properties of the complexes were also examined by cyclic voltammetry. An interesting feature of complexes is that the relatively large rings of macrocyclic ligands prevent the macrocyclic rings from approaching the metal center as closely as they would, if they were not constrained. So the Ru-N distances are longer than expected due to ring size. Electrochemical studies show that the macrocyclic ligand L1 is more effective electron donors to ruthenium than of L2 and L3. Electronic spectral properties also show that the sulphur donor atom of L1 weakens the ligand field with respect to ligand-to-metal charge-transfer band. However it is expected that second-row transition metal-ligand bonds tend to be weaker than third-row transition metal-ligand bonds. There are well-established examples of reactions in which decreased of reactivity down a triad of transition metals is not observed. These novelties are usually attributed to pi-bonding effects for ligands such as carbon monoxide, solvent effects, or a change in mechanism. 相似文献