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51.
The thermolysis of a pentacoordinate fluorodisilane bearing an 8-(dimethylamino)-1-naphthyl group in the presence of 2,3,4,5,6-pentaphenylfulvene or 14-phenyldibenzofulvene affords a silylene-fulvene adduct bearing a zwitterionic structure attributable to the silaylide, but it spontaneously undergoes subsequent intramolecular cyclization reaction between the silicon atom and the aromatic carbon atom in the fulvene moiety followed by a sigmatropic proton migration to form a neutral silicon-containing six- or five-membered ring product. 相似文献
52.
Yoshihisa Kiso Makoto Kumada Kohei Tamao Masayuki Umeno 《Journal of organometallic chemistry》1973,50(1):297-310
A variety of dihalodiphosphinenickel(II) complexes have been found to be effective catalysts for hydrosilylation of olefins and acetylenes. Reactions with nickel(II) catalysts, at least those containing a bidentate phosphine ligand, scarcely proceed below 90°. At 120° the reaction proceeds smoothly to form, in many cases, an unexpected (“abnormal”) adduct which has arisen from an interchange of hydrogen and chlorine on silicon in addition to the expected (“normal”) one. Both total yields, and the ratios of the “abnormal” to the “normal” adduct increase, in general, with increasing electron-donating ability of both the phosphine ligands and the substituents on the olefins. Isomerization of olefins occurs during the course of hydrosilylation. cis-Addition occurs preferentially. The reactivity of the silicon hydrides decreases in the order HSiCl3 ? HSiMeCl2 ? HSiMe2Cl ? HSiMe3. 相似文献
53.
A general, versatile method for alkylation and arylation of haloheterocyclic compounds is reported. In the presence of a catalytic quantity of [NiCl2(dppp)], where dppp stands for Ph2P(CH2)3PPh2, bromothiophenes, halopyridines, haloquinoline, and haloisoquinolines reacted with alkyl and aryl Grignard reagents at room temperature or at ether refluxing temperature to give the cross-coupling products. The coupling reaction has been applied to the synthesis of isoquinoline alkaloids. Reactivities of 2-thienyl and 2-pyridyl Grignard reagents have also been examined. 相似文献
54.
(E)-Alkenylpentafluorosilicates react with copper(II) thiocyanate in DMF at ambient temperature to give (E)-alkenyl thiocyanates stereoselectively in high yields. 相似文献
55.
Yoshihisa Kiso Makoto Kumada Kimio Maeda Koji Sumitani Kohei Tamao 《Journal of organometallic chemistry》1973,50(1):311-318
Two ethylene-nickel(0) complexes, viz., [1,2-bis(diphenylphosphino)ethane]-(ethylene)nickel(0) and bis(triphenylphosphine)(ethylene)nickel(0) have been used in a comparison of their catalytic activities in hydrosilylation reactions with those of the corresponding nickel(II) complexes, viz., dichloro [1,2-bis(diphenylphosphino)-ethane]nickel(II) and dichlorobis(triphenylphosphine)nickel(II). The reaction profiles are similar, apart from a significant difference in the induction period; the nickel(II) catalysts requiring a substantially longer time. A mechanism involving a nickel(0) species is proposed for the hydrosilylation.The interchange of hydrogen and chlorine on silicon accompanying the hydrosilylation is related to a high electron density at the nickel atom bearing the phosphine, olefin, and silicon hydride ligands. 相似文献
56.
S Odake K Nakahashi T Morikawa S Takebe K Kobashi 《Chemical & pharmaceutical bulletin》1992,40(10):2764-2768
A series of dipeptidyl hydroxamic acids (H-X-Gly-NHOH: X = amino acid residues) was synthesized, and the inhibitory activity against Jack bean and Proteus mirabilis ureases [EC 3.5.1.5] was examined. A number of H-X-Gly-NHOH inhibited Jack bean urease with an I50 of the order of 10(-6) M and inhibited Proteus mirabilis urease with an I50 of the order of 10(-5) M. The inhibition against Jack bean urease was more potent than that with the corresponding aminoacyl hydroxamic acids (H-X-NHOH). 相似文献
57.
Akio Minato Kohei Tamao Tamio Hayashi Keizo Suzuki Makoto Kumada 《Tetrahedron letters》1981,22(52):5319-5322
1-Methyl-2-pyrrolyl-magnesium bromide and -zinc chloride, which were prepared from 1-methyl-2-pyrrolyllithium with MgBr2 and ZnCl2 respectively, reacted with aryl- and heteroaromatic halides to give the corresponding 2-substituted pyrroles in good to excellent yields in the presence of palladium-phosphine complexes as catalysts. 相似文献
58.
We present a q-difference realization of the quantum superalgebra Uq(sl(M|N)), which includes Grassmann even and odd coordinates and their derivatives. Based on this result, we obtain a free boson realization of the quantum affine superalgebra Uq
of an arbitrary level k. 相似文献
59.
60.
The on-chip derivatization of nitrite ions with 2,3-diaminonaphthalene (DAN) utilizing a pH gradient formed in a Y-shaped microchannel was investigated. Nitrite ions react with DAN at low pH, and strongly fluoresced at high pH. Therefore, a reaction at low pH followed by the addition of a strong alkaline solution is the usual procedure in a batch scheme. However, a strong alkaline solution, like an NaOH aqueous solution, erodes the wall of the microchannels in substrates made of glass or polymers, and has not been considered suitable for use in microchannels. We first investigated the derivatization reaction and fluorescent properties of nitrite ions with DAN. We found that the on-chip fluorescent derivatization reaction and detection without the addition of an alkaline solution is possible by controlling the pH values of the nitrite solution and the DAN solution to form a suitable pH gradient by utilizing a buffering effect of triethanolamine solution, which is used as an NO2 gas-absorption medium. These results have suggested the feasibility of novel reaction schemes which can provide the desired products due to a controlled pH gradient in the microchannels, as well as the possibility of an on-site monitoring microchip device for ambient NO2. 相似文献