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41.
Hideo Kondo Kouki Matsubara Hideo Nagashima 《Journal of the American Chemical Society》2002,124(4):534-535
Coordinatively unsaturated diruthenium complexes, [(eta5-C5Me5)Ru(mu2-iPrNC(Me)=NiPr)Ru(eta5-C5Me5)]+, of which crystallography revealed structures bearing a bridging amidinate ligand perpendicular to the Ru-Ru axis, were synthesized by anion exchange of [(eta5-C3Me5(Ru(mu2-iPrNC(Me)=NiPr)Ru(eta5-C5Me5)]+ Br- by weakly coordinating anions. Variable-temperature NMR showed rapid motion of the bridging amidinate ligand. The coordinatively unsaturated nature of the cationic complexes provides their high reactivity toward a series of two electron donor ligands. Oxidative addition of molecular hydrogen occurred to give [(eta5-C5Me5)Ru(mu2-iPrNC(Me)=NiPr)(mu-H)Ru(eta5-C5Me5)(H)]+, which was isolated and characterized. 相似文献
42.
Fukuyama T Yamaura R Higashibeppu Y Okamura T Ryu I Kondo T Mitsudo TA 《Organic letters》2005,7(26):5781-5783
[reaction: see text] Catalytic [2 + 2 + 1 + 1] cocyclization reaction of an alkyne, an alkene, and two molecules of carbon monoxide, leading to functionalized hydroquinones, was studied. Using [Cp*RuCl2]2 as a catalyst, we found that a variety of electron-deficient alkenes, such as alpha,beta-unsaturated ketones, esters, amides, and nitriles, can be employed as an alkene coupling partner to give the corresponding hydroquinones. 相似文献
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Incubation of diosgenone (1, 25D-spirost-4-en-3-one) with Verticillium theobromae (Turconi) Mason et Hughes (CBS) afforded 20α-hydroxypregn-4<ne-3,16-dione (3) and 3α,11β,20α-trihydroxy-5α-pregnan-16-one (4). The same transformation products were also obtained by the use of Stachylidium bicolor Link (IFO 6647). Isolation and identification processes of the products are discussed. 相似文献
45.
Yoshiyuki Tanaka Makoto Arakawa Yohei Yamaguchi Chieko Hori Masahiro Ueno Takeyuki Tanaka Tatsushi Imahori Yoshinori Kondo 《化学:亚洲杂志》2006,1(4):581-585
A metal‐free acetylide was observed by using NMR spectroscopy. Metal‐free acetylides are closely related to reactive intermediates (carbanions) in solution; therefore, they have been regarded as unobservable species. However, we generated this highly reactive and unstable species through the deprotonation of phenylacetylene by using the strong nonmetallic phosphazene base tBu‐P4. In the presence of tBu‐P4, the J coupling between the ethynyl carbon and hydrogen nuclei (1JC,H) of phenylacetylene disappeared; this indicates the deprotonation of the alkyne terminal. Furthermore, a large low‐field shift (approximately 90 ppm) of the alkyne carbon resonance was observed. We concluded that we have observed a metal‐free carbanion with a formal charge on an sp‐hybridized carbon atom for the first time. 相似文献
46.
Kondo M Miyazawa M Irie Y Shinagawa R Horiba T Nakamura A Naito T Maeda K Utsuno S Uchida F 《Chemical communications (Cambridge, England)》2002,(18):2156-2157
A coordination polymer [Zn(pyta)(OH)] (pyta = 4-pyridylthioacetate), was synthesized and structurally characterized; it is constructed by an alternating assembly of two types of homo-chiral helices, [Zn-OH] and [Zn-pyta], in which the sulfide moieties are fastened in the latter columns. 相似文献
47.
Abstract— The kinetics of enzymatic photoreactivation (PR) of u.v.-induced killing was compared among E. coli Bs-1, phage T1 in Bs-1 and phage T1 in irradiated Bs-1. The PR action spectrum showed no substantial difference between PR of Bs-1 and PR of T1 in Bs-1. The PR D37 (i.e. the PR dose required to reactivate all but 37 per cent of the reactivable lethal lesions) was found to decrease linearly with decreasing U.V. dose whether U.V. was given to produce pyrimidine dimers in Bs-1 DNA, which then compete with irradiated T1 DNA for PR enzyme, or to Bs-1 or T1 DNA to produce dimers serving as substrate for the PR enzyme. A generalized Michaelis-Menten formula was used to analyze the data and the following conclusions were drawn. (1) The number of PR enzyme molecules per cell available for PR of T1 DNA inside the Bs-1 host is only a quarter of the number available for PR of the Bs-1 host itself. (2) The Michaelis constant Km for reaction of host-DNA-damage and PR-enzyme becomes larger when the host damage acts as competitive inhibitor to PR of T1 DNA than when it is the substrate for PR enzyme. (3) PR enzyme retains almost all its initial catalytic efficiency even after about two-hundred rounds of catalytic functioning. Conclusions (1) and (2) suggest that PR enzyme is concentrated within the nuclear area surrounding the host DNA. 相似文献
48.
Copolyamides and copolyesters containing the phenoxasilin ring were prepared from 2,8-dichloroformyl-10,10-diphenylphenoxasilin, isophthaloyl chloride and m-phenylenediamine or bisphenol A by interfacial polycondensation in chloroform-aqueous alkali mixture. They were obtained in yields of 80% or above and at relatively high viscosities up to 1.30 dl/g. The copolymers with high phenoxasilin content were freely soluble in dimethylacetamide, dimethylformamide and N-methyl-2-pyrrolidone, but decreasing phenoxasilin content led to copolymers with slight solubilities in these solvents; the copolyesters also dissolved in chloroform, m-cresol and phenol-sym tetrachloroethane (60:40 in wt%). Flexible transparent films were obtained from chloroform solutions of the copolyesters, but the films cast from DMF solutions of the copolyamides became brittle as the phenoxasilin content decreased. The phenoxasilin-containing copolymers hardly degraded below 400° and had good thermal stability. Introduction of the phenoxasilin ring into the polymer backbones by copolycondensation did not reduce thermal stability. 相似文献
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50.
Aiming to develop a high performance fiber reinforced rubber of SBR, a special technique using electron beam (EB) irradiation-induced graft-polymerization was applied to ultra-high molecular-weight polyethylene (UHMWPE) fibers. Although UHMWPE is chemically inert, N-vinyl formamide (NVF) could be graft-polymerized onto the UHMWPE fiber surface with this special technique. A maximum grafting percentage of 23.6% was achieved. The composite of SBR and grafted UHMWPE fibers with maximum grafting indicated a linear increase in the initial modulus and strength with the fiber content. At the fiber content of 10%, the initial modulus was improved about five times with respect to that of the pure SBR, while the strength was done about twice. At this moment, only a small reduction could be observed in the strain compared with that of pure SBR. The fiber reinforced rubber with a good performance was obtained in the system of SBR and grafted UHMWPE fibers. 相似文献