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81.
Fumiko Fujisaki Sachi Hiromatsu Yumiko Matsumura Aki Fukami Nobuhiro Kashige Fumio Miake Kunihiro Sumoto 《Journal of heterocyclic chemistry》2013,50(2):417-424
In connection with our studies on antibacterial active compounds in the class of new oxazolidinones against Gram‐positive (Staphylococcus aureus) and Gram‐negative (Escherichia coli) strains, some molecular modifications were attempted. In this study, molecular modifications of 4‐aminomethyloxazolidin‐2‐ones ( 3a ) to the corresponding 4‐acylaminomethyloxazolidin‐2‐one derivatives ( 3c–d ) and preparations of the represented twin‐drug type molecules ( 10–14 ) were investigated. Some additional 4‐dialkylaminomethyloxazolidin‐2‐ones ( 2 ) were also synthesized. The synthesized compounds were evaluated for antibacterial activity with Gram‐positive (S. aureus) and Gram‐negative (E. coli) strains. 相似文献
82.
Nobutaka Shibata Daisuke Nagao Haruyuki Ishii Mikio Konno 《Colloid and polymer science》2013,291(1):137-142
Janus composite particles with a combination of organic and inorganic substances were synthesized by soap-free emulsion polymerization in which an amphoteric initiator of 2,2′-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was employed to introduce a polystyrene (PSt) lobe onto silica cores surface-modified with 3-methacryloxypropyltrimethoxy silane (MPTMS). Thermogravimetric analysis and X-ray photoelectron spectroscopy were used to characterize the surface-modified silica particles and showed that a small amount of MPTMS introduced onto the surface of silica particles could successfully prepare SiO2–PSt Janus particles. The oxide part of SiO2–PSt Janus particles obtained with the polymerization was further surface-modified with 3-aminopropyltriethoxysilane (APS) to introduce positively charged amino groups on the silica surface. The silica surface modified with APS was covered with gold by electroless deposition in which a gold precursor of auric chloride was reduced with ascorbic acid in the presence of polyvinylpyrrolidone. The electroless deposition of gold successfully produced Janus particles with a combination of gold and PSt surfaces. Furthermore, dissolution of the polymer component of the Au–PSt Janus particles in tetrahydrofuran led to another Janus type of particles with an inorganic combination of Au and SiO2. 相似文献
83.
84.
Manabu Yamada Muniyappan Rajiv Gandhi Yoshihiko Kondo Fumio Hamada 《Supramolecular chemistry》2014,26(7-8):620-630
The ability of chloroform solutions of p-diethylaminomethylthiacalix[4]arene 1 to extract platinum from HCl media was tested. As an ion-pair extractant, compound 1 had the highest platinum extraction ability among all the thiacalix[n]arene derivatives tested in this study. Compound 1 was a highly specific extractant for Pt(IV) ions from single-metal solutions and platinum-group metal solutions from automotive catalyst residue. Various conditions such as contact time, pH, concentration of 1, effect of chloride ions, effect of acidity and Pt(IV) concentration were studied. The distribution ratio of platinum ions (D) was calculated. The platinum complex stoichiometry ratio was obtained using slope analysis. The 1–Pt(IV) complex was characterised using X-ray photoelectron spectroscopy, FT-IR and 1H NMR. Finally, the Pt(IV) extraction percentage of compound 1 was compared with that of previously reported thiacalix[n]arene-based extractants. 相似文献
85.
Satoshi Nagao Ayaka Suda Hisashi Kobayashi Naoki Shibata Yoshiki Higuchi Shun Hirota 《化学:亚洲杂志》2020,15(11):1743-1749
Domain swapping is an exception to Anfinsen's dogma, and more than one structure can be produced from the same amino acid sequence by domain swapping. We have previously shown that myoglobin (Mb) can form a domain‐swapped dimer in which the hinge region is converted to a helical structure. In this study, we showed that domain‐swapped dimerization of Mb was achieved by a single Ala mutation of Gly at position 80. Multiple Ala mutations at positions 81 and 82 in addition to position 80 facilitated dimerization of Mb by stabilization of the dimeric states. Domain swapping tendencies correlated well with the helical propensity of the mutated residue in a series of Mb mutants with amino acids introduced to the hinge region. These findings demonstrate that a single mutation in the hinge loop to modify helical propensity can control oligomer formation, providing new ideas to create high‐order protein oligomers using domain swapping. 相似文献
86.
Benzenetellurinyl trifluoromethanesulfonate in conjunction with acetonitrile readily effected amidotellurinylation reactions with alkynes. Most of the addition reactions proceeded in a trans fashion to form the (E)-β-acetamidovinyl phenyl telluroxides. Subsequently, it was found that the prevailing Markovnikov adducts from terminal alkynes immediately isomerized to (Z)-isomers which were isolated as the corresponding vinyltellurides. On the other hand, the adducts derived from internal alkynes thermally underwent a spontaneous intramolecular cyclization to be transformed eventually into oxazoles. 相似文献
87.
Takahiro Gunji Yukinori Nagao Takahisa Misono Yoshimoto Abe 《Journal of polymer science. Part A, Polymer chemistry》1992,30(3):371-377
From polytitanosiloxanes (PTS), SiO2–TiO2 oxide fibers with fairly good tensile strength were prepared, and their mechanical and thermal properties were investigated. The precursor fibers PTS-0.5 and PTS-1.0 were obtained by dry spinning of a highly viscous PTS solution which were formed as the reaction mixture of silicic acid (SA) with bis(2,4-pentanedionato)titanium diisopropoxide (PTP) in the molar ratios (SA/PTP) of 0.5 and 1.0. The precursor fibers PTS-0.5 were too brittle to measure their tensile strength, whereas PTS-1.0 and the heat-treated fibers were found to have tensile strength of 130 (precursor), 540 (500°C), and 450 (900°C) MPa, respectively. Heat-treatment of the fibers PTS-1.0 at above 1000°C forms anatase and rutile of titanium dioxide. The crystallization is resulted from the unreacted PTP which is not incorporated into the polymer network. 相似文献
88.
Tadashi Okazaki Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1996,34(10):2029-2035
Synthesis and radical ring-opening polymerization of vinylcyclopropane bearing six-membered cyclic acetal moiety, 1-vinyl-4,8-dioxaspiro[2.5]octane (1), were carried out. 1 was prepared by the reaction of 1,1-dichloro-2-vinylcyclopropane and 1,3-propanediol in DMF in the presence of a base. Radical polymerization of 1 was carried out in the presence of an appropriate initiator (3 mol % vs. 1) at 60 and 120°C in degassed sealed ampoules for 20 h. A colorless transparent viscous polymer was obtained by the isolation with preparative HPLC. The structure of poly(1) was determined to consist of two 1,5-ring-opened units and a unit bearing no olefinic moiety. The difference of the activation energies for the ring-opening reaction of the cyclopropane ring calculated by the molecular orbital method could explain the selectivity in the direction of the cleavage of the cyclopropane ring. Acid hydrolysis of poly(1) afforded the corresponding polyketone in quantitative conversion. © 1996 John Wiley & Sons, Inc. 相似文献
89.
Fumio Sanda Toru Abe Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1996,34(10):1969-1975
Syntheses and radical polymerizations of vinyl and isopropenyl carbamates having L -leucine methyl ester structures, N-vinyloxycarbonyl-L -leucine methyl ester (VOC-L-M) and N-isopropenyloxycarbonyl-L -leucine methyl ester (IOC-L-M), were carried out. VOC-L-M and IOC-L-M were prepared by the reactions of L -leucine methyl ester with vinyl and isopropenyl chloroformates in the presence of sodium hydrogen carbonate. The radical polymerization of VOC-L-M with AIBN (1 mol %) in bulk, chlorobenzene, methanol, and N,N-dimethylformamide afforded the corresponding polymer (poly(VOC-L-M)) with M n 7,400–19,000. Meanwhile, IOC-L-M afforded no polymer with AIBN at 60°C but afforded a polymer having low molecular weight with BPO at 80°C. The glass transition temperatures of poly(VOC-L-M) and poly(IOC-L-M) were 53 and 65°C, respectively. The 10% weight loss temperatures of poly(VOC-L-M) and poly(IOC-L-M) under nitrogen were 255 and 173, respectively. The copolymerization parameters of VOC-L-M (M1) and vinyl acetate (M2) were evaluated as r1 = 0.92 and r2 = 0.63. © 1996 John Wiley & Sons, Inc. 相似文献
90.
Yuzuru Uchida Katsumi Onoue Nobuaki Tada Fumio Nagao Hideaki Kozawa Shigeru Oae 《Heteroatom Chemistry》1990,1(4):295-306
Phosphine oxides bearing two or three 2-pyridyl groups react with organometallic reagents affording 2,2′-bipyridyl, 2-substituted pyridines and pyridine in good yields. Phosphonium salts and phosphine oxides, bearing at least two 2-pyridyl or substituted 2-pyridyl groups also give the corresponding 2,2′-bipyridyls and pyridines upon treatment with acid or neutral solvents such as water and alcohols in substantial yields. The 2,2′-bipyridyls are considered to be formed by ligand coupling within the pentacoordinated phosphorus intermediate formed incipiently during the reaction. 相似文献