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21.
Atsunori Morigaki Kazuki Tsukade Satoru Arimitsu Tsutomu Konno Toshio Kubota 《Tetrahedron》2013,69(5):1521-1525
The reaction of β-fluoroalkylated α,β-unsaturated ketones with various enamines gave 4-fluoroalkylated 3,4-dihydro-2H-pyrans as a major product in good yields by a one-pot operation, and these products display the high diastereoselection just after single recrystallization. This unexpected result is rationalized by the unique reactivity of β-fluoroalkylated α,β-unsaturated ketones. As the synthetic application, 4-trifluoromethyl tetrahydropyran was synthesized in moderate isolated yield with high diastereoselectivity. 相似文献
22.
Atsushi Kubono Kazuki Yoshino Toshiro Ninomiya Ryuichi Akiyama Katsufumi Tanaka 《Liquid crystals》2013,40(8):1089-1095
The visco-elastic properties for binary mixtures of 4-n -hexyloxy-4′-cyanobiphenyl (6OCB) and 4-n-octyloxy-4′-cyanobiphenyl (8OCB) are investigated in detail by a light scattering technique. The mixtures exhibit a reentrant nematic (RN) phase between the smectic A (SmA) and crystal phases in the range 22.0–29.5 wt % of 6OCB. The viscosity and the elastic constant increase with cooling in both the nematic and reentrant nematic phases. It is also found that the mixtures exhibit anomalously large values of viscosity and elastic constant near the phase transition, i.e. a pretransitional phenomenon can be observed. The activation energy for viscosity is smaller in the RN phase than in the ordinary nematic phase appearing at higher temperatures, while the normalized elastic constant (defined as the ratio of the elastic constant to the square of the dielectric anisotropy) is larger. Moreover, the visco-elastic behaviour depends on the specific time during which the sample has been kept in the SmA phase. These results confirm that the SmA phase has a strong influence on the formation of molecular aggregates, which plays an important role in the reentrant phenomenon of these systems. 相似文献
23.
Xingzhong Guo Wenyan Li Hui Yang Kazuyoshi Kanamori Yang Zhu Kazuki Nakanishi 《Journal of Sol-Gel Science and Technology》2013,67(2):406-413
An in situ two-step processing using an initial acid catalysis step accompanied by an epoxide-mediated condensation step in the presence of ammonium chloride (NH4Cl) is reported, and macroporous cocontinuous methylsilsesquioxane (MSQ) monoliths have been successfully prepared by this processing. We explain the hydrolysis, gelation behavior and phase separation of MTMS(methyltrimethoxysilane)-MeOH(methanol)-HCl-PO(propylene oxide) system and the in situ effect of NH4Cl, and examine the macroporous morphology and pore structures of MSQ monoliths obtained under different conditions. Macroporous MSQ monolith under optimized conditions possesses a narrow macropore size distribution between 3 to 10 μm, surface area as high as 366 m2·g?1 and minimal shrinkage of only 1 %. 相似文献
24.
Application of plug–plug technique to ACE experiments for discovery of peptides binding to a larger target protein: A model study of calmodulin‐binding fragments selected from a digested mixture of reduced BSA 下载免费PDF全文
Kazuki Saito Mamiko Nakato Takaaki Mizuguchi Shinji Wada Hiromasa Uchimura Hiroshi Kataoka Shigeyuki Yokoyama Hiroshi Hirota Yoshiaki Kiso 《Electrophoresis》2014,35(6):846-854
To discover peptide ligands that bind to a target protein with a higher molecular mass, a concise screening methodology has been established, by applying a “plug–plug” technique to ACE experiments. Exploratory experiments using three mixed peptides, mastoparan‐X, β‐endorphin, and oxytocin, as candidates for calmodulin‐binding ligands, revealed that the technique not only reduces the consumption of the protein sample, but also increases the flexibility of the experimental conditions, by allowing the use of MS detection in the ACE experiments. With the plug–plug technique, the ACE–MS screening methodology successfully selected calmodulin‐binding peptides from a random library with diverse constituents, such as protease digests of BSA. Three peptides with Kd values between 8–147 μM for calmodulin were obtained from a Glu‐C endoprotease digest of reduced BSA, although the digest showed more than 70 peaks in its ACE–MS electropherogram. The method established here will be quite useful for the screening of peptide ligands, which have only low affinities due to their flexible chain structures but could potentially provide primary information for designing inhibitors against the target protein. 相似文献
25.
Hitoshi Tamiaki Shun Koizumi Kazuki Tsuji Yusuke Kinoshita Tomohiro Miyatake 《Tetrahedron letters》2014
Chlorophyll-a derivatives possessing an un/mono/disubstituted methylene moiety at the 131-position were prepared by (un)substituted methylation of the 13-carbonyl group and successive dehydration. Substitution of the 131-oxo to the methylene group slightly blue-shifted electronic absorption and emission bands in a solution and decreased chemical stability to give an oxidation product cleaved at the E-ring. Further mono/disubstitution at the methylene terminal increased wavelengths of absorption and emission maxima as well as oxidative tolerance. 相似文献
26.
Koji Yamamoto Kazuki Higuchi Masahiro Ogawa Hiromitsu Sogawa Shigeki Kuwata Yoshihiro Hayashi Susumu Kawauchi Toshikazu Takata 《化学:亚洲杂志》2020,15(3):356-359
We synthesised palladium and platinum complexes possessing cyclic and acyclic pincer‐type polyaromatic ligands and investigated their structural effect on the catalysis. The pincer‐type bis(6‐arylpyridin‐2‐yl)benzene skeleton was constructed via Kröhnke pyridine synthesis under transition metal‐free conditions on gram‐scale quantity. Ligand structure significantly influenced catalytic activity toward the platinum‐catalysed hydrosilylation of diphenyl acetylenes, despite the ligand‐independence of the conformations and electronic properties of these complexes. 相似文献
27.
Kazuyoshi Kanamori Norio Ishizuka Kazuki Nakanishi Kazuyuki Hirao Hiroshi Jinnai 《Journal of Sol-Gel Science and Technology》2003,26(1-3):157-160
The organo-siloxane gel with co-continuous structure derived from methyltrimethoxysilane (MTMS) was synthesized in a confined space between parallel plates by inducing spinodal decomposition during sol-gel transition. The resultant gel morphology was 3-dimensionally observed by laser scanning confocal microscopy (LSCM). The sliced LSCM photographs revealed that the confined gels have inhomogeneity perpendicular to the plate, exhibiting a layered structure. The layered structure can be divided into three regions according to their morphology; interface, near-surface layer, bulk phase. The organo-siloxane depletion layer had formed in the vicinity of both hydrophobic and hydrophilic plates, and the bulk phase had formed slight away from the plates exhibited co-continuous structure. In addition, the confined gels exhibited no shrinkage during drying process that resulted in the larger domain size compared to the monolithic gel. The attractive interaction between the plates and the resultant organo-siloxane phase accounts for the inhibition of shrinkage of confined gels. 相似文献
28.
Preparation and physical properties of flame retardant acrylic resin containing nano-sized aluminum hydroxide 总被引:1,自引:0,他引:1
Kazuki Daimatsu Yasunori Kato Katsuhiro Inomata Kazuki Takemura 《Polymer Degradation and Stability》2007,92(8):1433-1438
Poly(methylmethacrylate) (PMMA) shows high strength and transparency but is a flammable material. In this study, the surface of aluminum hydroxide was modified with methacrylate containing phosphoric acid moieties before dispersion in MMA, and organic-inorganic nano-hybrid materials were obtained by bulk polymerization in the presence of the surface-modified aluminum hydroxide. The resulting hybrid materials retained the high transparency of PMMA, with transparency values similar to that of pure PMMA. Moreover, the flame resistance of the hybrid materials was improved in comparison with that of pure PMMA, with depression of the horizontal burning rate becoming a maximum at an inorganic content of 3 wt%. These results suggest that the use of aluminum hydroxide surface-modified with phosphoric acid groups is an efficient method for obtaining good performance fire-resistant polymer materials. 相似文献
29.
Hidenori Kinoshita Kazuki Yaguchi Takayuki Tohjima Katsukiyo Miura 《Tetrahedron letters》2017,58(16):1607-1610
The diisobutylaluminum hydride (DIBAL-H)-promoted benzocyclization, recently developed by this group, was adopted for the synthesis of a natural product containing a 9,10-dihydrophenanthrene skeleton to demonstrate its synthetic utility. One of the extracts from the roots of Salvia hydrangea DC. ex Bentham (Lamiaceae), a 20-norabietane derivative, was selected as the target molecule. The key step forming the 9,10-dihydrophenanthrene skeleton was achieved by the DIBAL-H-promoted cyclization of a silylated 1,3-dien-5-yne easily accessible from a substituted α-tetralone. 相似文献
30.