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11.
12.
Shuhei Akahori Prof. Dr. Takahiro Sasamori Prof. Dr. Hiroshi Shinokubo Prof. Dr. Yoshihiro Miyake 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(18):5675-5682
Self-assembly of π-conjugated molecules in solution generally occurs owing to either an enthalpic or an entropic gain; however, designing π-conjugated systems that simultaneously exhibit enthalpically and entropically favorable self-assembly behavior is challenging. Herein, the self-assembly behavior of tetraazatetrathia[8]circulenes is disclosed, which is driven by both enthalpy and entropy. Single-crystal X-ray diffraction analysis demonstrated that molecules of these tetraazatetrathia[8]circulenes form face-to-face stacked dimers with a 1D columnar structure owing to the circularly arranged dipole moments. Importantly, concentration- and temperature-dependent 1H NMR spectra revealed that the formation of self-assemblies of tetraazatetrathia[8]circulenes in chloroform and methanol is favored by both enthalpic and entropic factors. The unique association behavior is due to the presence of sp2-hybridized nitrogen atoms, which weakly coordinate to the hydrogen atoms of these solvents and reduce the π-electron density of the circulene cores. 相似文献
13.
Prof. Kengo Hanaya Kaho Yamoto Prof. Kazuaki Taguchi Prof. Kazuaki Matsumoto Prof. Shuhei Higashibayashi Prof. Takeshi Sugai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(47):e202201677
The chemical modification of proteins is an effective technique for manipulating the properties and functions of proteins, and for creating protein-based materials. The N-terminus is a promising target for single-site modification that provides modified proteins with uniform structures and properties. In this paper, a copper(II)-mediated aldol reaction with 2-pyridinecarboxaldehyde (2-PC) derivatives is proposed as an operationally simple method to selectively modify the N-terminus of peptides and proteins at room temperature and physiological pH. The copper(II) ion activates the N-terminal amino acids by complexation with an imine of the N-terminal amino acid and 2-PCs, realizing the selective formation of the nucleophilic intermediate at the N-terminus. This results in a stable carbon-carbon bond between the 2-PCs and the α-carbon of various N-terminal amino acids. The reaction is applied to four different proteins, including biopharmaceuticals such as filgrastim and trastuzumab. The modified trastuzumab retains the human epidermal growth factor receptor 2 recognition activity. 相似文献
14.
Kazuhisa Sato Shunya Tashiro Shuhei Matsunaga Yohei Yamaguchi Takanori Kiguchi Toyohiko J. Konno 《哲学杂志》2018,98(21):1945-1960
We have studied three-dimensional (3D) structures and growth processes of 14H-type long-period stacking order (LPSO) formed in Mg97Zn1Gd2 cast alloys by single tilt-axis electron tomography (ET) using high-angle annular dark-field scanning transmission electron microscopy. Evolution of the solute-enriched stacking faults (SFs) and the 14H LPSO by ageing were visualised in 3D with a high spatial resolution in multi-scale fields of views from a few nanometres to ~10 μm. Lateral growth of the solute-enriched SFs and the LPSO in the (0?0?0?1)Mg plane is notable compared to the out-of-plane growth in the [0?0?0?1]Mg direction. The 14H LPSO grows at the cost of decomposition of the (Mg, Zn)3Gd-type precipitates, and accompany a change of in-plane edge angles from 30 to 60°. We have updated the Time–Temperature–Transformation diagram for precipitation in Mg97Zn1Gd2 alloys: starting temperatures of both solute-enriched SFs and LPSO formation shifted to a shorter time side than those in the previous diagram. 相似文献
15.
A measurement technique for depth profiling in a time-domain low-coherence interferometer has been proposed. The spatial variation
of the optical path caused by a diffraction grating in the Littrow configuration produces a white-light interferogram. A one-dimensional
charge-coupled device (1D-CCD) detector is used to measure the undersampled white-light interferogram. The position of the
reflective boundary is calculated from the rate of phase change with spatial frequency, which is based on the sub-Nyquist
sampling of the white-light interferogram in the frequency domain. 相似文献
16.
Yoshiaki Miyamoto Norihiro Wada Dr. Takahiro Soeta Dr. Shuhei Fujinami Prof. Dr. Katsuhiko Inomata Prof. Dr. Yutaka Ukaji 《化学:亚洲杂志》2013,8(4):824-831
The stereoselective direct transformation of N‐(propargylic)hydroxylamines into cis‐2‐acylaziridines was achieved by the combined use of AgBF4 and CuCl. Copper salts were found to promote the transformation of the intermediary 4‐isoxazolines into 2‐acylaziridines and both 3‐aryl‐ and 3‐alkyl‐substituted 2‐acylaziridines could be prepared by using this method. Furthermore, subsequent 1,3‐dipolar cycloaddition of azomethine ylides that were generated in situ from the intermediary 2‐acylaziridines with maleimides was achieved in a stereoselective one‐pot procedure to afford the corresponding 2‐acylpyrrolidines, which consisted of an octahydropyrrolo[3,4‐c]pyrrole skeleton. 相似文献
17.
Toshiaki Yamashita Shuhei Matsushita Takuya Nagatomo Ryosuke Yamauchi Masahide Yasuda 《Research on Chemical Intermediates》2013,39(1):111-126
Photoirradiation of Me2CO–H2O solution of pent-4-en-1-ol (1a) with a high-pressure mercury lamp in a test tube gave 8-hydroxyoctan-2-one (3a) in 66 % yield along with oxetane (4a) and the isomer (4a′) in 10 % yield. Irradiation of the running Me2CO–H2O solution of 1a in the flow system of a microchannel reactor (MCR) gave mainly 4a. The photoreaction of 1,1-diphenylethene (2a) with triethylamine gave a Markovnikov-type adduct (5a) and an anti-Markovnikov-type adduct (6a). The use of the MCR enhanced the production of 5a. These phenomena were explained by the light-path length effects of the MCR. 相似文献
18.
Dr. Bernd M. Schmidt Berit Topolinski Dr. Mihoko Yamada Dr. Shuhei Higashibayashi Prof. Dr. Mitsuhiko Shionoya Prof. Dr. Hidehiro Sakurai Prof. Dr. Dieter Lentz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13872-13880
The syntheses and properties of corannulenes carrying electron‐withdrawing groups (F, CF3, C6F5) are reported. Direct fluorination of corannulene (C20H10) was carried out with xenon difluoride, and the crystal structure of the product was confirmed by the X‐ray analysis. Novel trifluoromethylated corannulenes, including the versatile 4,9‐dibromo‐1,2‐bis(trifluoromethyl)corannulene, were obtained by various established ring‐closing reactions. Besides the use of hexafluorobutyne for the construction of fluoranthenes by Diels–Alder reaction as precursor molecules to form 1,2‐disubstituted corannulenes, bis(pentafluorophenyl)acetylene was employed as dienophile. The molecular structure and crystal packing of a trifluoromethylated corannulene was determined by single‐crystal X‐ray analysis and compared with those known brominated and trifluoromethylated corannulenes. The general electron‐acceptor properties of corannulenes bearing substituents introduced in particular positions by liquid‐phase synthesis are discussed together with published computational results. 相似文献
19.
Ryan Gianatassio Shuhei Kawamura Cecil L Eprile Klement Foo Jason Ge Aaron C. Burns Michael R. Collins Phil S. Baran 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(37):10009-10013
A simple method to convert readily available carboxylic acids into sulfinate salts by employing an interrupted Barton decarboxylation reaction is reported. A medicinally oriented panel of ten new sulfinate reagents was created using this method, including a key trifluoromethylcyclopropanation reagent, TFCS‐Na. The reactivity of six of these salts towards C H functionalization was field‐tested using several different classes of heterocycles. 相似文献
20.
In this study, we achieved the first total synthesis of natural prunustatin A (1), a novel inhibitor of glucose-regulated protein 78 (GRP78) expression. A key feature included a 15-membered ring macrocyclization, which was successfully accomplished by employing Shiina macrolactonization using 2-methyl-6-nitrobenzoic anhydride (MNBA) and 4-dimethylaminopyridine (DMAP). 相似文献