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1.
Breviones A∼E (1∼5), allelopathic agents isolated from Penicillium brevicompactum Dierckx, are structurally unique pentacyclic or hexacyclic diterpenoid derivatives. The first synthesis of brevione B (2) was achieved by employing the double SN2′-type tandem reaction as a key step. 相似文献
2.
Hirosato Monobe Shoji Mima Takushi Sugino Yo Shimizu Masakatsu Ukon 《Liquid crystals》2013,40(8):1253-1258
The orientational behaviour of the nematic discotic phase of 2,3,6,7,10,11-hexa(4-n-octyloxybenzoyloxy)triphenylene (C8OBT) on substrates coated with a polyimide or cetyltrimethylammonium bromide (CTAB) was investigated by polarizing optical microscopy. The averaged order parameters and directions of the triphenylene core and the carbonyl groups of C8OBT were evaluated by an infrared dichroic method. The discotic nematic (ND) phase of C8OBT exhibits a homeotropic alignment on a polyimide film, a typical nematic schlieren texture on a glass substrate, and a tilted or planar homogeneous alignment on a CTAB-coated substrate. The order parameter of the triphenylene core is higher on a polyimide film (S = 0.6) than on a CTAB-coated substrate (S = 0.2), whereas that of the carbonyl groups remains roughly constant at 0.2 to 0.3 independent of the substrate for the ND phase. 相似文献
3.
Single crystals of amylose V complexes with the 81 helical configuration can be obtained from aqueous solutions of amylose by using α-naphthol as a complexing agent. Morphological observations suggest that the differences in crystallization behavior among the α-naphthol complex and other complexes with alcohols are due to differences in solubility of the complexes in water. Electron diffraction studies indicate a two-dimensional tetragonal unit cell with a = b = 22.9 Å. It is deduced that the space group providing a satisfactory arrangement of two helices is one of the enantiomorphs P41212 and P43212. From x-ray diffraction it was found that the c axis spacing of the α-naphthol complex is equivalent to that in 61 and 71 helical amylose crystals. Consequently, the geometry of the helical configuration requires an integral number of glucose residues per turn. The true helical diameters of the n-butanol, isopropanol, and α-naphthol complexes were calculated from experimental data. The ratio was 6:7:8 and indicated that the helix of the α-naphthol complex has eight glucose residues per turn. The diversity of helical configurations in V amylose crystals is discussed. 相似文献
4.
Highly Segregated Lamello‐Columnar Mesophase Organizations and Fast Charge Carrier Mobility in New Discotic Donor–Acceptor Triads
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Prof. Dr. Ke‐Qing Zhao Ling‐Ling An Xiao‐Bo Zhang Wen‐Hao Yu Prof. Ping Hu Prof. Bi‐Qin Wang Jing Xu Dr. Qing‐Dao Zeng Dr. Hirosato Monobe Dr. Yo Shimizu Dr. Benoît Heinrich Dr. Bertrand Donnio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10379-10390
Four new donor–acceptor triads (D–A–D) based on discotic and arylene mesogens have been synthesized by using Sonogashira coupling and cyclization reactions. This family of triads consists of two side‐on pending triphenylene mesogens, acting as the electron‐donating groups (D), laterally connected through short lipophilic spacers to a central perylenediimide (PI), benzo[ghi]perylenediimide (BI), or coronenediimide (CI) molecular unit, respectively, playing the role of the electron acceptor (A). All D–A–D triads self‐organize to form a lamello‐columnar oblique mesophase, with a highly segregated donor–acceptor (D–A) heterojunction organization, consequent to efficient molecular self‐sorting. The structure consists in the regular alternation of two disrupted rows of triphenylene columns and a continuous row of diimine species. High‐resolution STM images demonstrate that PI‐TP2 forms stable 2D self‐assembly nanostructures with some various degrees of regularity, whereas the other triads do not self‐organize into ordered architectures. The electron‐transport mobility of CI‐TP2, measured by time‐of‐flight at 200 °C in the mesophase, is one order of magnitude higher than the hole mobility. By means of this specific molecular designing idea, we realized and demonstrated for the first time the so‐called p–n heterojunction at the molecular level in which the electron‐rich triphenylene columns act as the hole transient pathways, and the coronenediimide stacks form the electron‐transport channels. 相似文献
5.
Saiko KitaharaTakuya Tashiro Yukihiro SugimotoMitsuru Sasaki Hirosato Takikawa 《Tetrahedron letters》2011,52(6):724-726
Sorgomol, isolated from Sorghum bicolor, is the germination stimulant for seeds of root parasitic weeds. The first synthesis of (±)-sorgomol has been achieved by starting from ethyl 2-oxocyclohexanecarboxylate. 相似文献
6.
Niikura K Kamitani R Kurogochi M Uematsu R Shinohara Y Nakagawa H Deguchi K Monde K Kondo H Nishimura S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(13):3825-3834
We have developed an effective and practical trap-and-release method based on chemoselective ligation of carbohydrates with reactive aminooxyl groups attached to the surface of nanoparticles (referred to as glycoblotting nanoparticles). These glycoblotting nanoparticles were synthesized by UV irradiation of diacetylene-functionalized lipids that contain the aminooxyl group. The glycoblotting nanoparticles captured carbohydrates in aqueous solution under mild conditions and were collected by simple centrifugation. The trapped carbohydrates were effectively released from the nanoparticles under acidic conditions to give pure oligosaccharides. This glycoblotting process reduced the time required for the purification process of carbohydrates to less than 6 h, compared to the several days needed for conventional chromatographic techniques. The oligosaccharides (N-glycan) were released from ovalbumin (glycoprotein) by PNGase F after tryptic digestion. MALDI-TOF mass spectra before purification did not show any significant signals corresponding to N-glycans because these signals were hidden by the large signals of the abundant peptides. However, after purification with the glycoblotting nanoparticles, only signals corresponding to oligosaccharides appeared. We also demonstrated a clear analysis of the oligosaccharides contained in the mice dermis by means of glycoblotting. 相似文献
7.
Hironori Okamura Takanobu Fujioka Naoki Mori Tohru Taniguchi Kenji Monde Hidenori Watanabe Hirosato Takikawa 《Tetrahedron letters》2019,60(32):150917
Salinipostins are cyclic enol-phosphotriesters isolated from a marine-derived Salinispora sp. as antimalarial compounds. Herein, the first enantioselective synthesis of salinipostin A was achieved. Organocatalyst-mediated asymmetric cyclopropanation and regioselective cyclopropane ring opening were the key steps. 相似文献
8.
Ryuji Hirase Koji Honda Mari Ishihara Hideki Yoshioka Hirosato Monobe 《Tetrahedron letters》2018,59(5):469-472
We have investigated synthesis as well as purification of 5,5?-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2?-quaterthiophene (BFH-4?T, n-type organic semiconducting material) using supercritical carbon dioxide (scCO2) as a green solvent. BFH-4T was obtained in good selectivity and high yield by TDAE/PdCl2-catalyzed reductive coupling reaction of 5-bromo-5′-(tridecafluorohexyl)-2,2′-bithiophene in scCO2. We have also successfully established purification of the reaction mixture by passing scCO2 in the reaction vessel. The product was yellow powder of BFH-4T with purity of more than 99% and Pd catalyst was not contained. 相似文献
9.
Fumoto M Hinou H Ohta T Ito T Yamada K Takimoto A Kondo H Shimizu H Inazu T Nakahara Y Nishimura S 《Journal of the American Chemical Society》2005,127(33):11804-11818
The chemoselective polymer blotting method allows for rapid and efficient synthesis of glycopeptides based on a "catch and release" strategy between solid-phase and water-soluble polymer supports. We have developed a heterobifunctional linker sensitive to glutamic acid specific protease (BLase). The general procedure consists of five steps, namely (i) the solid-phase synthesis of glycopeptide containing BLase sensitive linker, (ii) subsequent deprotections and the release of the glycopeptide from the resin, (iii) chemoselective blotting of the glycopeptide intermediates in the presence of water-soluble polymers with oxylamino functional groups, (iv) sugar elongations using glycosyltransferases, and (v) the release of target glycopeptides from the polymer platform by selective BLase promoted hydrolysis. The combined use of the solid-phase chemical syntheses of peptides and the enzymatic syntheses of carbohydrates on water-soluble polymers would greatly contribute to the production of complicated glycopeptide libraries, thereby enhancing applicative research. We report here a high-throughput synthetic system for the various types of MUC1 glycopeptides exhibiting a variety of sugar moieties. It is our belief that this concept will become part of the entrenched repertoire for the synthesis of biologically important glycopeptides on the basis of glycosyltransferase reactions in automated and combinatorial syntheses. 相似文献
10.
Litseaone A, isolated from the stem barks of Litsea rubescens and Litsea pedunculata, is a chalcone derivative with a novel spiro-epoxide moiety. The structural revision of litseaone A was achieved by the racemic synthesis of the proposed structure and the asymmetric synthesis of the revised structure. The major tautomeric structure of litseaone A and the relative stereochemistry at the epoxide carbon center were also clarified. 相似文献