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161.
Tomoyasu Hirose 《Tetrahedron》2005,61(25):6015-6039
In this report, we describe an efficient, highly convergent, stereocontrolled first total synthesis and a second-generation synthesis of madindolines A 1 and B 2, potent selective inhibitors of interleukin 6. The key steps include (1) asymmetric oxidative ring-closure reaction of tryptophol 3 to construct a chiral 3a-hydroxyfuroindoline 4 using the modified Sharpless asymmetric epoxidation condition, (2) highly diastereoselective acylation to build up the quaternary carbon center, and (3) intramolecular acylation of ester 32 with allylsilanes to produce the full substituted cyclopentenedione units. Our first synthetic route defines for the first time both their relative and absolute configurations. Moreover, a more efficient second-generation synthesis was designed, which is suitable for gram-scale preparation of these compounds. 相似文献
162.
Ten lanostane glycosides (1-10), including two new norlanostane glycosides (2 and 7) and a new lanostane glycoside with a spirolactone ring system (9), were isolated from the fresh bulbs of Chionodoxa luciliae (Liliaceae). The structures of the new compounds were determined on the basis of extensive spectroscopic analysis and the results of hydrolytic cleavage to be (23S)-3beta-[(O-beta-D-apiofuranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranosyl)oxy]-17alpha,23-epoxy-28,29-dihydroxy-27-norlanost-8-en-24-one (2), (23S)-17alpha,23-epoxy-29-hydroxy-3beta-[(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranosyl)oxy]-27-norlanost-8-ene-15,24-dione (7), and (23S,25R)-17alpha,23-epoxy-29-hydroxy-3beta-[(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranosyl)oxy]lanost-8-en-23,26-olide (9), respectively. The cytotoxic activity of the isolated compounds against HSC-2 human oral squamous cell carcinoma cells are also reported. 相似文献
163.
K. Mima K. A. Tanaka R. Kodama T. Johzaki H. Nagatomo H. Shiraga N. Miyanaga M. Murakami H. Azechi M. Nakai T. Norimatu K. Nagai T. Taguchi H. Sakagami 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):259-264
Reviewed are the present status of the fast ignition researches. Since
1997, the fast ignition experiment and theory researches have been
extensively continued at the Institute of Laser Engineering of Osaka
University. In particular, the cone-shell target experiments and simulation
research have been progressing. In order to demonstrate heating of imploded
high density plasma to the ignition temperature, in the April of 2003, the
construction of heating laser of 10 kJ/10 ps/1.06 μm (Laser for Fusion
Experiment; LFEX), for FIREX-I (Fast Ignition Realization Experiment) has
started. The fabrication of DT foam cryogenic cone target is also under
development as a collaboration program between Osaka University and NIFS (National Institute for Fusion Science). The LFEX
will be completed in 2008.
After the completion of LFEX, the foam cryogenic cone shell target
experiment will start in 2008. As a new approach toward a compact ignition,
an impact fusion has been proposed, where the ablative acceleration to the
order of 108 cm/s is the key issue. The ablation acceleration related
to the impact fusion has been explored by experiments. 相似文献
164.
Design, synthesis, and evaluation of carbamate-substituted analogues of (+)-discodermolide 总被引:1,自引:0,他引:1
Smith AB Freeze BS Lamarche MJ Hirose T Brouard I Rucker PV Xian M Sundermann KF Shaw SJ Burlingame MA Horwitz SB Myles DC 《Organic letters》2005,7(2):311-314
[Structure: see text] The design, syntheses, and biological evaluation of 22 totally synthetic analogues of the potent microtubule-stabilizing agent (+)-discodermolide (1) have been achieved. Structure-activity relationships of the C(19) carbamate were defined, exploiting two synthetically simplified scaffolds, as well as the parent (+)-discodermolide framework. 相似文献
165.
Sphingolipids and glycerolipids. I. Chemical structures and ionophoretic activities of soya-cerebrosides I and II from soybean 总被引:4,自引:0,他引:4
H Shibuya K Kawashima M Sakagami H Kawanishi M Shimomura K Ohashi I Kitagawa 《Chemical & pharmaceutical bulletin》1990,38(11):2933-2938
Two glycosphingolipids named soya-cerebrosides I and II were isolated from soybean, the seeds of Glycine max Merrill (Leguminosae), and their chemical structures have been elucidated on the basis of physicochemical evidence and several chemical degradation reactions. By using a newly constructed liquid membrane-type apparatus (W-08) for measurement of ion-transport and ion-binding activities and by employing a method using human erythrocyte membranes for measurement of ion-permeability, it has been found that soya-cerebroside II exhibits ionophoretic activity for Ca2+ ion. 相似文献
166.
Monohydrocalcite (CaCO(3)·H(2)O: MHC) is similar in composition and synthetic conditions to hydrated amorphous calcium carbonate (ACC), which is focused recently as a key intermediate compound of biomineralization and biomimetic mineralization of calcium carbonate polymorphs. Detailed comparisons of the physicochemical property and reactivity of those hydrated calcium carbonates are required for obtaining fundamental information on the relevancy of those compounds in the mineralization processes. In the present study, kinetics of the thermal dehydration of spherical particles of crystalline MHC was investigated in view of physico-geometrical mechanism. The reaction process was traced systematically by means of thermogravimetry under three different modes of temperature program. A distinguished induction period for the thermal dehydration and cracking of the surface product layer on the way of the established reaction were identified as the characteristic events of the reaction. By interpreting the kinetic results in association with the morphological changes of the reactant particles during the course of reaction, it was revealed that nucleation and crystal growth of calcite regulate the overall kinetics of the thermal dehydration of MHC. In comparison with the thermal dehydration of hydrated ACC, which produces anhydrous ACC as the solid product, the kinetic characteristics of the thermal dehydration of MHC were discussed from the viewpoint of physico-geometry of the component processes. 相似文献
167.
Tomoyasu Hirose Takako KasaiTakafumi Akimoto Ayako EndoAkihiro Sugawara Kazuo NagasawaKazuro Shiomi Satoshi ōmura Toshiaki Sunazuka 《Tetrahedron》2011,67(35):6633-6643
A solution-phase total synthesis of argifin using 3,4,5-tris(octadecyloxy)benzyl tag as a hydrophobic protective group of carboxylic acid was developed to produce 44% overall yield for 16 linear steps. Argifin, a novel class of natural product chitinase inhibitor, is a highly water-soluble cyclic pentapeptide, so hitherto, only solid-phase synthesis techniques have been used to conveniently prepare the compound and its derivatives. 3,4,5-Tris(octadecyloxy)benzyl alcohol (HO-TAGa) and its esters are highly crystalline materials and highly capable of dissolving in less-polar solvents such as dichloromethane, benzene, THF, etc., but insoluble in polar solvents such as methanol and DMSO. The combination of HO-TAGa and Fmoc-based peptide synthesis, together with simple purification by recrystallization from MeOH solution, furnished an efficient and practical route of argifin production in the liquid-phase. 相似文献
168.
This paper presents low Curie temperature magnetic materials for induction heating. These materials are alloys based on SUS430. The magnetization decreases with increasing amount of additives. In order to increase the saturation magnetization, while keeping the Curie temperature constant, rare earth materials were added in this study. The compositions of alloys were investigated to realize a suitable Curie temperature. The temperature self-controlling function was also investigated in measurement of temperature distribution by using thermograph apparatus. Furthermore, thermoelectromagnetic field analysis was carried out as a numerical examination. 相似文献
169.