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21.
From the bark of Cryptomeria japonica were isolated sugikurojins I (1) and J (2), and an abietane derivative (3) was obtained for the first time as a natural product. These structures were elucidated primarily through extensive NMR experiments. Sugikurojin I (1) has a unique skeleton incorporating an abietane diterpene and a 1,10-secocadinane sesquiterpene. Sugikurojin J (2) is a peroxyester of hydroxyabietane diterpene and isopimarane acid diterpene. Compound 3 was p-quinone acid, which occurred by cleavage between C-7 and C-8 of sugiol; it was deduced to [4'-isopropyl-1(S),3,3-trimethyl-3',6'-dioxo-bicyclohexyl-1',4'-dien-2(R)-yl]-acetic acid. Also obtained in this investigation were three known diterpenes (4-6). 相似文献
22.
Yoshiyuki Kawase Seiji Yamaguchi Osamu Maeda Akemi Hayashi Ichihiro Hayashi Kazuko Tabata Masako Kondo 《Journal of heterocyclic chemistry》1979,16(3):487-491
Benzofuro[2,3-b]quinoline ( Ia ) and its 11-methyl derivative ( Ib ) were synthesized by demethylcyclization of 3-(o-methoxyphenyl)-1,2-dihydroquinolin-2-ones (VIa,b). Benzofuro[2,3-b]quinoline-11-carboxylic acid (Id) was synthesized by chlorination followed by the action of potassium hydroxide of a lactone (IX) prepared by demethyl-cyclization of 3-(o-methoxyphenyl)-2-oxo-1,2-dihydroquinoline-4-carboxylic acid (VIII). Isomeric benzofuro[3,2-c]quinoline (Ha) and its 6-methyl derivative (IIb) were synthesized by demethyl-cyclization of 3-(o-methoxyphenyl)-1,4-dihydroquinolin-4-ones (XIa,b). Both the methyl derivatives (Ib and IIb) were converted to the carboxylic acids (Id and IId) through condensation with benzaldehyde followed by oxidation. The benzofuroquinolines (Ia,b,d and IIa,b) thus obtained were oxidized to the corresponding N-oxides (IIIa,b,d and IVa,b). 相似文献
23.
Yamashita M Yadav ND Sawaki T Takao I Kawasaki I Sugimoto Y Miyatake A Murai K Takahara A Kurume A Ohta S 《The Journal of organic chemistry》2007,72(15):5697-5703
The first asymmetric total synthesis of (-)-Linderol A, a potent inhibitor of melanin biosynthesis of cultured B-16 melanoma cells, has been achieved via two key reactions: a diastereoselective [2+2] photocycloaddition of a coumarin-3-carboxylate bearing a chiral auxiliary with 3-methyl-1-butene and a subsequent stereoconvergent transformation of the photoadducts with use of dimethylsulfoxonium methylide to afford a tetrahydrodibenzofuran derivative. 相似文献
24.
Yutaka Amao Akemi Tadokoro Miki Nakamura Naho Shuto Ayumi Kuroki 《Research on Chemical Intermediates》2014,40(9):3257-3265
Photovoltaic conversion has been achieved by use of chloroplasts (photosynthetic organs) from spinach adsorbed on a nanocrystalline TiO2 film on an indium tin oxide (ITO) glass electrode (chloroplast/TiO2 electrode). The shape of the absorption spectrum of the chloroplast/TiO2 electrode is almost the same that of a dispersion of the chloroplasts. Absorption maxima of the chloroplast/TiO2 electrode observed at 430, 475, and 670 nm were attributed to carotenoid and chlorophyll molecules, suggesting that chloroplasts have been adsorbed by the nanocrystalline TiO2 film on the ITO electrode. The photocurrent responses of chloroplast/TiO2 electrodes were measured by using a solution of 0.1 M tetrabutylammonium hexafluorophosphate in acetonitrile as redox electrolyte in the presence or absence of water and 100 mW cm?2 irradiation. The photocurrent of the chloroplast/TiO2 electrode was increased by adding water to the redox electrolyte. The photocurrent responses of chloroplast/TiO2 electrodes irradiated with monochromatic light (680 nm, the absorption band of photosystem II complexed with evolved oxygen) were measured by use of a solution of 0.1 M tetrabutylammonium hexafluorophosphate in acetonitrile as redox electrolyte in the presence or absence of water. A chloroplast/TiO2 electrode photocurrent was observed only when the redox electrolyte containing water was used, indicating that the oxygen evolved from water by photosystem II in chloroplasts adsorbed by a nanocrystalline TiO2 film on an ITO electrode irradiated at 680 nm is reduced to water by the catalytic activity of the platinum electrode. The maximum incident photon-to-current conversion efficiency (IPCE) was 0.8 % on irradiation at 670 nm. 相似文献
25.
In order to provide a general synthetic method for carbocyclic nucleosides, regioselectivities in Mitsunobu reaction of purine, pyrimidin-2-one and their substituted derivatives with a variety of alcohols were examined and found to depend upon both substituents of the bases and kind of the alcohols. 相似文献
26.
Michael E. Jung Akemi Toyota Erik de Clercq Jan Balzarini 《Monatshefte für Chemie / Chemical Monthly》2002,133(4):499-520
Summary. A series of methylene-expanded oxetanocin nucleoside analogues, e.g. analogues of 2 and the known antiviral nucleosides AZT, FLT, and ddC (3) were prepared by a very direct route beginning with the readily available (S )-glycidol 4 and proceeding via the dihydrofuran-3-methanols 9a,b. Biological testing of these modified nucleosides indicates that they are non-cytotoxic compounds with generally weak antiviral
activity. However, the guanosine analogue 2G showed pronounced activity vs. herpes simplex virus type 1 (HSV-1) in cell culture and was HSV-1-encoded thymidine kinase dependent. This compound is therefore
an interesting new lead structure for the development of new anti-HSV agents.
Received September 3, 2001. Accepted September 17, 2001 相似文献
27.
Thermal decomposition behaviors of a fluororubber are observed with linear heating mode at constant rate, controlled rate mode and isothermal mode of TG/DTA, and, with isothermal mode of TG/mass-spectrometer. The results suggest that this material decomposes with, at least, three consecutive reactions. From the results of TG/DTA and TGMS in isothermal mode, it is considered that the first reaction is the first-order reaction, the second reaction is chain reaction and the last reaction is vaporization of residue. Supposing these three consecutive reactions, the decomposition behaviors of the rubber is simulated. The observed curves of fraction of mass loss, , against time, t, are well reproduced by the simulation. The relationship between d/dt and is reproduced also, though the differences between observed and the calculated values of d/dt are slightly larger than noise level of d/dt. 相似文献
28.
Kohji Yoshinaga Shouhei Satoh Emiko Mouri Akemi Nakai 《Colloid and polymer science》2006,284(6):694-698
Immobilization of colloidal crystals by gelation of polymer-grafted silica suspension in acetonitrile with alkyl amides derived from amino acids was investigated. Addition of N-benzyloxycarbonyl-l-isoleucylaminooctadecane (Z-Ile-C18) and 1,12-bis(N-benzyloxycarbonyl-l-valylamino)dodecane [Bis(Z-Val)-C12] to poly(maleic anhydride-co-styrene)-grafted silica suspension in acetonitrile resulted in formation of physical gels preserved colloidal crystal structure. From the reflection spectra, intersphere distance and size of crystallite in the gel formed with Bis(Z-Val)-C12 were confirmed to be mostly same as those of colloidal crystals in suspension. 相似文献
29.
Akemi Yamaguchi Kazuyuki Matsuda Masayuki Uehara Takayuki Honda Yasunori Saito 《Analytica chimica acta》2016
We report a novel automated device for nucleic acid extraction, which consists of a mechanical control system and a disposable cassette. The cassette is composed of a bottle, a capillary tube, and a chamber. After sample injection in the bottle, the sample is lysed, and nucleic acids are adsorbed on the surface of magnetic silica beads. These magnetic beads are transported and are vibrated through the washing reagents in the capillary tube under the control of the mechanical control system, and thus, the nucleic acid is purified without centrifugation. The purified nucleic acid is automatically extracted in 3 min for the polymerase chain reaction (PCR). The nucleic acid extraction is dependent on the transport speed and the vibration frequency of the magnetic beads, and optimizing these two parameters provided better PCR efficiency than the conventional manual procedure. There was no difference between the detection limits of our novel device and that of the conventional manual procedure. 相似文献
30.
Akemi Suzuki 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2006,82(3):93-103
Sialic acid is a family of acidic monosaccharides and consists of over 30 derivatives. Two major derivatives are N-acetylneuraminic acid (NeuAc) and N-glycolylneuraminic acid (NeuGc), and the hydroxylation of CMP-NeuAc is the rate limiting reaction for the production of NeuGc. The hydroxylation was carried out by a complex formed with hydroxylase, cytochrome b5, and NADH-cytochrome b5 reductase. Mouse hydroxylase was purified from the cytosolic fraction of the liver and its cDNA was cloned. Normal human tissues do not contain NeuGc. Human hydroxylase cDNA was also cloned and the sequence revealed that human hydroxylase has 92 bp deletion. The deletion is the cause of defective expression of NeuGc in human. Chimpanzee has intact hydroxylase gene and the 92 bp deletion occurred after the divergence of human ancestor from chimpanzee ancestor. Biochemical and molecular biological studies on the biosynthesis of NeuGc and biological functions of NeuGc are reviewed. 相似文献