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61.
62.
Ichikawa Y Matsuda Y Okumura K Nakamura M Masuda T Kotsuki H Nakano K 《Organic letters》2011,13(10):2520-2523
The first nonracemic synthesis of (+)-geranyllinaloisocyanide, starting with (-)-lactic acid methyl ester, has been accomplished by exploiting a [3.3] sigmatropic rearrangement of allyl cyanate. The synthesis enables assignment of the S configuration of the C(3) isocyano substituted, quaternary stereogenic center in natural geranyllinaloisocyanide. 相似文献
63.
Nagakawa Yoshiyasu Uemoto Michihisa Kurosawa Takahide Shutoh Kohtaroh Hasegawa Hiroshi Sakurai Noboru Harada Emiko 《Journal of Radioanalytical and Nuclear Chemistry》2019,319(1):185-196
Concentrations of 134+137Cs and 133Cs in aquatic macrophytes, water, and sediment were measured in samples collected from Fukushima Prefecture, Japan. The concentrations of 137Cs in submerged and floating-leaved plants were higher than the values for emergent plants according to their main Cs uptake mode. The geometric mean water-to-plant concentration ratio for 137Cs and 133Cs was comparable observed in submerged and floating-leaved plants, while the geometric mean sediment-to-plant concentration ratio for 137Cs in emergent plants was higher than that of 133Cs, which suggest that the mobility of Fukushima accident-derived 137Cs is not in steady state 4–5 years after the accident.
相似文献64.
Miwa Kubo Kana Kobayashi Jian-Mei Huang Kenichi Harada Yoshiyasu Fukuyama 《Tetrahedron letters》2012,53(10):1231-1235
Two seco-prezizaane-type sesquiterpenoids (2R)-hydroxy-norneomajucin (1) and jiadifenone (2) that represent the first examples of nor-type were isolated from the methanol extract of the pericarps of Illicium jiadifengpi. Their structures and the absolute configuration of 1 were established by the analysis of spectroscopic data and chemical conversion of (2S)-hydroxyneomajucin to 1, respectively. In addition, compound 1 exhibited neurotrophic activity to significantly promote neurite outgrowth in the primary cultured rat cortical neurons at concentrations ranging from 1 to 10 μmol L?1. 相似文献
65.
Taketoshi Matsumoto Patricia Nickut Hironori Tsunoyama Tatsuya Tsukuda Yoshiyasu Matsumoto 《Surface science》2007,601(22):5121-5126
Deposition and fabrication of films of Au nanoclusters protected by alkanethiolate ligands are attempted on a TiO2(1 1 0) surface and the structures of films are observed by a scanning tunneling microscope (STM). Effects of oxygen and hydrogen-plasma etching in addition to UV irradiation on the structure and chemical composition of the films are also investigated by using STM and X-ray photoelectron spectroscopy. Alkanethiolate Au nanoclusters are produced using a modified Brust synthesis method and their LB films are dip-coated on TiO2(1 1 0). Alkanethiolate Au nanoclusters are weakly bound to the substrate and can be manipulated with an STM tip. Net-like structures of alkanethiolate Au nanoclusters are formed by a strong blast of air. Oxygen-plasma etching removes alkanethiolate ligands and simultaneously oxidizes Au clusters. At room temperature, prolonged oxygen-plasma etching causes agglomeration of Au nanoclusters. UV irradiation removes ligands partly, which makes Au nanoclusters less mobile. The net-like structure of alkanethiolate Au clusters produced by a blast of air is retained after oxygen and hydrogen-plasma etching. 相似文献
66.
Inoue M Lee N Kasuya S Sato T Hirama M Moriyama M Fukuyama Y 《The Journal of organic chemistry》2007,72(8):3065-3075
(-)-Merrilactone A [(-)-1], isolated from Illicium merrillianum in 2000, possesses neurite outgrowth activity in cultures of fetal rat cortical neurons, and, therefore, is expected to show therapeutic potential for the treatment of neurodegeneration associated with Alzheimer's and Parkinson's diseases. Apart from its biological aspects, the caged pentacyclic skeleton of 1 poses interesting synthetic challenges. Here, we report the total synthesis of the unnatural enantiomer of merrilactone A [(+)-1], based on a novel desymmetrization strategy. The chiral lithium amide 16g promoted an enantioselective transannular aldol reaction of eight-membered meso-diketone 3d, establishing the absolute stereochemistries of four chiral centers of the cis-bicyclo[3.3.0]octane framework of 1 in a single step. The obtained compound 4d served as a platform for the subsequent functional group manipulations necessary for the construction of (+)-1. Surprisingly, both the natural and unnatural enantiomers of synthetic merrilactone A equally promoted neurite outgrowth in primary neuronal cultures. 相似文献
67.
Nguyen Manh Cuong Ninh The Son Ngu Truong Nhan Yoshiyasu Fukuyama Amer Ahmed Simona Saponara Alfonso Trezza Beatrice Gianibbi Ginevra Vigni Ottavia Spiga Fabio Fusi 《Molecules (Basel, Switzerland)》2022,27(14)
Hypertension is a risk factor for cardiovascular diseases, which are the main cause of morbidity and mortality in the world. In the search for new molecules capable of targeting KCa1.1 and CaV1.2 channels, the expression of which is altered in hypertension, the in vitro vascular effects of a series of flavonoids extracted from the heartwoods, roots, and leaves of Dalbergia tonkinensis Prain, widely used in traditional medicine, were assessed. Rat aorta rings, tail artery myocytes, and docking and molecular dynamics simulations were used to analyse their effect on these channels. Formononetin, orobol, pinocembrin, and biochanin A showed a marked myorelaxant activity, particularly in rings stimulated by moderate rather than high KCl concentrations. Ba2+ currents through CaV1.2 channels (IBa1.2) were blocked in a concentration-dependent manner by sativanone, 3′-O-methylviolanone, pinocembrin, and biochanin A, while it was stimulated by ambocin. Sativanone, dalsissooside, and eriodictyol inhibited, while tectorigenin 7-O-[β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside], ambocin, butin, and biochanin A increased IKCa1.1. In silico analyses showed that biochanin A, sativanone, and pinocembrin bound with high affinity in target-sensing regions of both channels, providing insight into their potential mechanism of action. In conclusion, Dalbergia tonkinensis is a valuable source of mono- and bifunctional, vasoactive scaffolds for the development of novel antihypertensive drugs. 相似文献
68.
Yoshiyasu Ozeki 《Journal of Number Theory》2013,133(11):3810-3861
69.
Y Matsumoto 《The Journal of chemical physics》2012,137(9):091705
This paper begins with describing the excitation mechanisms in surface photochemistry and nuclear dynamics of adsorbate induced by electronic excitation. An illustrative example is Cs adsorbate on a Cu(111) surface. This adsorption system shows drastic changes in the electronic structure with coverage; this allows us to examine different types of electronic excitations that stimulate nuclear motions of Cs. Remarks are made on challenges in photoinduced processes at well-defined surfaces: direct observations of adsorbate-substrate vibrational modes and photoinduced reactions between adsorbates. Then, the paper addresses some issues in more complex systems: metal-liquid interfaces and powdered photocatalysts of metal oxides. Photochemistry and photoinduced nuclear dynamics at metal-liquid interfaces have not been well explored. Studies on this subject may make it possible to bridge the gap between surface photochemistry and electrochemistry. Photocatalysis with powdered catalysts has been extensively studied and is still an active area, but our understanding of the mechanism of photocatalysis is far from satisfactory. Although complicated, the highly integrated systems provide an opportunity to extend our knowledge of surface photochemistry. 相似文献
70.
Komatsu Y Watanabe R Ikishima H Nakano K Ichikawa Y Kotsuki H 《Organic & biomolecular chemistry》2012,10(15):2993-3001
A practical method for the synthesis of 1,3-aminohydroxyacetone synthons was developed, and their utility in the organocatalytic asymmetric aldol reaction was demonstrated in a short synthesis of aza-sugars. 相似文献