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941.
Dr. Haruhisa Kikuchi Kosuke Kawai Yota Nakashiro Takayuki Yonezawa Kumi Kawaji Prof. Dr. Eiichi. N. Kodama Prof. Dr. Yoshiteru Oshima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(4):1106-1112
The structural diversity of natural products and their derivatives have long contributed to the development of new drugs. However, the difficulty in obtaining compounds bearing skeletally novel structures has recently led to a decline of pharmaceutical research into natural products. This paper reports the construction of a meroterpenoid-like library containing 25 compounds with diverse molecular scaffolds obtained from diversity-enhanced extracts. This method constitutes an approach for increasing the chemical diversity of natural-product-like compounds by combining natural product chemistry and diversity-oriented synthesis. Extensive pharmacological screening of the library revealed promising compounds for anti-osteoporotic and anti-lymphoma/leukemia drugs. This result indicates that the use of diversity-enhanced extracts is an effective methodology for producing chemical libraries for the purpose of drug discovery. 相似文献
942.
Dr. Chihiro Maeda Shuichi Nomoto Koki Akiyama Dr. Takayuki Tanaka Prof. Tadashi Ema 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(63):15699-15705
Carbazole-based aza[7]helicenes and hetero[9]helicenes were successfully obtained via the intramolecular Scholl reaction of 3,6-bis(biphenyl-2-yl)carbazole congeners, while the reaction of 3,6-bis(naphthylphenyl)-appended carbazole gave a triple helicene via an unexpected simultaneous double aryl rearrangement. DFT calculations suggested that the rearrangement proceeded via an arenium cation intermediate. In addition, the reaction of methoxy-appended substrate gave an azahepta[8]circulene via the concurrent C−C bond formation. These helical dyes showed circularly polarized luminescence. The azahepta[8]circulene was further transformed into deeply saddle-distorted dibenzodiaza[8]circulenes as the first example of its solution-based synthesis and unambiguous structural determination. 相似文献
943.
944.
Atsushi OkazawaKei Fujiwara Ryo WatanabeNorimichi Kojima Shunsuke YoshiiHiroyuki Nojiri Takayuki Ishida 《Polyhedron》2011,30(18):3121-3126
Heterometallic polymeric coordination compounds [{Ln(hfac)2(CH3OH)}2{Cu(dmg)(Hdmg)}2]n (abbreviated as [Ln2Cu2]n) involving light lanthanoid ions, Pr, Nd, Sm, and Eu, were synthesized, where H2dmg and Hhfac stand for dimethylglyoxime and 1,1,1,5,5,5-hexafluoropentane-2,4-dione, respectively. The X-ray crystallographic analysis shows that their structures are isomorphous to those of the known heavy lanthanoid analogs. The exchange couplings were evaluated by high-frequency electron paramagnetic resonance and pulsed-field magnetization studies, giving ferromagnetic exchange parameters: JPr-Cu/kB = 0.039(1) K, JNd-Cu/kB = 0.38(1) K, JSm-Cu/kB = 0.95(2) K, and no interaction between Eu and Cu ions. A significant trend is found in the order of the periodic table. The ferro- and antiferromagnetic 4f-3d couplings were characterized for the light and heavy lanthanoid derivatives, respectively. The magnitude of JLn-Cu decreases with a decrease of the 4f-spin portion, i.e., the number of unpaired electrons, whether the coupling is ferro- or antiferromagnetic. 相似文献
945.
946.
Takayuki FurukawaHiroshi Hinou Ken ShimawakiShin-Ichiro Nishimura 《Tetrahedron letters》2011,52(43):5567-5570
Development of β-selective glucuronylation reaction using phenyl 2,4-di-O-acetyl-1-thio-β-d-glucopyranosidurono-6,3-lactone was described. Glycosylations of this glycosyl donor with hexosamine derivatives proceeded with excellent yield and β-stereoselectivity to afford glycosaminoglycan-type disaccharides. 相似文献
947.
Takayuki Nagai 《Topology and its Applications》2012,159(2):545-554
We investigate the Gauss map of a hypersurface in Euclidean n-sphere as an application of the theory of Legendrian singularities. We can interpret the image of the Gauss map as the wavefront set of a Legendrian immersion into a certain contact manifold. We interpret the geometric meaning of the singularities of the Gauss map from this point of view. 相似文献
948.
Yuya Sugiyama Yuki Kurata Yoko Kunda Atsushi Miyazaki Junko Matsui Shuichi Nakamura Hiromi Hamamoto Takayuki Shioiri Masato Matsugi 《Tetrahedron》2012,68(20):3885-3892
The entire study of condensation reactions using various fluorous Mukaiyama reagents, including a novel medium-fluorous strategy, is described. A Mukaiyama reagent bearing a medium-fluorous content tag, between 40 and 60% fluorine by weight, was prepared and examined in ester and amide-forming condensation reactions. At the end of the reactions, the fluorous pyridone by-product was effectively separated from non-fluorous components by increasing the water content of the crude reaction mixture and subsequent filtration of the precipitate. It is also shown that Mukaiyama reagents bearing a fluorous tag increase the reaction rate considerably when compared to their non-fluorous tagged counterpart. Interestingly, it was observed that the longer the fluorous chain, the higher the activity of the Mukaiyama reagent. 相似文献
949.
Shigenobu Fujimoto Kenji Matsumoto Takayuki Iwata Mitsuru Shindo 《Tetrahedron letters》2017,58(10):973-976
We have developed a heterogeneous catalytic oxidative homocoupling reaction of dimethoxyanilides under an oxygen atmosphere. The resulting homo-dimers are useful for the construction of heterocycles, demonstrating the potential of heterogeneous metal catalysts. 相似文献
950.
A fully conservative high‐order upwind multi‐moment method using moments in both upwind and downwind cells
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We propose a fully conservative high‐order upwind multi‐moment method for the conservation equation. The proposed method is based on a third‐order polynomial interpolation function and semi‐Lagrangian formulation and is a variant of the constrained interpolation profile conservative semi‐Lagrangian scheme with third‐order polynomial function method. The third‐order interpolation function is constructed based on three constraints in the upwind cell (two boundary values and a cell average) and a constraint in the downwind cell (a cell center value). The proposed method shows fourth‐order accuracy in a benchmark problem (sine wave propagation). We also propose a less oscillatory formulation of the proposed method. The less oscillatory formulation can minimize numerical oscillations. These methods were validated through scalar transport problems, and compressible flow problems (shock tube and 2D explosion problems). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献