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901.
Masato Fujiwara Naoki Takada Hiromitsu Araki Shohei Ikawa Yuki Maeda Hiroaki Niwase Minoru Oikawa Takashi Kakue Tomoyoshi Shimobaba Tomoyoshi Ito 《中国光学快报(英文版)》2018,(8)
We propose a method for color electroholography using a simple red–green–blue(RGB) gradation representation method without controlling the respective brightness of the reference RGB-colored lights. The proposed method uses RGB multiple bit planes comprising RGB binary-weighted computer-generated holograms with various light transmittances. The object points of a given three-dimensional(3D) object are assigned to RGB multiple bit planes according to their RGB gradation levels. The RGB multiple bit planes are sequentially displayed in a time-division-multiplexed manner. Consequently, the proposed method yields a color gradation representation of a reconstructed 3D object. 相似文献
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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
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Dr. Kyohei Kanomata Yuki Nagasawa Yukihiro Shibata Prof. Dr. Masahiro Yamanaka Fuyuki Egawa Dr. Jun Kikuchi Prof. Dr. Masahiro Terada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3364-3372
The precise mechanism of the chiral phosphoric acid-catalyzed aldol-type reaction of azlactones with vinyl ethers was investigated. DFT calculations suggested that the reaction proceeds through a Conia-ene-type transition state consisting of the vinyl ether and the enol tautomer of the azlactone, in which the catalyst protonates the nitrogen atom of the azlactone to promote enol tautomerization. In addition, the phosphoryl oxygen of the catalyst interacts with the vinyl proton of the vinyl ether. The favorable transition structure features dicoordinating hydrogen bonds. However, these hydrogen bonds are not involved in the bond recombination sequence and hence the catalyst functions as a template for binding substrates. From the results of theoretical studies and experimental supports, the high enantioselectivity is induced by the steric repulsion between the azlactone substituent and the binaphthyl backbone of the catalyst under the catalyst template effect. 相似文献
910.
Asymmetric Synthesis of an Amino Acid Derivative from Achiral Aroyl Acrylamide by Reversible Michael Addition and Preferential Crystallization 下载免费PDF全文
Yuki Kaji Naohiro Uemura Prof. Yoshio Kasashima Hiroki Ishikawa Prof. Yasushi Yoshida Prof. Takashi Mino Prof. Masami Sakamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16429-16432
Single‐handed α‐amino acid derivatives were generated from achiral precursors without an external chiral source. Conjugate addition of phenethylamine to an achiral aroyl acrylamide under homogeneous conditions gave the α‐amino amides in quantitative yields, which crystallized as a conglomerate of a P21 crystal system. Dynamic preferential crystallization or attrition‐enhanced deracemization resulted in the formation of enantiomorphic crystals of 99 % ee. 相似文献