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941.
Babak Kaboudin Jun-ya Kato Hiroshi Aoyama Tsutomu Yokomatsu 《Tetrahedron: Asymmetry》2013,24(24):1562-1566
A simple and convenient method has been developed for the preparation of (R)- and (S)-pyrrolidine-2-phosphonic acids. The thermal reaction of proline with diethyl phosphite in the presence of benzaldehyde gave an N-benzyl derivative of diethyl pyrrolidine-2-phosphonate, which was transformed into two diastereomeric amides by sequential debenzylation and acylation with (+)-dibenzoyl-l-tartaric anhydride. The two diastereomeric amides were separated by column chromatography and the structure of one of them was determined by X-ray crystallographic analysis. Hydrolysis of the amides in the usual manner afforded (R)- and (S)-pyrrolidine-2-phosphonic acids. The advantages of the present method are that it is easy, rapid, and prepares both enantiomers of pyrrolidine-2-phosphonic acids. 相似文献
942.
Abstract Although sol-gel method is an easy procedure to form a thin film, it's extremely difficult to coat on the surface of small size particles, fibers, and fiber ceramics, because concentration occurs by capillary phenomena and causes peeling or breakage of film. In order to solve this problem, we use supercritical CO2 rapid expansion from supercritical solution (RESS), nano-sized particles of TiO2 with high intensity can be sprayed out of a nozzle, then collected on the surface of substrates, but can be absorbed into fibers or porous materials, being not interfered by viscosity of a solution. TiO2 sol made by hydrolysis process is set in a pressure cell and mixed together with super-critical CO2. Controlling the pressure and the temperature, we could obtain TiO2 sol and super critical fluid mixture, and then discharge to the substrate. At this point, Titania sol viscosity is so low that a surface wettability of the substrate becomes negligible. By the use of the characteristics of the supercritical fluid, without constraint condition of viscosity or capillarity, this sol can penetrate into the interstices of the substance's structure. Thus, clearing obstruction of capillary phenomena, supercritical fluid coating method shows its capability to penetrate deep into inside of entangled fiber of the three-dimensional structure so as considered to be a heat resistant filter with 95% porosity. 相似文献
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946.
Shape‐Memory Platinum(II) Complexes: Intelligent Vapor‐History Sensor with ON–OFF Switching Function
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Yasuhiro Shigeta Dr. Atsushi Kobayashi Dr. Tadashi Ohba Dr. Masaki Yoshida Dr. Takeshi Matsumoto Prof. Ho‐Chol Chang Prof. Masako Kato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(8):2682-2690
A novel platinum(II)–diimine complex, [Pt(CN)2(H2dcphen)] ( 1 ; H2dcphen=4,7‐dicarboxy‐1,10‐ phenanthroline), was synthesized and its vapochromic shape‐memory behavior was evaluated. The as‐synthesized amorphous purple solid, [Pt(CN)2(H2dcphen)]?2 H2O ( 1 P ), exhibited vapochromic behavior in the presence of alcoholic vapors through transformation to a red, crystalline, porous, vapor‐adsorbed form, 1 R?vapor . The obtained 1 R?vapor complex released the adsorbed vapors upon heating without collapse of the porous structure. The vaporfree, porous 1 R?open could detect water or n‐hexane vapor, although these vapors could not induce 1 P ‐to‐ 1 R?vapor transformation, and 1 R?open could easily be converted to the initial 1 P by manual grinding. These results indicate that 1 is a new shape‐memory material that functions through formation and collapse of the porous framework with an emission change upon vapor‐adsorption and grinding; this enables it to exhibit vapor history and ON–OFF switching sensing functions. 相似文献
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Hideki Saitoh Taro Sampei Tsutomu Kimura Yuichi Kato Naoyuki Ishida Tsuyoshi Satoh 《Tetrahedron letters》2012,53(24):3004-3008
1-Chloro-3-cyanoalkyl p-tolyl sulfoxides were easily prepared from 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from carbonyl compounds and chloromethyl p-tolyl sulfoxide, with lithium α-cyano carbanion of acetonitrile derivatives in good yields. Treatment of these sulfoxides with i-PrMgCl resulted in the formation of multi-substituted α-chlorocyclobutanones in good to high yields via the 4-Exo-Dig nucleophilic ring closure of the generated magnesium carbenoid intermediates to the nitrile group. This procedure provides a new and good way for the synthesis of multi-substituted α-chlorocyclobutanones from carbonyl compounds and substituted acetonitriles with formation of three carbon–carbon bonds in relatively short steps. 相似文献
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