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71.
Ikeda M Miyake Y Nishibayashi Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(11):3321-3328
The enantioselective propargylic alkylation of propargylic alcohols with β-ketoesters in the presence of a thiolate-bridged diruthenium complex and a copper complex as co-catalyst affords the corresponding propargylic alkylated products in excellent yields as a mixture of two diastereoisomers with high enantioselectivity (up to 95% enantiomeric excess (ee)). The findings reported herein not only open up a new type of enantioselective propargylic substitution reaction, but also a new aspect of cooperative catalytic reactions using distinct transition metals to realize a useful transformation that cannot be achieved by a single catalyst. 相似文献
72.
Enantioselective direct aldol reaction of α-substituted nitroacetates with aqueous formaldehyde for the synthesis of α-alkyl serines has been achieved under base-free neutral phase-transfer conditions with a bifunctional chiral phase-transfer catalyst. 相似文献
73.
A Pd-catalyzed asymmetric synthesis of Si-stereogenic dibenzosiloles is developed through enantioselective C-H bond functionalization of prochiral 2-(arylsilyl)aryl triflates. High chemo- and enantioselectivities are achieved by employing a Josiphos-type ligand under mild conditions. 相似文献
74.
75.
Keiichi Kimura Akira Matsui Yoshiaki Inaki Kiichi Takemoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1231-1241
Polymerization of acrylonitrile initiated by triazole-copper(II) complexes was studied in dimethylsulfoxide solution. It was found that the polymerization proceeds by a free radical mechanism; however, the complexes can hardly homopolymerize methyl methacrylate and styrene. Ability of the complexes to initiate polymerization seems to depend on the substituents of triazole, the sort of solvents, and the counterions of copper(n) salts. From the data of visible spectroscopy and the spin trapping, the initiation mechanism was discussed in terms of reduction of copper(II) followed by forming active species. 相似文献
76.
Yoshiaki Miyamoto Norihiro Wada Dr. Takahiro Soeta Dr. Shuhei Fujinami Prof. Dr. Katsuhiko Inomata Prof. Dr. Yutaka Ukaji 《化学:亚洲杂志》2013,8(4):824-831
The stereoselective direct transformation of N‐(propargylic)hydroxylamines into cis‐2‐acylaziridines was achieved by the combined use of AgBF4 and CuCl. Copper salts were found to promote the transformation of the intermediary 4‐isoxazolines into 2‐acylaziridines and both 3‐aryl‐ and 3‐alkyl‐substituted 2‐acylaziridines could be prepared by using this method. Furthermore, subsequent 1,3‐dipolar cycloaddition of azomethine ylides that were generated in situ from the intermediary 2‐acylaziridines with maleimides was achieved in a stereoselective one‐pot procedure to afford the corresponding 2‐acylpyrrolidines, which consisted of an octahydropyrrolo[3,4‐c]pyrrole skeleton. 相似文献
77.
Yoshiaki Hidaka Hiromitsu Masaoka Hidekazu Oshita Takuji Nakamura Koji Tanaka Hiroyuki Kawano 《国际化学动力学杂志》1992,24(10):871-885
The thermal decomposition of vinylacetylene (C4H4) was studied behind reflected shock waves using both a single-pulse method (reaction time between 0.8 and 3.3 ms) and a time-resolved UV-absorption method (230 nm). The studies were done over the temperature range of 1170–1690 K at the total pressure range of 1.3–2.3 atm. The mechanism was used to interpret both the early and late stages of vinylacetylene decomposition at the high temperatures. It was confirmed that C4H4 dissociation proceeded through the following three channels. The rate constant expression of reaction (1) was determined as k1 = 6.3 × 1013 exp(?87.1 kcal/RT) s?1. The rate constants of the succeeding reactions (chain reaction, C4H4 + H → i-C4H3 + H2 and C4H4 + H → C2H2 + C2H3 and decomposition reactions of free radicals, i-C4H3 + M → C4H2 + H + M) were confirmed or estimated. © John Wiley & Sons, Inc. 相似文献
78.
Yoshiaki?YuguchiEmail author Takahiro?Hirotsu Jun?Hosokawa 《Cellulose (London, England)》2005,12(5):469-477
Xyloglucan is a type of hemicellulose with a cellulose backbone containing (1→6)-α-xylose or (1→2)-β-galactoxylose as a side chain. It is soluble in water. Its aqueous solution forms a gel or gel-like precipitate by addition
of Congo red. Xyloglucan gel structures with various concentrations of Congo red were observed by small angle X-ray scattering
(SAXS) at the nano-level. SAXS results indicated that the xyloglucan chains interacted with Congo red, and that an increase
of concentration of Congo red induced a characteristic cross-linking domain, which consisted of a flat structure containing
stacked xyloglucan chain assemblies. The Congo red molecules are inserted between the xyloglucan chains. 相似文献
79.
[reaction: see text] Double phosphinylation of propargylic alcohols with diphenylphosphine oxide in the presence of a thiolate-bridged diruthenium complex as catalyst gives the corresponding 2,3-bis(diphenylphosphinyl)-1-propenes in high yields with a complete selectivity. 相似文献
80.
A nickel catalyst coordinated by trimethylphosphine is found to effect the addition reaction of Ar-CN bonds in aromatic nitriles across alkynes to give rise to various beta-arylalkenenitriles. 相似文献