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91.
Hiroya Takada Yoshiaki Nishibayashi Kouichi Ohe Sakae Uemura 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):363-364
Prochiral sulfides reacted with Phl=NTs in the presence of a catalytic amount of Cu(I) salt together with a chiral 4,4′-disubstituted bis(oxazoline) ligand to afford the corresponding chiral sulfimides. 相似文献
92.
Yoshio Aso Shoji Nishiguchi Tetsuya Jigami Tetsuo Otsubo Fumio Ogura 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):417-418
Several well-defined 3,4-thienylene-ethynylene oligomers with different chain lengths have been synthesized and characterized. X-Ray crystallographic analyses proved their unique, totally helical conformations. 相似文献
93.
Type I (α-) and II cleavages are two of the best known photochemical processes of alkanone.2 Extensive and intensive investigations have been done on both types of reactions in order to clarify the influence of structural changes on the reactivity, specificity, and efficiency of photoreactions of alkanones.3 The type I cleavage of medium-ring alkanones is believed to produce a radical pair, the fate of which will be determined by the ready formation of transition states for transfer of Ha, Hb, and recyclization. We now wish to report 相似文献
94.
95.
Toshio Matsuda Yoshiyuki Takada 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):75-79
Abstract In a previous paper,1 we reported the formation of a resinous material (1) from the reaction of sulfur chloride with acetophenone which, upon treatment with DMF, yielded phenylglyoxylthiodimethylamide (4). We now report two additional resinous materials (5, 6), resulting from bromination of sodium phenacylthiosulfate (3) and diphenacyl disulfide (7) respectively, both of which not only resemble resinous 1 in appearance, but also yield 4 upon treatment with DMF in aqueous alkali. Resinous 1, 5, and 6 appear to have the same common basic structure and differ only in the number of sulfur atoms bonded between the common units. Cleavage at the sulfur-sulfur bonds and elimination of hydrogen halide then yields identical oxothioamides from 1, 5, or 6. The latter appears to be a general reaction, and several oxothioamides were prepared by this synthetic method from 1, 5, and 6 and various amides and amines. 相似文献
96.
Patrick Metzner Jean-François Brière Hiroya Takada 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):965-968
Abstract The reaction of novel chiral selenonium and telluronium ylides was investigated with aldehydes and compared to the sulfur analogues. (2R,5R)-2,5-Dimethylselenolane was prepared and reacted as a catalyst for the benzylidenation of aldehydes. Disubstituted epoxides were readily prepared with a (surprising) absence of diastereoselectivity, and with enantiomeric excesses higher than 90%. The reaction of a tellurium analogue, (2S,5S)-2,5-diethyltellurolane, afforded the oxirane in very moderate yield and e.e.'s in the range of 62–82%. Though this was less productive, it is the first report of a chiral telluronium ylide leading to an asymmetric epoxidation of aldehydes. 相似文献
97.
Yanting Song Katsuya Takatsuki Muneki Isokawa Tetsushi Sekiguchi Jun Mizuno Takashi Funatsu Shuichi Shoji Makoto Tsunoda 《Analytical and bioanalytical chemistry》2013,405(25):7993-7999
In this study, a fast and quantitative determination method for branched-chain amino acids (BCAAs), namely leucine, isoleucine, and valine, was developed using a pillar array column. A pillar array column with low-dispersion turns was fabricated on a 20?×?20-mm2 microchip using multistep ultraviolet photolithography and deep reactive ion etching. The BCAAs were fluorescently labeled with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), followed by reversed-phase separation on the pillar array column. The NBD derivatives of the three BCAAs and an internal standard (6-aminocaproic acid) were separated in 100 s. The calibration curves for the NBD-BCAAs had good linearity in the range of 0.4–20 μM, using an internal standard. The intra- and interday precisions were found to be in the ranges of 1.42–3.80 and 2.74–6.97 %, respectively. The accuracies for the NBD-BCAA were from 90.2 to 99.1 %. The method was used for the analysis of sports drink and human plasma samples. The concentrations of BCAAs determined by the developed method showed good agreements with those determined using a conventional high-performance liquid chromatography system. As BCAAs are important biomarkers of some diseases, these results showed that the developed method could be a potential diagnostic tool in clinical research. 相似文献
98.
Atsushi Tarui Shoji Kondo Kazuyuki Sato Masaaki Omote Hideki Minami Yoshihisa Miwa Akira Ando 《Tetrahedron》2013,69(5):1559-1565
A highly diastereoselective cross-coupling reaction of an α-bromo-α-fluoro-β-lactam with a wide range of aryl Grignard reagents was catalyzed by Ni/bis(oxazoline) in yields of up to 98%. The product was obtained diastereoselectively as an anti-isomer. This is the first successful α-arylation of an α-fluoro-β-lactam to produce diverse α-aryl-α-fluoro-β-lactams. 相似文献
99.
A mechanistic study was carried out for the asymmetric Michael addition reaction of malonates to enones catalyzed by a primary amino acid lithium salt to elucidate the origin of the asymmetric induction. A primary β-amino acid salt catalyst, O-TBDPS β-homoserine lithium salt, exhibited much higher enantioselectivity than that achieved with the corresponding catalysts derived from α- and γ-amino acids for this reaction. Detailed studies of the transition states with DFT calculations revealed that the lithium cation and carboxylate group of the β-amino acid salt catalyst have important roles in achieving high enantioselectivity in the Michael addition reaction of malonates to enones. 相似文献