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排序方式: 共有102条查询结果,搜索用时 15 毫秒
1.
Thermal Cyclization of Copper Carbenoid of α‐Dizao α‐Phosphorylacetate: Unexpected and Novel Access to Oxaphosphirane 下载免费PDF全文
Under the catalysis of Cu(OTf)2 in refluxing CH2Cl2, ethyl α‐dizao α‐(diethylphosphoryl)acetate was shown to undergo a new cyclization reaction to afford a pentacovalent oxaphosphirane product. The reaction is proposed to occur through the addition of the P=O double bond to the copper carbenoid, followed by the hydrolysis of the ylide intermediate. Our finding represents the first example on producing oxaphosphiranes from dizao phosphoryl compounds. On the other hand, the corresponding rhodium carbenoid displayed the different reactivity under the same thermal conditions, to produce the β‐propiolactone through the well‐recognized C‐H insertion pathway. 相似文献
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Liang‐Yun Wang Jia‐Ling Ko Prof. Chien‐Chen Lai Yi‐Hung Liu Prof. Shie‐Ming Peng Prof. Sheng‐Hsien Chiu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(27):8850-8860
Herein, we report a “threading followed by shrinking” approach for the synthesis of rotaxanes by using an “oxygen‐deficient” macrocycle that contained two arylmethyl sulfone units and the dumbbell‐shaped salt bis(3,5‐dimethylbenzyl)ammonium tetrakis(3,5‐trifluoromethylphenyl)borate as the host and guest components, respectively. The extrusion of SO2 from both of the arylmethyl sulfone units of the macrocyclic component in the corresponding [2]pseudorotaxane resulted in a [2]rotaxane that was sufficiently stable to maintain its molecular integrity in CD3SOCD3 at 393 K for at least 5 h. 相似文献
4.
Danni Wu Kathleen Joyce D. Carillo Shen‐Long Tsai Jiun‐Jie Shie Der‐Lii M. Tzou 《中国化学会会志》2019,66(10):1318-1326
The neurosteroid trans‐dehydroandrosterone (DHEA) and its analogs with slightly different modifications in the side chain attached to C17, that is, (3S)‐acetoxypregn‐5‐en‐20‐one ( 1 ) and (3S,20R)‐acetoxypregn‐5‐en‐20‐ol ( 2 ), have been synthesized to investigate DHEA–cation interactions. In this study, we applied solid‐state 1H/13C cross‐polarization/magic‐angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy to a series of DHEA analog/Mg2+ mixtures at different Mg2+ concentrations. The high‐resolution 13C NMR spectra of 1 /Mg2+ mixtures exhibit two distinct 13C spectral patterns, one attributable to 1 free from Mg2+, and the other attributable to 1 with bound Mg2+. For 2 , the 13C NMR spectra exhibit three distinct spectral patterns; besides that of the free form, the other two can be assigned to Mg2+‐bound forms. Based on the analysis of the chemical shift deviations (CSDs), we conclude that both 1 and 2 might be subject to a cation–π interaction via the C5–C6 double bond, in contrast to that observed previously for DHEA. As demonstrated, DHEA possesses two Mg2+ binding sites, that is, C17–O and C5–C6 double bond, in which the binding affinity of the former is at least three times stronger than that of the latter. The solid‐state 13C NMR investigation allows better understanding of the underlying cation binding effects of neurosteroid molecules in vitro. 相似文献
5.
Lin Yung-Sen Shie Bing-Shiun Lai Yan-Hong Chen Jui-Hung Gu Zhi-Wei Chen Hsiang Lin Chia-Feng 《Journal of Solid State Electrochemistry》2019,23(2):441-453
Journal of Solid State Electrochemistry - Lithium ionic intercalation and conduction performance of tantalum oxides films improved by adding with iron oxides using an atmospheric pressure plasma... 相似文献
6.
In this paper, we establish existence theorems of quasivariational inclusion problems; from them, we establish existence theorems
of mathematical programs with quasivariational inclusion constraint, bilevel problems, mathematical programs with equilibrium
constraint and semi-infinite problems.
This research was supported by the National Science Council of the Republic of China. The authors express their gradtitude
to the referees for valuable suggestions. 相似文献
7.
Po‐Yeng Feng Yi‐Hung Liu Prof. Tien‐Sung Lin Prof. Shie‐Ming Peng Prof. Ching‐Wen Chiu 《Angewandte Chemie (International ed. in English)》2014,53(24):6237-6240
Chemical reduction of a hydroxyphenyl‐substituted borane triggers a sequential electron‐ and intramolecular hydrogen‐atom‐transfer process to afford a hydridoborate phenoxide dianion. On the other hand, hydrogen‐atom abstraction of the borane leads to the isolation of a neutral borylated phenoxyl radical, which can be transformed to the corresponding benzoquinone borataalkene derivative by reduction with cobaltocene. 相似文献
8.
IR,Raman, and Surface‐enhanced Raman Spectroscopic Study on Triruthenium Dipyridylamide Diruthenium Nickel Dipyridylamide Family: Metal‐metal Bonding and Structures 下载免费PDF全文
Yu‐Chun Chiu Kuan‐Yi Ho a I‐Chia Chen Shao‐An Hua Ming‐Chuan Cheng Shie‐Ming Peng 《中国化学会会志》2014,61(12):1289-1296
We report the infrared, Raman, and surface‐enhanced Raman scattering (SERS) spectra of triruthenium dipyridylamido complexes and of diruthenium mixed nickel metal‐string complexes. From the results of analysis on the vibrational modes, we assigned their vibrational frequencies and structures. The infrared band at 323–326 cm?1 is assigned to the Ru3 asymmetric stretching mode for [Ru3(dpa)4Cl2]0–2+. In these complexes we observed no Raman band corresponding to the Ru3 symmetric stretching mode although this mode is expected to have substantial Raman intensity. There is no frequency shift in the Ru3 asymmetric stretching modes for the complexes with varied oxidational states. No splitting in Raman spectra for the pyridyl breathing line indicates similar bonding environment for both pyridyls in dpa– , thus a delocalized structure in the [Ru3]6–8+ unit is proposed. For Ru3(dpa)4(CN)2 complex series, we assign the infrared band at 302 cm?1 to the Ru3 asymmetric stretching mode and the weak Raman line at 285 cm?1 to the Ru3 symmetric stretching. Coordination to the strong axial ligand CN– weakens the Ru‐Ru bonding. For the diruthenium nickel complex [Ru2Ni(dpa)4Cl2]0–1+, the diruthenium stretching mode νRu‐Ru is assigned to the intense band at 327 and 333 cm?1 in the Raman spectra for the neutral and oxidized forms, respectively. This implies a strong Ru‐Ru metal‐metal bonding. 相似文献
9.
The quantum states are presented in these processions of fabricating poly-Si films. Amorphous silicon films prepared by PECVD has been crystallized by conventional furnace annealing (FA) and rapid thermal annealing (RTA), respectively. It is found that the thin films grain size present quantum states with the increasing of the gas flow ratios of SiH4, H2 mixture, substrate temperatures, frequency power, annealing temperature and time. 相似文献
10.