排序方式: 共有197条查询结果,搜索用时 342 毫秒
51.
Bertrand MP Escoubet S Gastaldi S Timokhin VI 《Chemical communications (Cambridge, England)》2002,(3):216-217
Thiyl radical promotes the isomerisation of allylic amines into enamines via two consecutive hydrogen atom abstraction steps, and the subsequent polar addition of the corresponding thiol to the enamine results in the cleavage of the C-N bond via a thioaminal intermediate: this reaction provides a mild, metal-free methodology for the deprotection of allylated primary and secondary amines. 相似文献
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Palladium(II)-catalyzed aerobic oxidative amination of styrene with oxazolidinone proceeds with catalyst-controlled regioselectivity: (CH3CN)2PdCl2 (1) and (Et3N)2PdCl2 (2) catalyze formation of the anti-Markovnikov and Markovnikov enecarbamate products, 3 and 4, respectively. Kinetic studies and deuterium kinetic isotope effects demonstrate that these two reactions possess different rate-limiting steps, and the data indicate that the product regiochemistry arises from the presence or absence of an effective Br?nsted base in the reaction. In the presence of a Br?nsted base such as triethylamine or acetate, the kinetically preferred Markovnikov aminopalladation adduct of styrene is trapped via rapid deprotonation of a zwitterionic intermediate and leads to formation of 4. In the absence of an effective Br?nsted base, however, slow deprotonation of this adduct enables aminopalladation to be reversible, and product formation proceeds through the thermodynamically preferred anti-Markovnikov aminopalladation adduct to yield 3. 相似文献
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Nonlinear Dynamics - In this paper, we investigate the behavior of an underactuated mixed-dynamic nonholonomic system, a Chaplygin sleigh, subjected to viscous dissipation and sinusoidal forcing.... 相似文献
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Bulavin Viktor I. V’yunnik Ivan N. Kramarenko Andrey V. Minakov Vitaliy A. 《Journal of solution chemistry》2022,51(11):1334-1352
Journal of Solution Chemistry - To quantitatively describe the kind of interaction between ion and solvent, it is convenient to use the concept of negative or positive solvation. We have... 相似文献
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Dyachenko Alla Ischenko Olena Diyuk Vitaliy Goncharuk Olena Borysenko Mykola Mischanchuk Oleksandr Zakharova Tetiana Pryhunova Olha Sternik Dariush Lisnyak Vladyslav 《Research on Chemical Intermediates》2022,48(6):2607-2625
Research on Chemical Intermediates - Oxide Ni(80)Fe(20)/SiO2, Co(93)Fe(7)/SiO2, and Ni(19)Co(77)Fe(4)/SiO2 nanocomposites (NCs) were prepared using highly dispersed silica. It was modified by... 相似文献
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Orienting Effect of the Cage Addends: The Case of Nucleophilic Cyclopropanation of C2‐C70(CF3)8 下载免费PDF全文
Dr. Marina G. Apenova Olesya O. Semivrazhskaya Eugenia V. Borkovskaya Nikita M. Belov Dr. Ilya N. Ioffe Dr. Vitaliy Yu. Markov Prof. Dr. Sergey I. Troyanov Dr. Natalia S. Lukonina Prof. Dr. Lev N. Sidorov Dr. Alexey A. Goryunkov 《化学:亚洲杂志》2015,10(6):1370-1378
C2‐C70(CF3)8 was found to be a very promising substrate in the Bingel and the Bingel–Hirsch reactions combining perfect regioselectivity with much higher reactivity compared to its analogs. The reactions with diethyl malonate yield a single isomer of the monoadduct C70(CF3)8[C(CO2Et)2] and a single C2‐symmetrical bisadduct C70(CF3)8[C(CO2Et)2]2. The Bingel–Hirsch variation is particularly interesting in that it additionally affords, in a similar regioselective manner, the unexpected alkylated derivatives C70(CF3)8[CH(CO2Et)2]H and C70(CF3)8[C(CO2Et)2][CH(CO2Et)2]H. The novel compounds have been isolated and structurally characterized by means of 1H and 19F NMR spectroscopy as well as single‐crystal X‐ray diffraction. The mechanistic and regiochemical aspects of the reaction are explained with the aid of DFT calculations. 相似文献
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Yuri V. Vishnevskiy Natalja Vogt Vitaliy I. Korepanov Arkadii A. Ivanov Lev V. Vilkov Vladimir V. Kuznetsov Nina N. Mahova 《Structural chemistry》2009,20(3):435-442
The molecular structure of N-chlorosuccinimide has been studied by GED method at the nozzle temperature of 116 °C. Vibrational corrections to the r
a parameters, Δ(r
a − r
e), have been calculated using the scaled quadratic and cubic force constants from B3LYP/6-31G(df,p) calculations. The force
field scaling has been carried out using the IR and Raman spectra of the solid N-chlorosuccinimide. The molecular skeleton and the bond conformation around nitrogen were found to be planar within large experimental
errors. The equilibrium geometrical parameters derived from the experimental data assuming C
2v
molecular symmetry and those from MP2(fc)/6-311G(3df,2pd) calculations are in a good agreement. 相似文献