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排序方式: 共有106条查询结果,搜索用时 15 毫秒
1.
Cycloaddition reactions between 2-vinylthiophen and the dienophiles maleic anhydride, dimethyl acetylenedicarboxylate,' methyl propiolate, and methyl acrylate, are reported. Products include simple benzo[b]thiophen carboxylates (6, 13, 17) and reduced derivatives (3, 4, 18). The acetylenic dienophiles also gave a dihydrobenzthienyl-acrylate (16) or -fumarate (11), and the dithienylcyclohexene esters (7) and (14). 相似文献
2.
Krayushkin M. M. Shirinian V. Z. Belen"kii L. I. Shadronov A. Yu. Vorontsova L. G. Starikova Z. A. 《Russian Chemical Bulletin》2002,51(8):1510-1514
The conditions for acylation of 2,5-dimethylthiophene with squaric acid dichloride were optimized, and 3,4-bis(2,5-dimethylthiophen-3-yl)cyclobut-3-ene-1,2-dione was obtained in good yield. X-ray diffraction analysis demonstrated that the by-product has the structure of 1a,1b-dichloro-5-(2,5-dimethylthiophen-3-yl)-3-hydroxy-4,5a-dimethyl-1b,4a,5,5a-tetrahydro-1aH-1-thiacyclopropa[a]pentalen-2-one. 相似文献
3.
A. V. Kolotaev L. I. Belen’kii A. S. Kononikhin M. M. Krayushkin 《Russian Chemical Bulletin》2006,55(5):892-897
Symmetrical and unsymmetrical α-diketones of the indole series were synthesized by the Friedel-Crafts reaction of 3-indolylglyoxyl
chlorides with heterocycles. A nonconventional reaction of N-unsubstituted diketones with hydrazine producing 3H-pyrazolo[3,4-c]quinoline derivatives was found.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 862–866, May, 2006. 相似文献
4.
Armstrong A Ahmed G Dominguez-Fernandez B Hayter BR Wailes JS 《The Journal of organic chemistry》2002,67(24):8610-8617
Several alpha-substituted N-carbethoxytropinones have been evaluated as catalysts for asymmetric epoxidation of alkenes with Oxone, via a dioxirane intermediate. alpha-Fluoro-N-carbethoxytropinone (2) has been studied in detail and is an efficient catalyst which does not suffer from Baeyer-Villiger decomposition and can be used in relatively low loadings. This ketone was prepared in enantiomerically pure form using chiral base desymmetrization of N-carbethoxytropinone. Asymmetric epoxidation catalyzed by 2 affords epoxides with up to 83% ee. Among other derivatives tested, the alpha-acetoxy derivative 7 affords the highest enantioselectivities. 相似文献
5.
L. I. Belen’kii A. V. Kolotaev V. Z. Shirinyan M. M. Krayushkin Yu. P. Strokach T. M. Valova Z. O. Golotyuk V. A. Barachevskii 《Chemistry of Heterocyclic Compounds》2005,41(1):86-92
The polar [4+2] cycloaddition reaction of 1,2-bis(2,5-dimethyl-3-thienyl)acetylene with thiobenzamide and certain aldehydes of the thiophene and furan series catalyzed by boron trifluoride etherate gives the corresponding 4-hetaryl-5,6-di(2,5-dimethyl-3-thienyl)-2-phenyl-4H-1,3-thiazines. The photochromic properties of the products have been studied.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 100–106, January, 2005. 相似文献
6.
Paired electrosynthesis of cyanoacetic acid 总被引:1,自引:0,他引:1
Batanero B Barba F Sánchez-Sánchez CM Aldaz A 《The Journal of organic chemistry》2004,69(7):2423-2426
Cyanoacetic acid is formed by cathodic reduction of CO(2) and anodic oxidation of the tetraalkylammonium salt anion; the process is conduced in acetonitrile using a divided cell with a medium porosity glass-frit diaphragm. A mechanism for this paired electrochemical reaction is proposed. 相似文献
7.
Cathodic reduction of phenacyl bromides N-acyl hydrazones lead to dimeric 1,4-diaryl-1,4-butanedione di-N-acylhydrazones, which give the corresponding 1-N-acylamino-2,5-diarylpyrroles in good yields. 相似文献
8.
Selma Belen Erik Kropat Gerhard-Wilhelm Weber 《Central European Journal of Operations Research》2011,19(1):1-17
In this paper, the Maki–Thompson model is slightly refined in continuous time, and a new general solution is obtained for
each dynamics of spreading of a rumour. It is derived an equation for the size of a stochastic rumour process in terms of
transitions. We give new lower and upper bounds for the proportion of total ignorants who never learned a rumour and the proportion
of total stiflers who either forget the rumour or cease to spread the rumour when the rumour process stops, under general
initial conditions. Simulation results are presented for the analytical solutions. The model and these numerical results are
capable to explain the behaviour of the dynamics of any other dynamical system having interactions similar to the ones in
the stochastic rumour process and requiring numerical interpretations to understand the real phenomena better. The numerical
process in the differential equations of the model is investigated by using error-estimates. The estimated error is calculated
by the Runge–Kutta method and found either negligible or zero for a relatively small size of the population. This pioneering
paper introduces a new mathematical method into Operations research, motivated by various areas of scientific, social and
daily life, it presents numerical computations, discusses structural frontiers and invites the interested readers to future
research. 相似文献
9.
Najwa Sbei Belen Batanero Fructuoso Barba Beya Haouas Mohamed Lamine Benkhoud Isidoro Barba 《Tetrahedron》2018,74(16):2068-2072
A new series of 3,4-disubstituted quinazolin-2-ones, with potential T-type calcium channel antagonist activity, and new 4-methylene-quinazolin-2-ones, promising catalysts as N-heterocyclic olefins, have been prepared in good yield by a simple reaction between 2-aminobenzophenone, or 2-aminoacetophenone, and cyanomethyl anion electrogenerated by acetonitrile reduction at a graphite electrode, followed by the addition of different organic isocyanates and subsequent heterocyclization. 相似文献
10.
L. I. Belen’kii G. P. Gromova V. I. Smirnov 《Chemistry of Heterocyclic Compounds》2008,44(9):1092-1100
We have studied the possible modification of 2,5-di(thienyl)pyrroles with the aim of preparing compounds which can serve as
precursors of polymers and monomers showing electrical conductivity and specific photochemical properties.
Dedicated to Boris Aleksandrovich Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1356–1365, September, 2008. 相似文献