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Regio- and stereoselectivity of polar [2+3] cycloaddition reactions between (Z)-C-(3,4,5-trimethoxyphenyl)-N-methylnitrone and selected (E)-2-substituted nitroethenes

100%
Jasiński R., Ziółkowska M., Demchuk O., Maziarka A.
Open Chemistry
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2014
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vol. 12
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issue 5
586-593
EN
[2+3] Cycloaddition reactions of the highly reactive (Z)-C-(3,4,5-trimethoxyphenyl)-N-methylnitrone with (E)-2-R-nitroethenes proceed under mild conditions and yield mixtures of stereoisomeric 2-methyl-3-(3,4,5-trimethoxyphenyl)-4-nitro-5-R-isoxazolidines. The effect of regiospecificity of the cycloadditions may be accounted for by the theory of electrophilicity indexes. Stereoselectivity, however, is determined by a compilation of steric and secondary orbital effects.
2
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A B3LYP/6-31G(d) study of Diels-Alder reactions between cyclopentadiene and (E)-2-arylnitroethenes

100%
Jasiński R., Koifman O., Barański A.
Open Chemistry
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2011
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vol. 9
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issue 6
1008-1018
EN
The B3LYP/6-31G(d) simulations of competing CDA and HDA reactions between cyclopentadiene and (E)-2-arylnitroethenes prove that regardless of the medium polarity, the processes leading to respective 5-nitro-6-aryl-bicyclo-[2,2,0]-hept-2-enes 3,4 (paths A and B) should be most favoured, and the more electrophilic (E)-2-(p-nitrophenyl)-nitroethene should be more reactive than the less electrophilic (E)-2-(p-methoxyphenyl)-nitroethene. Asymmetry of the transition complexes on the favoured pathways increases with increase of medium polarity, but not sufficiently to enforce the zwitterionic mechanism. Analysis of competing pathways leading to HDA adducts proves that not all these compounds can be formed directly from the adducts. In particular, on the path C, the initially formed 5-nitro-6-aryl-bicyclo-[2,2,0]-hept-2-enes 3 is converted to 2-phenyl-4-aza-5-oxy-bicyclo-[3,4,0]-nona-3,7-diene N-oxides 5 as a result of a [3.3]-sigmatropic shift. On the paths D–F leading to 2-phenyl-4-aza-5-oxy-bicyclo-[3,4,0]-nonadienes N-oxides 6–8, the reaction proceeds according to a one-step mechanism. [...]
3
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An experimental and theoretical study of the polar [2+3] cycloaddition reactions between 1-chloro-1-nitroethene and (Z)-C-aryl-N-phenylnitrones

100%
Jasiński R., Mikulska M., Barański A.
Open Chemistry
|
2013
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vol. 11
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issue 9
1471-1480
EN
Abstract Kinetic studies and B3LYP/6-31g(d) calculations indicate the polar nature of [2+3] cycloadditions between 1-chloro-1-nitroethene to (Z)-C-aryl-N-phenylnitrones. This is clearly confirmed by the activation parameters and the substituent and solvent effects. Graphical abstract [...]
4
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Regio-and stereoselectivity of [2+3] cycloaddition of α-substituted nitroethenes with 1,3-dipoles propargyl-allene and allyl type

100%
Jasiński R., Mikulska M., Socha J., Barański A.
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PL
The paper is a critical review of available literature data about regio- and stereoselectivity of [2+3] cycloaddition reactions of α-substituted nitroethenes.
5
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Regio-and stereoselectivity of [2+3] cycloaddition of α-substituted nitroethenes with 1,3-dipoles propargyl-allene and allyl type

100%
Jasiński R., Mikulska M., Socha J., Barański A.
|
PL
The paper is a critical review of available literature data about regio- and stereoselectivity of [2+3] cycloaddition reactions of α-substituted nitroethenes.
6
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The reaction mechanism of the [2+3] cycloaddition between α-phenylnitroethene and (Z)-C,N-diphenylnitrone in the light of a B3LYP/6-31G(d) computational study

100%
Jasiński R., Mikulska M., Barański A.
Open Chemistry
|
2013
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vol. 11
|
issue 3
404-412
EN
Abstract The analysis of reactivity indices suggests the polar nature of the [2+3] cycloaddition of a-phenylnitroethene to (Z)-C,N-diphenylnitrone. Similar conclusions can be drawn from the investigation of the reaction pathways using the B3LYP/6-31g(d) algorithm. This shows that the cycloaddition mechanism depends on the polarity of the reaction medium. A one-step mechanism is followed in the gas phase and toluene in all the theoretically possible pathways. In more polar media (nitromethane, water), a zwitterionic, two-step rather than a one-step mechanism occurs in the pathway leading to 3,4-trans-2,3,5-triphenyl-4-nitroisoxazolidine. Graphical abstract [...]
7
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Synthesis of nitrones

76%
Socha J., Jabłońska M., Głąb K., Mikulska M., Jasiński R., Barański A.
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PL
The paper is a critical review of available literature data that are connected with synthesis of nitrones.
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