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A B3LYP/6-31G(d) study of Diels-Alder reactions between cyclopentadiene and (E)-2-arylnitroethenes

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Jasiński R. , Koifman O. , Barański A.

Open Chemistry

2011

tom 9

nr 6

1008-1018

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. [...]

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

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Jasiński R. , Mikulska M. , Barański A.

Open Chemistry

2013

tom 11

nr 3

404-412

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 [...]

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.

Czasopismo Techniczne

The paper is a critical review of available literature data about regio- and stereoselectivity of [2+3] cycloaddition reactions of α-substituted nitroethenes.

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.

The paper is a critical review of available literature data about regio- and stereoselectivity of [2+3] cycloaddition reactions of α-substituted nitroethenes.

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

tom 11

nr 9

1471-1480

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 [...]

Synthesis of nitrones

75%

Socha J. , Jabłońska M. , Głąb K. , Mikulska M. , Jasiński R. , Barański A.

Czasopismo Techniczne

The paper is a critical review of available literature data that are connected with synthesis of nitrones.