Wyniki wyszukiwania - Biblioteka Nauki

1

Synthesis and Properties of Azoles and Their Derivatives. Part LVIII. DFT Study on [2+3] Cycloaddition of trans-Nitroethenes to Z-C,N-Diphenylnitrone

100%

Jasiński R. , Barański A.

|

2007

|

tom Vol. 81, nr 8

1441-1447

EN

DFT calculations indicate that the transition states of [2+3] cycloaddition of trans-2- phenylnitroethene to Z-C,N-diphenylnitrone led to 3,4-cis and 3,4-trans 4-nitroisoxazolidines are almost perfectly symmetrical. Asymmetry of the transition states appears for the reaction with more -deficient trans-2-(trichloromethyl)-nitroethene. Nevertheless, in both cases the formation of azolidine rings occurs in one step. The calculational results correlate well with experimental data.

2

New Thiocarbonyl Ylides Derived from 3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione; Generation and Reactions

100%

Woźnicka M. , Rutkowska M. , Mlostoń G. , Majchrzak A. , Heimgartner H.

|

2006

|

tom Vol. 80, nr 10

1683-1693

3

Synthesis and Properties of Azoles and Their Derivatives. Part LXII. Secondary Deuterium Kinetic Isotope Effects in [2+3] Cycloaddition of (E)-2-Phenylnitroethene to (Z)-C,N-Diphenylnitrone

100%

Barański A. , Lyubimtsev A. , Jasiński R. , Kwiatkowska M.

|

2008

|

tom Vol. 82, nr 5

1037-1042

EN

SKIE analysis of [2+3] cycloaddition of (E)-2-phenylnitroethene to (Z)-C,N-diphenyl - nitrone suggests that for both stereoisomeric reaction paths (Scheme 1), the O1-C5 bond of the adduct forms faster than the corresponding C3-C4 bond. Never the less, both stereo isomers are formed by an one-step mechanism. According to Hammond's terminology, the transition states in volved in the reaction mechanism can be classified as asynchronous early states.

4

Synthesis and Properties of Azoles and Their Derivatives. Part LXIV. [2+3] Cycloaddition of trans-1-Nitropropene-1 to C,C,N-Triphenylnitrone in the Light of AM1/COSMO Calculations

100%

Jasiński R. , Barański A.

|

2008

|

tom Vol. 82, nr 5

1043-1049

EN

Quantum-chemical simulations of [2+3] cycloaddition of trans-1-nitropropene with triphenylnitrone in nitromethane and formamide have been carried out using AM1/COSMO algorithm. The results suggest that the reaction leading to 2,3,3- tri - phenyl-4-methyl-5-nitroisoxazolidine occurs by a concerted mechanism, while the alternative reaction leading to regioisomeric 2,3,3-triphenyl-4-ni tro-5- methyl isoxazolidine occurs by anionic mechanism.

5

An experimental and theoretical study of the polar [2+3] cycloaddition reactions between 1-chloro-1-nitroethene and (Z)-C-aryl-N-phenylnitrones

88%

Jasiński R. , Mikulska M. , Barański A.

Open Chemistry

|

2013

|

tom 11

|

nr 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 [...]

6

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

88%

Jasiński R. , Ziółkowska M. , Demchuk O. , Maziarka A.

Open Chemistry

|

2014

|

tom 12

|

nr 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.

7

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

88%

Jasiński R. , Mikulska M. , Barański A.

Open Chemistry

|

2013

|

tom 11

|

nr 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 [...]

8

Synthesis and Properties of Azoles and Their Derivatives. Part LVI. Mechanistic Aspects on the [2+3] Cycloaddition of Z-C,N-Diphenylnitrone with trans-1-Nitropropene-1 and trans-3,3,3-Trichloro-1-nitropropene-1

88%

Jasiński R. , Barański A.

|

2006

|

tom Vol. 80, nr 9

1493-1502

EN

The [2+3] cycloaddition reactions of diphenylnitrone with trans-1-nitropropene-1 and trans-3,3,3-trichloro-1-nitropropene-1 occur via a concerted mechanism despite high -deficient character of dipolarophiles. This mechanism is indicated by cis-stereospecificity of the cycloaddition, the obtained values of activation parameters and weak solvent effect on the reaction kinetics.

9

Synthesis and Properties of Azoles and Their Derivatives. Part LXV*. Kinetic Study on the [2+3] Cycloaddition of Triphenylnitrone to trans-1-Nitroprop-1-ene

88%

Jasiński R. , Barański A.

|

2008

|

tom Vol. 82, nr 11

2125-2131

EN

The [2+3] cycloaddition of triphenylnitrone to trans-1-nitroprop-1-ene proceeds according to concerted mechanism, in spite of pi-deficient character of dipolarophile and strongly shielded one of the reaction centers in molecule of 1,3-dipole. This mechanism is indicated by the obtained values of activation parameters and weak kinetic solvent effect.

10

Regionoselektywność [2+3] cykloaddycji nitroetenu z Z-C,N-diarylonitronami w świetle teorii FMO

63%

Jasiński R. , Mikulska M. , Pawlik H. , Barański A.

|

2008

|

tom R. 105, z. 2-M

121-127

PL

Na podstawie danych obliczeń kwantowochemicznych przeprowadzono analizę pierwotnych efektów orbitalnych oraz coulombowskich w reakcjach [2+3] cykloaddycji diarylonitronów z nitroetenem. Ustalono, że efekty te generalnie sprzyjają powstawaniu odpowiednich 4-nitroizoksazolidyn.

EN

Using quantum-chemical calculations we have carried out an analysis of frontier molecular orbital interactions in the [2+3] cycloaddition reactions of nitroethene with diarylnitrones. In all cases the primary orbital effects and coulombic interactions favored the corresponding 4-nitroisoxazolidines.

11

Termodynamiczne aspekty [2+3] cykloaddycji C-m,m,p-trimetoksyfenylo - N-p - metylofenylonitronu z E-3,3,3-trichloro-1-nitropropenem-1

63%

Szczepanek A. , Jasiński R.

|

2008

|

tom R. 105, z. 1-Ch

143-147

PL

Zbadano termodynamikę [2+3] cykloaddycji C-m,m,p-trimetoksyfenylo-N-p-metylofenylonitronu z E-3,3,3-trichloro-1-nitropropenem-1. Ustalono, że czynniki termodynamiczne najsilniej sprzyjają powstawaniu 3,4-trans-2-p-metylofenylo-3-m,m,p-trimetoksyfenylo-4-trichlorometylo- 5-nitroizoksazolidyny.

EN

The thermodynamics of [2+3] cycloaddition reaction of C-m,m,p-trimethoxyphenyl-N-pmethylophenylnitrone with E-3,3,3-trichloro-1-nitropropene-1 were carried out. The thermodynamics effects indicate that 3,4-trans-2-p-methylophenyl-3-m,m,p-trimethoxyphenyl-4- -trichloromethylo-5-nitroisoxazolidines in this reaction are favored.