Competition between one-step and two-step mechanism in polar [3 + 2] cycloadditions of (Z)-C-(3,4,5-trimethoxyphenyl)-N-methyl-nitrone with (Z)-2-EWG-1-bromo-1-nitroethenes

Jasiński, Radomir

doi:10.1016/j.comptc.2018.01.009

Cited by 42 publications

(18 citation statements)

References 38 publications

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“…On the other hand, earlier reports [42] suggest a stepwise mechanism, with zwitterionic intermediate. It should be additionally underlined that stepwise mechanisms have been recently documented based on comprehensive experimental and quantum-chemical studies regarding a group of different type cycloadditions involving conjugated nitroalkenes [35,43,44]. Therefore, neither one-step nor stepwise mechanisms can be excluded a priori for the reactions studied (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

Competition between [2 + 1]- and [4 + 1]-cycloaddition mechanisms in reactions of conjugated nitroalkenes with dichlorocarbene in the light of a DFT computational study

Alnajjar

Jasiński

2019

J Mol Model

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The competition between [2 + 1] and [4 + 1] channels regarding reactions of conjugated nitroalkenes with dichlorocarbene was explored based on B3LYP/6-31G(d) calculations. It was found that, in the case of cycloadditions involving parent nitroethene and its 1-substituted analogs, the [2 + 1] scheme should be treated as possible only from the kinetic process point of view. On the other hand, in similar reactions involving 2-substituted nitroethenes, both channels considered may compete. Additionally, mechanistic aspects of all cycloadditions were analyzed. It was found that the considered [2 + 1]-cycloadditions proceed via a non-polar mechanism with a biradicaloidal transition state (TS), whereas [4 + 1]-cycloadditions proceed via a polar mechanism with a zwitterionic TS.

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Section: Resultsmentioning

confidence: 99%

Competition between [2 + 1]- and [4 + 1]-cycloaddition mechanisms in reactions of conjugated nitroalkenes with dichlorocarbene in the light of a DFT computational study

Alnajjar

Jasiński

2019

J Mol Model

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“…This point of view was confirmed very recently also by other theoretician chemists. [13][14][15][16][17] In addition, some examples of reactions involving diaryl diazomethanes and different types of ethylene derivatives have been explored recently using comprehensive experimental and quantum chemical methods. [18,19] It has been found that the initial stage of these reactions is the formation of a zwitterionic intermediate.…”

Section: Introductionmentioning

confidence: 99%

A DFT Study on the Barton–Kellogg Reaction – The Molecular Mechanism of the Formation of Thiiranes in the Reaction between Diphenyldiazomethane and Diaryl Thioketones

et al. 2019

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The mechanism of the reaction of diphenyldiazomethane with thiobenzophenone and related hetaryl thioketones leading to the corresponding tetrasubstituted thiiranes was studied by means of DFT computational methods at the M06-2X/6-311+G(d) level of theory. The study showed that the initial step of this conversion is a classic one-step (3+2) cycloaddition to give 1,3,4-thiadiazolines in a regioselective manner. These initially formed products undergo a spontaneous extrusion of N2 resulting in the formation of tetraaryl-substituted thiocarbonyl ylides as reactive intermediates. The calculated parameters of the activation for the subsequent 1,3-dipolar electrocyclizations are low (ΔG = 10.8-11.9 kcal/mol) and the only products formed in these reactions are the corresponding thiiranes. The alternative pathways leading to thiocarbonyl ylides via stepwise mechanisms involving zwitterionic or biradical nitrogen-containing intermediates were ruled out.

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“…Such molecular complexes have been recently detected for 32CAs of disubstituted nitrones. [42][43][44] The molecular complexes (MCs) for present study were found to be enthalpic in nature with ∆H values of -6.7, -7.4, -4.0 and -1.5 kcal* mol -1 in gas phase and -0. The gas phase activation energy of TSox is lower than that of TSon, TSmx and TSmn by 1.5, 0.8 and 2.3 kcal mol -1 .…”

Section: Study Of the Energy Profile Associated With The 32ca Betweenmentioning

confidence: 63%

Understanding the regio-and diastereoselective synthesis of a potent antinociceptive isoxazolidine from C-(pyridin-3-yl)-N-phenylnitrone in the light of molecular electron density theory

Acharjee

2020

JSCS

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[3+2] cycloaddition reaction of C-(pyridin-3-yl)-N-phenylnitrone and 2-propen-1-ol yields stereochemically defined potent antinociceptive isoxazolidine derivative. Computational quantum calculations (CQC) are performed for this synthesis to predict the polar character, mechanism and selectivity within the framework of molecular electron density theory (MEDT). Topological analysis of the electron localization function (ELF) classifies the nitrone as a zwitter-ionic(zw-) type three atom component (TAC) showing absence of any pseudoradical or carbenoid centre. Four reaction channels corresponding to the possible regio-and stereoselective pathways are studied at DFT/ /B3LYP/6-311G(d,p) level of theory. The reaction follows one-step mechanism with asynchronous transition states and the computed activation energies agree well with experimental data. The reaction can be differentiated into nine ELF topological phases, with faster CC bond formation. Global electron density theory (GEDT) at the favoured transition state and conceptual density functional theory (CDFT) indices at the ground state of the reagents indicate non-polar character. Non-covalent interactions are predicted by atoms-in-molecules (AIM) analysis and non-covalent interaction (NCI) plots at the transition states.

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Competition between one-step and two-step mechanism in polar [3 + 2] cycloadditions of (Z)-C-(3,4,5-trimethoxyphenyl)-N-methyl-nitrone with (Z)-2-EWG-1-bromo-1-nitroethenes

Cited by 42 publications

References 38 publications

Competition between [2 + 1]- and [4 + 1]-cycloaddition mechanisms in reactions of conjugated nitroalkenes with dichlorocarbene in the light of a DFT computational study

Competition between [2 + 1]- and [4 + 1]-cycloaddition mechanisms in reactions of conjugated nitroalkenes with dichlorocarbene in the light of a DFT computational study

A DFT Study on the Barton–Kellogg Reaction – The Molecular Mechanism of the Formation of Thiiranes in the Reaction between Diphenyldiazomethane and Diaryl Thioketones

Understanding the regio-and diastereoselective synthesis of a potent antinociceptive isoxazolidine from C-(pyridin-3-yl)-N-phenylnitrone in the light of molecular electron density theory

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Competition between one-step and two-step mechanism in polar [3 + 2] cycloadditions of (Z)-C-(3,4,5-trimethoxyphenyl)-N-methyl-nitrone with (Z)-2-EWG-1-bromo-1-nitroethenes

Cited by 42 publications

References 38 publications

Competition between [2 + 1]- and [4 + 1]-cycloaddition mechanisms in reactions of conjugated nitroalkenes with dichlorocarbene in the light of a DFT computational study

Competition between [2 + 1]- and [4 + 1]-cycloaddition mechanisms in reactions of conjugated nitroalkenes with dichlorocarbene in the light of a DFT computational study

A DFT Study on the Barton–Kellogg Reaction – The Molecular Mechanism of the Formation of Thiiranes in the Reaction between Diphenyldiazomethane and Diaryl Thioketones

Understanding the regio-and diastereoselective synthesis of a potent antinociceptive isoxazolidine from C-(pyridin-3-yl)-N-phenylnitrone in the light of molecular electron density theory

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Competition between one-step and two-step mechanism in polar [3 + 2] cycloadditions of (Z)-C-(3,4,5-trimethoxyphenyl)-N-methyl-nitrone with (Z)-2-EWG-1-bromo-1-nitroethenes