Unveiling the Reactivity of Cyclic Azomethine Ylides in [3+2] Cycloaddition Reactions within the Molecular Electron Density Theory

Domingo, Luís R.; Kula, Karolina; Ríos‐Gutiérrez, Mar

doi:10.1002/ejoc.202000745

Cited by 55 publications

(57 citation statements)

References 28 publications

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“…For the 32CA reactions of DAAs 8-10 with NBD 11, the GEDT values are found between 0.02-0.05 e, predicting non-polar 32CA reactions, thus, being classified as reactions of null electron density flux (NEDF) [71]. This decrease in polarity is consistent with the increase in the energy barrier of the corresponding 32CA reactions.…”

Section: Gassupporting

confidence: 53%

Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

2021

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The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD), with simplest diazoalkane (DAA) and three DAAs of increased electrophilicity, have been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G (d,p) computational level. These pmr-type 32CA reactions follow an asynchronous one-step mechanism with activation enthalpies ranging from 17.7 to 27.9 kcal·mol−1 in acetonitrile. The high exergonic character of these reactions makes them irreversible. The presence of electron-withdrawing (EW) substituents in the DAA increases the activation enthalpies, in complete agreement with the experimental slowing-down of the reactions, but contrary to the Conceptual DFT prediction. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather non-polar 32CA reactions. The present MEDT study establishes the depopulation of the N–N–C core in this series of DAAs with the increase of the EW character of the substituents present at the carbon center is responsible for the experimentally found deceleration.

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Section: Gassupporting

confidence: 53%

Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

2021

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“…All stationary points were optimized using the M062X functional [35], together with the 6-31+G(d) basis set. This theory level has been commonly used for the mechanistic research aspects of 32CA reactions [8,[36][37][38][39].…”

Section: Computational Detailsmentioning

confidence: 99%

Application of β-Phosphorylated Nitroethenes in [3+2] Cycloaddition Reactions Involving Benzonitrile N-Oxide in the Light of a DFT Computational Study

Zawadzińska

Kula

2021

Organics

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The regiochemistry of [3+2] cycloaddition (32CA) processes between benzonitrile N-oxide 1 and β-phosphorylated analogues of nitroethenes 2a–c has been studied using the Density Functional Theory (DFT) at the M062X/6-31+G(d) theory level. The obtained results of reactivity indices show that benzonitrile N-oxide 1 can be classified both as a moderate electrophile and moderate nucleophile, while β-phosphorylated analogues of nitroethenes 2a–c can be classified as strong electrophiles and marginal nucleophiles. Moreover, the analysis of CDFT shows that for [3+2] cycloadditions with the participation of β-phosphorylatednitroethene 2a and β-phosphorylated α-cyanonitroethene 2b, the more favored reaction path forms 4-nitro-substituted Δ2-isoxazolines 3a–b, while for a reaction with β-phosphorylated β-cyanonitroethene 2c, the more favored path forms 5-nitro-substituted Δ2-isoxazoline 4c. This is due to the presence of a cyano group in the alkene. The CDFT study correlates well with the analysis of the kinetic description of the considered reaction channels. Moreover, DFT calculations have proven the clearly polar nature of all analyzed [3+2] cycloaddition reactions according to the polar one-step mechanism.

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“…Note the change of the sign of the GEDT at TS-r1-10, 0.14 e, and at TS-r1-18, −0.19 e; thus, while azomethine ylide 10 acts as electron-donor, nitrous oxide 18 acts as electron-acceptor. This is a consequence of the supernucleophilic character [59] of 10 and the moderate electrophilic character of 18 (see Table 3); and finally, (iii) the non-polar 32CA reactions of nitrile imine 14 and nitrone 15 can be classified as NEDF [29].…”

Section: Tacmentioning

confidence: 99%

“…Very recently, organic reactions have been classified as forward electron density flux (FEDF) and reverse electron density flux (REDF) reactions, depending on the direction of the flux of the electron density at the TS [28]. Non-polar reactions are classified as null electron density flux (NEDF) reactions [29]. This classification is unequivocal, as the GEDT is a measure of the actual electron density transfer at the TSs.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Origin of the Regioselectivity in Non-Polar [3+2] Cycloaddition Reactions through the Molecular Electron Density Theory

2020

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The regioselectivity in non-polar [3+2] cycloaddition (32CA) reactions has been studied within the Molecular Electron Density Theory (MEDT) at the B3LYP/6-311G(d,p) level. To this end, the 32CA reactions of nine simplest three-atom-components (TACs) with 2-methylpropene were selected. The electronic structure of the reagents has been characterized through the Electron Localisation Function (ELF) and the Conceptual DFT. The energy profiles of the two regioisomeric reaction paths and ELF topology of the transition state structures are studied to understand the origin of the regioselectivity in these 32CA reactions. This MEDT study permits to conclude that the least electronegative X1 end atom of these TACs controls the asynchronicity in the C−X (X=C, N, O) single bond formation, and consequently, the regioselectivity. This behaviour is a consequence of the fact that the creation of the non-bonding electron density required for the formation of the new single bonds has a lower energy demand at the least electronegative X1 atom than at the Z3 one.

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Unveiling the Reactivity of Cyclic Azomethine Ylides in [3+2] Cycloaddition Reactions within the Molecular Electron Density Theory

Cited by 55 publications

References 28 publications

Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

Application of β-Phosphorylated Nitroethenes in [3+2] Cycloaddition Reactions Involving Benzonitrile N-Oxide in the Light of a DFT Computational Study

Understanding the Origin of the Regioselectivity in Non-Polar [3+2] Cycloaddition Reactions through the Molecular Electron Density Theory

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