A molecular electron density theory study of the asymmetric hetero-Diels-Alder cycloaddition reaction between ferrocenyl-substituted thiabutadiene and methyl propiolate

2018 ◽  
Vol 1140 ◽  
pp. 117-124 ◽  
Author(s):  
Tooba Afshari ◽  
Mohsen Mohsennia
Keyword(s):  
Electron Density ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
Methyl Propiolate ◽  
Molecular Electron ◽  
Molecular Electron Density Theory

scholarly journals A molecular electron density theory study of the [3 + 2] cycloaddition reaction of nitrones with ketenes

2017 ◽  
Vol 15 (7) ◽  
pp. 1618-1627 ◽  
Author(s):  
Mar Ríos-Gutiérrez ◽  
Andrea Darù ◽  
Tomás Tejero ◽  
Luis R. Domingo ◽  
Pedro Merino
Keyword(s):  
Electron Density ◽  
Cycloaddition Reaction ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Electrophilic Character

The zw-type 32CA reactions of nitrones with ketenes are controlled by the nucleophilic character of the nitrone and the electrophilic character of the ketene. They are chemo- and regio-selective and the use of electrophilic ketenes changes the mechanism from one-step to two-step.

A molecular electron density theory study of the enhanced reactivity of aza aromatic compounds participating in Diels–Alder reactions

2020 ◽  
Vol 18 (2) ◽  
pp. 292-304 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
Patricia Pérez
Keyword(s):  
Electron Density ◽  
Aromatic Compounds ◽  
Activation Energies ◽  
Diels Alder ◽  
Aromatic Character ◽  
Molecular Electron ◽  
Molecular Electron Density Theory

The change of C–H by N: in these aromatic compounds decreases the ring electron density (RED), thus decreasing the activation energies of the aza Diels–Alder reactions mainly by the loss of the aromatic character of the reagents.

scholarly journals Unveiling the Intramolecular Ionic Diels–Alder Reactions within Molecular Electron Density Theory

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 834-853
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
María José Aurell
Keyword(s):  
Electron Density ◽  
Electronic Structures ◽  
Activation Enthalpy ◽  
Topological Analysis ◽  
Chair Conformation ◽  
Diels Alder ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism

The intramolecular ionic Diels–Alder (IIDA) reactions of two dieniminiums were studied within the Molecular Electron Density Theory (MEDT) at the ωB97XD/6-311G(d,p) computational level. Topological analysis of the electron localization function (ELF) of dieniminiums showed that their electronic structures can been seen as the sum of those of butadiene and ethaniminium. The superelectrophilic character of dieniminiums accounts for the high intramolecular global electron density transfer taking place from the diene framework to the iminium one at the transition state structures (TSs) of these IIDA reactions, which are classified as the forward electro density flux. The activation enthalpy associated with the IIDA reaction of the experimental dieniminium, 8.7 kcal·mol−1, was closer to that of the ionic Diels–Alder (I-DA) reaction between butadiene and ethaniminium, 9.3 kcal·mol−1. However, the activation Gibbs free energy of the IIDA reaction was 12.7 kcal·mol−1 lower than that of the intermolecular I-DA reaction. The strong exergonic character of the IIDA reaction, higher than 20.5 kcal·mol−1, makes the reaction irreversible. These IIDA reactions present a total re/exo and si/endo diastereo selectivity, which is controlled by the most favorable chair conformation of the tetramethylene chain. ELF topological analysis of the single bond formation indicated that these IIDA reactions take place through a non-concerted two-stage one-step mechanism. Finally, ELF and atoms-in-molecules (AIM) topological analyses of the TS associated with the inter and intramolecular processes showed the great similarity between them.

scholarly journals Unveiling the Ionic Diels-Alder Reactions within the Molecular Electron Density Theory

2021 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
María J. Aurell
Keyword(s):  
Electron Density ◽  
Topological Analysis ◽  
Activation Energies ◽  
High Reactivity ◽  
Diels Alder ◽  
Electron Density Transfer ◽  
Molecular Electron ◽  
Iminium Cations ◽  
Molecular Electron Density Theory ◽  
Density Transfer

The ionic Diels-Alder (I-DA) reactions of a series of six iminium cations with cyclopentadiene have been studied within the Molecular Electron Density Theory (MEDT). The superelectrophilic character of iminium cations,  > 8.20 eV, accounts for the high reactivity of these species participating in I-DA reactions. The activation energies are found between 13 and 20 kcal·mol-1 lower in energy than those associated to the corresponding Diels-Alder (DA) reactions of neutral imines. These reactions are low endo selective as a consequence of the cationic character of the TSs, but highly regioselective. Solvents have poor effects on the relative energies, and an unappreciable effect in the geometries. In dichloromethane the activation energies increase slightly as a consequence of the better solvation of the iminium cations than the cationic TSs. ELF topological analysis of the bonding changes along the I-DA reactions shows that they are very similar to those in polar DA reactions. The present MEDT study makes it possible establishing that the global electron density transfer (GEDT) taking place at the TSs of I-DA reactions, and not steric (Pauli) repulsions such as have been recently proposed, are responsible for the features of these type of DA reactions.

scholarly journals A molecular electron density theory study of the participation of tetrazines in aza-Diels–Alder reactions

RSC Advances ◽  
2020 ◽  
Vol 10 (26) ◽  
pp. 15394-15405 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
Patricia Pérez
Keyword(s):  
Electron Density ◽  
Diels Alder ◽  
Molecular Electron ◽  
Molecular Electron Density Theory ◽  
Electron Withdrawing Substituents

The electron-withdrawing substituents on the tetrazine favour aza-Diels–Alder reactions towards nucleophilic ethylenes, but they do not react with electrophilic ethylenes.

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