Mechanism and regioselectivity of 1,3-dipolar cycloaddition reactions of bicyclic monoterpenes with aryl and heteroaryl nitrile oxides: a DFT study

2015 ◽  
Vol 93 (7) ◽  
pp. 749-753 ◽  
Author(s):  
Hossein Eshghi ◽  
Amir Khojastehnezhad ◽  
Farid Moeinpour ◽  
Mehdi Bakavoli
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Energy Surface ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
Nitrile Oxides ◽  
Reactivity Indices ◽  
One Step ◽  
Step Mechanism

The reactivity and regioselectivity of 1,3-dipolar cycloaddition reactions of aryl and heteroaryl nitrile oxides (1a–1c) with bicyclic monoterpenes (R)-(+)-a-pinene (2a) and (S)-(–)-b-pinene (2b) have been investigated by using density functional theory based on reactivity indices and activation energy calculations at the B3LYP/6-31G(d) level of theory in the gas phase. The potential energy surface analyses for both reactions are in agreement with the experimental observations. Moreover, our calculations on the geometries, bond orders, and global electron density transfers at the transition state structures shows that these 1,3- dipolar cycloaddition reactions occur via an asynchronous one-step mechanism.

Prediction of the Regioselectivity of 1,3-Dipolar Cycloaddition Reactions of Nitrile Oxides with 2(5H)-Furanones Using Recent Theoretical Reactivity Indices

2017 ◽  
Vol 42 (3) ◽  
pp. 289-299 ◽  
Author(s):  
Imad Eddine Charif ◽  
Wafaa Benchouk ◽  
Sidi Mohamed Mekelleche
Keyword(s):  
Density Functional ◽  
Basis Set ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
Nitrile Oxides ◽  
Reactivity Indices ◽  
Nucleophilic Reactivity ◽  
Global And Local ◽  
Electrophilic Site

The regioselectivity of a series of 16 1,3-dipolar cycloaddition reactions of nitrile oxides with 2(5 H)-furanones has been analysed by means of global and local electrophilic and nucleophilic reactivity indices using density functional theory at the B3LYP level together with the 6-31G(d) basis set. The local electrophilicity and nucleophilicity indices, based on Fukui and Parr functions, have been calculated for the terminal sites, namely the C1 and O3 atoms of the 1,3-dipole and the C4 and C5 atoms of the dipolarophile. These local indices were calculated using both Mulliken and natural charges and spin densities. The results obtained show that the C5 atom of the 2(5 H)-furanones is the most electrophilic site whereas the O3 atom of the nitrile oxides is the most nucleophilic centre. It turns out that the experimental regioselectivity is correctly reproduced, indicating that both Fukui- and Parr-based indices are efficient tools for the prediction of the regiochemistry of the studied reactions and could be used for the prediction of new designed reactions of the same kind.

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

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 26-37
Author(s):  
Karolina Zawadzińska ◽  
Karolina Kula
Keyword(s):  
Density Functional ◽  
Reaction Path ◽  
Computational Study ◽  
Cyano Group ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Reaction Channels ◽  
One Step ◽  
Step Mechanism

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.

scholarly journals A comparative study of AumRhn (4 ≤ m + n ≤ 6) clusters in the gas phase versus those deposited on (100) MgO

2016 ◽  
Vol 18 (32) ◽  
pp. 22122-22128 ◽  
Author(s):  
Fernando Buendía ◽  
Jorge A. Vargas ◽  
Marcela R. Beltrán ◽  
Jack B. A. Davis ◽  
Roy L. Johnston
Keyword(s):  
Genetic Algorithm ◽  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Surface ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Functional Theory ◽  
Phase Versus ◽  
Combined Use

The combined use of a genetic algorithm and Density Functional Theory (DFT) calculations allows us to explore the potential energy surface. Our results show interesting effects on the geometries of the clusters on deposition. Two-dimensional clusters in the gas phase become three-dimensional and vice versa.

scholarly journals Understanding the Molecular Mechanism of the Rearrangement of Internal Nitronic Ester into Nitronorbornene in Light of the MEDT Study

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 462 ◽  
Author(s):  
Agnieszka Kącka-Zych
Keyword(s):  
Density Functional ◽  
Functional Theory ◽  
Molecular Electron ◽  
Bet Analysis ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism ◽  
Nitronic Ester ◽  
Computational Level

The characterization of the structure of nitronic esters and their rearrangement into nitronorbornene reactions has been analyzed within the Molecular Electron Density Theory (MEDT) using Density Functional Theory (DFT) calculations at the B3LYP/6-31G(d) computational level. Quantum-chemical calculations indicate that this rearrangement takes place according to a one-step mechanism. The sequential bonding changes received from the Bonding Evolution Theory (BET) analysis of the rearrangement of internal nitronic ester to nitronorbornene allowed us to distinguish seven different phases. This fact clearly contradicts the formerly-proposed concerted pericyclic mechanism.

scholarly journals MNDO and DFT Computational Study on the Mechanism of the Oxidation of 1,2-Diphenylhydrazine by Iodine

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Gideon A. Shallangwa ◽  
Adamu Uzairu ◽  
Victor O. Ajibola ◽  
Hamza Abba
Keyword(s):  
Reaction Mechanisms ◽  
Density Functional ◽  
Computational Study ◽  
The Other ◽  
Complex Mechanism ◽  
Functional Theory ◽  
One Step ◽  
The One ◽  
Activated Complex ◽  
Step Mechanism

The reaction mechanisms of the oxidation of 1,2-diphenylhydrazine by iodine have been examined using semiempirical and density functional theory methods, the oxidation proceeded via two independent pathways that can be separately monitored. One pathway involved the chain multistep mechanism. The other pathway occurred via a one-step mechanism in which a “cyclic” activated complex was formed which on disproportionation gave the products. The one-step “cyclic” activated complex mechanism proceeds more rapidly than the chain multistep mechanism. The results were explained by analyses based on computational energetics of the optimised reactants, intermediates, transition states, and products of the reaction of iodine with 1,2-diphenylhydrazine.

Sign in / Sign up

Export Citation Format

Share Document