A molecular electron density theory study for [3 + 2] cycloaddition reactions of1‐pyrroline‐1‐oxide with disubstituted acetylenes leading to bicyclic 4‐isoxazolines

Abstract

The [3 + 2] cycloaddition (32CA) reactions of 1‐pyrroline‐1‐oxide with acetylene and with a series of four symmetrically disubstituted acetylenes (XC ≡ CX, X = CH3, NH2, OH, F), leading to 4,5‐disubstituted bicyclic 4‐isoxazolines, have been studied within molecular electron density theory at the B3LYP‐D3/6‐311++G(d,p) computational level. These 32CA reactions take place through aone‐stepmechanism, with activation enthalpies in toluene between 24.4 (X = NH2) and 12.9 (X = F) kcal mol−1. Due to the strong exergonic character of these 32CA reactions, between −12.0 and −47.6 kcal mol−1, they are irreversible. The 32CA reaction of difluoroacetylene, involving fluorine as the most electronegative atom of this series attached to the acetylene carbons, presents the lowest activation enthalpy due to the increase of the polar character of this 32CA reaction, evidenced by the analysis of the global electron density transfer at the corresponding transition state structure. The topological analysis of the electron localization function along the reaction paths of these 32CA reactions allows us to characterize them as the zwitterionic‐type ones. The formation of the new CC and CO single bonds takes place at the end of the reactions through the coupling ofpseudoradicalcenters.

Unveiling the high regioselectivity and stereoselectivity within the synthesis of spirooxindolenitropyrrolidine: A molecular electron density theory perspective

“…The ELF [21,22] topological analysis presents a wellestablished procedure to determine the electron density changes along a reaction path. [17][18][19][28][29][30][31][32][33][34][35][36][37][38][39] The conjunction of ELF study and Thom's catastrophe theory, [72] namely, the bonding evolution theory (BET), [73] has been applied to structure the plausible mechanism of numerous chemical reactions. [28][29][30][31][32][33][34][35][36][37][38][39]74,75] Herein, for the BET study, the topological analysis of the ELF was performed at the nuclear configurations along the energetically favoured reaction path of the 32CA reaction between AZY 8 and BNS 9 leading to cycloadduct 10 via TS1.…”

“…[30] Very recently, the reactivity of cyclic azomethine ylides in 32CA reactions are explained within the MEDT framework. [31] Our recent MEDT studies have successfully analysed the strain promotion, [32,33] catalytic effects, [34] regioselectivities and stereoselectivities, [35,36] substituent effects [37] and molecular reactivity [38,39] observed in 32CA reactions.…”

Дослідження Фотохімічної Димеризації 3-Гетероарил (Фурил, Тіофіл, Селенофіл І Телурофіл)-Акрилатів Методом DFT

“…The ELF establishes a direct quantitative connection between the electron density distribution and the chemical structure [36][37][38][39][40][41][42][43]. Herein, the reactivity of reactants in dimerization reactions is studied from the ELF topological analysis.…”

Understanding the Reactivity of C-Cyclopropyl-N-Methylnitrone Participating in [3+2] Cycloaddition Reactions Towards Styrene with a Molecular Electron Density Theory Perspective

“…In the past few years, the advent of computational chemistry has gradually attracted theoretical chemists to analyze the reactivity and selectivity of organic molecules. A new theoretical outlook for organic reactions was proposed by Domingo in 2016 named the molecular electron density theory (MEDT) after interpretation of a vast array of organic reactivity, majority of them dedicated to Diels-Alder and 32CA reactions [14][15][16][17][18]. This theory analyzes the changes in electron density to study the molecular reactivity and has been successfully applied for several 32CA reactions since last four years.…”