Unveiling Intramolecular [3+2] Cycloaddition Reactions Leading to Functionalized Heterocycles in the Light of Molecular Electron Density Theory.

The relative reactivity and cis/trans selectivity of the intramolecular [3+2] cycloaddition (IM32CA) reactions of nitrile oxide (NO), azide (AZ), nitrile sulfide (NS) and nitrile ylide (NY), leading to functionalized heterocycles are studied within the Molecular Electron Density Theory. The kinetically controlled IM32CA reactions are predicted to be cis stereospecific, while the reaction feasibility follows the order NY > NS > NO > AZ with the respective activation Gibbs free energies of 13.7, 17.

An MEDT Study of the Reaction Mechanism and Selectivity of the Hetero-Diels-Alder Reaction Between 3-Methylene-2,4-Chromandione and Methyl Vinyl Ether.

The hetero-Diels-Alder (HDA) reaction between the ambident heterodiene 3-methylene-2,4-chromandione (MCDO) and non-symmetric methyl vinyl ether (MVE) is investigated using the molecular electron density theory (MEDT) at the B3LYP/6-311G(d,p) computational level. The aim of this study is to gain insight into its molecular mechanism and to elucidate the factors that control the selectivity found experimentally. DFT-based reactivity indices reveal that MCDO exhibits strong electrophilic characteristics, while MVE displays a strong nucleophilic character.

A molecular electron density theory study of the bimolecular nucleophilic substitution reactions on monosubstituted methyl compounds.

The nucleophilic substitution reactions involving methyl monosubstituted compounds have been studied within the Molecular Electron Density Theory (MEDT) at the B97X-D/6-311+G(d,p) computational level in DMSO. This study aims to characterize the electronic nature of the transition state structures (TSs) involved in the so-called S2 and Si reactions. Both electron localization function and atom-in-molecules topological analyses indicate that the TSs involved in these nucleophilic substitutions can be described as a central methyl CH carbocation, which is strongly stabilized by the presence of two neighbouring nucleophilic species through electron density transfer.

Understanding the Electronic Effects of Lewis Acid Catalysts in Accelerating Polar Diels-Alder Reactions.

The electronic effects of Lewis acid (LA) catalysts in reducing the activation energies of polar Diels-Alder (P-DA) reactions have been studied within Molecular Electron Density Theory. To this end, a quantum topological energy partitioning scheme, namely, the Relative Interacting Atomic Energy (RIAE) analysis, is applied to the transition state structures (TSs) and the ground state of the reagents of two different LA-catalyzed P-DA reactions. Analyses of the ξ total energies of the two interacting frameworks (X) show that the electronic energy stabilization of the electrophilic frameworks, resulting from the global electron density transfer (GEDT), is the cause of an effective decrease of the activation energies.

MEDT analysis of mechanism and selectivities in non-catalyzed and lewis acid-catalyzed diels-alder reactions between R-carvone and isoprene.

Within the context of Molecular Electronic Density Theory (MEDT), this study investigates the Diels-Alder reaction among isoprene (2) and R-carvone (1R) applying DFT simulations, with and without Lewis acid (LA) catalysis. The results show that carvone (1R) acts as an electrophile and isoprene (2) as a nucleophile in a polar process. LA catalysis increases the electrophilicity of carvone, thereby improving the reactivity and selectivity of the reaction by reducing the activation Gibbs free energy.