Compounds With Allene Moiety as a Component in the [3+2] Cycloaddition Reactions: A Molecular Electron Density Theory Study

ABSTRACT

The [3+2] cycloaddition (32CA) reactions involving C‐phenyl‐N‐methylnitrone and (phenylsulfonyl)propadiene have been theoretically studied within the molecular electron density theory (MEDT). Topological analysis of the electron localization function (ELF) of the reagents allowed us to learn the electronic structure of the mentioned reagents. Analysis of conceptual density functional theory (CDFT) indices indicates that the nitrone will play the role of a strong nucleophile, while (phenylsulfonyl)propadiene will act as a strong electrophile. According to the local Parr functions of the reagents, the most favorable reaction path of these 32CA reactions will be initialized by the nucleophilic attack of the O3 of nitrone on the central electrophilic C4 carbon of the (phenylsulfonyl)propadiene. In the study reaction, we noticed two theoretically possible reaction paths (A and B) leading to two stereoisomeric products. The Gibbs free energy for Path A of the 32CA reaction is higher than that for Path B of the 32CA reaction, and according to that, Path A should be considered kinetically unfavored. A bonding evolution theory (BET) study of the more favorable channel B associated with the 32CA reaction indicates that this reaction is associated with a highly asynchronous one‐step , two‐stage mechanism in which the activation energy is related to the formation of a pseudoradical center at the C4 carbon atom and V(N2) monosynaptic basin.