A Molecular Electron Density Theory Study of the [3+2] Cycloaddition Reaction of Pseudo(mono)radical Azomethine Ylides with Phenyl Vinyl Sulphone

The [3+2] cycloaddition (32CA) reaction of an azomethine ylide (AY), derived from isatin and L-proline, with phenyl vinyl sulphone has been studied within Molecular Electron Density Theory (MEDT) at the ?B97X-D/6-311G(d,p) level. ELF topological analysis AY classifies it as a pseudo(mono)radical species two monosynaptic basins C1 carbon, integrating total 0.76 e. While strong electrophilic character, is supernucleophile, suggesting high polar character low activation energy for reaction. nucleophilic Parr functions indicate that pseudoradical carbon most center. 32CA presents Gibbs free 13.1 kcal·mol?1 exergonic by ?26.8 kcal·mol?1. This endo stereoselectivity meta regioselectivity. Analysis global electron density transfer (GEDT) favorable meta/endo TS, 0.31 e, accounts this reaction, classified forward flux (FEDF). A Bonding Evolution (BET) study along path characterizes taking place through non-concerted two-stage one-step mechanism, pseudo(mono)radical-type in agreement AY.