Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD), with simplest diazoalkane (DAA) and three DAAs increased electrophilicity, have been studied within the Molecular Electron Density Theory (MEDT) at MPWB1K/6-311G (d,p) computational level. These pmr-type 32CA follow an asynchronous one-step mechanism activation enthalpies ranging from 17.7 to 27.9 kcal·mol?1 in acetonitrile. high exergonic character these makes them irreversible. presence electron-withdrawing (EW) substituents DAA increases enthalpies, complete agreement experimental slowing-down reactions, but contrary Conceptual DFT prediction. Despite electrophilic reagents, global electron density transfer TSs indicates rather non-polar reactions. present MEDT study establishes depopulation N–N–C core this series increase EW carbon center is responsible for experimentally found deceleration.