Ring Expansion of Donor–Acceptor Cyclopropane via Substituent Controlled Selective <i>N</i>‑Transfer of Oxaziridine: Synthetic and Mechanistic Insights

A distinctive <i>N</i>-substituent controlled electrophilic <i>N</i>-transfer of oxaziridines with donor–acceptor cyclopropanes in the presence of MgI<sub>2</sub> is reported. Contrary to earlier reports, the oxaziridine having bulkier <i>N</i>-substituents can also give <i>N</i>-transferred product instead of the <i>O</i>-transferred one. Interestingly, the oxaziridines having α-H containing <i>N</i>-substituents lead to the pyrrolidine derivatives through [3 + 2] cycloaddition. A mechanistic reasoning for this divergent reactivity is depicted by density functional theory calculations and validated through energy decomposition analysis.