Accessing Azetidines through Magnesium-Mediated Nitrogen Group Transfer from Iminoiodinane to Donor-Acceptor Cyclopropanes

Herein, we report a Lewis acid-mediated ring expansion of donor-acceptor cyclopropanes (DACs) to substituted azetidines via nucleophilic nitrogen group transfer from readily accessible iminoiodinane. This protocol operates under mild, transition-metal-free conditions, and showcases excellent chemoselectivity, along with broad functional group tolerance. We report for the first time that challenging alkyl donor-acceptor cyclopropanes can undergo ring expansion leading to aliphatic azetidines without relying on external oxidants or precious transition-metal catalysts. Mechanistically, the coordination of a magnesium (Mg)-Lewis acid to the DAC promotes nucleophilic ring opening with a putative Mg-amide species generated from the iminoiodinane under the reaction conditions to furnish the azetidine products.