Metal-Controlled Enantiodivergent Tandem Rearrangement to Synthesize 2H-Azirines

A metal-controlled enantiodivergent rearrangement of α-diazo-β-keto oxime ethers has been developed. Switching the metal catalyst from Co(II) to Fe(II) with an identical ligand completely reverses the asymmetric induction. Both enantiomers of chiral 2H-azirines and its derivatives are accessible under thermal or photolytic conditions. The cobalt-based reaction is highly efficient even at 0.05 mol% catalyst loading. Mechanistic studies, including kinetic experiments and density functional theory calculations, reveal that distinct electronic properties of cobalt and iron modulate intermediate conformations, thereby altering the enantioselectivity.