Copper‐Catalyzed Skeletal Rearrangement of O ‐Propargyl Oximes: A Mechanistic Manifold

The Cu‐mediated skeletal rearrangement of O ‐propargyl oximes features a mechanistic manifold that yields different compounds. Strategic modification of the substituent at the oxime moiety (R 3 ) allows the selection of a preferred mechanistic route that leads to azete oxides/amidodienes (if R 3 is an electron‐poor/‐rich aryl group) or to pyridine N ‐oxides (if R 3 is an olefin). In the present work, we explore the mechanism that leads to each product. All the computed mechanisms have in common an initial stepwise 2,3‐rearrangement that generates the key N ‐allenylnitrone intermediate the further reactivity of which will depend on the nature of the R 3 substituent. Our calculations reveal the subtle details that govern the different behavior of this reaction with each of the aforementioned substituents and disclose a complex and multistep pathway to different aminodienes.