Copper-catalyzed [1,3]-nitrogen rearrangement of O- aryl ketoximes via oxidative addition of N-O bond in inverse electron flow.

The [1,3]-nitrogen rearrangement reactions of O -aryl ketoximes were promoted by N- heterocyclic carbene (NHC)-copper catalysts and BF 3 ·OEt 2 as an additive, affording ortho- aminophenol derivatives in good yields. The reaction of substrates with electron-withdrawing substituents on the phenol moiety are accelerated by adding silver salt and modifying the substituent at the nitrogen atom. Density functional theory calculations suggest that the rate-determining step of this reaction is the oxidative addition of the N-O bond of the substrate to the copper catalyst. The negative ρ values of the substituent at both the oxime carbon and phenoxy group indicate that the donation of electrons by the oxygen and nitrogen atoms accelerates the oxidative addition.