Iron(iii)/quinoxaline-derived N,N-ligand catalyzed oxygen transfer reaction of N-vinyl nitrones through selective 4-electrocyclization and N-O bond cleavage

We describe an iron(iii)/quinoxaline-derived N,N-ligand catalyzed oxygen transfer reaction of N-vinyl nitrones to prepare a variety of 2,5-dihydrooxazoles in good yields under mild reaction conditions. Experimental results revealed that the reaction might undergo an initial O-4 pi-azaelectrocyclization, N-O bond cleavage, and sequential intramolecular cyclization over three steps. The present method highlights a broad substrate scope, good functional group tolerance, novel N,N-ligand promoted selective O-4 pi-azaelectrocyclization, and the new application of N-vinyl nitrones.