Iron‐Promoted Radical Cyclization of β, γ‐Unsaturated Oximes: Dual Role of Iron(III) Nitrate as a Promoter and Nitrooxy Source

A method for the radical cyclization of β,γ‐unsaturated oximes to access the isoxazoline backbone has been developed, in which iron(III) nitrate plays a dual role as a promoter and a nitrooxy source. Iron‐promoted cyclization is well tolerated with a series of aryl‐ and alkyl‐substituted β,γ‐unsaturated oximes, which readily affords the desired isoxazolines that can be easily transformed into useful compounds. Mechanistic experiments support that a radical pathway may be involved in the cyclization of β,γ‐unsaturated oximes.