Utilizing a weak-field dipyrrin ligand, we have observed the formation of high-spin iron imido complexes which feature a high-spin ferric center antiferromagnetically coupled to an imidyl radical. The radical intermediate has been shown to be active for inter- and intramolecular transfer. We have applied this strategy to realize the direct amination of aliphatic C�H bonds to furnish cyclic amine products under mild conditions. Using organic azides as the oxidizing agent, allylic, benzylic, tertiary, secondary, and primary C�H bonds have been catalytically functionalized to furnish azetidine (4-membered), pyrrolidine (5-membered), and piperidine (6-membered) N�heterocyclic products. The oxidative amination of C�H bonds preferentially to more electron-rich substrates (olefins and aromatics) is made possible by the unique electronic structure of the putative iron-stabilized imido radical intermediate.

High-spin catalysis using iron: C-H bond functionalization

247th National Meeting (2014)

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