Iron Catalysis of C(sp)-H Azidation Using a Heteroarene Radical Cation Strategy.

The Fe(phen) catalysis of the benzylic C(sp)-H azidation of indoles has been investigated. The Fe(III) complex can selectively oxidize indoles to form arene radical cations, which are transformed into benzylic C(sp) radical intermediates. This strategy exhibits a difference in reactivity between -heteroarenes and benzene, which is difficult to achieve via direct hydrogen abstraction approaches. Various biorelevant azide precursors were constructed, highlighting the utility of this mild first-row transition-metal catalyst system.