Iron Catalysis of C(sp 3 )-H Azidation Using a Heteroarene Radical Cation Strategy.

The Fe III (phen) 3 catalysis of the benzylic C(sp 3 )-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 3 ) radical intermediates. This strategy exhibits a difference in reactivity between N -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.