From the bottle: simple iron salts for the efficient synthesis of pyrrolidines via catalytic C-H bond amination.

Commercially available iron salts FeX2 are remarkably active catalysts for pyrrolidine formation from organic azides via direct C-H bond amination. With FeI2, amination is fast and selective, (<30 min for 80% yield at 2 mol% loading), TONs up to 370 are reached with just 0.1 mol% catalyst, different functional groups are tolerated, and a variety of C-H bonds were activated.