A Hydrazone‐Based exo‐Directing‐Group Strategy for β C—H Oxidation of Aliphatic Amines.

Described is a new hydrazone-based exo-directing group (DG) strategy developed for the functionalization of unactivated primary β C−H bonds of aliphatic amines. Conveniently synthesized from protected primary amines, the hydrazone DGs are shown to site-selectively promote the β-acetoxylation and tosyloxylation via five-membered exo-palladacycles. Amines with a wide scope of skeletons and functional groups are tolerated. Moreover, the hydrazone DG can be readily removed, and a one-pot C−H acetoxylation/DG removal protocol was also discovered.