A Hydrazone-Based exo-Directing-Group Strategy for β C-H Oxidation of Aliphatic Amines

Abstract

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 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. All about the DGs: A hydrazone-based exo-directing group (DG) strategy is developed for the functionalization of unactivated primary β C-H bonds of aliphatic amines. The hydrazone DGs can be conveniently installed and removed, and promote β-acetoxylation and tosyloxylation via a five-membered exo-palladacycle. PG=protecting group, Ts=4-toluenesulfonyl.