Transient Directing Group-Assisted C─H Bond Functionalization of Aliphatic Amines: Strategies for Efficiency and Site-Selectivity

The synthesis of amine skeletons and catalytic bond formation in aliphatic amines are important synthetic methodologies. Although various metal-catalyzed organic transformations have been successfully used to functionalize and construct amine molecules, there are still many hurdles toward practical application. Moreover, site-selectivity is generally achieved using a traditional directing group (DG) strategy, which requires at least two additional steps for the installation and removal of the DGs. Recently, a transient directing group (TDG) strategy, also known as traceless DG and temporary DG, has been widely studied for a range of selective transition metal-catalyzed C─H bond functionalization. In this account, we have focused on the recent developments of the TDG strategy toward the site-selective C─H bond functionalization of aliphatic amines. The design of the TDGs used for the target reaction and their critical roles in the reaction mechanism will be covered along with their selectivity and synthetic utility.