A novel protocol has been developed for the direct synthesis of protected secondary N-alkylamines through the reductive amination of aldehydes with N-protected primary N-alkylamines by using Me2SiHCl as the reducing agent. We examined the substrate generality and limitations of this method across a broad range of aldehydes, N-protecting groups, and N-alkyl substituents, and the protocol reliably furnished the corresponding protected secondary amines in moderate to excellent yields. In addition, the synthetic utility of this protocol was demonstrated through gram-scale preparation and downstream derivatization of the resulting amine products.
Ryu et al. (Fri,) studied this question.