An Unprecedented Ruthenium-Catalyzed Reductive Amination of Aldehydes with Tertiary Amines

The reductive amination of ketones and aldehydes with amines has been used as a tool for N-alkylation of amines. The process generally proceeds in two tandem steps, condensation between carbonyl compounds and amines to form an imine and reduction of the imine by a reducing agent.1,2 In sharp contrast to reductive amination of ketones and aldehydes with primary and secondary amines, little has known for that with teriary amines. During the course of our ongoing studies on homogeneous ruthenium catalysis,3-5 we recently developed an alkyl group transfer from alkylamines to N-atom of anilines3 as well as α-carbon atom of ketones4 by an activation of C-N bond of alkylamines. Prompted by these findings and intrigued by diverse reactivities of ruthenium catalysis, we have directed our attention to the reductive amination of aldehydes with tertiary amines, th