Dynamic Covalent Chemistry of Aldehyde Enamines: Bi - and Sc -Catalysis of Amine-Enamine Exchange.

The dynamic exchange of enamines from secondary amines and enolizable aldehydes has been demonstrated in organic solvents. The enamine exchange with amines was efficiently catalyzed by Bi(OTf) and Sc(OTf) (2 mol %) and the equilibria (60 mm) could be attained within hours at room temperature. The formed dynamic covalent systems displayed high stabilities in basic environment with <2 % by-product formation within one week after complete equilibration. This study expands the scope of dynamic C-N bonds from imine chemistry to enamines, enabling further dynamic methodologies in exploration of this important class of structures in systems chemistry.