Carbon-carbon bond formation by transition
metal-catalyzed C–H activation has become an important strategy to fabricate
new bonds in a rapid fashion. Despite the pharmacological importance of <i>ortho</i>-arylbenzylamines, however,
effective <i>ortho</i>-C–C bond formation
from C–H bond activation of free primary and secondary benzylamines using Pd<sup>II</sup>
remains an outstanding challenge. Presented herein is a new strategy for
constructing <i>ortho</i>-arylated primary
and secondary benzylamines mediated by carbon dioxide (CO<sub>2</sub>). The use
of CO<sub>2</sub> is critical to allowing this transformation to proceed under milder
conditions than previously reported, and that are necessary to furnish free
amine products that can be directly used or elaborated without the need for
deprotection. In cases where diarylation is possible, a chelate effect is
demonstrated to facilitate selective monoarylation.
