Mechanistic Insight into Cu-Catalyzed C–N Coupling of Hindered Aryl Iodides and Anilines Using a Pyrrol-ol Ligand Enables Development of Mild and Homogeneous Reaction Conditions

Mechanistic studies of the Cu-catalyzed C–N coupling
of
sterically hindered aryl iodides with sterically hindered anilines
are carried out to shed light on how a recently reported pyrrol-ol
ligand affects the reaction. Kinetic, spectroscopic, and computational
tools help to probe the nature of the active catalyst species and
the rate-determining step in the cycle. In contrast to most known
Cu systems, oxidative addition is found to precede coordination of
the amine. These studies help to design an efficient process under
mild conditions using a fully homogeneous system as well as protocols
that enable high yields by temperature scanning and controlled addition
of the base. The insights obtained for the XX-type ligand may lead
to a general approach for challenging substrate classes in Cu-catalyzed
coupling reactions.