(NHC)Cu-Catalyzed Mild C–H Amidation of (Hetero)arenes with Deprotectable Carbamates: Scope and Mechanistic Studies

Primary arylamines are an important
unit broadly found in synthetic,
biological, and materials science. Herein we describe the development
of a (NHC)Cu system that mediates a direct C–H amidation of
(hetero)­arenes by using N-chlorocarbamates or their
sodio derivatives as the practical amino sources. A facile stoichiometric
reaction of reactive copper-aryl intermediates with the amidating
reagent led us to isolate key copper arylcarbamate species with the
formation of a C–N bond. The use of tBuONa base made this transformation catalytic under mild conditions.
The present (NHC)­Cu-catalyzed C–H amidation works efficiently
and selectively on a large scale over a range of arenes including
polyfluorobenzenes, azoles, and quinoline N-oxides.
Deprotection of the newly installed carbamate groups such as Boc and
Cbz was readily performed to afford the corresponding primary arylamines.