Mechanistic Study of Copper-Catalyzed Decarboxylative C–N Cross-Coupling with Hypervalent Iodine Oxidant

Copper-catalyzed directed decarboxylative
C–N cross-coupling, which is promoted by a hypervalent iodine
oxidant, provides a new strategy for the site-selective formation
of aliphatic C–N bonds. Despite the great synthetic potential,
the mechanism of this reaction and especially the origin of the radical
species still remain controversial. To resolve this problem, herein
density functional theory (DFT) calculations have been employed to
elucidate the mechanistic details of this reaction. As a result, a
comprehensive reaction pathway involving IIII–O
bond heterolysis, single electron transfer (SET), hydrogen atom transfer
(HAT), decarboxylation, proton transfer, and reductive elimination
is reported. Meanwhile, analyzing the necessity of the directing groups
in realizing the site selectivity, we found that the chelation of
the directing group to the Cu­(III) center can remarkably facilitate
the proton transfer process.