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 I^III–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.