Tracking electron motion driving the Suzuki-Miyaura cross-coupling reaction.

The electron motion driving the transmetalation process of the Suzuki-Miyaura cross-coupling reaction is elucidated based on the reactive orbital energy theory (ROET). We investigated the transmetalation process in the palladium-catalyzed synthesis of biphenyl from phenylboronic acid and chlorobenzene, focusing on two proposed pathways: the boronate mechanism and the oxo-palladium mechanism. Intrinsic reaction coordinate (IRC) calculations were performed for both mechanisms, followed by ROET analysis. The results indicate that the boronate mechanism proceeds with a lower activation barrier and a simpler reaction pathway, while also exhibiting electron motion patterns consistent with experimental observations. Furthermore, the ROET analysis clarified the electronic roles of the organoboronic acid and the ancillary ligand in a manner consistent with experimental findings. These results demonstrate that ROET provides a novel perspective on metal-catalyzed reactions by offering insights into the underlying electron motions.