Suzuki-Miyaura (SM) cross-coupling is a powerful technique for constructing C-C bonds and is widely used in pharmaceutical, agrichemical, and natural product syntheses. Although Pd has been used as major catalysts for SM reactions, Cu has emerged as an alternative to Pd because Cu is inexpensive, less toxic, and readily available. A survey of the literature shows that most Cu-catalyzed SM reactions were carried with organic ligand-stabilized Cu catalysts, and little is known about catalytically active species in ligand-free reactions. We report findings of ligand-free Cu-catalyzed-SM reactions using CuI as a precatalyst and benzene iodide and phenylboronic acid as coupling agents in the presence of potassium hydroxide and polyethylene glycol 300. Catalytically active Cu species are in the solution rather than on the surface of the Cu precipitate. The soluble Cu species are stable for at least seven weeks as shown by the product yield. The active Cu species are not from the leaching of the Cu precipitate as experiments with the Cu solid form yielded no product. Unlike Pd-catalyzed SM reactions, the Cu catalyzed coupling may not involve oxidative addition.

Ligand-free Suzuki-Miyaura cross-coupling reactions catalyzed by water-soluble and stabilized Cu species

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.