Double Time For Cross-Coupling

Abstract

In a case of teaching an old dog a new trick, Boston College researchers have discovered how to merge two important chemical transformations involving widely used organoboron reagents into one. Liang Zhang, James P. Morken, and coworkers combined key steps of the Suzuki-Miyaura cross-coupling catalytic cycle with a stoichiometric metallate rearrangement process to generate a multicomponent catalytic reaction that delivers chiral products. This new concept, which they call conjunctive cross-coupling, could have major implications in the broad field of cross-coupling reactions (Science 2016, DOI: 10.1126/science.aad6080). Suzuki-Miyaura cross-coupling typically proceeds by insertion of a palladium catalyst into the carbon-halogen bond of an aryl halide electrophile (oxidative addition). This process is followed by a ligand passing from an organoboron reagent to palladium (transmetallation) and concluded by the catalyst coupling the aryl group and ligand together via formation of a new C–C bond and shedding the product molecule (reductive elimination). In contrast, noncatalytic