Palladium-Catalyzed Defluorinative Coupling of Difluoroalkenes and Aryl Boronic Acids for Ketone Synthesis

The transition-metal-catalyzed carbonylation reaction is a useful approach for ketone synthesis. However, it is often problematic to use exogenous carbonyl reagents, such as gaseous carbon monoxide. In this manuscript, we report a novel palladium-catalyzed coupling reaction of gem-difluoroalkenes and aryl boronic acids that yields bioactive indane-type ketones with an all-carbon alpha-quaternary center. Characterization and stoichiometric reactions of the key intermediates RCF2PdII support a water-induced defluorination and cross-coupling cascade mechanism. The vinyl difluoromethylene motif serves as an in situ carbonyl precursor which is unprecedented in transition-metal-catalyzed coupling reactions. It is expected to raise broad research interest from the perspectives of ketone synthesis, fluoroalkene functionalization, and rational design of new synthetic protocols based on the unique reactivity of difluoroalkyl palladium(II) species.

Automated summary

In this manuscript, a novel palladium-catalyzed coupling reaction between gem-difluoroalkenes and aryl boronic acids is reported, which yields bioactive indane-type ketones with an all-carbon alpha-quaternary center. The mechanism involves a water-induced defluorination and cross-coupling cascade pathway, supported by characterization and stoichiometric reactions of the key intermediates RCF2PdII. The use of vinyl difluoromethylene motif as an in situ carbonyl precursor is unprecedented in transition-metal-catalyzed coupling reactions, and it is expected to spark broad interest in ketone synthesis, fluoroalkene functionalization, and design of new synthetic protocols based on the unique reactivity of difluoroalkyl palladium(II) species.