Triflate-Selective Suzuki Cross-Coupling of Chloro- and Bromoaryl Triflates Under Ligand-Free Conditions

In the absence of strong ancillary ligands such as phosphines or N-heterocyclic carbenes, palladium salts are selective for C-OTf cleavage in the room-temperature Suzuki couplings of chloroaryl triflates in acetonitrile. Similar ligand-free conditions in DMSO also promote triflate-selective Suzuki coupling of bromoaryl triflates. This triflate selectivity complements the typical preference for reaction of bromides in prior reports of Suzuki couplings using phosphine ligands. DFT calculations and additional experimental evidence are consistent with triflate-selective oxidative addition taking place at homogeneous, possibly mononuclear, anionic palladium supported by a solvent molecule.

Automated summary

In the absence of strong ancillary ligands, palladium salts selectively cleave C-OTf in the room-temperature Suzuki couplings of chloroaryl triflates in acetonitrile. Ligand-free conditions in DMSO also promote triflate-selective Suzuki coupling of bromoaryl triflates. DFT calculations and experimental evidence suggest the triflate-selective oxidative addition takes place at homogeneous, possibly mononuclear, anionic palladium supported by a solvent molecule.