Highly Active Monoligated Arylpalladacyles for Cross-Coupling Reactions

A series of new monoligated arylpalladacyclic complexes with amide, urea, and carbamate frameworks have been developed and were found to be highly active for Suzuki–Miyaura cross-couplings. These palladacycle precatalysts are derived from simple, inexpensive starting materials and are air- and moisture-stable. The most active congeners among those tested are the urea-based palladacycles, which in conjunction with a tBu₃P ligand induce high conversions for a range of aryl halide and boronate coupling partners. Notably, aryl chlorides are viable coupling partners even under relatively mild conditions at short reaction times (e.g., 1 h at 60 °C). One of the best catalysts described here exhibits improved turnover frequency for a particularly difficult coupling reaction involving an aryl chloride and a sterically congested boronic ester.