Highly active, air-stable palladium catalysts for Kumada–Tamao–Corriu cross-coupling reaction of inactivated aryl chlorides with aryl Grignard reagents

Palladium(II) chlorides possessing phosphinous acid ligands have proved to be remarkably active and efficient catalysts for cross-coupling reactions of inactivated aryl chlorides with aryl Grignard reagents (Kumada–Tamao–Corriu reaction) at room temperature to yield the corresponding biaryls with isolated product yields ranging from 51 to 99%. 1H- and 31P-NMR studies argue that these phosphinous acid ligands in the complexes can be deprotonated to yield electron-rich anionic species, which is anticipated not only to accelerate the rate-determining oxidative addition of aryl chlorides in the catalytic cycle, but also to stabilize the transition-metal complexes.