Ruthenium-catalyzed direct arylations with aryl chlorides

Aryl chlorides are readily available at lower cost than the corresponding bromides and iodides, but are much more challenging as substrates in metal-catalyzed cross-couplings. Using arenes as nucleophilic partners by means of C-H activation instead of arylorganometallics also carries significant cost and environmental advantages. Finally, Ru catalysts, characterized by lower metal cost, excellent chemoselectivity, and high activity in C-H functionalization even in "green solvents" such as water, compound the economic and environmental benefits of chelation-assisted direct arylation. The current state-of-the-art of the Ru-catalyzed direct aryl-aryl coupling with chloroarenes will be reviewed.