title: Pd-catalyzed aerobic oxidative coupling of arenes: evidence for transmetalation between two Pd(II)-aryl intermediates.
abstract: Pd-catalyzed aerobic oxidative coupling of arenes provides efficient access to biaryl compounds. The biaryl product forms via C-H activation of two arenes to afford a Pd(II)ArAr' intermediate, which then undergoes C-C reductive elimination. The key Pd(II)ArAr' intermediate could form via a "monometallic" pathway involving sequential C-H activation at a single Pd(II) center, or via a "bimetallic" pathway involving parallel C-H activation at separate Pd(II) centers, followed by a transmetalation step between two Pd(II)-aryl intermediates. Here, we investigate the oxidative coupling of o-xylene catalyzed by a PdX2/2-fluoropyridine catalyst (X = trifluoroacetate, acetate). Kinetic studies, H/D exchange experiments, and kinetic isotope effects provide clear support for a bimetallic/transmetalation mechanism.
authors: Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States.
authors: Dian
authors: D
authors: Wang
authors: Yusuke
authors: Y
authors: Izawa
authors: Shannon S
authors: SS
authors: Stahl
mesh_terms: D002384:Catalysis; D003903:Deuterium / Q000737:chemistry; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D007202:Indicators and Reagents; D007700:Kinetics; D010100:Oxygen / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D014269:Trifluoroacetic Acid / Q000737:chemistry
chemical_list: D006841:Hydrocarbons, Aromatic; D007202:Indicators and Reagents; D010165:Palladium; D003903:Deuterium; D014269:Trifluoroacetic Acid; D010100:Oxygen