title: Detection of Palladium(I) in Aerobic Oxidation Catalysis.
abstract: Palladium(II)-catalyzed oxidation reactions exhibit broad utility in organic synthesis; however, they often feature high catalyst loading and low turnover numbers relative to non-oxidative cross-coupling reactions. Insights into the fate of the Pd catalyst during turnover could help to address this limitation. Herein, we report the identification and characterization of a dimeric PdIspecies in two prototypical Pd-catalyzed aerobic oxidation reactions: allylic C-H acetoxylation of terminal alkenes and intramolecular aza-Wacker cyclization. Both reactions employ 4,5-diazafluoren-9-one (DAF) as an ancillary ligand. The dimeric PdIcomplex, [PdI(μ-DAF)(OAc)]2, which features two bridging DAF ligands and two terminal acetate ligands, has been characterized by several spectroscopic methods, as well as single-crystal X-ray crystallography. The origin of this PdIcomplex and its implications for catalytic reactivity are discussed.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Jaworski
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: McCann
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Guzei
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
authors.forename: Shannon S
authors.identifier: 0000-0002-9000-7665
authors.initials: SS
authors.lastname: Stahl
mesh_terms: D000475:Alkenes / Q000737:chemistry; D002384:Catalysis; D018360:Crystallography, X-Ray; D003500:Cyclization; D019281:Dimerization; D005449:Fluorenes / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: C531330:4,5-diazafluoren-9-one; D000475:Alkenes; D005449:Fluorenes; D011725:Pyridines; D010165:Palladium
keywords: Wacker cyclization; aerobic; homogeneous catalysis; oxidation; palladium