title: Mechanistic Investigations of Cu-Catalyzed Fluorination of Diaryliodonium Salts: Elaborating the CuI/CuIIIManifold in Copper Catalysis.
abstract: A combination of experimental and density functional theory (DFT) investigations suggests that the Cu-catalyzed fluorination of unsymmetrical diaryliodonium salts with general structure [Mes(Ar)I]+inN,N'-dimethylformamide proceeds through a CuI/CuIIIcatalytic cycle. A low concentration of fluoride relative to combined iodonium reagent plus copper ensures that [Mes(Ar)I]+is available as the reactive species for oxidative "Ar+" transfer to a CuIcenter containing one or two fluoride ligands. A series of different possible CuIactive catalysts (containing fluoride, triflate, and DMF ligands) have been evaluated computationally, and all show low-energy pathways to fluorinated products. The oxidation of these CuIspecies by [Mes(Ar)I]+to formcis-Ar(F)CuIIIintermediates is proposed to be rate-limiting in all cases. Ar-F bond-forming reductive elimination from CuIIIis computed to be very facile in all of the systems examined. The conclusions of the DFT experiments are supported by several experimental studies, including tests showing that CuIis formed rapidly under the reaction conditions and that the fluoride concentration strongly impacts the reaction yields/selectivities.
authors.affiliation: Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
authors.forename: Naoko
authors.initials: N
authors.lastname: Ichiishi
authors.affiliation: School of Chemistry, University of Tasmania , Private Bag 75, Hobart, Tasmania 7001, Australia.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Canty
authors.affiliation: School of Chemistry, University of Tasmania , Private Bag 75, Hobart, Tasmania 7001, Australia.
authors.forename: Brian F
authors.initials: BF
authors.lastname: Yates
authors.affiliation: Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
authors.forename: Melanie S
authors.initials: MS
authors.lastname: Sanford