title: Nickel-mediated hydrogenolysis of C-O bonds of aryl ethers: what is the source of the hydrogen?
abstract: Mechanistic studies of the hydrogenolysis of aryl ethers by nickel were undertaken with (diphosphine)aryl methyl ethers. A Ni(0) complex containing Ni-arene interactions adjacent to the aryl-O bond was isolated. Heating led to aryl-O bond activation and generation of a nickel aryl methoxide complex. Formal β-H elimination from this species produced a nickel aryl hydride which can undergo reductive elimination in the presence of formaldehyde to generate a carbon monoxide adduct of Ni(0). The reported complexes map out a plausible mechanism of aryl ether hydrogenolysis catalyzed by nickel. Investigations of a previously reported catalytic system using isotopically labeled substrates are consistent with the mechanism proposed in the stoichiometric system, involving β-H elimination from a nickel alkoxide rather than cleavage of the Ni-O bond by H(2).
authors.affiliation: Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Kelley
authors.forename: Sibo
authors.initials: S
authors.lastname: Lin
authors.forename: Guy
authors.initials: G
authors.lastname: Edouard
authors.forename: Michael W
authors.initials: MW
authors.lastname: Day
authors.forename: Theodor
authors.initials: T
authors.lastname: Agapie
mesh_terms: D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D004987:Ethers / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010720:Phosphines / Q000737:chemistry*
chemical_list: D004987:Ethers; D010720:Phosphines; D002244:Carbon; D009532:Nickel; D006859:Hydrogen; D010100:Oxygen